WO2019124519A1

WO2019124519A1 - Method for producing ethylene

Info

Publication number: WO2019124519A1
Application number: PCT/JP2018/047090
Authority: WO
Inventors: 雅寛原; 青島　敬之
Original assignee: 三菱ケミカル株式会社
Priority date: 2017-12-20
Filing date: 2018-12-20
Publication date: 2019-06-27
Also published as: JPWO2019124519A1; JP7251481B2

Abstract

The invention addresses the problem of providing a method for producing ethylene that uses propylene as starting material and that, during ethylene production, stably produces ethylene on a long-term basis while minimizing reductions in the ethylene yield. The method for producing ethylene is characterized by comprising: a step (I) for feeding propylene to a reactor and allowing the propylene to be in contact with a catalyst so as to produce ethylene; and a step (II) for regenerating the catalyst that has been used in the step (I).

Description

Method of producing ethylene

The present invention relates to a process for the production of ethylene. Specifically, in the method of mainly producing propylene by contacting propylene with a catalyst in a reactor, the step (I) of supplying propylene to the reactor and contacting with the catalyst to produce ethylene, and regeneration of the catalyst And a process (II). The present invention also relates to a method for producing ethylene by using a catalyst in contact with a gas containing hydrogen in a method for producing ethylene by contacting propylene with a catalyst in a reactor.

Heretofore, a steam cracking method using naphtha as a raw material is known as a main production method of ethylene. However, in the steam cracking method of naphtha, a large amount of olefins other than ethylene such as propylene and butene are produced, and it is difficult to largely change the production ratio of each olefin. Therefore, technologies for converting olefins other than ethylene into ethylene are being studied. In particular, a method of producing ethylene from propylene with a large amount of by-product is desired.

For example, in patent document 1, the method of making various olefins, such as ethylene, propylene, and a butene, contact with silicoaluminophosphate, and converting into another olefin is examined.
For example, Non-Patent Document 1 discloses a method for producing ethylene from propylene as a raw material using a phosphorus-modified MFI-type zeolite catalyst.

Japanese Patent Application Laid-Open No. 60-166639

However, although the technology of Patent Document 1 is capable of producing ethylene with a yield of up to 8% by reacting silicoaluminophosphate SAPO-34 catalyst with propylene, the activity of the catalyst is largely reduced, and the reaction takes a long time It is not possible to produce ethylene stably over time, and it is not a production method that can withstand practical use.
Further, the technique of Non-Patent Document 1 states that the ethylene selectivity can be increased to about 70 C-mol% at a propylene conversion of 36% by modifying the MFI-type zeolite catalyst with phosphoric acid, but the propylene is very low. It was found that the catalyst activity decreased over time also at the concentration (6.5 mol%, nitrogen dilution).

An object of the present invention is to provide a method for stably producing ethylene for a long time while minimizing the decrease in ethylene yield when producing ethylene from propylene as a raw material.

As a result of intensive studies to solve the above problems, the present inventors supply propylene to the reactor and contact propylene with the catalyst to supply propylene to the reactor and contact the catalyst. It has been found that ethylene can be stably produced over a long time by having the step (I) of producing ethylene and the step (II) of regenerating the catalyst obtained through the step (I). It came to achieve.

That is, the first subject matter of the present invention is as follows.
(A1) A process comprising: supplying propylene to a reactor and bringing it into contact with a catalyst to produce ethylene (a) and a process (II): regenerating the catalyst whose propylene conversion rate has been reduced through the process (I) Process for producing ethylene characterized in that
(A2) The ethylene according to (A1), wherein in the step (II), the catalyst having a reduced conversion of propylene is regenerated by a gas containing at least one selected from oxygen, hydrogen and steam. Production method.
(A3) The method for producing ethylene according to (A1) or (A2), wherein in the step (II), the catalyst having a reduced conversion of propylene is regenerated by a gas containing hydrogen.
(A4) The process for producing ethylene according to any one of (A1) to (A3), wherein the temperature of the step (II) is 300 ° C. or more and 800 ° C. or less.
(A5) The amount of coke accumulated in the catalyst having passed through the step (II) is 0.1% by mass or more and 30% by mass or less based on the mass of the catalyst according to any one of (A1) to (A4) Method of producing ethylene.
(A6) The method for producing ethylene according to any one of (A1) to (A5), wherein the catalyst is a zeolite.
(A7) The manufacturing method of ethylene as described in (A6) whose pore diameter of the said zeolite is less than 0.5 nm.
(A8) The method for producing ethylene according to (A6) or (A7), wherein the zeolite has an oxygen 8-membered ring structure.
(A9) The method for producing ethylene according to any one of (A6) to (A8), wherein the zeolite is an aluminosilicate containing at least aluminum.
(A10) The ethylene according to any one of (A1) to (A9), wherein the step (II) is performed such that the conversion of propylene in the step (I) is 5% to 80%. Production method.

The second aspect of the present invention is as follows.
(B1) A method for producing ethylene by contacting propylene and a catalyst in a reactor to produce ethylene, wherein the catalyst is a catalyst in contact with a gas containing hydrogen.
(B2) The method for producing ethylene according to (B1), wherein the catalyst is a catalyst in which a catalyst containing coke produced by contact with propylene is contacted with a gas containing hydrogen.
(B3) The manufacturing method of ethylene as described in (B1) or (B2) which is a catalyst which contacted the said catalyst and gas containing hydrogen at the temperature of 300 degreeC or more.
(B4) The method for producing ethylene according to any one of (B1) to (B3), wherein the catalyst is a catalyst which is in contact with a gas containing hydrogen of 0.001 MPa or more in absolute hydrogen partial pressure.
(B5) The method for producing ethylene according to any one of (B1) to (B4), wherein the catalyst contains a zeolite.
(B6) The method for producing ethylene according to (B5), wherein the zeolite has pores with a pore diameter of less than 0.5 nm.
(B7) The method for producing ethylene according to (B5) or (B6), wherein the zeolite has an oxygen 8-membered ring structure.
(B8) The method for producing ethylene according to any one of (B5) to (B7), wherein the zeolite contains an aluminosilicate containing at least aluminum.
(B9) The process for producing ethylene according to any one of (B1) to (B8), wherein propylene is brought into contact with the catalyst under the condition that the conversion of propylene is 5% to 80%.

The third aspect of the present invention is as follows.
(C1) A method for producing ethylene by bringing a hydrocarbon and a catalyst into contact in a reactor having a raw material inlet and a product gas outlet,
The hydrocarbon contains at least propylene and a hydrocarbon having 4 or more carbon atoms,
The manufacturing method of ethylene whose mass ratio of C4 or more hydrocarbon with respect to propylene contained in the said hydrocarbon is 0.01 or more and 10 or less.
(C2) The method for producing ethylene according to (C1), wherein the hydrocarbon having 4 or more carbon atoms contains butene.
(C3) The method for producing ethylene according to (C2), wherein the proportion of butenes contained in the hydrocarbon having 4 or more carbon atoms is 10 mol% or more with respect to the total amount of hydrocarbons having 4 or more carbon atoms.
(C4) The method for producing ethylene according to (C2) or (C3), wherein the butene contains 10 mol% or more of linear butene.
(C5) The process for producing ethylene according to any one of (C1) to (C4), wherein the reaction temperature in the reactor is 300 ° C. or more and 800 ° C. or less.
(C6) Any one of (C1) to (C5) in which at least 10% of hydrocarbons having 4 or more carbon atoms contained in the product gas discharged from the product gas outlet of the reactor is circulated to the reactor The manufacturing method of ethylene as described in.
(C7) The method for producing ethylene according to any one of (C1) to (C6), wherein the catalyst contains a zeolite.
(C8) The method for producing ethylene according to (C7), wherein the zeolite has pores with a pore diameter of 0.8 nm or less.
(C9) The method for producing ethylene according to (C7) or (C8), wherein the zeolite has an oxygen 8-membered ring structure.
(C10) The method for producing ethylene according to any one of (C7) to (C9), wherein the zeolite contains an aluminosilicate containing at least aluminum.
_{_{(C11) SiO 2 / Al 2}} O 3 molar ratio of the zeolite is 5 to 500, the production method of ethylene according to (C10).
(C12) The method for producing ethylene according to any one of (C7) to (C11), wherein the structure of the zeolite is CHA according to a code defined by International Zeolite Association (IZA).

The fourth aspect of the present invention is as follows.
(D1) A method for producing ethylene by bringing a hydrocarbon into contact with a catalyst containing zeolite as an active component in a reactor having a raw material inlet and a product gas outlet,
And the hydrocarbon contains at least a hydrocarbon having 4 or more carbon atoms, and
The method for producing ethylene, wherein the zeolite has at least an oxygen 8-membered ring structure, and a ratio of an outer surface acid amount to a total acid amount is 3% or less.
(D2) The manufacturing method of ethylene as described in (D1) in which the said zeolite contains the aluminosilicate containing at least aluminum.
_{_{(D3) SiO 2 / Al 2}} O 3 molar ratio of the zeolite, the production method of the ethylene according to at 5 to 500 (D1) or (D2).
(D4) The method for producing ethylene according to any one of (D1) to (D3), wherein the zeolite is silylated.
(D5) The method for producing ethylene according to any one of (D1) to (D4), wherein the structure of the zeolite is CHA according to a code defined by International Zeolite Association (IZA).
(D6) The method for producing ethylene according to any one of (D1) to (D5), wherein the hydrocarbon having 4 or more carbon atoms contains at least butene.
(D7) The manufacturing method of ethylene as described in (D6) whose ratio of the linear butene contained in the said butene is 10 mol% or more.
(D8) The process for producing ethylene according to any one of (D1) to (D7), wherein the reaction temperature in the reactor is 300 ° C. or more and 800 ° C. or less.
(D9) Any one of (D1) to (D8) in which at least 10% of the hydrocarbon having 3 or more carbon atoms contained in the product gas discharged from the product gas outlet of the reactor is circulated to the reactor The manufacturing method of ethylene as described in.

According to the first aspect of the present invention, ethylene is stably produced by minimizing the fluctuation range of ethylene yield in a method of feeding propylene to a reactor and contacting with a catalyst to produce ethylene. be able to.
Further, according to the second aspect of the present invention, in the method for producing ethylene by contacting propylene with a catalyst, a high yield can be obtained by reacting propylene with a catalyst brought into contact with a gas containing hydrogen. Can stably produce ethylene.
Further, according to the third aspect of the present invention, propylene is supplied to a reactor and contacted with a catalyst to produce ethylene, by supplying a predetermined amount of hydrocarbon having 4 or more carbon atoms together with propylene, It is possible to produce ethylene stably with high yield by minimizing the fluctuation range of the ethylene / propylene ratio in the product.
Further, according to the fourth aspect of the present invention, when ethylene is produced from a hydrocarbon having 4 or more carbon atoms as a raw material, high ethylene yield can be obtained without increasing the amount of by-products of branched olefins unsuitable for recycling as the raw material. A method can be provided to produce ethylene at a rate.

It is a graph which shows the ethylene yield change with respect to the cumulative time obtained by Example A-1 and Comparative Example A-1. It is a graph which shows the change of the propylene conversion rate with respect to reaction time in Example A-2, and the relationship of a propylene conversion rate-ethylene selectivity. Fig. 16 is a graph showing the change of the yield of ethylene with respect to the cumulative reaction time in Example A-3. FIG. 18 is a graph showing changes in propylene conversion and ethylene selectivity with respect to reaction time in Example A-4. FIG. It is a graph which shows the result of the ethylene yield of Example B-1, comparative example B-1, and B-2.

Hereinafter, typical embodiments for carrying out the present invention will be specifically described. However, the present invention is not limited to the following embodiments as long as the gist thereof is not exceeded, and various modifications may be made. Can.

The first embodiment of the present invention is a method of supplying propylene to a reactor and contacting with a catalyst to produce ethylene, supplying propylene to the reactor and contacting with a catalyst to produce ethylene (I A process for producing ethylene comprising at least two steps of (2) and (II) of regenerating a catalyst having a reduced conversion of propylene through the step (I).

<A1. Catalyst>
The catalyst used in the first embodiment of the present invention will be described. The catalyst used in the reaction according to the present embodiment is not particularly limited as long as it is a solid having a Br ステッド nsted acid point, and a conventionally known catalyst is used. For example, clay minerals such as kaolin, acidic ion And solid acid catalysts such as exchange resins, zeolites and mesoporous silica-alumina. In the first embodiment, by introducing a step of regenerating a catalyst having a reduced propylene conversion rate, the amount of coke components accumulated by the conversion of propylene is reduced to produce ethylene in a stable yield. it can.

Among these solid acid catalysts, those having a molecular sieving effect are preferable, and zeolite is more preferable. In addition, although the said catalyst can use a well-known catalyst, below, the zeolite which is a preferable form as a catalyst is demonstrated in detail.

Zeolite is a crystalline material in which TO ₄ units (T is a central atom) having a tetrahedral structure share an O atom and are three-dimensionally connected to form an open regular micropore. Point to. Specifically, silicates, phosphates, germanium salts, arsenates, etc. described in the data collection of the International Zeolite Association (International Zeolite Association; hereinafter sometimes referred to as "IZA") included.

Here, the silicate includes, for example, aluminosilicate, gallosilicate, ferrisilicate, titanosilicate, borosilicate and the like.
Phosphate includes, for example, aluminophosphate, gallophosphate, beryllophosphate and the like.
Germanium salts include, for example, aluminogermanium salts and the like, and arsenates include, for example, aluminoarsenate and the like.
Furthermore, the aluminophosphates include, for example, silicoaluminophosphates in which T atoms are partially substituted with Si, and those containing divalent or trivalent cations such as Ga, Mg, Mn, Fe, Co, Zn, etc. .

The average pore size of the zeolite is not particularly limited, and is usually 0.80 nm or less, preferably 0.55 nm or less, more preferably 0.50 nm or less, still more preferably 0.45 nm or less, particularly preferably 0.40 nm or less. Usually, it is 0.25 nm or more, preferably 0.30 nm or more, more preferably 0.33 nm or more, and still more preferably 0.35 nm or more.
Here, the average pore size indicates the crystallographic free diameter of the channels defined by IZA. The average pore diameter of 0.55 nm or less means that the shape of the pore (channel) is 0.55 nm or less when the shape of the pore is a perfect circle, but when the shape of the pore is an ellipse, It means that a minor axis is 0.55 nm or less.

By using a zeolite, ethylene can be produced in high yield from propylene as a raw material. That is, if the average pore diameter is in the above range, the diffusion of propylene into the zeolite crystal can be promoted, and ethylene can be generated more selectively. Furthermore, it is considered to be more preferable because the quality of coke components can be reformed while the amount of coke components accumulated in the catalyst can be appropriately reduced by contact with a gas containing hydrogen.

From the above viewpoint, in the present embodiment, the zeolite is preferably an oxygen 8-membered ring structure zeolite.

The oxygen 8-membered ring structure zeolite is a framework type code defined by IZA, for example, preferably AEI, AFX, CHA, ERI, KFI, LEV, SAS, SAV, SZR, PAU, RHO, LTA, etc. It can be mentioned.

The framework density (unit: T / nm ³ ) of the zeolite is not particularly limited, and is usually 20.0 or less, preferably 18.0 or less, more preferably 17.0 or less, further preferably 16.0 or less, Usually, it is 12.0 or more, preferably 14.0 or more, more preferably 14.5 or more.
Here, the framework density (unit: T / nm ³ ) means the number of T atoms (atoms other than oxygen among atoms constituting the skeleton of zeolite) present per unit volume (1 nm ³ ) of zeolite. This value is determined by the structure of the zeolite.

From these viewpoints, it is preferable that the oxygen 8-membered ring structure zeolite is a zeolite containing d6r in its framework defined by International Zeolite Association (IZA) as a composite building unit, and more preferably AEI, AFX, CHA, ERI, KFI, LEV, SAV, more preferably AEI, AFX, CHA, or ERI, particularly preferably AEI, CHA or ERI, particularly preferably CHA or ERI, most preferably CHA .

Specifically as an oxygen 8-membered ring structure zeolite, a silicate and a phosphate are mentioned. As described above, examples of the silicate include aluminosilicates, gallosilicates, ferrisilicates, titanosilicates, borosilicates and the like, and as phosphates, aluminophosphates composed of aluminum and phosphorus, silicon And silicoaluminophosphates composed of aluminum and phosphorus. Among these, aluminosilicates and silicoaluminophosphates are preferable, and aluminosilicates are more preferable.

Normally, the ion exchange site of the zeolite is a proton exchange type of proton (H), but a part thereof is an alkali metal such as Li, Na, K, Rb, Cs, etc., alkali earth such as Ca, Sr, Ba etc. It may be replaced by a transition metal such as Cr, Cu, Ni, Fe, Mo, W, Pt, Re and the like. In this case, the zeolite may be subjected to the ion exchange treatment described later.

In addition to these ion exchange sites, alkali metals such as Na and K; alkaline earth metals such as Ca and Sr; metals supported by transition metals such as Cr, Cu, Ni, Fe, Mo, W, Pt, Re, etc. It is also good. Here, metal loading can be carried out usually by an impregnation method such as an equilibrium adsorption method, evaporation to dryness, or a pore filling method.

When the zeolite is a silicate, SiO ₂ / M ₂ O ₃ (wherein the denominator of the above molar ratio represents the total amount of Al ₂ O ₃ , Ga ₂ O ₃ , B ₂ O ₃ and Fe ₂ O ₃ ) The ratio is usually 5 or more, preferably 8 or more, more preferably 10 or more, more preferably 15 or more, and usually less than 100, preferably 80 or less, more preferably 60 or less, more preferably 40 or less. is there. The above ratio is a value obtained on the assumption that all Si atoms in the zeolite are contained as SiO _{2 and} all the M contained in the zeolite is contained as M ₂ O ₃ . When the SiO ₂ / M ₂ O ₃ molar ratio is in the above range, the amount of acid derived from the strong acid point and the weak acid point can be sufficiently obtained, and high propylene conversion activity can be obtained. In addition, it is possible to prevent phenomena such as deactivation of the catalyst due to coke deposition, detachment of the T atom other than silicon from the skeleton, and a decrease in acid strength per acid point. The SiO ₂ / M ₂ O ₃ molar ratio of the zeolite of the present invention can usually be measured by ICP elemental analysis or fluorescent X-ray analysis. X-ray fluorescence analysis creates a calibration curve of the fluorescence X-ray intensity of the analysis element in the standard sample and the atomic concentration of the analysis element, and this calibration curve determines the silicon in the zeolite sample by X-ray fluorescence analysis (XRF) The content of atoms, aluminum, gallium and iron can be determined. In addition, since the fluorescent X-ray intensity of the boron element is relatively small, the content of the boron atom is preferably measured by ICP elemental analysis.

When zeolite is phosphate, (Al + P) / Si molar ratio of silicoaluminophosphate or (Al + P) / M of metalloaluminophosphate having divalent metal (where M represents a divalent metal) The molar ratio is usually 5 or more, preferably 10 or more, and usually 500 or less, preferably 100 or less. Specific examples of the divalent metal include Ga, Mg, Mn, Fe, Co and Zn. By setting it as the said lower limit or more, the fall of durability of a catalyst can be prevented, and a catalyst activity can prevent a fall by setting more than the said upper limit.

The total acid content (hereinafter referred to as the total acid content) of the zeolite used in the present embodiment is the amount of acid sites present in the crystal pores of the zeolite and the amount of acid sites outside the crystal of the zeolite (hereinafter exterior surfaces) It is the sum total of the amount of acid. The total acid amount is not particularly limited, but is usually 0.01 mmol / g or more, preferably 0.1 mmol / g or more, more preferably 0.3 mmol / g or more, and still more preferably 0.5 mmol / g or more It is. Also, it is usually 2.5 mmol / g or less, preferably 1.5 mmol / g or less, more preferably 1.2 mmol / g or less, and still more preferably 0.9 mmol / g or less. By setting the total acid amount in the above range, the conversion activity of propylene is secured, and the formation of coke inside the pores of the zeolite can be suppressed to promote the formation of ethylene. Here, the total amount of acid is calculated from the amount of desorption in ammonia temperature-programmed desorption (NH ₃ -TPD). Specifically, the zeolite is dried at 500 ° C. under vacuum for 30 minutes as pretreatment, and then the pretreated zeolite is brought into contact with excess ammonia at 100 ° C. to adsorb the ammonia on the zeolite. Excess ammonia is removed from the obtained zeolite by vacuum drying at 100 ° C. or by contacting with steam at 100 ° C. Subsequently, the zeolite adsorbed with ammonia is heated at a temperature rising rate of 10 ° C./min in a helium atmosphere, and the amount of ammonia desorbed at 100-600 ° C. is measured by mass spectrometry. The amount of ammonia desorbed per zeolite is the total amount of acid. However, the total amount of acid in the present invention is the total of the area of the waveform having the peak top at 240 ° C. or higher by separating the TPD profile by the Gaussian function. The “240 ° C.” is an index used only for determining the position of the peak top, and is not intended to determine the area of a portion of 240 ° C. or more. As long as the peak top has a waveform of 240 ° C. or more, the “area of the waveform” obtains the total area including portions other than 240 ° C. When there are a plurality of waveforms having a peak top at 240 ° C. or more, the sum of the areas is used. In addition, the amount of acids derived from weak acid points having a peak top below 240 ° C. is not included in the total amount of acids in the present embodiment. This is because it is not easy to distinguish between adsorption from weak acid points and physical adsorption in the TPD profile.

The amount of outer surface acid of the zeolite is not particularly limited, but generally 8% or less, preferably 5% or less, more preferably 3% or less, still more preferably 1% or less based on the total acid amount of the zeolite , Most preferably 0%. When the amount of outer surface acid is too large, the side reaction occurring at the outer surface acid point tends to lower the yield of ethylene. This is presumed to be due to the progress of the reaction to generate hydrocarbons other than the target substance at the outer surface acid point. Further, it is presumed that the ethylene generated in the pores of the zeolite further reacts at the outer surface acid point, which is one of the causes of the decrease in selectivity.
In addition, the value of the outer surface acid amount of the zeolite used by this embodiment can be measured by the method as described in WO 2010/128644. Specifically, the zeolite is dried at 500 ° C. under vacuum for 1 hour as a pretreatment, and then the pretreated zeolite is brought into contact with pyridine vapor at 150 ° C. to adsorb the pyridine onto the zeolite, and vacuum exhaust and helium at 150 ° C. The desorption amount of pyridine per weight of zeolite at 150 to 800 ° C. by a temperature rising desorption method at a temperature rising rate of 10 ° C./min of a zeolite adsorbed with pyridine obtained by removing excess pyridine from the zeolite by flow It is determined from
The outer surface acid amount and the like of the zeolite are not particularly limited, but can be adjusted by silylation treatment, steam treatment, heat treatment, acid treatment, ion exchange treatment and the like. Methods such as supporting treatment of metal elements can be mentioned. In addition, there is a method in which a binder and an outer surface acid point of the zeolite are bonded when forming the zeolite.

<Silylation treatment>
The method for silylation treatment of the zeolite is not particularly limited, and a known method can be appropriately used. Specifically, liquid phase silylation, gas phase silylation and the like can be performed.

In the zeolite, it is considered that the amount of outer surface acid is reduced by silylation treatment, usually, the acid points on the outer surface are coated and inactivated. When the amount of outer surface acid decreases, side reactions occurring on the outer surface of the zeolite are suppressed. Specifically, a reaction in which components other than the target product are generated by the lower olefin such as ethylene and butenes generated in the zeolite pore coming into contact with the acid point on the outer surface of the zeolite by the conversion reaction of propylene. It is considered to be effective. In addition, in the silylation of the outer surface acid point, since the silyl group is also bonded to the acid point constituting the pores possessed by the zeolite, the pore diameter of the outer surface opening is slightly reduced, and molecular diffusion to the outside of the crystal Is considered to have the effect of suppressing As a result, it can be considered that the formation of hydrocarbons having 5 or more carbon atoms, which are larger molecules, can be suppressed, and the selectivity of ethylene is improved.
Hereinafter, the silylation treatment will be specifically described taking liquid phase silylation as an example.

The silylating agent is not particularly limited, and usually, one capable of silylating the outer surface of the zeolite and incapable of silylating the pores of the zeolite is used. Specifically, silicones, chlorosilanes, alkoxysilanes, siloxanes, silazanes and the like can be used. Among these, chlorosilanes are usually used for gas phase silylation, and alkoxysilanes are usually used for liquid phase silylation, and more preferable silylating agents are high in reactivity and relatively easy to handle. , Alkoxysilanes.
As silicones, specifically, dimethyl silicone, diethyl silicone, phenyl methyl silicone, methyl hydrogen silicone, ethyl hydrogen silicone, phenyl hydrogen silicone, methyl ethyl silicone, phenyl ethyl silicone, diphenyl silicone, methyl trifluoropropyl silicone Ethyl trifluoropropyl silicone, tetrachlorophenylmethyl silicone, tetrachlorophenylethyl silicone, tetrachlorophenyl hydrogen silicone, tetrachlorophenyl silicone, methyl vinyl silicone, ethyl vinyl silicone and the like are used.

Specifically, tetrachlorosilane, trichlorosilane, trichloromethylsilane, dichlorodimethylsilane, chlorotrimethylsilane, trichloroethylsilane, dichlorodiethylsilane, chlorotriethylsilane and the like are used as chlorosilanes.
Specific examples of alkoxysilanes include quaternary alkoxysilanes such as tetramethoxysilane and tetraethoxysilane; trimethoxymethylsilane, trimethoxyethylsilane, triethoxymethylsilane, triethoxyethylsilane and the like; Alkoxysilane, dimethoxydimethylsilane, dimethoxydiethylsilane, diethoxydimethylsilane, diethoxydiethylsilane etc .; Secondary alkoxysilanes, methoxytrimethylsilane, methoxytriethylsilane, ethoxytrimethylsilane, ethoxytriethylsilane etc .; Primary alkoxysilanes Is used. It is preferably a secondary or higher alkoxysilane, more preferably a tertiary or higher alkoxysilane, and still more preferably a quaternary alkoxysilane.

Specific examples of siloxanes include hexamethyldisiloxane, hexaethyldisiloxane, pentamethyldisiloxane, tetramethyldisiloxane and the like, with hexamethyldisiloxane being preferred.
Specific examples of silazanes include hexamethyldisilazane, dipropyltetramethyldisilazane, diphenyltetramethyldisilazane, and tetraphenyldimethyldisilazane, with hexamethyldisilazane being preferred.

The amount of the silylating agent to the zeolite is not particularly limited, but is usually 0.001 mol or more, preferably 0.01 mol or more, more preferably 0.1 mol or more, per 1 mol of the zeolite. It is. Also, it is usually 5 mol or less, preferably 3 mol or less, more preferably 1 mol or less. By setting the amount of the silylating agent in the above range, it is preferable from the viewpoint that the silylation coating of the outer surface acid point proceeds efficiently and the catalyst activity decrease due to the excessive silylation coating can be suppressed. The amount of the silylating agent is represented by the number of moles of Si atoms contained in the silylating agent, and in the case of a silylating agent having a plurality of Si atoms in the molecule, the number of moles of the total of the Si atoms is Treat as the number of moles of the agent.

When liquid phase silylation is carried out, a solvent can be used, and the solvent is not particularly limited, but hydrocarbons such as hexane, heptane, octane, nonane, decane, cyclopentane, cyclohexane, benzene, toluene, xylene etc. And water can be used. When liquid phase silylation is performed with an aqueous solvent, an acidic aqueous solution to which an acid such as sulfuric acid or nitric acid is added can be used to accelerate the silylation reaction.

When liquid phase silylation is carried out, the concentration of the silylating agent in the solution for carrying out the liquid phase silylation reaction is not particularly limited, but usually 0.01 mass% or more, preferably 0.5 mass% The content is more preferably 1% by mass or more. Moreover, it is 80 mass% or less normally, Preferably it is 60 mass% or less, More preferably, it is 40 mass% or less. By setting the concentration of the silylating agent in the above range, it is preferable in that condensation of the silylating agents can be suppressed and the rate of silylation can be maintained.

The amount of the solvent for the zeolite in the liquid phase silylation is not particularly limited, but is usually 1 g or more, preferably 3 g or more, more preferably 5 g or more, per 1 g of the zeolite. Also, it is usually 100 g or less, preferably 80 g or less, more preferably 50 g or less. By setting the amount of the solvent in the above-mentioned range, it is preferable in that sufficient stirring efficiency of the slurry can be obtained and a certain productivity can be secured.

When liquid phase silylation is carried out, the zeolite to be subjected to the silylation treatment may be provided with a specific range of water content. The water contained in the zeolite may be adjusted to a specific range by artificially supplying water, even if it is originally contained in the zeolite. In general, the zeolite used in the present embodiment is one obtained by calcining one obtained by hydrothermal synthesis, and further, converting it into an ammonium type, if necessary, and then calcining it to use a proton type. Therefore, the water content of the zeolite before the silylation treatment is usually assumed to be very small, and may be subjected to the silylation treatment as it is, or water is supplied to the zeolite so as to have a specific water content, The water content may be adjusted and used (hereinafter, it may be referred to as humidity control treatment).

The water content is not particularly limited, but the weight of water contained in the zeolite is represented by mass% with respect to the weight of the dried zeolite, and is usually 30 mass% or less, preferably 25 mass% or less, Is 0% by mass in a completely dry state. By setting the water content to the above-mentioned range, the silylation coating of the outer surface acid point can proceed efficiently, and it is preferable in that the pore blockage due to excessive silylation can be prevented.

The humidity control method is not particularly limited as long as it can be adjusted to a predetermined water content. For example, a method of leaving the zeolite in the atmosphere having a suitable relative humidity, allowing the zeolite to coexist with a water or a saturated aqueous solution of inorganic salt in a closed vessel (such as a desiccator), and leaving it under a saturated steam atmosphere And a method of circulating a gas with an appropriate water vapor pressure. In the above method, in order to perform more uniform humidity control, the humidity control process may be performed while mixing or stirring the zeolite.

The temperature for the silylation treatment is appropriately adjusted according to the type of silylating agent and solvent used, and is not particularly limited, but is usually 20 ° C. or higher, preferably 40 ° C. or higher, more preferably 60 ° C. or higher . Moreover, it is 140 degrees C or less normally, Preferably it is 120 degrees C or less, More preferably, it is 100 degrees C or less. By setting the silylation treatment temperature in the above range, it is preferable in that the silylation coating of the outer surface acid point can proceed efficiently and the silylation rate can be maintained.

The time required to raise the temperature to the silylation temperature after the addition of the silylation agent is not particularly limited, and the silylating agent may be added at the silylation temperature, but it is usually 0.01 hour. The above period is preferably 0.05 hours or more, more preferably 0.1 hours or more, and there is no particular upper limit of the time required for the temperature rise. When the silylation temperature is high, by setting the time required for the temperature rise to the above range, the hydrolysis and polymerization reaction of the silylating agent in the solution are suppressed, and the silylation of the zeolite proceeds efficiently. preferable.

The treatment time of the silylation depends on the reaction temperature, but is usually 0.1 hour or more, preferably 0.5 hour or more, more preferably 1 hour or more, and the treatment time as long as the catalyst performance is not impaired. There is no particular upper limit. By setting the treatment time to the above-mentioned range, the silylation coating of the outer surface acid point of the zeolite proceeds, and the amount of the outer surface acid is preferably sufficiently reduced.

<Steam treatment>
Although the steam treatment method is not particularly limited, it can be brought into contact with a gas containing steam as long as the effects of the present invention are not impaired. Specifically, a method of contacting with a reaction atmosphere containing water vapor, water vapor diluted with air or inert gas, a lower olefin such as ethylene or propylene, or a reaction atmosphere generating water vapor, etc. may be mentioned. The reaction that produces steam is a reaction in which dehydration occurs to produce steam, such as dehydration of alcohol. Depending on the conditions, water vapor may partially exist as liquid water, but in order to give a uniform water vapor treatment effect to the zeolite, it is preferable that the whole be present in the state of water vapor.

It is considered that not only the outer surface acid amount but also the total acid amount decreases because the zeolite causes the elimination of the T atoms other than silicon forming the skeleton from the skeleton throughout the steam treatment. The reduction of the total acid content suppresses the formation of coke inside the pores of the zeolite, thereby improving the intracrystalline diffusion of molecules. For this reason, it is presumed that the reactivity of propylene which is a reaction raw material relatively increases. If excessive steam treatment is performed, the activity decreases with the decrease of the total acid content, and the intra-crystal diffusivity of the molecule excessively increases, so that hydrocarbon molecules having 4 or more carbon atoms such as butene, pentene and hexene The amount of production tends to increase.

The steam treatment temperature is not particularly limited, but is usually 400 ° C. or more, preferably 500 ° C. or more, more preferably 600 ° C. or more. The temperature is usually 1000 ° C. or less, preferably 900 ° C. or less, more preferably 800 ° C. or less. By setting the steam treatment temperature in the above range, it is preferable in that T atoms other than silicon can be efficiently removed from the skeleton in a short treatment time without causing the collapse of the skeleton structure.

The steam (steam) used for steam treatment can be used after diluting with air or an inert gas such as helium or nitrogen. The water vapor concentration at that time is not particularly limited, but usually 5% by volume or more, preferably 10% by volume or more, more preferably 20% by volume or more with respect to the whole gas used when steaming the zeolite It is more preferably 30% by volume or more, usually 100% by volume or less, preferably 90% by volume or less, more preferably 80% by volume or less, and still more preferably 70% by volume or less. The upper limit is not particularly limited, and 100% by volume of water vapor can be used. By setting the water vapor concentration to the above-mentioned range, the T atom can be efficiently removed from the skeleton in a short processing time, which is preferable.

The pressure for steam treatment (total pressure including dilution gas) is not particularly limited, but is usually 0.05 MPa or more (absolute pressure, the same applies hereinafter), preferably 0.075 MPa or more, more preferably 0.1 MPa or more The pressure is usually 2 MPa or less, preferably 1 MPa or less, more preferably 0.5 MPa or less. By setting the pressure of the steam treatment to the above pressure range, the T atoms can be efficiently removed from the skeleton in a short time, which is preferable.

The partial pressure of the water vapor is not particularly limited, but is usually 0.01 MPa or more (absolute pressure, the same applies hereinafter), preferably 0.03 MPa or more, more preferably 0.05 MPa or more, and usually 2 MPa or less It is 1 MPa or less, more preferably 0.5 MPa or less, and still more preferably 0.2 MPa or less. By setting the partial pressure of water vapor to the above pressure range, the T atom can be efficiently removed from the skeleton in a short time, which is preferable.

The steam treatment time is not particularly limited, but is usually 0.1 hour or more, preferably 0.5 hour or more, and more preferably 1 hour or more. In addition, there is no upper limit of the treatment time unless the catalyst activity is significantly inhibited. The treatment time can be appropriately adjusted by the steam treatment temperature and the steam concentration.

The steam treatment may be performed in the state where an organic substance is present in the pores. The presence of the organic substance inside the pore makes it possible to significantly reduce the outer surface acid point while preventing the extreme reduction of the acid point inside the pore, particularly when the strong steam treatment is performed.
Although it does not specifically limit as said organic substance, The structure direct agent used at the time of the hydrothermal synthesis of a zeolite, the coke produced | generated by reaction, etc. are mentioned. These organic substances can be removed by subjecting zeolite after hydrothermal synthesis (hereinafter sometimes referred to as zeolite before calcination) to a steam treatment and then through a combustion process such as air calcination, or oxygen-containing gas such as air It is also possible to carry out steam treatment while removing organic substances by treating with steam diluted with.

<Heat treatment>
The heat treatment method is not particularly limited, but specifically, the zeolite may be subjected to high temperature treatment under at least one atmosphere selected from air and inert gas. This can reduce the total acid content of the zeolite.

The heat treatment temperature is not particularly limited, but is usually 500 ° C. or more, preferably 600 ° C. or more, more preferably 700 ° C. or more, and usually 1200 ° C. or less, preferably 1000 ° C. or less, more preferably 900 ° C. or less is there. By setting the heat treatment temperature in the above range, it is preferable in that the T atom can be efficiently removed from the skeleton in a short treatment time without causing the collapse of the skeleton structure.

Helium, nitrogen, air or the like can be used as a gas species used in the heat treatment.
The heat treatment may also be performed in the state where an organic substance is present inside the pores, as in the steam treatment. When an inert gas such as helium or nitrogen is used, the organic matter may be carbonized by heat treatment, but it can be removed by calcination in air.

The heat treatment may be carried out simultaneously with the calcination carried out when producing the above-mentioned zeolite or separately. The heat treatment is performed at a relatively high temperature for the purpose of desorption of the T atoms in the skeleton, etc., and is not particularly limited. Specifically, if the above-mentioned firing and heat treatment are performed separately, the heat treatment is performed Is usually performed at a temperature higher than the baking.
The heat treatment time is not particularly limited, but is usually 0.1 hour or more, preferably 0.5 hour or more, more preferably 1.0 hour or more. Further, there is no upper limit of the treatment time as long as the catalyst activity is not significantly inhibited, and the treatment time can be appropriately adjusted depending on the heat treatment temperature.

<Acid treatment>
Although the method of the acid treatment of the zeolite used by this embodiment is not specifically limited, Specifically, the method of using an acidic aqueous solution is mentioned.
The type of acid used in the acidic aqueous solution is not particularly limited, but inorganic acids such as sulfuric acid, nitric acid, hydrochloric acid and phosphoric acid, carboxylic acids such as formic acid, acetic acid and propionic acid, oxalic acid, malonic acid and the like And the like can be used. Among these, preferred are sulfuric acid, nitric acid and hydrochloric acid.

The acid concentration of the acidic aqueous solution is not particularly limited, but is usually 0.01 M or more, preferably 0.1 M or more, more preferably 1 M or more, and usually 10 M or less, preferably 8 M or less More preferably, it is 6 M or less. By setting the concentration of the acid in the above range, it is preferable in that the total amount of acid can be efficiently reduced in a short processing time without causing the collapse of the skeletal structure.

The amount of the acidic aqueous solution to the zeolite is not particularly limited, but the total amount of the acidic aqueous solution is usually 3 g or more, preferably 5 g or more, more preferably 10 g or more, and usually 100 g or less. Preferably it is 80 g or less, More preferably, it is 50 g or less. By setting the amount of the acidic aqueous solution in the above range, it is preferable from the viewpoint that a sufficient productivity of the slurry can be obtained and a certain productivity can be secured.

The temperature of the acid treatment is not particularly limited, but it can also be performed usually at room temperature to 100 ° C. under normal pressure, and at 100 ° C. or higher in a pressure resistant vessel, and is usually 40 ° C. or higher, preferably 60 ° C. or higher The temperature is more preferably 80 ° C. or more, usually 200 ° C. or less, preferably 180 ° C. or less, more preferably 160 ° C. or less. It is preferable at the point which can reduce the total acid amount efficiently in short processing time, suppressing collapse of frame structure by making temperature of acid treatment into said range.

The treatment time of the acid treatment is not particularly limited, and is usually 0.01 hours or more, preferably 0.1 hours or more, although it depends on the concentration of the acid and the reaction temperature, as long as it does not inhibit the performance of the catalyst. There is no particular upper limit on the treatment time. The treatment time can be appropriately adjusted depending on the concentration of the acid and the reaction temperature.
The acid treatment and the silylation treatment can be simultaneously performed by adding a silylating agent to the acidic aqueous solution. The silylating agent used in that case is the same as the silylating agent.

<Ion exchange treatment>
The counter cation of the zeolite is usually an alkali metal such as sodium, an alkaline earth metal, ammonium (NH ₄ ) or proton (H). These counter cations can be ion-exchanged, and can optionally be used after metal ion-exchange. The metal to be exchanged is not particularly limited, and examples thereof include alkali metals such as lithium, sodium, potassium, rubidium and cesium, and alkaline earth metals such as calcium, strontium and barium. It is preferably sodium, potassium, calcium or strontium, more preferably sodium, potassium or calcium, still more preferably calcium.

By performing ion exchange, the acid amount of zeolite can be adjusted, and furthermore, since the cage space volume can be adjusted, coke accumulation during reaction can be suppressed. Moreover, it is preferable also from the point which thermal / hydrothermal stability becomes high and can suppress deterioration. The method of metal ion exchange is not particularly limited, but can be performed by known ion exchange methods. The cation of the zeolite to be used in the ion exchange method is not particularly limited, and usually, sodium type, ammonium type or proton type is used.

As the metal source, generally, nitrates, sulfates, acetates, carbonates, chlorides, bromides, iodides and the like are used, preferably nitrates, sulfates, chlorides and more preferably nitrates. It is. The solvent to be used is not particularly limited as long as it dissolves the metal source, but water is usually used.

The concentration of the metal source solution is not particularly limited, but is usually 0.1 M or more, preferably 0.5 M or more, more preferably 1 M or more, and the upper limit is usually 10 M or less, preferably 8 M or less, More preferably, it is 6 M or less. It is desirable to adjust the concentration to match the solubility of the metal source.

The temperature at which ion exchange is performed is from room temperature to the boiling point of the solvent. The treatment time may be any time as long as the ion exchange reaches sufficient equilibrium, and is usually about 1 to 6 hours. It is also possible to repeat ion exchange several times in order to increase the rate of metal exchange.

The atmosphere for drying the zeolite after ion exchange is not particularly limited, and may be performed, for example, in air, in an inert gas, in vacuum, or the like. The drying temperature is usually from room temperature to the boiling point of the solvent. The zeolite after ion exchange is suitably used after calcination. The firing temperature may be higher than the decomposition temperature of the metal source, and is usually 200 ° C. to 600 ° C., preferably 300 ° C. to 500 ° C. When the calcination temperature is too low, the metal source tends to remain, and when the calcination temperature is too high, structural collapse of the zeolite and sintering of the metal tend to proceed.

In addition to the above, the amount of outer surface acid can also be adjusted by a method of supporting treatment of a metal element or bonding a binder and the outer surface acid point of the zeolite when forming the zeolite.

The average primary particle diameter of the zeolite used in the present embodiment is not particularly limited, but is usually 0.01 μm or more, preferably 0.03 μm or more, more preferably 0.05 μm or more, and usually 10 μm or less. It is preferably 5 μm or less, more preferably 1 μm or less, still more preferably 0.5 μm or less, and particularly preferably 0.3 μm or less. By setting it in the above-mentioned range, the diffusivity in the zeolite crystal in the catalytic reaction and the catalytic efficiency coefficient become sufficiently high, the zeolite crystallinity becomes sufficient, and it is preferable in that the hydrothermal stability is high.
The average primary particle size in the present specification corresponds to the particle size of primary particles. Therefore, it is different from the particle size of the aggregate measured by the light scattering method or the like. The average primary particle size is optionally 20 or more particles in observation of particles by a scanning electron microscope (hereinafter abbreviated as "SEM") or a transmission electron microscope (hereinafter abbreviated as "TEM") It measures and it calculates | requires by averaging the particle diameter of the primary particle. When the particle is rectangular, the long side and short side of the particle are measured (the depth is not measured), and the average of the sum, that is, (long side + short side) ÷ 2, is calculated. Primary particle size.

(BET specific surface area)
The BET specific surface area of the zeolite used in the present embodiment is not particularly limited, but is usually 300 m ² / g or more, preferably 400 m ² / g or more, more preferably 500 m ² / g or more, and usually 1000 m ^{It is 2} / g or less, preferably 800 m ² / g or less, more preferably 750 m ² / g or less. By being in the above range, the number of active sites present on the inner surface of the pores is sufficiently large, and the catalytic activity is preferably high. In addition, a BET specific surface area can be measured by the measuring method according to JIS8830 (The specific surface area measuring method of powder (solid) by gas adsorption). Using nitrogen as an adsorption gas, the BET specific surface area can be determined by a one-point method (relative pressure: p / p0 = 0.30).

The pore volume of the zeolite used in the present embodiment is not particularly limited, but is usually 0.1 ml / g or more, preferably 0.2 ml / g or more, and usually 3 ml / g or less, preferably 2 ml It is less than / g. By being in the above range, the number of active sites present on the inner surface of the pores is sufficiently high, and the catalyst activity is preferably high. The pore volume is preferably a value determined from the adsorption isotherm of nitrogen obtained by relative pressure method.

The zeolite used in this embodiment can be generally prepared by a hydrothermal synthesis method. For example, in the case of a silicate, at least one selected from an aluminum source, a gallium source, a boron source, and an iron source, a silicon source, an alkaline aqueous solution and the like are added to water to form a uniform gel, The structure directing agent is added according to and stirred to prepare a raw material gel. The raw material gel thus obtained is crystallized by heating in a closed vessel and reacting under autogenous pressure. The reaction temperature at this time is not particularly limited, but crystallization is usually carried out by maintaining at 100 to 200 ° C. At the time of crystallization, seed crystals may be added as necessary, and from the viewpoint of productivity, it is preferable to add the seed crystals in that the reaction time can be shortened and the crystal particles can be micronized. Then, the crystallized solid component is filtered and washed, and the solid content is dried and subsequently calcined to obtain a zeolite of the alkali (earth) metal type. The drying temperature is not limited, but is usually 100 to 200 ° C. The above-mentioned firing temperature is not limited, but is usually 400 to 700 ° C. Thereafter, ion exchange is carried out with an acidic solution or ammonium salt solution and calcination is carried out to obtain H-type zeolite.

Specifically, CHA-type zeolite can be produced by a known method such as the method described in US Pat. No. 4,544,538. Moreover, as ERI type zeolite, it can manufacture by well-known methods, such as the method as described in U.S. Pat. No. 7,344,694.

The cation used as the structure directing agent is an anion that does not inhibit the formation of the zeolite of the present embodiment. The anion is not particularly limited, and specifically, it includes halogen ions such as Cl ⁻ , Br ⁻ and I ⁻ , hydroxide ions, acetates, sulfates and carboxylates. Among them, hydroxide ion is particularly preferably used.

Further, as a structure directing agent, a phosphorus-containing structure directing agent or a nitrogen-based structure directing agent can also be used. Examples of the phosphorus-containing structure directing agent include substances such as tetraethylphosphonium hydroxide and tetraethylphosphonium bromide. However, the phosphorus compound is preferably a nitrogen-based structure directing agent because it may generate phosphorus pentoxide, which is a harmful substance, when the structure directing agent is removed from the synthetic zeolite by calcination.

After hydrothermal synthesis and calcination, the obtained zeolite is preferably subjected to at least one treatment selected from silylation treatment, steam treatment, heat treatment, acid treatment and ion exchange as described above. Among them, preferably at least one treatment selected from silylation treatment, steam treatment, heat treatment and ion exchange, more preferably at least one treatment selected from silylation treatment, steam treatment and ion exchange It is more preferably treated with at least one treatment selected from silylation treatment and steam treatment, and particularly preferably with silylation treatment.

Since zeolite is a catalytically active component, zeolite may be used as it is in the reaction as a zeolite catalyst, or it may be granulated or shaped using a substance or binder inert to the reaction, or these may be mixed and reacted You may use.
As the substance and binder inert to the reaction, alumina or alumina sol, silica, silica sol, quartz, and mixtures thereof can be mentioned.

The total acid amount and the outer surface acid amount of the whole zeolite catalyst can be measured by the same method as the total acid amount and the outer surface acid amount of the above-mentioned zeolite. The total acid amount of the zeolite catalyst is not particularly limited, but is usually 0.01 mmol / g or more, preferably 0.1 mmol / g or more, more preferably 0.3 mmol / g or more, still more preferably 0.5 mmol It is more than / g. Also, it is usually 2.5 mmol / g or less, preferably 1.5 mmol / g or less, more preferably 1.2 mmol / g or less, and still more preferably 0.9 mmol / g or less. By making the total acid amount of the zeolite catalyst in the above range, the conversion activity of propylene is secured, and the formation of coke inside the pores of the zeolite is suppressed, which is preferable in that the formation of ethylene can be promoted.

The amount of outer surface acid of the zeolite catalyst is not particularly limited, but generally 8% or less, preferably 5% or less, more preferably 3% or less, more preferably 1% or less based on the total acid amount of the catalyst Below, most preferably it is 0%. When the amount of outer surface acid is too large, the side reaction occurring at the outer surface acid point tends to significantly reduce the selectivity of ethylene.
In addition, in order to adjust the total acid amount and outer surface acid amount of the zeolite catalyst, it is preferable to use as a binder such as silica or alumina having no acid point. When a binder having an acid point such as alumina is used, the total acid amount of the catalyst and the outer surface acid amount are measured as a total value including the acid amount of the binder as well as the acid amount of the zeolite. Ru. In that case, it is possible to obtain the amount of acid of the zeolite alone which does not contain the amount of acid derived from the binder by obtaining the amount of acid derived from the binder by another method and subtracting the value from the amount of acid of the catalyst. The acid amount of the binder is determined by determining the acid amount of zeolite from the peak strength of tetracoordinated Al derived from the acid point of zeolite in ²⁷ Al-NMR, and the value is calculated from the acid amount of catalyst determined by ammonia thermal desorption. It is determined by the method of subtraction.

The amount of the phosphorus compound contained in the zeolite catalyst is not particularly limited, but is usually 10% by mass or less, preferably 5% by mass or less, more preferably 1% by mass or less, still more preferably 0.1% by mass % Or less, particularly preferably 0.01% by mass or less. The term "phosphorus compound" as used herein refers to a substance such as phosphorus oxide, and does not mean zeolite itself such as aluminophosphate or gallophosphate.

The average particle size of the zeolite catalyst varies depending on the synthesis conditions of the zeolite, in particular, the granulation and molding conditions, but it is usually 0.01 μm to 500 μm and preferably 0.1 to 100 μm as the average particle size. When the average particle size of the zeolite catalyst is too large, the effective coefficient of the catalyst tends to decrease, and when it is too small, the handling becomes poor. The average particle size can be determined by SEM observation or the like.

A2. Production method of ethylene>
The method for producing ethylene comprises a step (I) of contacting with a catalyst to produce ethylene, and a step (II) of regenerating the catalyst that has been subjected to step (I). Each step will be described in detail below.

<A2-1. Process (I)>
As mentioned above, ethylene can be produced by contacting propylene with a catalyst such as zeolite.

The origin of production of propylene, which is a raw material, is not particularly limited. For example, those obtained by the decomposition of naphtha by steam decomposition method or catalytic decomposition method (hereinafter referred to as naphtha decomposition product), ethane, propane, n-butane, atmospheric pressure gas oil (AGO), vacuum gas oil (VGO), natural gas liquid Those produced by thermal decomposition such as (NGL) (hereinafter referred to as thermal decomposition products), those produced by fluid catalytic cracking (FCC) of vacuum gas oil and residual oil, produced by MTO (Methanol to Olefin) reaction , Those produced by ETO (Ethylene / Ethanol to Olefin) reaction, those produced by the dehydrogenation reaction of alkanes such as propane, and the like, and hydrogen / carbon monoxide mixed gas obtained by gasification of coal as a raw material What is manufactured by performing a Tropsch synthesis etc. is mentioned. Among these, the naphtha decomposition product and the thermal decomposition product are preferable, and the naphtha decomposition product is more preferable.

The raw material may contain, in addition to propylene, hydrocarbons other than propylene (hereinafter sometimes referred to as “other hydrocarbons”). That is, any raw material containing propylene may be used. As compounds other than propylene, for example, olefins other than propylene such as ethylene, butene, pentene and hexene; paraffins such as methane, ethane, propane, butane, pentane and hexane; alkynes such as acetylene and methylacetylene; propadiene And dienes such as butadiene, pentadiene and hexadiene; and aromatic hydrocarbons such as benzene, toluene and xylene. The above-mentioned olefins, paraffins, alkynes and dienes may have a linear structure or a cyclic structure, and may contain branched isomers in any ratio. In addition to propylene, methanol or dimethyl ether may be contained, and the mixing ratio is not limited.

Usually, in the production of ethylene from propylene, it is preferable to use propylene in a state in which ethylene is separated, since ethylene, which is the target product, is easily converted to another olefin such as butene or hexene by contact with a catalyst. . The mass ratio of propylene to ethylene contained in the raw material is not particularly limited, but is usually 1 or more, preferably 5 or more, more preferably 10 or more, still more preferably 15 or more, particularly preferably 30 or more. The bigger the better.
In addition, olefins having a carbon number greater than butene are partially converted to ethylene by contacting with the same catalyst, and the ethylene yield can be improved, and therefore, they may be contained together with propylene in the raw material And butene produced by this reaction can be recycled and used. The mass ratio of propylene to butene contained in the raw material is not particularly limited, but is usually 1 or more, preferably 5 or more, more preferably 10 or more, and usually 1000 or less, preferably 100 or less, more preferably Is less than 50.

The reactor used for ethylene production is not particularly limited as long as the propylene feedstock is in the gas phase in the reaction zone, but fixed bed reactors, moving bed reactors and fluidized bed reactors are selected. Fluidized bed reactors are preferred in order to produce with a constant ethylene yield when the propylene conversion is highly variable.
In addition, although it can be carried out either batchwise, semicontinuously or continuously, it is preferable to carry out continuously, and the method may be a method using a single reactor, or in series or in parallel. It may be a method using a plurality of reactors arranged.
In addition, when the above-mentioned catalyst is loaded into the fluidized bed reactor, in order to keep the temperature distribution of the catalyst layer small, particulates inert to the reaction such as quartz sand, alumina, silica, silica-alumina, etc. are mixed with the catalyst May be filled. In this case, the amount of the inert granular material such as quartz sand is not particularly limited. In addition, it is preferable that a granular material is a particle size comparable as a catalyst from the surface of uniform mixing property with a catalyst.
The reaction substrate (reaction raw material) may be separately supplied to the reactor for the purpose of dispersing the heat generated by the reaction.

(Substrate concentration)
The concentration of propylene in all the feed components fed to the reactor is not particularly limited, but usually 3 mol% or more, preferably 5 mol% or more, more preferably 10 mol% or more, more preferably 20% or more in the total feed components. The content is usually at most 100 mol%, preferably at most 80 mol%, more preferably at most 60 mol%, further preferably at most 40 mol%. By setting the substrate concentration in the above range, the formation of aromatic compounds and paraffins can be suppressed, and the ethylene yield can be improved. Moreover, since the reaction rate can be maintained, the amount of catalyst can be suppressed, and the size of the reactor can also be suppressed.
Therefore, it is preferable to dilute the reaction substrate with the diluent described below, as necessary, to achieve such a preferred substrate concentration.

(Diluent)
In the reactor, in addition to the raw material containing propylene, helium, argon, nitrogen, carbon monoxide, carbon dioxide, hydrogen, water, paraffins, hydrocarbons such as methane, aromatic compounds, and the like Although a mixture etc. can be made to exist, it is preferable that hydrogen, helium, nitrogen, and water (steam) coexist, and it is most preferable that hydrogen coexists from the point which can raise an ethylene yield among these. . As such a diluent, impurities contained in the reaction raw material may be used as it is as a diluent, or a diluent separately prepared may be used by mixing with the reaction raw material. Also, the diluent may be mixed with the reaction material before entering the reactor, or may be supplied to the reactor separately from the reaction material.

(Weight space velocity)
The weight space velocity referred to here is the flow rate (weight / hour) of propylene which is a reactive raw material per weight of the catalyst (catalytic active component), and the weight of the catalyst is used for granulation and shaping of the catalyst. It is the weight of the catalytically active component which does not contain an inactive component or a binder.

The weight space velocity is not particularly limited, but is usually 0.01 Hr ^-1 or more, preferably 0.1 Hr ^-1 or more, more preferably 0.2 Hr ^-1 or more, still more preferably 0.5 Hr ^-1 or more. , and the normal 50 hr ^-1 or less, preferably 10 hr ^-1 or less, more preferably ^{5 Hr -1} or less, more preferably ^{3HR -1} or less. By setting the weight space velocity to the above range, the proportion of unreacted propylene in the reactor outlet gas can be reduced, and by-products such as aromatic compounds and paraffins can be reduced. It is preferable at the point which can improve a rate. In addition, the amount of catalyst required to obtain a constant production amount can be suppressed, and the size of the reactor can be suppressed, which is preferable.

(Reaction temperature)
The reaction temperature is not particularly limited as long as propylene contacts with the catalyst to produce ethylene, but is usually 300 ° C. or more, preferably 400 ° C. or more, more preferably 425 ° C. or more, more preferably The temperature is 450 ° C. or more, particularly preferably 475 ° C. or more, most preferably 500 ° C. or more, usually 800 ° C. or less, preferably 700 ° C. or less, more preferably 650 ° C. or less, still more preferably 600 ° C. or less. By setting the reaction temperature within the above range, the formation of aromatic compounds and paraffins can be suppressed, and thus the yield of ethylene in one pass can be improved. In addition, the conversion activity of propylene can be maintained at a high level, and further, when hydrogen is contained together with propylene in the reaction gas, the contact effect can be maximized, and therefore, the production is carried out with a high ethylene yield for a long time. can do. Furthermore, when the zeolite is a silicate, it is preferable in that the catalyst life can be maintained since the dealumination from the zeolite skeleton is suppressed. Here, the reaction temperature refers to the temperature at the outlet of the catalyst layer.

(Reaction pressure)
The reaction pressure (total pressure) is not particularly limited, but is usually 0.01 MPa (absolute pressure, the same as the following) or more, preferably 0.05 MPa or more, more preferably 0.1 MPa or more, still more preferably 0.2 MPa It is the above, normally 5 MPa or less, preferably 1 MPa or less, more preferably 0.7 MPa or less, and still more preferably 0.4 MPa or less. By setting the reaction pressure in the above range, the formation of by-products such as aromatic compounds and paraffins can be suppressed, and the yield of ethylene can be improved. Also, the reaction rate can be maintained.

(Propylene partial pressure)
The partial pressure of propylene is not particularly limited, but is usually 0.001 MPa or more (absolute pressure, the same as the following), preferably 0.005 MPa or more, more preferably 0.0075 MPa or more, still more preferably 0.010 MPa or more Particularly preferably, it is 0.015 MPa or more, most preferably 0.020 MPa or more, and usually 1 MPa or less, preferably 0.5 MPa or less, more preferably 0.2 MPa or less, further preferably 0.1 MPa or less. Coking can be suppressed by setting the partial pressure of the raw material in the above range, and the yield of ethylene can be improved.

(Coke component)
Due to the conversion of propylene, a portion thereof accumulates on the inner / outer surface of the crystal as coke (heavy components such as polycyclic aromatics) which need to be removed by regeneration treatment, which tends to lower the catalytic activity. Therefore, the content (coke content) of the above-mentioned coke is usually 30% by mass or less with respect to the catalyst which is the active component, in order to obtain appropriate catalyst activity and high ethylene selectivity. % Is preferably kept, more preferably 15% by weight or less, and usually 0.1% by weight or more, and preferably 1.0% by weight or more, preferably 3.0% by weight or more. Is more preferable, and it is further preferable to keep it at 5.0% by mass or more. If the coke content in the catalyst is at least the above lower limit, molecular diffusion in the catalyst can be suppressed, cracking of olefins having 4 or more carbon atoms into ethylene can be promoted, and ethylene can be produced. Since the ethylene selectivity can be maintained high, the catalyst preferably maintains a coke content of at least the above lower limit. On the other hand, when the amount of coke accumulated in the catalyst becomes equal to or more than the upper limit value, the catalyst activity tends to decrease. Therefore, it is preferable to adjust the regeneration conditions so that the amount of coke accumulated in the catalyst falls within the above range by the regeneration method described later.
In the embodiment, the amount of coke accumulated in the catalyst means that the catalyst accumulated coke by the conversion reaction of propylene is heated up to 550 ° C. under a flow of inert gas such as helium (50 cc / min) at a temperature increase rate of 10 ° C. Heats up to 60 / C and holds for 30 minutes to remove adsorbed water and light-boiling hydrocarbon components, and then switches to air circulation (50 cc / min) and heats up to 600 ° C at a heating rate of 10 ° C / min. It can hold for 60 minutes, and it can calculate by calculating | requiring the weight loss by oxidative combustion in the temperature area | region of 550 degreeC or more at this time.

(Conversion rate)
In the present embodiment, the conversion of propylene is not particularly limited, but the conversion is usually 5% or more, preferably 20% or more, more preferably 30% or more, and still more preferably 40% or more. It is 100% or less, preferably 80% or less, more preferably 60% or less, and further preferably 50% or less. In the present embodiment, by adjusting the conversion rate of propylene to be in the above-mentioned range, it is possible to suppress by-production of butenes, aromatic compounds and paraffins, and accumulation of coke in pores. The yield of ethylene can be improved. In addition, the separation efficiency of components such as ethylene and propylene from the product can be enhanced. That is, in the present embodiment, the catalyst is preferably subjected to the regeneration step so that the conversion rate of propylene is in the above-mentioned range.

Usually, the accumulation of coke proceeds with the progress of the reaction time, and the conversion of propylene tends to decrease. Therefore, as described later, when the amount of coke accumulated in the catalyst increases, the catalyst is used as a regeneration step. It is preferable to provide. Moreover, it does not restrict | limit especially as a method to operate | move in the range of said conversion rate.

(yield)
In the present embodiment, the yield of ethylene is not particularly limited, but the yield is usually 5% or more, preferably 20% or more, more preferably 30% or more, and still more preferably 40% or more. It is 100% or less, preferably 80% or less, more preferably 60% or less. When the yield of ethylene is in the above range, the ratio of the target product at the outlet of the reactor becomes sufficient, which is preferable in that the cost of raw materials and the load of separation / purification can be reduced.
The yield of the by-product butenes is not particularly limited, but is usually 50% or less, preferably 30% or less, more preferably 20% or less, still more preferably 10% or less, particularly preferably 5% The less, the less, the better. It is preferable at the point which can reduce isolation | separation and recycling load of a butene component because the yield of butenes is in the said range.

The conversion is a value calculated by the following equation.
Propylene conversion rate (%) = [[reactor inlet propylene (mol / Hr) -reactor outlet propylene (mol / Hr)] / reactor inlet propylene (mol / Hr)] × 100

The selectivity in the present specification is a value calculated by each of the following formulas. In each of the following formulas, "derived carbon flow rate (mol / Hr)" of hydrocarbons such as ethylene, butene, C5 +, paraffin and aromatic compound means a molar flow rate of carbon atoms constituting each hydrocarbon. The paraffin is the sum of paraffins of 1 to 4 carbons, the aromatic compound is the sum of benzene, toluene and xylene, and C5 + is the sum of hydrocarbons having 5 or more carbons excluding the aromatic compounds.
· Ethylene selectivity (%) = [reactor outlet ethylene-derived carbon molar flow rate (mol / Hr) / [reactor outlet total carbon molar flow rate (mol / Hr)-reactor outlet propylene-derived carbon molar flow rate (mol / Hr) ]] × 100
· Butene selectivity (%) = [reactor outlet butene-derived carbon molar flow rate (mol / Hr) / [reactor outlet total carbon molar flow rate (mol / Hr)-reactor outlet propylene-derived carbon molar flow rate (mol / Hr) ]] × 100
C5 + selectivity (%) = [reactor outlet C5 + derived carbon molar flow rate (mol / Hr) / [reactor outlet total carbon molar flow rate (mol / Hr) -reactor outlet propylene derived carbon molar flow rate (mol / Hr) ]] × 100
· Paraffin selectivity (%) = [reactor outlet paraffin-derived carbon molar flow rate (mol / Hr) / [reactor outlet total carbon molar flow rate (mol / Hr)-reactor outlet propylene-derived carbon molar flow rate (mol / Hr) ]] × 100
Aromatic compound selectivity (%) = [Reactor outlet aromatic compound derived carbon molar flow rate (mol / Hr) / [reactor outlet total carbon molar flow rate (mol / Hr) −reactor outlet propylene derived carbon molar flow rate ( mol / Hr)]] × 100
In addition, the yield in this specification is calculated | required by the product of the said raw material conversion ratio and the selectivity of each produced | generated component, and ethylene yield and butene yield are specifically represented by the following formula, respectively .
· Ethylene yield (%) = propylene conversion rate (%) x ethylene selectivity (%) / 100
-Butene yield (%) = propylene conversion rate (%) x butene selectivity (%) / 100

(Reaction product)
As a reactor outlet gas (reactor effluent), a mixed gas containing ethylene as a reaction product, propylene as a raw material, butenes as a by-product, paraffins, an aromatic compound, and a diluent is obtained. The concentration of ethylene in the mixed gas is not particularly limited, but is usually 5% by mass or more, preferably 10% by mass or more, more preferably 20% by mass or more, and usually 95% by mass or less, preferably 90% by mass or less It is.
Depending on the reaction conditions, although propylene is contained as an unreacted raw material in the reaction product, when the selectivity of ethylene is low, that is, when the selectivity of by-products is high, this leads to loss of raw material and increases the production cost Therefore, there are also cases where it is preferable to operate under conditions where the ethylene selectivity is high even under conditions where the propylene conversion rate is lowered. In the present embodiment, if desired, components other than ethylene may be separated and recovered. The residue from which the desired component has been separated and recovered contains light paraffin, light olefin, aromatic compounds and the like. At least a portion of the remaining portion can be mixed with a portion of the above-described source gas and used as a so-called recycle gas.

(Separation of product)
A mixed gas containing ethylene as a reaction product, unreacted raw materials, by-products and a diluent as a reactor outlet gas is introduced into a known separation / purification facility, and recovered and purified according to the respective components, It is sufficient to process recycling and discharge.

(recycling)
Components other than ethylene (olefins, paraffins, etc.), in particular some or all of the hydrocarbons having 3 or more carbon atoms, are separated and / or purified and then mixed with the reaction materials or recycled directly to the reactor You may Further, among the by-products, components inert to the reaction can be reused as a diluent.

<A2-2. Process (II)>
By regenerating the catalyst in which the conversion rate of propylene is lowered through the step (I), it is possible to stably produce ethylene while minimizing the fluctuation range of the ethylene yield. In the present embodiment, regeneration of the catalyst means that the catalyst in a state of reduced propylene conversion has a higher propylene conversion rate than that before the regeneration treatment.

As the propylene is converted, the amount of coke components accumulated in the catalyst increases. The amount of coke component accumulated in the catalyst when the catalyst in which the accumulated amount of coke component is increased is subjected to the step (II) of regenerating the catalyst is usually 0% by mass or more, preferably 0.01% by mass Or more, more preferably 0.1% by mass or more, still more preferably 1.0% by mass or more, particularly preferably 3.0% by mass or more, particularly preferably 5.0% by mass or more, and usually 30% by mass or less, Preferably it is 25 mass% or less, More preferably, it is 20 mass% or less, More preferably, it is 15 mass% or less, Especially preferably, it is 10 mass% or less. If the amount of coke components accumulated in the catalyst is equal to or more than the above lower limit value, the catalyst activity is in a reduced state, which is preferable because the catalyst activity can be effectively recovered in the regeneration step. On the other hand, if the amount of coke components accumulated in the catalyst exceeds the above upper limit value, the diffusion of the regenerated gas and the decomposition gas in the catalyst in the regeneration step is inhibited and the regeneration efficiency tends to be significantly reduced. It is preferred to contact the regeneration gas below. In this regeneration step, the catalyst activity can be recovered while appropriately reducing the amount of coke components accumulated in the catalyst, so ethylene can be stably produced in a high yield.

There is no particular limitation on the step (II) of regenerating the catalyst. For example, when producing ethylene from propylene, after stopping the supply of propylene when the coke content of the catalyst increases, the gas used for regeneration (hereinafter sometimes referred to as regeneration gas) is supplied into the reactor Thus, the catalyst with an increased coke content can be brought into contact with the regeneration gas. Also, the catalyst with an increased coke content is removed from the reactor of step (I) of contacting propylene with the catalyst and transferred to the reactor of step (II) of regenerating the catalyst, and the gas used for regeneration is transferred to the catalyst. It may be supplied to regenerate the catalyst.

In particular, when the above step (I) is carried out using a fixed bed reactor, the supply of propylene is stopped when the amount of coke accumulated in the catalyst becomes equal to or more than the above upper limit, A regeneration gas can be supplied to contact the catalyst. Alternatively, the catalyst may be withdrawn from the reactor, charged in a reactor separate from the reactor, and then contacted with the regeneration gas.

When the step (I) is carried out using a moving bed reactor or a fluidized bed reactor, an apparatus for contacting the regenerated gas with the catalyst is attached separately from the reactor, and the catalyst withdrawn from the reactor It is preferable to continuously feed the catalyst to the apparatus in which the catalyst is contacted with the regeneration gas, and then to carry out the reaction of ethylene production while continuously returning the catalyst contacted with the regeneration gas to the reactor.

The gas used in the step (II) of regenerating the catalyst is not particularly limited, but a suitable example is a gas containing at least one selected from oxygen, hydrogen and water vapor. Specific regeneration methods include combustion regeneration using oxygen as a regeneration gas, steam reforming regeneration using steam (water) as a regeneration gas, and hydrocracking using hydrogen as a regeneration gas. Among these, the regeneration gas is preferably a gas containing oxygen or hydrogen, and more preferably a gas containing hydrogen.

The method for producing oxygen is not particularly limited, and oxygen that is cryogenically separated from air in the atmosphere, oxygen generated from hydrogen peroxide, and the like can be mentioned, and those recovered from the air in the atmosphere are preferable.

It does not specifically limit as a manufacturing method of water vapor | steam (water), What evaporated normal water can be used. Water obtained by various production methods such as tap water, demineralized water, process water of a plant, etc. can be used arbitrarily.

The method for producing hydrogen contained in the gas containing hydrogen is not particularly limited. For example, those obtained by steam reforming of methane and methanol, those obtained by partial oxidation of hydrocarbons, those for reforming hydrocarbons with carbon dioxide , Obtained by gasification of coal, obtained by thermal decomposition of water represented by IS (Idine-Sulfur) process, obtained by photoelectrochemical reaction, obtained by electrolysis of water Those obtained by various manufacturing methods such as those that can be used can be used arbitrarily.

A mixture of other gases may be used, or purified hydrogen may be used.

As gases other than these contained in gases including oxygen, hydrogen and water vapor, for example, hydrocarbons such as helium, argon, nitrogen, carbon monoxide, carbon dioxide, paraffins, methane and the like if there is no safety problem. The class may be included. Among these, helium, nitrogen, carbon dioxide, paraffins and methane are preferable in view of low reactivity.

The pressure (total pressure) of the entire regeneration gas is not particularly limited, but it is usually at least 0.01 MPa (absolute pressure, the same applies hereinafter) or more, preferably 0.05 MPa or more, more preferably 0.1 MPa in absolute pressure. The pressure is more preferably 0.2 MPa or more, usually 5 MPa or less, preferably 1 MPa or less, more preferably 0.7 MPa or less, still more preferably 0.5 MPa or less. By setting the pressure in the above-mentioned range, the partial pressure of the hydrocarbon component in the processing gas can be suppressed low while the regeneration efficiency is enhanced, so that high catalytic activity can be maintained.

(Hydrogen partial pressure)
The hydrogen-containing gas in the regeneration gas is not particularly limited, but the hydrogen partial pressure in terms of absolute pressure is usually 0.001 MPa or more, preferably 0.01 MPa or more, and more preferably 0.03 MPa Or more, more preferably 0.05 MPa or more, particularly preferably 0.1 MPa or more, usually 4 MPa or less, preferably 1 MPa or less, more preferably 0.7 MPa or less, still more preferably 0.5 MPa or less, particularly preferably 0. It is 3 MPa or less. By setting the hydrogen partial pressure in the above range, the removal / reformation of coke components accumulated in the catalyst proceeds rapidly, so that the catalyst state giving high propylene conversion activity and high ethylene selectivity is made efficient. be able to. In addition, equipment and energy for producing high pressure hydrogen can be reduced.

The space velocity of the regeneration gas is not particularly limited, but is usually 0.001 Hr ^-1 or more, preferably 0.01 Hr ^-1 or more, more preferably 0.1 Hr ^-1 or more, and usually 20 Hr ^-1 or less. , preferably 10 hr ^-1 or less, more preferably ^{5 Hr -1} or less. By setting the weight space velocity to the above range, the concentration of the hydrocarbon component and the water vapor contained in the catalyst can be reduced, so that the propylene conversion activity can be maintained at a high level. Furthermore, since the distribution of coke components accumulated in the catalyst can be made uniform, it is possible to suppress the nonuniform reaction in the catalyst and to increase the ethylene selectivity.

The space velocity is the flow rate of the regeneration gas per weight of the catalyst (catalytic active component). Further, the weight of the catalyst is the weight of the active component (zeolite) which does not contain an inactive component or a binder used for granulation / molding of the catalyst.

The concentration of the regeneration gas in the supply gas of the regeneration step (II) is not particularly limited, but is usually 5% by volume or more, preferably 10% by volume or more, more preferably 30% by volume or more, It is 100 volume% or less, preferably 90 volume% or less, more preferably 80 volume% or less. The regeneration gas concentration is preferably high, and is usually 5% by volume or more, preferably 30% by volume or more, more preferably 60% by volume or more, and usually 100% by volume or less. By setting the concentration of regeneration gas within the above range, the contact between the catalyst and the regeneration gas becomes sufficient, and the removal / reformation of coke components proceeds rapidly, giving high propylene conversion activity and high ethylene selectivity. The catalyst state can be made efficient.

The temperature at which the catalyst and regeneration gas are brought into contact (hereinafter sometimes referred to as "regeneration temperature") is not particularly limited, but is usually 300 ° C. or higher, preferably 400 ° C. or higher, more preferably 500 ° C. The temperature is more preferably 525 ° C. or more, particularly preferably 550 ° C. or more, usually 800 ° C. or less, preferably 700 ° C. or less, more preferably 650 ° C. or less, still more preferably 600 ° C. or less. By setting the degree of regeneration within the above range, the removal of coke components proceeds rapidly, so the catalyst activity can be kept high. Furthermore, since the structural collapse of the catalyst is suppressed, it is preferable in that the catalyst life can be maintained.

The time for contacting with the regeneration gas is not particularly limited, but is usually 1 second or more, preferably 10 seconds or more, more preferably 1 minute or more, still more preferably 5 minutes or more, and usually 5 hours or less, Preferably it is 2 hours or less, More preferably, it is 1 hour or less. Since the appropriate time changes depending on the concentration of the regeneration gas and the processing temperature, it is preferable to adjust appropriately. When the device to be contacted with the regeneration gas is a fluid bed device, the above processing time means the residence time of the catalyst in the device.

A second embodiment of the present invention is a method for producing ethylene by contacting propylene with a catalyst in a reactor to produce ethylene, using the catalyst contacted with a gas containing hydrogen as the catalyst. is there. Hereinafter, although this embodiment is described in detail, points different from the first embodiment will be described, and others can refer to the description of the first embodiment as appropriate.

<B1. Catalyst>
The catalyst used in the reaction according to the present embodiment is not particularly limited as long as it is a solid having a Br ステッド nsted acid point, and a conventionally known catalyst is used. For example, clay minerals such as kaolin, acidic ion And solid acid catalysts such as exchange resins, zeolites and mesoporous silica-alumina. When ethylene is produced from propylene, coke components such as aromatic compounds having a skeleton such as benzene, naphthalene and anthracene are accumulated in the catalyst, but by contacting the catalyst with a gas containing hydrogen And reforming the quality of the coke component while appropriately reducing the amount of coke accumulated in the catalyst by the decomposition of the above-mentioned aromatic compounds etc. which are the coke component accumulated in the catalyst and the progress of the rereaction Can. Thereby, the catalyst is regenerated, and ethylene can be efficiently produced from propylene.

Among these solid acid catalysts, those having a molecular sieving effect are preferable, and zeolite is more preferable. In addition, although the said catalyst can use a well-known catalyst, about the zeolite which is a preferable form as a catalyst, description of 1st embodiment <A1. Catalyst> can be referred to.
Although non-patent document 1 describes that ethylene selectivity is improved by modifying MFI-type zeolite catalyst with phosphoric acid, in the present embodiment, the catalyst is contacted with a gas containing hydrogen. By doing this, ethylene can be obtained in high yield without modifying the catalyst with phosphoric acid or the like. Therefore, in the present embodiment, by setting the amount of the phosphorus compound in the catalyst to the upper limit value or less described in the description of the first embodiment, corrosion of the reactor due to the phosphorus compound is suppressed, and the yield is high. Ethylene can be obtained.

<B2. Production method of ethylene>
Ethylene can be produced by contacting a raw material containing propylene with a zeolite catalyst. The present embodiment is a method suitable for ethylene production and linear butene production, in particular a method suitable for ethylene production. Also with regard to the method for producing ethylene, the description of the first embodiment <A2-1. Method of Producing Ethylene> can be referred to.

In this embodiment, it is preferable to use the catalyst in contact with a gas containing hydrogen so as to achieve the conversion of propylene described in the description of the first embodiment. Usually, the accumulation of coke proceeds with the progress of the reaction time, and the conversion of propylene tends to decrease. Therefore, when the amount of coke accumulated in the catalyst increases, the catalyst is brought into contact with hydrogen to carry out the catalyst It is preferable to play Note that a reproduction method other than the above method may be used in combination.

<B3. Method of contacting catalyst with gas containing hydrogen>
In the present embodiment, in the method of producing ethylene by contacting propylene with a catalyst in a reactor, ethylene is obtained with high selectivity and high yield by using a catalyst contacted with a gas containing hydrogen as the catalyst. Can be manufactured stably.

Incidentally, referring to the known Japanese Patent No. 5545114, it is known that in the reaction of producing propylene using ethylene as a raw material, the catalyst is regenerated by treating it with hydrogen. However, in the present embodiment where propylene having high reactivity and adsorption ability is used as a raw material compared to ethylene, the sequential reaction easily proceeds, and thus the coke component to be produced is a heavier component, which is easy by hydrogen treatment It is unlikely that the coke component will be removed. In addition, under the condition where propylene coexists, it is considered that the effect of contacting hydrogen is not sufficiently obtained because the adsorption of the catalyst and the hydrogen is relatively suppressed (the adsorption of the catalyst and the propylene is prioritized). However, it has been surprisingly found that even in the method of producing ethylene from propylene as in the present embodiment, the catalyst can be regenerated by contacting a gas containing hydrogen with the catalyst to produce ethylene in high yield. . Although the reason for this is not clear, by bringing the catalyst into contact with a gas containing hydrogen, the above-mentioned aromatic compounds and the like which are coke components accumulated in the catalyst are decomposed and the reaction proceeds, whereby the catalyst is accumulated. It is considered that the quality of coke components could be modified while appropriately reducing the amount of coke produced, and as a result, the catalyst was regenerated and ethylene could be produced from propylene with high yield. it is conceivable that.

In particular, the content of the coke component increases in the catalyst used with the conversion of propylene, but the content of the coke component is increased by contacting the catalyst having the increased content of the coke component with a gas containing hydrogen It is possible to modify the quality of coke components while appropriately reducing the amount of ethylene so that ethylene can be stably produced in a high yield. Therefore, the contact of the catalyst with the gas containing hydrogen is preferably performed in the state where the catalyst contains a coke component, and the amount of the coke component accumulated in the catalyst when contacting the hydrogen gas is usually 0% by mass Or more, preferably 0.01% by mass or more, more preferably 0.1% by mass or more, still more preferably 1.0% by mass or more, particularly preferably 3.0% by mass or more, particularly preferably 5.0% by mass or more The amount is usually 30% by mass or less, preferably 25% by mass or less, more preferably 20% by mass or less, still more preferably 15% by mass or less, and particularly preferably 10% by mass or less. If the amount of coke component accumulated in the catalyst is equal to or more than the above lower limit value, the catalyst activity is lowered, and the catalyst activity can be effectively recovered by hydrogen contact, which is preferable. On the other hand, when the amount of coke components accumulated in the catalyst exceeds the above upper limit, the diffusion of hydrogen gas and cracked gas in the catalyst is inhibited, and the regeneration efficiency tends to be significantly reduced. Contact with a gas is preferred.

There is no particular limitation on the method of contacting the catalyst with the gas containing hydrogen. For example, when producing coke from propylene, at the stage where the coke content of the catalyst is increased, the catalyst containing hydrogen and hydrogen is simultaneously supplied into the reactor to increase the coke-increased catalyst into a gas containing hydrogen. It can be in contact. In addition, after stopping the supply of propylene, the catalyst containing increased coke content can be brought into contact with the gas containing hydrogen by supplying a gas containing hydrogen into the reactor. Furthermore, the catalyst with increased coke content may be removed from the reactor and contacted with hydrogen.

In particular, when producing ethylene from propylene using a fixed bed reactor, it is preferable to feed propylene and a gas containing hydrogen simultaneously or separately without removing the catalyst from the ethylene production reactor. Used. That is, when the amount of coke accumulated in the catalyst exceeds the above upper limit value, the gas containing hydrogen is supplied into the reactor simultaneously with propylene or after the supply of propylene is stopped, the amount of coke is The increased catalyst can be contacted with a gas comprising hydrogen.
Preferably, the catalyst is withdrawn from the reactor and charged in a reactor separate from the reactor and then contacted with hydrogen gas.

In addition, when a moving bed reactor or fluidized bed reactor is used in producing ethylene from propylene, an apparatus for contacting a gas containing hydrogen and a catalyst separately from the reactor is attached, and the reactor The catalyst withdrawn from the reactor is continuously sent to the apparatus, and the catalyst is contacted with hydrogen gas in the apparatus, and then the catalyst in contact with the gas containing hydrogen is continuously returned to the reactor while the reaction of ethylene production is conducted It is preferred to do.

The time for contacting the gas containing hydrogen with the catalyst is not particularly limited, and may be appropriately selected in consideration of the amount of coke accumulated in the catalyst.

The method for producing hydrogen contained in the hydrogen-containing gas of the present invention is not particularly limited. For example, those obtained by steam reforming of methane and methanol, those obtained by partial oxidation of hydrocarbons, hydrocarbons with carbon dioxide Those obtained by reforming, those obtained by gasification of coal, those obtained by thermal decomposition of water represented by the IS (Iodine-Sulfur) process, those obtained by photoelectrochemical reaction, and the electricity of water Those obtained by various production methods such as those obtained by decomposition can be used arbitrarily.

A mixture of gases other than hydrogen may be used, or purified hydrogen may be used.

Gases other than hydrogen may include, for example, helium, argon, nitrogen, oxygen, carbon monoxide, carbon dioxide, paraffins, hydrocarbons such as methane, and the like. Among these, helium, nitrogen, carbon dioxide, paraffins and methane are preferable in view of low reactivity.

Although the gas after being used for the treatment with the gas containing hydrogen includes hydrocarbon components (olefin, paraffin, etc.) in addition to hydrogen, it may be recycled as it is, or any gas other than hydrogen may be used. You may recycle and use what removed partially or totally.

When supplying a gas containing hydrogen together with propylene, the pressure (total pressure) of the entire gas containing hydrogen is not particularly limited, but it is usually 0.01 MPa (absolute pressure, the same applies hereinafter) or more as an absolute pressure. Preferably, it is 0.05 MPa or more, more preferably 0.1 MPa or more, still more preferably 0.2 MPa or more, usually 5 MPa or less, preferably 1 MPa or less, more preferably 0.7 MPa or less, more preferably 0.5 MPa or less is there. By setting the pressure in the above-mentioned range, the partial pressure of the hydrocarbon component in the processing gas can be suppressed low while the contact efficiency with hydrogen gas can be enhanced, and high catalytic activity can be maintained.

When a gas containing hydrogen is supplied into the reactor simultaneously with propylene, the pressure of the gas containing hydrogen is not particularly limited, but the hydrogen partial pressure is usually 0.001 MPa or more, preferably 0 MPa in absolute pressure. It is more preferably 0.01 MPa or more, more preferably 0.03 MPa or more, still more preferably 0.05 MPa or more, particularly preferably 0.1 MPa or more, usually 4 MPa or less, preferably 1 MPa or less, more preferably 0.7 MPa or less More preferably, it is 0.5 MPa or less, and particularly preferably 0.3 MPa or less. By setting the hydrogen partial pressure in the above range, the removal / reformation of coke components accumulated in the catalyst proceeds rapidly, so that the catalyst state giving high propylene conversion activity and high ethylene selectivity is made efficient. be able to. In addition, equipment and energy for producing high pressure hydrogen can be reduced.

The space velocity of the gas containing hydrogen, is not particularly limited, usually 0.001Hr ^-1 or more, preferably 0.01 hr ^-1 or more, more preferably 0.1 hr ^-1 or more and usually 20 hr ^{- 1} or less, preferably 10 hr ^-1 or less, more preferably ^{5 Hr -1} or less. By setting the weight space velocity to the above range, the concentration of the hydrocarbon component contained in the catalyst can be reduced, so that it is possible to maintain the propylene conversion activity at a high level. Furthermore, since the distribution of coke components accumulated in the catalyst can be made uniform, it is possible to suppress the nonuniform reaction in the catalyst and to increase the ethylene selectivity. Moreover, when recovering the gas containing hydrogen, the separation and purification load can be suppressed. In addition, since the amount of hydrogen gas used can be reduced, the manufacturing cost can be reduced.

The space velocity is the flow rate of hydrogen per weight of the catalyst (catalyst active component). Further, the weight of the catalyst is the weight of the active component (zeolite) which does not contain an inactive component or a binder used for granulation / molding of the catalyst.

The concentration of hydrogen in the gas containing hydrogen is not particularly limited, but is usually 5% by volume or more, preferably 10% by volume or more, more preferably 30% by volume or more, and is usually 100% by volume or less, preferably Is 90 volume% or less, more preferably 80 volume% or less. If the step of contacting the catalyst with the gas containing hydrogen is at the front or the back of the step of producing ethylene by contacting the catalyst with propylene in the reactor, the hydrogen concentration is preferably higher. It is usually 5% by volume or more, preferably 30% by volume or more, more preferably 60% by volume or more, and usually 100% by volume or less. By setting the hydrogen concentration in the above range, the contact between the catalyst and the hydrogen molecule becomes sufficient and the removal / reformation of coke components proceeds rapidly, so a catalyst giving high propylene conversion activity and high ethylene selectivity The state can be made efficient. In addition, the amount of hydrogen gas used can be reduced, and the separation and purification load can be reduced.

The temperature at which the catalyst is brought into contact with the gas containing hydrogen (hereinafter sometimes referred to as "hydrogen contact temperature") is not particularly limited, but usually 300 ° C. or higher, preferably 400 ° C. or higher, more preferably Is preferably 450 ° C. or more, more preferably 500 ° C. or more, particularly preferably 525 ° C. or more, usually 800 ° C. or less, preferably 700 ° C. or less, more preferably 650 ° C. or less, still more preferably 600 ° C. or less. By setting the hydrogen contact temperature in the above range, the removal of coke components proceeds rapidly, so the catalyst activity can be kept high. Furthermore, since the structural collapse of the catalyst is suppressed, it is preferable in that the catalyst life can be maintained.

The contact time with a gas containing hydrogen is not particularly limited, but is usually 1 second or more, preferably 10 seconds or more, more preferably 1 minute or more, still more preferably 5 minutes or more, and usually 5 hours The reaction time is preferably 2 hours or less, more preferably 1 hour or less. Since the appropriate time changes depending on the concentration of hydrogen gas and the processing temperature, it is preferable to adjust appropriately. When the device to be contacted with the gas containing hydrogen is a fluid bed device, the above processing time means the residence time of the catalyst in the device.

A third embodiment of the present invention is a method for producing ethylene by contacting a hydrocarbon and a catalyst in a reactor to produce ethylene, wherein the hydrocarbon contains at least propylene and a hydrocarbon having 4 or more carbon atoms. The mass ratio of the hydrocarbon having 4 or more carbon atoms to propylene contained in the hydrocarbon is 0.01 or more and 10 or less.

<C1. Catalyst>
The catalyst used in the present embodiment will be described. The catalyst used in the reaction according to the present embodiment is one which can produce ethylene from a hydrocarbon containing propylene, and is not particularly limited as long as it is a solid having a Bronsted acid point, and a conventionally known catalyst is Used. Examples thereof include clay minerals such as kaolin, acid type ion exchange resins, zeolites, and solid acid catalysts such as mesoporous silica alumina. In the present embodiment, a step may be introduced to regenerate the catalyst in which the conversion of propylene and hydrocarbon having a carbon number of 4 or more is reduced, and the introduction of the regeneration step results in the amount of coke components accumulated by raw material conversion. It is possible to reduce and produce ethylene in a stable yield.

By using the zeolite having the above average pore diameter, ethylene can be produced with high yield using propylene as a raw material. That is, if the average pore diameter is in the above range, the diffusion of propylene into the zeolite crystal can be promoted, and ethylene can be generated more selectively.
From the above viewpoint, in the present invention, the zeolite is preferably an oxygen 8-membered ring structure zeolite.

The oxygen 8-membered ring structure zeolite is, for example, preferably AEI, AFX, CHA, ERI, KFI, LEV, SAS, SAV, SZR, PAU, RHO, RTH, LTA by a structure code (Framework Type Code) defined by IZA. , UFI, etc.

Normally, the ion exchange site of the zeolite is a proton exchange type of proton (H), but a part thereof is an alkali metal such as Li, Na, K, Rb, Cs, etc., alkali earth such as Ca, Sr, Ba etc. It may be replaced by a transition metal such as Cr, Cu, Ni, Fe, Mo, W, Pt, Re and the like. Such zeolite can be prepared by subjecting the zeolite to the ion exchange treatment described later.

When the zeolite is a silicate, SiO ₂ / M ₂ O ₃ (wherein the denominator of the above molar ratio represents the total amount of Al ₂ O ₃ , Ga ₂ O ₃ , B ₂ O ₃ and Fe ₂ O ₃ ) The ratio is usually 5 or more, preferably 8 or more, more preferably 10 or more, more preferably 15 or more, and usually 500 or less, preferably 100 or less, more preferably 80 or less, more preferably 60 or less, Particularly preferably, it is 40 or less. The above ratio is a value obtained on the assumption that all Si atoms in the zeolite are contained as SiO _{2 and} all the M contained in the zeolite is contained as M ₂ O ₃ . When the SiO ₂ / M ₂ O ₃ molar ratio is in the above range, the amount of acid derived from the strong acid site and the weak acid site is sufficiently obtained, and the conversion activity of propylene is further increased. In addition, the SiO ₂ / M ₂ O ₃ molar ratio is because it tends to be able to suppress deactivation of the catalyst due to coke deposition, detachment of the T atom other than silicon from the skeleton, and reduction in acid strength per acid point, etc. It is preferable to exist in the said range. The SiO ₂ / M ₂ O ₃ molar ratio of the zeolite is usually determined by ICP elemental analysis or fluorescent X-ray analysis. X-ray fluorescence analysis creates a calibration curve of the fluorescence X-ray intensity of the analysis element in the standard sample and the atomic concentration of the analysis element, and this calibration curve determines the silicon in the zeolite sample by X-ray fluorescence analysis (XRF) The content of atoms, aluminum, gallium and iron can be determined. In addition, since the fluorescent X-ray intensity of the boron element is relatively small, the content of the boron atom is preferably measured by ICP elemental analysis.

When zeolite is phosphate, (Al + P) / Si molar ratio of silicoaluminophosphate or (Al + P) / M of metalloaluminophosphate having divalent metal (where M represents a divalent metal) The molar ratio is usually 5 or more, preferably 10 or more, and usually 500 or less, preferably 100 or less. Specific examples of the divalent metal include Ga, Mg, Mn, Fe, Co and Zn. The durability of the catalyst can be improved by setting the content to the above lower limit, and the catalyst activity can be kept high by setting the content to the above upper limit.

The total acid content of the zeolite (hereinafter referred to as total acid content) is the sum of the amount of acid sites present in the crystal pores of the zeolite and the amount of acid sites on the crystal outer surface of the zeolite (hereinafter referred to as the surface acid content). It is. The total acid amount is not particularly limited, but is usually 0.01 mmol / g or more, preferably 0.1 mmol / g or more, more preferably 0.3 mmol / g or more, and still more preferably 0.5 mmol / g or more It is. Also, it is usually 2.5 mmol / g or less, preferably 1.5 mmol / g or less, more preferably 1.2 mmol / g or less, and still more preferably 0.9 mmol / g or less. By making the total acid amount in the above range, the conversion activity of propylene is maintained high, and the formation of coke inside the pores of the zeolite is suppressed, and ethylene formation can be promoted. Here, the total amount of acid is calculated from the desorption amount of ammonia in ammonia temperature-programmed desorption (NH ₃ -TPD). Specifically, the zeolite is dried at 500 ° C. under vacuum for 30 minutes as pretreatment, and then the pretreated zeolite is brought into contact with excess ammonia at 100 ° C. to adsorb the ammonia on the zeolite. Excess ammonia is removed from the obtained zeolite by vacuum drying at 100 ° C. or by contacting with steam at 100 ° C. Next, the zeolite adsorbed with ammonia is heated at a heating rate of 10 ° C./min in a helium atmosphere, and the amount of ammonia desorbed at 100-600 ° C. is measured by mass spectrometry, and the amount of ammonia desorbed per zeolite is all Let it be the amount of acid. However, the total amount of acid is obtained by separating the TPD profile by a Gaussian function, and the sum of the areas of the waveforms having peak tops at 240 ° C. or higher. The “240 ° C.” is an index used only for determining the position of the peak top, and is not intended to determine the area of a portion of 240 ° C. or more. As long as the peak top has a waveform of 240 ° C. or more, the “area of the waveform” is the entire area of the waveform separated. When there are a plurality of waveforms having a peak top at 240 ° C. or more, the sum of the areas is used. The total amount of acid of the present invention does not include the amount of acid derived from a weak acid point having a peak top below 240 ° C. This is because it is not easy to distinguish between adsorption from weak acid points and physical adsorption in the TPD profile.

The amount of outer surface acid of the zeolite is not particularly limited, but generally 8% or less, preferably 5% or less, more preferably 3% or less, still more preferably 1% or less based on the total acid amount of the zeolite , Most preferably 0%. By making the amount of outer surface acid below the upper limit value, it is possible to reduce side reactions which generate unintended hydrocarbons and to further improve the yield of ethylene.

The value of the amount of outer surface acid of zeolite is determined by the method described in WO 2010/128644.
Specifically, the zeolite is dried at 500 ° C. under vacuum for 1 hour as a pretreatment, and then the pretreated zeolite is brought into contact with pyridine vapor at 150 ° C. to adsorb the pyridine onto the zeolite, and vacuum exhaust and helium at 150 ° C. The desorption amount of pyridine per weight of zeolite at 150 to 800 ° C. by a temperature rising desorption method at a temperature rising rate of 10 ° C./min of a zeolite adsorbed with pyridine obtained by removing excess pyridine from the zeolite by flow It is determined from
The outer surface acid amount and the like of the zeolite are not particularly limited, but can be adjusted by silylation treatment, steam treatment, heat treatment, acid treatment, ion exchange treatment and the like. Moreover, it can adjust also by methods, such as the support processing of a metallic element. Furthermore, it can be adjusted also by a method in which a binder and the outer surface acid point of the zeolite are bonded when the zeolite is molded.

When the zeolite contains an aluminosilicate, SiO ₂ / Al ₂ O ₃ of the crystal surface layer obtained by XPS is not particularly limited, but usually SiO ₂ / Al _{2 of the} whole crystal obtained by ICP elemental analysis It is 1.0 times or more, preferably 1.5 times or more, more preferably 2.0 times or more, still more preferably 3.0 times or more, and most preferably 5.0 times or more that of O ₃ . By setting this range, side reactions in the crystal surface layer can be suppressed, and ethylene formation inside the zeolite crystal can be promoted.

The SiO ₂ / Al ₂ O ₃ ratio of the zeolite crystal surface layer is a numerical value obtained by X-ray photoelectron spectroscopy (XPS). XPS is an analysis method for obtaining information on the crystal surface, and it is possible to obtain SiO ₂ / Al ₂ O ₃ of the crystal surface layer by this analysis method. Although the measuring method is not particularly limited, the contents of Si and Al can usually be calculated from the Si2p spectrum and the Al2p spectrum, respectively.

Zeolites may be used as they are without special treatment, but at least one treatment selected from silylation, steam treatment, heat treatment, acid treatment and ion exchange, total acid amount, outer surface acid amount and / or external amount Use of a zeolite whose pore diameter at the surface opening is properly adjusted may minimize the fluctuation range of the ethylene / propylene ratio in the product, and may be able to stably produce ethylene in a high yield. Among these, in order to adjust the total acid amount of zeolite, a method of performing at least one treatment selected from steam treatment, heat treatment and ion exchange is preferable, and among them, at least one treatment selected from steam treatment and ion exchange The method of applying water, especially the method of applying steam treatment may be preferred because of the simplicity of the process. On the other hand, in order to adjust the amount of acid on the outer surface, it may be effective to perform at least one treatment selected from silylation treatment and steam treatment. Moreover, in order to adjust the pore diameter of the outer surface opening, it may be effective to perform silylation treatment. As described above, it may be preferable to perform the above treatments appropriately in combination, because the total acid amount, the outer surface acid amount and / or the pore diameter of the outer surface opening of the zeolite can be appropriately adjusted.
Hereinafter, these processing methods will be described.

In the zeolite, it is considered that the amount of outer surface acid is reduced by silylation treatment, usually, the acid points on the outer surface are coated and inactivated. When the amount of outer surface acid decreases, side reactions occurring on the outer surface of the zeolite are suppressed. Specifically, the lower conversion olefin such as ethylene and butene generated in the zeolite pore comes into contact with the acid point on the outer surface of the zeolite by the conversion reaction of propylene, thereby suppressing the reaction to generate the component other than the desired product. It is considered to be effective. In addition, in the silylation of the outer surface acid point, since the silyl group is also bonded to the acid point constituting the pores possessed by the zeolite, the pore diameter of the outer surface opening is slightly reduced, and molecular diffusion to the outside of the crystal Is considered to have the effect of suppressing As a result, it can be considered that the formation of hydrocarbons having 5 or more carbon atoms, which are larger molecules, can be suppressed, and the selectivity of ethylene is improved.
Hereinafter, the silylation treatment will be specifically described taking liquid phase silylation as an example.

When liquid phase silylation is carried out, the zeolite to be subjected to the silylation treatment may be provided with a specific range of water content. The water contained in the zeolite may be adjusted to a specific range by artificially supplying water, even if it is originally contained in the zeolite. In general, the zeolite of the present invention is obtained by calcining one obtained by hydrothermal synthesis, and further, if necessary, converting it to an ammonium type and then calcining it to use it to a proton type. Therefore, the water content of the zeolite before the silylation treatment is usually assumed to be very small, and may be subjected to the silylation treatment as it is, or water is supplied to the zeolite so as to have a specific water content, The water content may be adjusted and used (hereinafter, it may be referred to as humidity control treatment).

The treatment time of the silylation depends on the reaction temperature, but is usually 0.1 hour or more, preferably 0.5 hour or more, more preferably 1 hour or more, and the treatment time as long as the catalyst performance is not impaired. There is no particular upper limit. By setting the treatment time to the above-mentioned range, the silylation coating of the outer surface acid point of the zeolite proceeds, and the amount of the outer surface acid is preferably sufficiently reduced. Such silylation or steam treatment described next may be carried out at the time of powder of zeolite alone, or may be carried out on a material which is molded with a binder or the like and used as a zeolite catalyst. Good.

The steam treatment temperature is not particularly limited, but is usually 400 ° C. or more, preferably 500 ° C. or more, more preferably 600 ° C. or more. The temperature is usually 1000 ° C. or less, preferably 900 ° C. or less, more preferably 800 ° C. or less. By setting the steam treatment temperature in the above range, T atoms other than silicon can be efficiently removed from the skeleton in a short treatment time without causing destruction of the skeleton and the total acid amount and the outer surface acid amount can be reduced. It is preferable in that it can be done.

The steam (steam) used for steam treatment can be used after diluting with air or an inert gas such as helium or nitrogen. The water vapor concentration at that time is not particularly limited, but usually 5% by volume or more, preferably 10% by volume or more, more preferably 20% by volume or more with respect to the whole gas used when steaming the zeolite It is more preferably 30% by volume or more, usually 100% by volume or less, preferably 90% by volume or less, more preferably 80% by volume or less, and still more preferably 70% by volume or less. The upper limit is not particularly limited, and 100% by volume of water vapor can be used. By setting the water vapor concentration in the above-mentioned range, it is preferable in that the T atom can be efficiently removed from the skeleton in a short processing time, and the total acid amount and the outer surface acid amount can be reduced.

The pressure for steam treatment (total pressure including dilution gas) is not particularly limited, but is usually 0.05 MPa or more (absolute pressure, the same applies hereinafter), preferably 0.075 MPa or more, more preferably 0.1 MPa or more The pressure is usually 2 MPa or less, preferably 1 MPa or less, more preferably 0.5 MPa or less. By setting the pressure of the steam treatment to the above pressure range, the T atoms can be efficiently removed from the skeleton in a short time, and the total acid amount and the outer surface acid amount can be reduced, which is preferable.

The partial pressure of the water vapor is not particularly limited, but is usually 0.01 MPa or more (absolute pressure, the same applies hereinafter), preferably 0.03 MPa or more, more preferably 0.05 MPa or more, and usually 2 MPa or less It is 1 MPa or less, more preferably 0.5 MPa or less, and still more preferably 0.2 MPa or less. By setting the partial pressure of the water vapor in the above pressure range, the T atoms can be efficiently removed from the skeleton in a short time, which is preferable in that the total acid amount and the outer surface acid amount can be reduced.

<Heat treatment>
The heat treatment method is not particularly limited, but specifically, the zeolite may be subjected to high temperature treatment under at least one atmosphere selected from air and inert gas. Thereby, the total amount of acid and the amount of outer surface acid of the zeolite can be reduced.

<Acid treatment>
Although the method of acid treatment of zeolite is not particularly limited, specifically, a method using an acidic aqueous solution may be mentioned.
The type of acid used in the acidic aqueous solution is not particularly limited, but inorganic acids such as sulfuric acid, nitric acid, hydrochloric acid and phosphoric acid, carboxylic acids such as formic acid, acetic acid and propionic acid, oxalic acid, malonic acid and the like And the like can be used. Among these, preferred are sulfuric acid, nitric acid and hydrochloric acid.

The acid concentration of the acidic aqueous solution is not particularly limited, but is usually 0.01 M or more, preferably 0.1 M or more, more preferably 1 M or more, and usually 10 M or less, preferably 8 M or less More preferably, it is 6 M or less. By setting the concentration of the acid in the above range, it is preferable in that the total acid amount and the outer surface acid amount can be efficiently reduced in a short treatment time without causing the collapse of the skeletal structure.

The temperature of the acid treatment is not particularly limited, but it can also be performed usually at room temperature to 100 ° C. under normal pressure, and at 100 ° C. or higher in a pressure resistant vessel, and is usually 40 ° C. or higher, preferably 60 ° C. or higher The temperature is more preferably 80 ° C. or more, usually 200 ° C. or less, preferably 180 ° C. or less, more preferably 160 ° C. or less. By setting the temperature of the acid treatment in the above range, it is preferable in that the total acid amount and the outer surface acid amount can be efficiently reduced in a short treatment time while suppressing the collapse of the skeletal structure.

The average primary particle size of the zeolite is not particularly limited, but is usually 0.01 μm or more, preferably 0.03 μm or more, more preferably 0.05 μm or more, and usually 10 μm or less, preferably 5 μm or less Preferably it is 1 micrometer or less, More preferably, it is 0.5 micrometer or less, Especially preferably, it is 0.3 micrometer or less. By setting it in the above-mentioned range, the diffusivity in the zeolite crystal in the catalytic reaction and the catalytic efficiency coefficient become sufficiently high, the zeolite crystallinity becomes sufficient, and it is preferable in that the hydrothermal stability is high.
The average primary particle size in the present embodiment corresponds to the particle size of primary particles. Therefore, it is different from the particle size of the aggregate measured by the light scattering method or the like. The average primary particle size is optionally 20 or more particles in observation of particles by a scanning electron microscope (hereinafter abbreviated as "SEM") or a transmission electron microscope (hereinafter abbreviated as "TEM") It measures and it calculates | requires by averaging the particle diameter of the primary particle. When the particle is rectangular, the long side and short side of the particle are measured (the depth is not measured), and the average of the sum, that is, (long side + short side) ÷ 2, is calculated. Primary particle size.

(BET specific surface area)
The BET specific surface area of the zeolite is not particularly limited, but is usually 300 m ² / g or more, preferably 400 m ² / g or more, more preferably 500 m ² / g or more, and usually 1000 m ² / g or less, preferably Is 800 m ² / g or less, more preferably 750 m ² / g or less. By being in the above range, the number of active sites present on the inner surface of the pores is sufficiently large, and the catalytic activity is preferably high. In addition, a BET specific surface area can be measured by the measuring method according to JIS8830 (The specific surface area measuring method of powder (solid) by gas adsorption). Using nitrogen as an adsorption gas, the BET specific surface area can be determined by a one-point method (relative pressure: p / p0 = 0.30).

The pore volume of the zeolite is not particularly limited, but is usually 0.1 ml / g or more, preferably 0.2 ml / g or more, and usually 3 ml / g or less, preferably 2 ml / g or less. By being in the above range, the number of active sites present on the inner surface of the pores is sufficiently high, and the catalyst activity is preferably high. The pore volume is preferably a value determined from the adsorption isotherm of nitrogen obtained by relative pressure method.

Zeolites can generally be prepared by hydrothermal synthesis. For example, in the case of a silicate, at least one selected from an aluminum source, a gallium source, a boron source, and an iron source, a silicon source, an alkaline aqueous solution and the like are added to water to form a uniform gel, The structure directing agent is added according to and stirred to prepare a raw material gel. The raw material gel thus obtained is crystallized by heating in a closed vessel and reacting under autogenous pressure. The reaction temperature at this time is not particularly limited, but crystallization is usually carried out by maintaining at 100 to 200 ° C. At the time of crystallization, seed crystals may be added as necessary, and from the viewpoint of productivity, it is preferable to add the seed crystals in that the reaction time can be shortened and the crystal particles can be micronized. Then, the crystallized solid component is filtered and washed, and the solid content is dried and subsequently calcined to obtain a zeolite of the alkali (earth) metal type. The drying temperature is not limited, but is usually 100 to 200 ° C. The above-mentioned firing temperature is not limited, but is usually 400 to 700 ° C. Thereafter, ion exchange is carried out with an acidic solution or ammonium salt solution and calcination is carried out to obtain H-type zeolite.

The cation used as the structure directing agent is an anion that does not inhibit the formation of zeolite. The anion is not particularly limited, and specifically, it includes halogen ions such as Cl ⁻ , Br ⁻ and I ⁻ , hydroxide ions, acetates, sulfates and carboxylates. Among them, hydroxide ion is particularly preferably used.

Since zeolite is a catalytically active component, zeolite may be used as it is in the reaction as a zeolite catalyst, or it may be granulated or shaped using a substance or binder inert to the reaction, or these may be mixed and reacted You may use.
As the substance and binder inert to the reaction, alumina or alumina sol, silica, silica sol, quartz, and mixtures thereof can be mentioned.
Even if the zeolite is not used as a single zeolite but is used after being shaped using a binder or the like, the method of measuring the total acid amount and the outer surface acid amount should be measured by the same method as described above. And the preferred range is also the same value.
Hereinafter, a preferable aspect in the case of using and shaping | molding using a binder etc. instead of using with a single zeolite as mentioned above is demonstrated using the word "zeolite catalyst."

The total acid amount and the outer surface acid amount of the whole zeolite catalyst can be measured by the same method as the total acid amount and the outer surface acid amount of the above-mentioned zeolite. The total acid amount of the zeolite catalyst is not particularly limited, but is usually 0.01 mmol / g or more, preferably 0.1 mmol / g or more, more preferably 0.3 mmol / g or more, still more preferably 0.5 mmol It is more than / g. Also, it is usually 2.5 mmol / g or less, preferably 1.5 mmol / g or less, more preferably 1.2 mmol / g or less, and still more preferably 0.9 mmol / g or less. By setting the total acid content of the zeolite catalyst in the above range, the conversion activity of propylene is maintained at a high level, the formation of coke inside the pores of the zeolite is suppressed, and the formation of ethylene can be further promoted. preferable.

The amount of outer surface acid of the zeolite catalyst is not particularly limited, but generally 8% or less, preferably 5% or less, more preferably 3% or less, more preferably 1% or less based on the total acid amount of the catalyst Below, most preferably it is 0%. By setting the upper limit value or less, side reactions are suppressed and ethylene selectivity can be easily maintained in a high state.
In addition, in order to adjust the total acid amount and outer surface acid amount of the zeolite catalyst, it is preferable to use as a binder such as silica or alumina having no acid point. When a binder having an acid point such as alumina is used, the total acid amount of the catalyst and the outer surface acid amount are measured as a total value including the acid amount of the binder as well as the acid amount of the zeolite. Ru. In that case, it is possible to obtain the amount of acid of the zeolite alone which does not contain the amount of acid derived from the binder by obtaining the amount of acid derived from the binder by another method and subtracting the value from the amount of acid of the catalyst. The acid amount of the binder is determined by determining the acid amount of zeolite from the peak strength of tetracoordinated Al derived from the acid point of zeolite in ²⁷ Al-NMR, and the value is calculated from the acid amount of catalyst determined by ammonia thermal desorption. It is determined by the method of subtraction.

The amount of the phosphorus compound which may be contained in the zeolite catalyst is not particularly limited, but is usually 10% by mass or less, preferably 5% by mass or less, more preferably 1% by mass or less, still more preferably 0.1% by mass % Or less, particularly preferably 0.01% by mass or less. The term "phosphorus compound" as used herein refers to a substance such as phosphorus oxide, and does not mean zeolite itself such as aluminophosphate or gallophosphate.

<C2. Production method of ethylene>
The method for producing ethylene according to the present embodiment is a method for producing ethylene by bringing a feedstock hydrocarbon containing at least propylene and a hydrocarbon having 4 or more carbon atoms into contact with a catalyst, and the feedstock hydrocarbon comprising carbon atoms relative to the propylene The mass ratio of four or more hydrocarbons is in the range of 0.01 or more and 10 or less. Each step will be described in detail below.

The origin of production of propylene, which is a raw material, is not particularly limited. For example, those obtained by decomposition of naphtha by steam decomposition method or catalytic decomposition method (hereinafter referred to as naphtha decomposition products), ethane, propane, n-butane, atmospheric pressure gas oil (AGO), vacuum gas oil (VGO), natural gas liquid Those produced by thermal decomposition such as (NGL) (hereinafter referred to as thermal decomposition products), those produced by fluid catalytic cracking (FCC) of vacuum gas oil and residual oil, produced by MTO (Methanol to Olefin) reaction , Those produced by ETO (Ethylene / Ethanol to Olefin) reaction, those produced by the dehydrogenation reaction of alkanes such as propane, and the like, and hydrogen / carbon monoxide mixed gas obtained by gasification of coal as a raw material What is manufactured by performing a Tropsch synthesis etc. is mentioned. Among these, the naphtha decomposition product, the thermal decomposition product, and the MTO reaction product are preferable, and the naphtha decomposition product is more preferable.

As hydrocarbons having 4 or more carbon atoms, olefins such as butene, pentene and hexene; paraffins such as butane, pentane and hexane; alkynes such as butyne, pentin and hexine; dienes such as butadiene, pentadiene and hexadiene; It may contain aromatic hydrocarbons such as benzene, toluene, xylene and the like. The above-mentioned olefins, paraffins, alkynes and dienes may contain linear or branched structures or isomers of cyclic structures, but from the viewpoint of reactivity, linear structures are preferred. Further, from the viewpoint of reactivity, olefins are preferable, preferably having 8 or less carbon atoms (butene, pentene, hexene, heptene, octene), more preferably 6 or less carbon atoms (butene, pentene, hexene), and further Preferably it is 5 or less carbon atoms (butene, pentene), most preferably butenes having 4 carbon atoms. As butene, any of four isomers can be used.

In addition, hydrocarbons which are raw materials may contain hydrocarbons other than propylene and hydrocarbons having 4 or more carbon atoms (hereinafter sometimes referred to as “other hydrocarbons”), for example, methane, ethane, It may contain a hydrocarbon having 3 or less carbon atoms such as ethylene, acetylene, propane and methylacetylene. In addition to propylene, methanol or dimethyl ether may be contained, and the mixing ratio is not limited.

Normally, in ethylene production from propylene, the target product ethylene may be contained in the raw material hydrocarbon, but it is likely to be converted to another olefin such as butene or hexene by contact with a catalyst It is preferable to use, as a raw material, propylene in a state in which ethylene is separated. The mass ratio of propylene to ethylene contained in the raw material hydrocarbon is not particularly limited, but is usually 1 or more, preferably 5 or more, more preferably 10 or more, and further preferably 15 or more. Particularly preferably, it is 30 or more, and the larger, the better. As the ratio is higher, consumption of ethylene which is a target product can be suppressed, and ethylene can be efficiently produced.

The reactor used for ethylene production is a reactor having a raw material inlet and a product gas outlet, and is not particularly limited as long as the propylene feedstock is in the gas phase in the reaction zone, but a fixed bed reactor, moving Bed reactors or fluidized bed reactors may be chosen. Fluidized bed reactors are preferred in order to produce with a constant ethylene yield when the propylene conversion is highly variable.
In addition, although it can be carried out either batchwise, semicontinuously or continuously, it is preferable to carry out continuously, and the method may be a method using a single reactor, or in series or in parallel. It may be a method using a plurality of reactors arranged.
In addition, when the above-mentioned catalyst is loaded into the fluidized bed reactor, in order to keep the temperature distribution of the catalyst layer small, particulates inert to the reaction such as quartz sand, alumina, silica, silica-alumina, etc. are mixed with the catalyst May be filled. In this case, the amount of the inert granular material such as quartz sand is not particularly limited. In addition, it is preferable that a granular material is a particle size comparable as a catalyst from the surface of uniform mixing property with a catalyst.
The reaction substrate (reaction raw material) may be separately supplied to the reactor for the purpose of dispersing the heat generated by the reaction.

(Substrate concentration)
The total concentration of propylene and hydrocarbon having 4 or more carbon atoms in all the feed components fed to the reactor is not particularly limited, but usually 3 mol% or more, preferably 5 mol% or more, more preferably in all the feed components. Is 10 mol% or more, more preferably 20 mol% or more, usually 100 mol% or less, preferably 80 mol% or less, more preferably 60 mol% or less, still more preferably 40 mol% or less. By setting the substrate concentration in the above range, the formation of aromatic compounds and paraffins can be suppressed to a lower level, and the ethylene yield can be improved. Further, since the reaction rate can be maintained high, the amount of catalyst can be reduced and the size of the reactor can be reduced.
Therefore, it is preferable to dilute the reaction substrate with the diluent described below, as necessary, to achieve such a preferred substrate concentration.

(Weight space velocity)
The weight space velocity referred to herein is the total flow rate (weight / hour) of propylene and hydrocarbon having 4 or more carbon atoms, which are reaction raw materials per weight of the catalyst (catalytic active component), where the weight of the catalyst is Is the weight of the catalytically active component which does not contain an inactive component and a binder used for granulation and molding of the catalyst.

The weight space velocity is not particularly limited, but is usually 0.01 Hr ^-1 or more, preferably 0.1 Hr ^-1 or more, more preferably 0.2 Hr ^-1 or more, still more preferably 0.5 Hr ^-1 or more. , and the normal 50 hr ^-1 or less, preferably 10 hr ^-1 or less, more preferably ^{5 Hr -1} or less, more preferably ^{3HR -1} or less. By setting the weight space velocity to the above range, the proportion of unreacted propylene in the product gas discharged from the product gas outlet of the reactor can be further reduced, and by-products such as aromatic compounds and paraffins are generated. It is preferable because it can reduce the amount of ethylene and can improve the ethylene yield. In addition, the amount of catalyst required to obtain a constant production amount can be reduced, and the size of the reactor can be reduced.

(Reaction temperature)
The reaction temperature is not particularly limited as long as it is a temperature at which propylene and hydrocarbons having 4 or more carbon atoms make contact with a catalyst to produce ethylene, but usually 300 ° C. or more, preferably 400 ° C. or more, more preferably Is 425 ° C. or higher, more preferably 450 ° C. or higher, particularly preferably 475 ° C. or higher, most preferably 500 ° C. or higher, usually 800 ° C. or lower, preferably 700 ° C. or lower, more preferably 650 ° C. or lower, more preferably 600 It is less than ° C. By setting the reaction temperature within the above range, the formation of aromatic compounds and paraffins can be suppressed, and thus the yield of ethylene in one pass can be improved. In addition, since the conversion activity of propylene can be maintained at a high level, and the reaction gas can contain hydrogen together with propylene and hydrocarbons having 4 or more carbon atoms, the contact effect can be maximized, It can be produced with high ethylene yield over time. Furthermore, when the zeolite is a silicate, it is preferable in that the catalyst life can be maintained since the dealumination from the zeolite skeleton is suppressed. Here, the reaction temperature refers to the temperature at the outlet of the catalyst layer.

(Reaction raw material partial pressure)
The partial pressure of propylene and hydrocarbon having 4 or more carbon atoms is not particularly limited, but usually 0.001 MPa or more (absolute pressure, the same applies hereinafter), preferably 0.005 MPa or more, more preferably 0.0075 MPa or more, More preferably, it is 0.010 MPa or more, particularly preferably 0.015 MPa or more, most preferably 0.020 MPa or more, and usually 1 MPa or less, preferably 0.5 MPa or less, more preferably 0.2 MPa or less, further preferably 0. It is 1 MPa or less. Coking can be suppressed by setting the partial pressure of the raw material in the above range, and the yield of ethylene can be improved.

(The ratio of hydrocarbon component of 4 or more carbon atoms to propylene)
The mass ratio of the hydrocarbon having 4 or more carbon atoms to propylene contained in the hydrocarbon which is the raw material is 0.01 or more and 10 or less. Preferably, it is 0.1 or more, more preferably 0.2 or more, further preferably 0.5 or more, preferably 5 or less, more preferably 2 or less, and still more preferably 1 or less.
When the mass ratio of hydrocarbons having 4 or more carbon atoms to propylene in the hydrocarbon is in the above range, the conversion efficiency of the raw material propylene to ethylene is enhanced, and the ethylene / propylene ratio of the reactor product gas outlet changes with time The reason why it can be reduced is still unclear, but is presumed as follows. In high-temperature catalytic reactions subject to thermodynamic equilibrium restrictions between olefins as in the present invention, propylene is converted to ethylene and hydrocarbons having 4 or more carbon atoms. On the other hand, part of hydrocarbons having 4 or more carbon atoms are also converted to propylene and ethylene. If the catalytic activity increases, it tends to approach the thermodynamic equilibrium composition between olefins, so mixing of hydrocarbons having 4 or more carbon atoms in the raw material propylene into the feed hydrocarbon in the above range restricts the reaction equilibrium. Since the conversion of propylene to hydrocarbons having 4 or more carbon atoms is suppressed, and the conversion of hydrocarbons having 4 or more carbon atoms to propylene is also suppressed, propylene and hydrocarbons having 4 or more carbon atoms are Since the conversion of ethylene to ethylene tends to be promoted more effectively, the conversion efficiency to ethylene can be synergistically enhanced, and ethylene can be produced at a high ethylene / propylene ratio.
The catalyst for obtaining the above effects is not limited, but is preferably zeolite whose shape selectivity by the pore diameter is effective, and more preferably zeolite having a small pore diameter oxygen 8-membered ring structure close to the molecular size of the target product .

(Proportion of butene)
The proportion of butenes contained in hydrocarbons having 4 or more carbon atoms is not particularly limited, but as described above, in order to efficiently promote the conversion of propylene to ethylene, it is usually 10 mol% because of reaction equilibrium constraints. The content is preferably 30 mol% or more, more preferably 50 mol% or more, still more preferably 80 mol% or more, and the upper limit is 100 mol%.

(Proportion of linear butene)
The proportion of linear butene (1-butene, 2-butene) contained in butene is not particularly limited, but it is usually 10 mol% or more, preferably 30 mol% or more, more preferably 50 mol% or more, more preferably Is 80 mol% or more, and the upper limit is 100 mol%. From the viewpoint of the diffusivity into the zeolite pores, the larger the proportion of linear butenes, the better the ethylene yield tends to be improved, which is preferable.

(Coke component)
By the conversion of propylene and hydrocarbons having 4 or more carbon atoms, a part of them accumulates on the inner / outer surface of the crystal as coke (heavy components such as polycyclic aromatics) which need to be removed by regeneration treatment, and the catalyst activity Tend to decrease. Therefore, the content (coke content) of the above-mentioned coke is usually 30% by mass or less with respect to the catalyst which is the active component, in order to obtain appropriate catalyst activity and high ethylene selectivity. % Is preferable, it is more preferable to keep it at 15% by mass or less, and generally it is preferable that the content be less than 15% by mass. However, it has the above-mentioned oxygen 8-membered ring structure and the International Zeolite Association (IZA) as a composite building unit In a zeolite containing a defined d6r in its framework (eg, AEI, AFX, CHA, ERI, KFI, LEV, SAV), a large space (cage space) inside the pore is occupied by a certain amount of coke, Since the pore space can be narrowed, high ethylene selectivity may be expressed, and is usually 0.1% by mass or more, and maintained at 1.0% by mass or more. , More preferably it is kept 3.0 mass% or more, further preferably maintained at least 5.0 wt%. When the coke content in the catalyst is at least the above lower limit, molecular diffusion in the catalyst can be further suppressed, and the conversion of hydrocarbons having 4 or more carbon atoms into ethylene can be promoted. In the production of ethylene, it is preferable to maintain the coke content above the above lower limit value because the ethylene selectivity can be maintained high. On the other hand, when the amount of coke accumulated in the catalyst becomes equal to or more than the upper limit value, the catalyst activity tends to decrease. Therefore, it is preferable to adjust the regeneration conditions so that the amount of coke accumulated in the catalyst falls within the above range by the regeneration method described later.

In the present invention, the amount of coke accumulated in the catalyst means that the catalyst accumulated in coke is heated to 550 ° C. at a heating rate of 10 ° C./min under a flow of inert gas such as helium (50 cc / min), By holding for 30 minutes, remove adsorbed water and light-boiling hydrocarbon components, then switch to air circulation (50 cc / min), heat to 600 ° C at a heating rate of 10 ° C / minute, and hold for 60 minutes. It can be calculated by determining the weight loss due to oxidative combustion in a temperature range of 550 ° C. or more at this time.

(Conversion rate)
In the present invention, the conversion of propylene and hydrocarbon having 4 or more carbon atoms is not particularly limited, but the conversion is usually 5% or more, preferably 20% or more, more preferably 30% or more, and still more preferably It is 40% or more, usually 100% or less, preferably 80% or less, more preferably 60% or less, and still more preferably 50% or less. By adjusting the conversion rate of propylene to be in the above range, byproducts of butene, aromatic compounds and paraffins, and accumulation of coke in pores can be suppressed, and the yield of ethylene is improved. It is preferable because it can be In addition, the separation efficiency of components such as ethylene and propylene from the product can be enhanced. That is, in the present invention, the catalyst is preferably subjected to a regeneration step so that the conversion of propylene is in the above-mentioned range.

In general, accumulation of coke proceeds with the passage of reaction time, and the conversion ratio of propylene and hydrocarbons having 4 or more carbon atoms tends to decrease. Therefore, as described later, the stage at which the amount of coke accumulated in the catalyst increases Preferably, the catalyst is subjected to a regeneration step. Moreover, it does not restrict | limit especially as a method to operate | move in the range of said conversion rate.

(yield)
In the present invention, the yield of ethylene is not particularly limited, but the yield is usually 5% or more, preferably 10% or more, more preferably 20% or more, still more preferably 30% or more, and usually 100 % Or less, preferably 80% or less, more preferably 60% or less. When the yield of ethylene is in the above range, the ratio of the target product at the outlet of the reactor becomes sufficient, which is preferable in that the cost of raw materials and the load of separation / purification can be reduced.

The yield in the present specification is a value calculated by each of the following formulas. In each of the following formulas, “derived carbon flow rate (mol / Hr)” of hydrocarbons such as ethylene, propylene, butene, C5 +, paraffin and aromatic compound means the molar flow rate of carbon atoms constituting each hydrocarbon. Do. The paraffin is the sum of paraffins of 1 to 4 carbons, the aromatic compound is the sum of benzene, toluene and xylene, and C5 + is the sum of hydrocarbons having 5 or more carbons excluding the aromatic compounds.
-Ethylene yield (%) = reactor generated gas outlet ethylene-derived carbon molar flow rate (mol / Hr) / reactor generated gas outlet total carbon molar flow rate (mol / Hr) x 100
Propylene yield (%) = reactor product gas outlet propylene-derived carbon molar flow rate (mol / Hr) / reactor product gas outlet total carbon molar flow rate (mol / Hr) × 100
-Butene yield (%) = reactor product gas outlet butene-derived carbon molar flow rate (mol / Hr) / reactor product gas outlet total carbon molar flow rate (mol / Hr) x 100
Here, the butene-derived carbon molar flow rate is treated without distinction of the isomers.
C5 + yield (%) = reactor generated gas outlet C5 + derived carbon molar flow rate (mol / Hr) / reactor generated gas outlet total carbon molar flow rate (mol / Hr) × 100
-Paraffin yield (%) = reactor generated gas outlet paraffin derived carbon molar flow rate (mol / Hr) / reactor generated gas outlet total carbon molar flow rate (mol / Hr) × 100
Aromatic compound yield (%) = reactor product gas outlet aromatic compound derived carbon molar flow rate (mol / Hr) / reactor product gas outlet total carbon molar flow rate (mol / Hr) × 100

(Reaction product gas)
Reactor product gas outlet gas (reactor exhaust gas) includes a mixed gas containing ethylene as a reaction product, propylene as a raw material, propylene as a raw material, a hydrocarbon having 4 or more carbon atoms, paraffin, an aromatic compound, and a diluent can get. The concentration of ethylene in the mixed gas is not particularly limited, but is usually 5% by mass or more, preferably 10% by mass or more, more preferably 20% by mass or more, and usually 95% by mass or less, preferably 90% by mass or less It is. It is preferable at the point which can reduce the load of isolation | separation / refinement | purification that the ethylene concentration in the said mixed gas is the said range.
Depending on the reaction conditions, propylene is contained as unreacted raw material in the reaction product gas, but when ethylene selectivity is low, that is, when by-product selectivity is high, this leads to raw material loss and increases the production cost Therefore, there are also cases where it is preferable to operate under conditions where the ethylene selectivity is high even under conditions where the propylene conversion rate is lowered. In the present invention, if desired, components other than ethylene may be separated and recovered. The residue from which the desired component has been separated and recovered contains light paraffin, light olefin, aromatic compounds and the like. At least a portion of the remaining portion can be mixed with a portion of the above-described source gas and used as a so-called recycle gas.

(Separation of reaction product gas)
A mixed gas containing ethylene as a reaction product, unreacted raw materials, by-products and a diluent as a reactor outlet gas is introduced into a known separation / purification facility, and recovered and purified according to the respective components, It is sufficient to process recycling and discharge.

(recycling)
Components other than ethylene (olefins, paraffins, etc.), particularly some or all of the hydrocarbons having 4 or more carbon atoms, may be recycled after being separated and / or purified and then mixed with the reaction materials or fed directly to the reactor You may Preferably, at least 10% of hydrocarbons having 4 or more carbon atoms contained in the product gas discharged from the product gas outlet of the reactor is preferably recycled to the reactor, and more preferably 20% or more. And 30% or more is more preferable. Further, among the by-products, components inert to the reaction can be reused as a diluent.

(Catalyst regeneration)
By converting the propylene and the hydrocarbon having 4 or more carbons (also referred to as C4 +) to regenerate the catalyst whose conversion is reduced, the fluctuation range of ethylene yield is minimized and ethylene is stabilized stably. Can be manufactured. In the present invention, regeneration of the catalyst means that the catalyst in a state in which the conversion rate of propylene and C4 + is reduced shows a conversion rate higher than that before the regeneration treatment.

With the conversion of propylene and hydrocarbons having 4 or more carbon atoms, the amount of coke components accumulated in the catalyst increases. The amount of coke component accumulated in the catalyst when the catalyst in which the accumulated amount of coke component is increased is subjected to a step of regenerating the catalyst is usually 0% by mass or more, preferably 0.01% by mass or more, and more The content is preferably 0.1% by mass or more, more preferably 1.0% by mass or more, particularly preferably 3.0% by mass or more, particularly preferably 5.0% by mass or more, and usually 30% by mass or less, preferably 25% by mass or less. It is not more than mass%, more preferably not more than 20 mass%, still more preferably not more than 15 mass%, particularly preferably not more than 10 mass%. When the amount of coke components accumulated in the catalyst used in the regeneration step is in the above range, diffusion of the regenerated gas and the decomposition gas in the catalyst can be secured in the regeneration step, and the catalyst activity can be effectively recovered. Because it is preferable. In this regeneration step, the catalyst activity can be recovered while appropriately reducing the amount of coke components accumulated in the catalyst, so ethylene can be stably produced in a high yield.

There is no particular limitation on the process of regenerating the catalyst. For example, when ethylene is produced from propylene and a hydrocarbon having 4 or more carbon atoms, supply of propylene and a hydrocarbon having 4 or more carbon atoms is stopped at a stage where coke content of the catalyst has increased, The catalyst having an increased coke content can be brought into contact with the regeneration gas by supplying a gas used for the regeneration (hereinafter also referred to as a regeneration gas). In addition, the catalyst with an increased coke content is removed from the reactor of the step of contacting propylene and hydrocarbons having 4 or more carbon atoms with the catalyst, transferred to the reactor of the step of regenerating the catalyst, and used for regeneration of the catalyst. Gas may be supplied to regenerate the catalyst.

In particular, in the case of performing the above-mentioned conversion process of propylene and hydrocarbons having 4 or more carbon atoms using a fixed bed reactor, the feed of the raw material is performed when the amount of coke accumulated in the catalyst becomes the above upper limit value. The regeneration gas can be supplied into the reactor and brought into contact with the catalyst. Alternatively, the catalyst may be withdrawn from the reactor, charged in a reactor separate from the reactor, and then contacted with the regeneration gas.

In addition, when using a moving bed reactor or a fluidized bed reactor to carry out the conversion process of propylene and hydrocarbons having 4 or more carbon atoms, an apparatus for contacting the regeneration gas with the catalyst is provided separately from the reactor. The catalyst withdrawn from the reactor is continuously fed to the apparatus, in which the catalyst is brought into contact with the regeneration gas, and then the catalyst brought into contact with the regeneration gas is continuously returned to the reactor while producing ethylene. It is preferable to carry out the reaction of

The gas used in the step of regenerating the catalyst is not particularly limited, but preferred examples include a gas containing at least one selected from oxygen, hydrogen and water vapor. Specific regeneration methods include combustion regeneration using oxygen as a regeneration gas, steam reforming regeneration using steam (water) as a regeneration gas, and hydrocracking using hydrogen as a regeneration gas. Among these, the regeneration gas is preferably a gas containing oxygen or hydrogen, and more preferably a gas containing hydrogen.

The method for producing oxygen is not particularly limited, and oxygen that is cryogenically separated from air in the atmosphere, oxygen generated from hydrogen peroxide, and the like can be mentioned, and those recovered from the air in the atmosphere are preferable. As the gas containing oxygen, air in the atmosphere may be used as it is.

A mixture of other gases may be used, or purified hydrogen may be used.

(Hydrogen partial pressure)
The hydrogen-containing gas in the regeneration gas is not particularly limited, but the hydrogen partial pressure in terms of absolute pressure is usually 0.001 MPa or more, preferably 0.01 MPa or more, and more preferably 0.03 MPa Or more, more preferably 0.05 MPa or more, particularly preferably 0.1 MPa or more, usually 4 MPa or less, preferably 1 MPa or less, more preferably 0.7 MPa or less, still more preferably 0.5 MPa or less, particularly preferably 0. It is 3 MPa or less. By setting the hydrogen partial pressure in the above range, the removal / reformation of coke components accumulated in the catalyst proceeds rapidly, so the catalyst state giving high raw material conversion activity and high ethylene selectivity is made efficient. be able to. In addition, equipment and energy for producing high pressure hydrogen can be reduced.

The space velocity of the regeneration gas is not particularly limited, but is usually 0.001 Hr ^-1 or more, preferably 0.01 Hr ^-1 or more, more preferably 0.1 Hr ^-1 or more, and usually 20 Hr ^-1 or less. , preferably 10 hr ^-1 or less, more preferably ^{5 Hr -1} or less. By setting the weight space velocity to the above range, the concentration of the hydrocarbon component and the water vapor contained in the catalyst can be reduced, so that the raw material conversion activity can be maintained at a high level. Furthermore, since the distribution of coke components accumulated in the catalyst can be made uniform, it is possible to suppress the nonuniform reaction in the catalyst and to increase the ethylene selectivity.

The concentration of the regeneration gas in the supply gas in the regeneration step is not particularly limited, but usually 5% by volume or more, preferably 10% by volume or more, more preferably 30% by volume or more, and usually 100% by volume The content is preferably 90% by volume or less, more preferably 80% by volume or less. The regeneration gas concentration is preferably high, and is usually 5% by volume or more, preferably 30% by volume or more, more preferably 60% by volume or more, and usually 100% by volume or less. By setting the concentration of regeneration gas within the above range, the contact between the catalyst and the regeneration gas becomes sufficient, and the removal / reformation of coke components proceeds rapidly, thus giving high raw material conversion activity and high ethylene selectivity. The catalyst state can be made efficient.

The fourth embodiment of the present invention is a method for producing ethylene by bringing a hydrocarbon into contact with a catalyst containing zeolite as an active component in a reactor, wherein the hydrocarbon has at least 4 carbon atoms or more. It contains a hydrocarbon, and the zeolite has at least an oxygen 8-membered ring structure, and the ratio of the outer surface acid amount to the total acid amount is 3% or less. Hereinafter, although this embodiment is described in detail, points different from the third embodiment will be described, and others can refer to the description of the third embodiment as appropriate.

<D1. Catalyst>
The catalyst used in the present embodiment will be described. The catalyst used in the reaction according to the present embodiment is one capable of producing ethylene from hydrocarbons, is a zeolite having at least an oxygen 8-membered ring structure, and the ratio of the amount of outer surface acid to the total amount of acid is 3 If it is% or less, it will not be limited in particular. For zeolite, the description in the third embodiment can be referred to.

In the present embodiment, the amount of outer surface acid of the zeolite is 3% or less with respect to the total amount of acid of the zeolite. The ratio of the outer surface acid amount to the total acid amount of the zeolite is preferably as small as possible, preferably 2% or less, more preferably 1% or less, still more preferably 0.5%, most preferably 0%. By setting the ratio of the amount of outer surface acid to the above range, the inside of the zeolite crystal in which the linear olefin contained in the hydrocarbon having 4 or more carbon atoms used as the raw material exhibits the shape selectivity of the oxygen 8-membered ring pore It is easy to obtain ethylene (dynamic molecular size: 0.39 nm) and propylene (dynamic molecular size: 0.45 nm) with high selectivity by reacting only with a high selectivity, and isobutene (dynamic molecular size: Since branched olefins having a large molecular size such as 0.50 nm do not easily diffuse through the oxygen 8-membered ring pore, by-products can be suppressed. Similarly, since the reaction point is limited to the inside of the crystal, branched olefins (isobutene, isopentene) of linear olefins (linear butene, linear penten, etc.) contained in hydrocarbon having 4 or more carbon atoms, which is the raw material, Etc.) can be suppressed. Furthermore, ethylene and propylene produced inside the crystal can be prevented from being consumed by side reactions at the outer surface acid point where the shape selectivity of the zeolite does not work, so high ethylene selectivity is maintained to maintain ethylene. Can be manufactured.

<D2. Production method of ethylene>
The method for producing ethylene according to the present embodiment is a method for producing ethylene by bringing a hydrocarbon into contact with a catalyst containing zeolite as an active component in a reactor, wherein the hydrocarbon has at least 4 carbon atoms. It contains hydrogen, and the zeolite has at least an oxygen 8-membered ring structure, and the ratio of the outer surface acid amount to the total acid amount is 3% or less. The respective steps will be described in detail below, but points different from the third embodiment will be described, and others can refer to the description of the third embodiment as appropriate.

There is no limitation on the method of producing a hydrocarbon feedstock having 4 or more carbon atoms, and for example, those produced by petroleum cracking feedstocks by catalytic cracking or steam cracking (C4 raffinate-1, C4 raffinate-2, etc.) ), Those obtained by performing FT (Fisher Tropsch) synthesis using hydrogen / CO mixed gas obtained by gasification of coal as raw material, those obtained by oligomerization reaction including dimerization reaction of ethylene, 4 or more carbon atoms Such as those obtained by paraffin dehydrogenation method or oxidative dehydrogenation method, those obtained by MTO reaction, those obtained by dehydration reaction of alcohol, those obtained by hydrogenation reaction of a diene compound having 4 or more carbon atoms, etc. Those obtained by various known methods can be used. At this time, the thing of the state in which compounds other than the C4 or more olefin resulting from each manufacturing method mixed arbitrarily may be used as it is, and you may use what was refine | purified.

In addition, the hydrocarbon which is a raw material may contain hydrocarbons other than C4 or more hydrocarbon (Hereinafter, it may be mentioned "other hydrocarbons."). For example, methane, ethane, ethylene, It may contain a hydrocarbon having 3 or less carbon atoms such as acetylene, propane, propylene and methylacetylene. In addition, methanol or dimethyl ether may be contained, and the mixing ratio is not limited.

Usually, in the production of ethylene from a hydrocarbon having 4 or more carbon atoms, ethylene which is a target product may be contained in a hydrocarbon which is a raw material, but propylene, butene, hexene and the like by contact with a catalyst It is preferable to use ethylene as a separated raw material since it is easily converted to another olefin. The mass ratio of the hydrocarbon having 4 or more carbon atoms to ethylene contained in the hydrocarbon which is the raw material is not particularly limited, but usually 1 or more, preferably 5 or more, more preferably 10 or more, further preferably It is 15 or more, preferably 30 or more, and the larger, the better. As the ratio is higher, consumption of ethylene which is a target product can be suppressed, and ethylene can be efficiently produced.

In addition, since propylene can be partially converted to ethylene by contact with the same catalyst and ethylene yield can be improved, it may be contained in the raw material, and propylene produced by this reaction is recycled. Can also be used. The mass ratio of propylene to the hydrocarbon having 4 or more carbon atoms contained in the raw material hydrocarbon is not particularly limited, but is usually 0 or more, preferably 0.01 or more, more preferably 0.1 or more. , More preferably 0.2 or more, and usually 1,000 or less, preferably 100 or less, more preferably 10 or less, and still more preferably 5 or less.

In the present embodiment, the conversion is a value calculated by the following equation. In addition, a C4 + component shows the sum total of the C4 or more hydrocarbon.
Hydrocarbon (C4 + component) conversion rate (%) of 4 or more carbons = [[Reactor raw material inlet C4 + component (mol / Hr)-reactor generated gas outlet C4 + component (mol / Hr))] / reactor raw material Input port C4 + component (mol / Hr)] × 100
In addition, calculation of the conversion rate here shall be calculated based on the component introduce | transduced as a C4 or more hydrocarbon, and suppose that the isomer is handled as the same component. For example, when only 1-butene is used as a raw material, the above conversion is calculated as follows. At this time, hydrocarbons having 4 or more carbon atoms other than butene are treated as products as “hydrocarbons having 4 or more carbon atoms other than the raw material”.
Hydrocarbon (C4 + component) conversion ratio (%) of 4 or more carbons = [[Reactor raw material inlet 1-butene (mol / Hr)-reactor generated gas outlet butene (isomer mixture) (mol / Hr) ] / Reactor feed inlet 1-butene (mol / Hr)] × 100

The selectivity in the present embodiment is a value calculated by the following equations. In each of the following formulas, “derived carbon flow rate (mol / Hr)” of hydrocarbons such as ethylene, propylene, hydrocarbons having 4 or more carbon atoms other than the raw material (C4 + other than the raw material), paraffin and aromatic compounds The molar flow rate of carbon atoms constituting a hydrocarbon is meant. Note that paraffin is the sum of paraffins of 1 to 4 carbons, aromatic compounds are the sum of benzene, toluene and xylene, and C4 + other than the raw material is the total of hydrocarbons having 4 or more carbons excluding the raw material and the aromatic compound. It is.
· Ethylene selectivity (%) = [Reactor generated gas outlet ethylene molar derived carbon molar flow rate (mol / Hr) / [reactor generated gas outlet total carbon molar flow rate (mol / hr)-reactor outlet C4 + component derived carbon Molar flow rate (mol / Hr)]] × 100
· Propylene selectivity (%) = [Reactor generated gas outlet propylene derived carbon molar flow rate (mol / Hr) / [reactor generated gas outlet total carbon molar flow rate (mol / Hr)-reactor generated gas outlet C4 + Component-derived carbon molar flow rate (mol / Hr)]] × 100
· C4 + selectivity (%) other than the raw material = [Molar C4 + derived carbon molar flow rate (mol / Hr) other than the reactor generated gas outlet raw material / [reactor generated gas outlet total carbon molar flow rate (mol / Hr)-reaction] Generator gas outlet C4 + component-derived carbon molar flow rate (mol / Hr)]] × 100
· Paraffin selectivity (%) = [reactor generated gas outlet paraffin derived carbon molar flow rate (mol / Hr) / [reactor generated gas outlet total carbon molar flow rate (mol / Hr)-reactor generated gas outlet C4 + Component-derived carbon molar flow rate (mol / Hr)]] × 100
· Aromatic compound selectivity (%) = [Reactor product gas outlet aromatic compound derived carbon molar flow rate (mol / Hr) / [reactor produced gas outlet total carbon molar flow rate (mol / Hr)-reactor formation Gas outlet C4 + component-derived carbon molar flow rate (mol / Hr)]] × 100
In addition, the yield in this embodiment is calculated | required by the product of the said raw material conversion ratio and the selectivity of each produced | generated component, and ethylene yield and a propylene yield are specifically represented by the following formula, respectively .
· Ethylene yield (%) = C4 + component conversion rate (%) x ethylene selectivity (%) / 100
· Propylene yield (%) = C4 + component conversion rate (%) × propylene selectivity (%) / 100

Hereinafter, the present invention will be described more specifically by showing Examples A to D (corresponding to the first to fourth embodiments, respectively), but the present invention is not limited thereto as long as the gist of the present invention is not exceeded. It is not limited by the examples.

Example A
<Catalyst Preparation Example A1>
2.09 g of sodium hydroxide (Kishida Chemical Co., Ltd.) and 47.3 g of 25% by weight aqueous solution of N, N, N-trimethyl-1-adamantane ammonium hydroxide (25% by mass made by Seychem) sequentially with 89.6 g of water And then mixed with 4.27 g of aluminum hydroxide (manufactured by Aldrich, 50 to 57% by weight in terms of aluminum oxide) and mixed, and then colloidal silica SI-30 (30% by weight of SiO ₂ , Na 2. 3 wt. Furthermore, 10 wt% of CHA-type zeolite (SiO ₂ / Al ₂ O ₃ ratio 25; average primary particle diameter about 200 nm) was added as seed crystals and further stirred with respect to added SiO ₂ . Next, this gel was charged into a 1000 ml autoclave, and hydrothermal synthesis was performed at 160 ° C. for 20 hours while stirring at 250 rpm under autogenous pressure. The product was filtered, washed with water and dried. The XRD pattern of the product confirmed that the product obtained was a CHA phase. According to XRF analysis, the SiO ₂ / Al ₂ O ₃ ratio was 22. The average primary particle size of the zeolite was about 100 nm according to SEM (JSM-6010 LV).

The CHA-type zeolite obtained by hydrothermal synthesis is calcined at 580 ° C. for 6 hours under air flow, then twice ion exchange at 80 ° C. for 1 hour with a 1 M aqueous ammonium nitrate solution, and dried at 100 ° C. The mixture was calcined at 500 ° C. for 6 hours under air flow to obtain a proton CHA-type zeolite.

To 2.0 g of the proton type CHA type zeolite, 20 ml of toluene as a solvent and 5 ml of tetraethoxysilane as a silylating agent were added, and heat treatment was performed at 70 ° C. for 4 hours while stirring. After completion of the reaction, the solid-liquid was separated by filtration and the solid content was dried at 100 ° C. to obtain a silylated proton CHA-type zeolite (Catalyst A). The total acid content of this zeolite was 0.66 mmol / g, and the outer surface acid content was 0.002 mmol / g. Furthermore, the protonated CHA-type zeolite steamed and silylated by treatment at 650 ° C. under normal pressure and 50% steam (water vapor / air = 50/50 (vol / vol)) flow for 5 hours (Catalyst A1).

<Catalyst Preparation Example A2>
0.570 g of sodium hydroxide (manufactured by Kishida Chemical Co., Ltd.) and 13.5 g of a 25% by weight aqueous solution of N, N, N-trimethyl-1-adamantane ammonium hydroxide (manufactured by Seichem, 25% by mass) sequentially with 15.8 g of water And then mixed with 0.152 g of aluminum hydroxide (manufactured by Aldrich, 50 to 57% by weight in terms of aluminum oxide) and mixed, and then colloidal silica ST-40 (40% by weight of SiO ₂ , Na ₂ O. 4% by weight (manufactured by Nissan Chemical Industries, Ltd.) 12.0 g was added and sufficiently stirred. Further, 5% by weight of CHA-type zeolite (SiO ₂ / Al ₂ O ₃ ratio 25; average primary particle size about 200 nm) was added as seed crystals and further stirred with respect to added SiO ₂ . Then, the gel was charged into a 100 ml autoclave, and hydrothermal synthesis was performed at 140 ° C. for 6 days while stirring at 15 rpm under autogenous pressure. The product was filtered, washed with water and dried. The XRD pattern of the product confirmed that the product obtained was a CHA phase. According to XRF analysis, the SiO ₂ / Al ₂ O ₃ ratio was 53. The average primary particle size of the zeolite was about 300 nm.

The CHA-type zeolite obtained by the above-mentioned hydrothermal synthesis was calcined at 580 ° C. for 6 hours under air flow, then ion exchanged twice at 80 ° C. for 1 hour with a 1 M aqueous ammonium nitrate solution, and dried at 100 ° C. Thereafter, the mixture was calcined at 500 ° C. for 6 hours under air flow to obtain a proton CHA-type zeolite (catalyst A2).

Example A1
A synthesis reaction of ethylene was carried out using catalyst A1 and propylene as a raw material. For the reaction, using a normal pressure fixed bed flow reactor, a mixture of 200 mg of the catalyst and 300 mg of quartz sand was filled in a quartz reaction tube with an inner diameter of 6 mm. Propylene and nitrogen are fed to the reactor so that the weight space velocity of propylene is 0.12 Hr ^-1 , 10 volume% of propylene and 90 volume% of nitrogen, and ethylene of 500 ° C., 0.1 MPa (absolute pressure) The synthesis reaction was performed for 3.33 hours. Next, 100% by volume of hydrogen gas was supplied to the reactor at a space velocity of 25 mmol / (Hr · g-cat) and treated at 525 ° C. and 0.1 MPa (absolute pressure) for 1.00 hours (catalyst regeneration Process). The synthesis reaction of ethylene was carried out for 1.58 hours under the above reaction conditions again. By repeating this reaction step and the regeneration step, the synthesis reaction of ethylene was carried out for a cumulative 6.50 hours. The reactor outlet gas was analyzed by gas chromatography. The reaction results of the ethylene synthesis reaction are shown in Table 1. Also, the change of the yield of ethylene with respect to the cumulative reaction time is shown in FIG. The amount of coke accumulated in the catalyst after the reaction step was 17% by mass, and the amount of coke accumulated in the catalyst after the regeneration step was 14% by mass.

Comparative Example A1
The same operation as in Example A1 was performed except that the synthesis reaction of ethylene was performed for 7.08 hours without undergoing the catalyst regeneration step under the reaction conditions of Example A1. The reaction results are shown in Table 2. Also, the change of the yield of ethylene with respect to the cumulative reaction time is shown in FIG.

Example A2
A synthesis reaction of ethylene was carried out using catalyst A2 and propylene as a raw material. For the reaction, using a normal pressure fixed bed flow reactor, a mixture of 90 mg of the catalyst and 300 mg of quartz sand was filled in a quartz reaction tube with an inner diameter of 6 mm. Propylene and nitrogen are fed to the reactor so that the weight space velocity of propylene is 5.0 Hr ^-1 , 40 volume% of propylene and 60 volume% of nitrogen, and ethylene at 550 ° C., 0.1 MPa (absolute pressure) The synthesis reaction was carried out for 30 minutes. Then, after lowering the temperature to room temperature, air gas is supplied to the reactor at a space velocity of 100 mmol / (Hr · g-cat) under the condition of 0.1 MPa (absolute pressure), and the temperature rising rate is 500 ° C./min. The temperature was raised to ° C., held for 1 minute, and allowed to cool (catalyst regeneration step). The synthesis reaction of ethylene was carried out for 5 minutes under the above reaction conditions again. The reactor outlet gas was analyzed by gas chromatography. The change in propylene conversion rate with respect to reaction time and the relationship between propylene conversion rate and ethylene selectivity in a synthesis reaction of ethylene are shown in FIG. The amount of coke accumulated in the catalyst after the reaction step was 18% by mass, and the amount of coke accumulated in the catalyst after the regeneration step was 13% by mass. In addition, the white circle plot in FIG. 2 shows the result when the catalyst is regenerated after performing synthetic reaction of ethylene for 30 minutes, and performing reaction for 5 minutes again.

Example A3
Using Catalyst A, a synthesis reaction of ethylene was carried out using propylene as a raw material. For the reaction, using a normal pressure fixed bed flow reactor, a mixture of 200 mg of the catalyst and 300 mg of quartz sand was filled in a quartz reaction tube with an inner diameter of 6 mm. Propylene and nitrogen are fed to the reactor so that the weight space velocity of propylene is 1.0 Hr ^-1 , 20 volume% of propylene and 80 volume% of nitrogen, and ethylene at 550 ° C. and 0.1 MPa (absolute pressure) The synthesis reaction was carried out for 5 minutes (reaction step). Next, 100% by volume of hydrogen gas was supplied to the reactor at a space velocity of 100 mmol / (Hr · g-cat) and treated at 550 ° C. and 0.1 MPa (absolute pressure) for 20 minutes (catalyst regeneration step) . By repeating this reaction step and the regeneration step, a synthesis reaction of ethylene was carried out for a cumulative 18 hours. The reactor outlet gas was analyzed by gas chromatography. The change of the yield of ethylene with respect to the cumulative reaction time is shown in FIG.

Example A4
Using Catalyst A, a synthesis reaction of ethylene was carried out using propylene as a raw material. For the reaction, using a normal pressure fixed bed flow reactor, a mixture of 200 mg of the catalyst and 300 mg of quartz sand was filled in a quartz reaction tube with an inner diameter of 6 mm. Propylene and nitrogen are supplied to the reactor so that the weight space velocity of propylene is 5.0 Hr ^-1 , 20 volume% of propylene, 50 volume% of hydrogen, and 80 volume% of nitrogen, 650 ° C., 0.1 MPa (absolute Reaction of ethylene for 3 minutes (reaction step). Next, 100% by volume of hydrogen gas was supplied to the reactor at a space velocity of 500 mmol / (Hr · g-cat) and treated at 650 ° C. and 0.1 MPa (absolute pressure) for 40 minutes (catalyst regeneration step) . By repeating this reaction step and the regeneration step, the synthesis reaction of ethylene was carried out for a cumulative 6 hours. The reactor outlet gas was analyzed by gas chromatography. Changes in propylene conversion rate and ethylene selectivity with respect to reaction time in the synthesis reaction of ethylene are shown in Table 3 and FIG. The amount of coke accumulated in the catalyst after the reaction step was 16% by mass.

In Examples A1 to A4, by providing the catalyst having a reduced ethylene yield in the step (I) of contacting the catalyst and propylene with the catalyst regeneration step (II), the high ethylene yield is maintained over a long period of time to obtain ethylene. It turned out that it could be manufactured. On the other hand, in Comparative Example A1 which did not go through the step (II), the ethylene yield could not be maintained, and the ethylene yield decreased to 5%. From this, it was found that ethylene can be stably and efficiently produced by having the step (I) of contacting with propylene and the step of catalyst regeneration (II) in the method of producing ethylene from propylene.

Example B
<Catalyst Preparation Example B1>
2.09 g of sodium hydroxide (Kishida Chemical Co., Ltd.) and 47.3 g of 25% by weight aqueous solution of N, N, N-trimethyl-1-adamantane ammonium hydroxide (25% by mass made by Seychem) sequentially with 89.6 g of water And then mixed with 4.27 g of aluminum hydroxide (manufactured by Aldrich, 50 to 57% by weight in terms of aluminum oxide) and mixed, and then colloidal silica SI-30 (30% by weight of SiO ₂ , Na 2. 3 wt. Furthermore, 10 wt% of CHA-type zeolite (SiO ₂ / Al ₂ O ₃ ratio 25; average primary particle diameter about 200 nm) was added as seed crystals and further stirred with respect to added SiO ₂ . Next, this gel was charged into a 1000 ml autoclave, and hydrothermal synthesis was performed at 160 ° C. for 20 hours while stirring at 250 rpm under autogenous pressure. The product was filtered, washed with water and dried. The XRD pattern of the product confirmed that the product obtained was a CHA phase. According to XRF analysis, the SiO ₂ / Al ₂ O ₃ ratio was 22. The average primary particle size of the zeolite was about 100 nm.

To 2.0 g of the proton type CHA type zeolite, 20 ml of toluene as a solvent and 5 ml of tetraethoxysilane as a silylating agent were added, and heat treatment was performed at 70 ° C. for 4 hours while stirring. After completion of the reaction, the solid-liquid was separated by filtration, and the solid content was dried at 100 ° C. to obtain a silylated proton CHA-type zeolite. Furthermore, the protonated CHA-type zeolite steamed and silylated by treatment at 650 ° C. under normal pressure and 50% steam (water vapor / air = 50/50 (vol / vol)) flow for 5 hours (Catalyst B1).

<Catalyst Preparation Example B2>
By treating the catalyst B1 at 650 ° C. under normal pressure and 50% steam (water vapor / air = 50/50 (vol / vol)) flow for 5 hours, steam treated and silylated proton type CHA type A zeolite was obtained (catalyst B2).

Example B1
A synthesis reaction of ethylene was carried out using catalyst B1 and propylene as a raw material. For the reaction, using a normal pressure fixed bed flow reactor, a mixture of 200 mg of the catalyst and 300 mg of quartz sand was filled in a quartz reaction tube with an inner diameter of 6 mm. Propylene and hydrogen are fed to the reactor so that the weight space velocity of propylene is 0.23 Hr ^-1 , 10 vol% of propylene and 90 vol% of hydrogen, and ethylene at 500 ° C. and 0.1 MPa (absolute pressure) The synthesis reaction was carried out and the reactor outlet gas was analyzed by gas chromatography. The reaction results are shown in Table 4. The amount of coke accumulated in the catalyst after the reaction was 12% by mass.

Comparative Example B1
The same operation as in Example B1 was performed except that nitrogen was used instead of hydrogen, and 10% by volume of propylene and 90% by volume of nitrogen were used. The reaction results are shown in Table 4. The amount of coke accumulated in the catalyst after the reaction was 18% by mass.

Comparative Example B2
A mixed gas of water vapor and nitrogen was used instead of hydrogen, and the same operation as in Example B1 was performed except that 10% by volume of propylene, 40% by volume of water vapor, and 50% by volume of nitrogen were used. The reaction results are shown in Table 4 and FIG.

Example B2
A synthesis reaction of ethylene was carried out using catalyst B2 and propylene as a raw material. For the reaction, using a normal pressure fixed bed flow reactor, a mixture of 200 mg of the catalyst and 300 mg of quartz sand was filled in a quartz reaction tube with an inner diameter of 6 mm. Propylene and nitrogen are fed to the reactor so that the weight space velocity of propylene is 0.12 Hr ^-1 , 10 volume% of propylene and 90 volume% of nitrogen, and ethylene of 500 ° C., 0.1 MPa (absolute pressure) The synthesis reaction was performed for 3.33 hours. At this time, the propylene conversion was 28.9%, the ethylene selectivity was 55.7%, the butene selectivity was 27.0%, and the ethylene yield was 16.1%. 100 vol% of hydrogen gas is supplied to the reactor at a space velocity of 25 mmol / (Hr · g-cat) of hydrogen to the reactor after the above reaction (hereinafter referred to as “catalyst B2A”) at 525 ° C., It processed for 1.00 hours on condition of 0.1MPa (absolute pressure). Then, a synthesis reaction of ethylene was carried out again using the catalyst contacted with hydrogen under the above reaction conditions. The reaction results after 0.33 hours are shown in Table 5.

Comparative Example B3
Example B2 except that with respect to the catalyst B2A, 100% by volume of nitrogen gas was used instead of 100% by volume of hydrogen gas, and nitrogen was supplied to the reactor at a space velocity of 25 mmol / (Hr · g-cat). The same operation was performed. The reaction results are shown in Table 5.

Comparative Example B4
For catalyst B2A, 50% water vapor gas (water vapor / nitrogen = 50/50 (vol / vol)) at a space velocity of 25 mmol / (Hr · g-cat) instead of 100% by volume of hydrogen gas The same operation as in Example B2 was performed except that the solution was supplied to The reaction results are shown in Table 5.

From Example B1, catalytic activity is stabilized because coking deterioration is largely suppressed by contacting propylene with a catalyst to produce ethylene using a gas containing hydrogen as a carrier gas, whereby the catalyst activity is stabilized, and Comparative Example B1 It was found that ethylene can be stably produced with a high yield as compared with the case of using nitrogen gas and steam / nitrogen gas of Comparative Example B2 as a dilution gas.
Further, in Example B2, by bringing hydrogen gas into contact with a catalyst whose ethylene yield has decreased over time due to propylene conversion, Comparative Example B3 using nitrogen gas or Comparative Example using steam / nitrogen gas It turned out that ethylene yield can be recovered | restored efficiently efficiently with respect to B4, without reducing ethylene selectivity.

Example C
Catalyst Preparation Example C1
2.09 g of sodium hydroxide (Kishida Chemical Co., Ltd.) and 47.3 g of 25% by weight aqueous solution of N, N, N-trimethyl-1-adamantane ammonium hydroxide (25% by mass made by Seychem) sequentially with 89.6 g of water And then mixed with 4.27 g of aluminum hydroxide (manufactured by Aldrich, 50 to 57% by weight in terms of aluminum oxide) and mixed, and then colloidal silica SI-30 (30% by weight of SiO ₂ , Na ₂ O. 3% by weight, 111 g manufactured by JGC Catalysts Chemical Co., Ltd. was added and sufficiently stirred. Furthermore, 10 wt% of CHA-type zeolite (SiO ₂ / Al ₂ O ₃ ratio 25; average primary particle diameter about 200 nm) was added as seed crystals and further stirred with respect to added SiO ₂ . Next, this gel was charged into a 1000 ml autoclave, and hydrothermal synthesis was performed at 160 ° C. for 20 hours while stirring at 250 rpm under autogenous pressure. The product was filtered, washed with water and dried. The XRD pattern of the product confirmed that the product obtained was a CHA phase. According to XRF analysis, the SiO ₂ / Al ₂ O ₃ ratio was 22. The average primary particle size of the zeolite was about 100 nm.

The CHA-type zeolite obtained by hydrothermal synthesis is calcined at 580 ° C. for 6 hours under air flow, then twice ion exchange at 80 ° C. for 1 hour with a 1 M aqueous ammonium nitrate solution, and dried at 100 ° C. The mixture was calcined at 500 ° C. for 6 hours under air flow to obtain a proton CHA-type zeolite.
To 2.0 g of the proton type CHA type zeolite, 20 ml of toluene as a solvent and 5 ml of tetraethoxysilane as a silylating agent were added, and heat treatment was performed at 70 ° C. for 4 hours while stirring. After completion of the reaction, the solid-liquid was separated by filtration, and the solid content was dried at 100 ° C. to obtain a silylated proton CHA-type zeolite (catalyst C1). The total acid content of this zeolite was 0.66 mmol / g, and the outer surface acid content was 0.002 mmol / g.

Example C1
A synthesis reaction of ethylene was carried out using catalyst C1 and propylene and trans-2-butene as raw materials. For the reaction, using a normal pressure fixed bed flow reactor, a mixture of 90 mg of the catalyst and 400 mg of quartz sand was filled in a quartz reaction tube with an inner diameter of 6 mm. Weight hourly space velocity of propylene 4.2 Hr ^-1 , weight hourly space velocity of trans-2-butene 0.8 Hr ^-1 , propylene 35 volume%, trans-2-butene 5 volume%, nitrogen 60 volume% The synthesis reaction of ethylene was carried out at 500 ° C. and 0.1 MPa (absolute pressure) for 10 to 12 minutes. The product gas discharged from the reactor was analyzed by gas chromatography. The reaction results of the ethylene synthesis reaction are shown in Table 6.

Example C2
The weight space velocity of propylene was 3.5 Hr ^-1 , the weight space velocity of trans-2-butene was 1.5 H r ^-1 , 30 volume% of propylene, and 30 volume% of trans-2-butene were supplied to the reactor except that The same operation as in Example C1 was performed. The reaction results are shown in Table 6.

Example C3
The weight space velocity of propylene was 2.1 Hr ^-1 , the weight space velocity of trans-2-butene was 2.9 Hr ^-1 , propylene was 20% by volume, trans-2-butene was 20% by volume, and the reactor was as follows: The same operation as in Example C1 was performed. The reaction results are shown in Table 6.

Example C4
Except that the weight space velocity of propylene was 1.0 Hr ^-1 , the weight space velocity of trans-2-butene was 4.0 H r ^-1 , 10 volume% of propylene, and 30 volume% of trans-2-butene were fed to the reactor, The same operation as in Example C1 was performed. The reaction results are shown in Table 6.

Comparative Example C1
The same operation as in Example C1 was performed, except that propylene alone was used as a raw material and the mixture was supplied to the reactor so that the weight hourly space velocity of propylene is 5.0 Hr ^-1 , and 40 vol% of propylene is obtained. The reaction results are shown in Table 6.
From these examples, it was found that ethylene can be produced stably by maintaining a high ethylene / propylene ratio by using a raw material containing butene as a specific amount of a hydrocarbon having 4 or more carbon atoms together with propylene. These results suggest that the equilibrium composition between ethylene and propylene and butene is shifted to the ethylene side by using a raw material containing butene in a specific ratio as a hydrocarbon having 4 or more carbon atoms. is there. That is, by using a raw material containing propylene and a hydrocarbon having 4 or more carbon atoms, the conversion efficiency from propylene to ethylene can be enhanced, and fluctuation of a high ethylene / propylene ratio is alleviated, and ethylene is stably produced. It is thought that it was possible.

According to this embodiment, ethylene can be produced with a high yield from a propylene raw material. In addition, since the ethylene / propylene ratio can be stably maintained, the complexity of the process and the load of separation and purification can be reduced.

Example D
<Physical property measurement>
In addition, in the following preparation examples, the X-ray diffraction (XRD) pattern of the crystal of the zeolite obtained by the synthesis was obtained using X'Pert Pro MPD manufactured by PANalytical. The X-ray source is CuKα (X-ray output: 40 kV, 30 mA), and the reading range is 0.016 °.
For fluorescent X-ray analysis (XRF), Rayny EDX-700 manufactured by Shimadzu Corporation was used.
In composition analysis by the ICP method, a sample solution was prepared by dissolving a sample with hydrofluoric acid. The sample solution was measured by inductively coupled plasma emission spectrometry (ICP-AES). The SiO ₂ / Al ₂ O ₃ ratio of the sample was determined from the measured values of Si and Al obtained.
The average primary particle size of the zeolite was determined using SEM (scanning electron microscope) JSM-6010 LV manufactured by JEOL.
The XPS (X-ray photoelectron spectroscopy) measurement of the zeolite crystal surface was performed using Quantum 2000 manufactured by PHI under the following conditions. X-ray source: monochromized Al-Kα, output 16 kV-34 W (X-ray generation area 170 μmφ), charge neutralization: electron gun (2 μA), ion gun (1 V) combined use, spectroscopy system: pulse energy 187.85 eV @ wide spectrum , 29.35 eV @ narrow spectrum (C1s, Al2p), 11.75 eV @ narrow spectrum (O1s, Si2p), measurement region: irradiation area 300 μm □, extraction angle: 45 ° (from the surface).
The SiO ₂ / Al ₂ O ₃ ratio of the zeolite crystal surface was determined from the measured values of Si and Al obtained.

<Catalyst Preparation Example D1>
2.09 g of sodium hydroxide (Kishida Chemical Co.) and 47.3 g of 25% by weight aqueous solution of N, N, N-trimethyl-1-adamantane ammonium hydroxide (Seichem, 25% by mass) sequentially with 89.6 g of water And then mixed with 4.27 g of aluminum hydroxide (Aldrich, 50 to 57% by weight in terms of aluminum oxide) and mixed, and then colloidal silica SI-30 (30% by weight of SiO ₂ , Na 2. 3% by weight (manufactured by JGC Catalyst Chemical Co., Ltd.) 111 g was added and sufficiently stirred. Furthermore, 10 wt% of CHA-type zeolite (SiO ₂ / Al ₂ O ₃ ratio 25; average primary particle diameter about 200 nm) was added as seed crystals and further stirred with respect to added SiO ₂ . Next, this gel was charged into a 1000 ml autoclave, and hydrothermal synthesis was performed at 160 ° C. for 20 hours while stirring at 250 rpm under autogenous pressure. The product was filtered, washed with water and dried. The XRD pattern of the product confirmed that the product obtained was a CHA phase. According to XRF analysis, the SiO ₂ / Al ₂ O ₃ ratio was 22. The average primary particle size of the zeolite was about 100 nm.

The CHA-type zeolite obtained by hydrothermal synthesis is calcined at 580 ° C. for 6 hours under air flow, then twice ion exchange at 80 ° C. for 1 hour with a 1 M aqueous ammonium nitrate solution, and dried at 100 ° C. The mixture was calcined at 500 ° C. for 6 hours under air flow to obtain a proton CHA-type zeolite (catalyst DA).
To 2.0 g of the proton type CHA type zeolite, 20 ml of toluene as a solvent and 5 ml of tetraethoxysilane as a silylating agent were added, and heat treatment was performed at 70 ° C. for 4 hours while stirring. After completion of the reaction, the solid-liquid was separated by filtration, and the solid content was dried at 100 ° C. to obtain a silylated proton CHA-type zeolite (Catalyst D1).

<Catalyst Preparation Example D2>
A solution of 59.2 g of N, N, N-trimethyl-1-adamantane ammonium hydroxide aqueous solution (Sechem, 25% by mass) and 145.6 g of 1 M aqueous sodium hydroxide solution is sequentially dissolved in 371 g of water, and then aluminum hydroxide After adding and stirring 8.90 g (made by Aldrich, 50 to 57% by weight in terms of aluminum oxide) and stirring as a silica source, 42.1 g of fumed silica was added as a silica source and stirred for 2 hours. 10% by weight of CHA-type zeolite (SiO ₂ / Al ₂ O ₃ ratio 15; average primary particle diameter: about 100 nm) was added as seed crystals and further stirred with respect to added SiO ₂ derived from the silica source. Then, this gel was charged into a 1000 ml autoclave, and hydrothermal synthesis was performed at 160 ° C. for 42 hours while stirring at 150 rpm under autogenous pressure. The product was filtered, washed with water and dried. The XRD pattern of the product confirmed that the product obtained was a CHA phase. According to XRF analysis, the SiO ₂ / Al ₂ O ₃ ratio was 14. The average primary particle size of the zeolite was about 100 nm.

The CHA-type zeolite obtained by hydrothermal synthesis is calcined at 580 ° C. for 6 hours under air flow, then twice ion exchange at 80 ° C. for 1 hour with a 1 M aqueous ammonium nitrate solution, and dried at 100 ° C. The mixture was calcined at 500 ° C. for 6 hours under air flow to obtain a proton CHA-type zeolite (catalyst DB).
To 1.0 g of the proton type CHA-type zeolite, 10 ml of hexamethyldisiloxane as a solvent and 2.5 ml of tetraethoxysilane as a silylating agent were added, and heat treatment was performed at 100 ° C. for 6 hours while stirring. After completion of the reaction, the solid-liquid was separated by filtration, and the solid content was dried at 100 ° C. to obtain a silylated proton CHA-type zeolite (catalyst D2). ICP analysis than is the a 14 _SiO 2 / _Al 2 _{O 3} ratio of the whole crystal, the _SiO 2 / _Al 2 _{O 3} ratio of from crystal surface XPS analysis was 30. The average primary particle diameter was about 100 nm as measured by a scanning electron microscope.

Example D1
A catalyst D1 was used to carry out a synthesis reaction of ethylene from trans-2-butene as a raw material. For the reaction, using a normal pressure fixed bed flow reactor, a mixture of 90 mg of the catalyst and 400 mg of quartz sand was filled in a quartz reaction tube with an inner diameter of 6 mm. C. trans-2-butene and nitrogen are fed to the reactor so that the weight space velocity of trans-2-butene is 5 Hr.sup.- ¹ , 40% by volume of trans-2-butene and 60% by volume of nitrogen, 500.degree. The synthesis reaction of ethylene was carried out for 8-10 minutes at 0.1 MPa (absolute pressure). The product gas discharged from the reactor was analyzed by gas chromatography. The reaction results of the synthesis reaction of ethylene are shown in Table 7.

Example D2
The ethylene synthesis reaction was carried out for 10 minutes in the same manner as in Example D1, except that the catalyst D2 was used. The reaction results of the synthesis reaction of ethylene are shown in Table 7.

Comparative Example D1
The ethylene synthesis reaction was carried out for 10 minutes in the same manner as in Example 1 except that the catalyst DA was used. The reaction results of the ethylene synthesis reaction are shown in Table 1.
The ethylene selectivity is high, the ethylene yield itself is equal or higher, and isobutene, ie, isobutene, that is, by using as the catalyst the zeolite in which the proportion of the outer surface acid point where shape selectivity does not work is reduced to 3% or less. It can be seen that the proportion of branched olefins that are difficult to recycle as raw materials is greatly reduced.

According to this embodiment, when ethylene is produced from a hydrocarbon having 4 or more carbon atoms, in particular butene and pentene, as a raw material, side reactions can be suppressed and high ethylene selectivity can be produced, and raw material hydrocarbons can be produced. Provided is a method for producing ethylene that can suppress the isomerization to branched olefins. As a result, the equipment and energy required for separation and purification of linear olefins and branched olefins can be reduced, and recycling of hydrocarbons having 4 or more carbon atoms can be facilitated.

Claims

A process for producing ethylene comprising the steps of: supplying propylene to a reactor and contacting it with a catalyst to produce ethylene (step (I)); and regenerating the catalyst obtained through the step (I).
The method for producing ethylene according to claim 1, wherein in the step (II), the catalyst is regenerated by bringing a gas containing at least one selected from oxygen, hydrogen and steam into contact with the catalyst.
The method for producing ethylene according to claim 1, wherein in the step (II), the catalyst is regenerated by contacting a gas containing hydrogen with the catalyst.
A process for producing ethylene by contacting propylene and a catalyst in a reactor,
The manufacturing method of ethylene whose said catalyst is a catalyst made to contact the gas containing hydrogen.
The method for producing ethylene according to claim 4, wherein the catalyst is a catalyst in which a catalyst containing coke produced by contact with propylene is brought into contact with a gas containing hydrogen.
The method for producing ethylene according to claim 4 or 5, wherein the catalyst is brought into contact with a gas containing hydrogen at a temperature of 300 ° C or higher.
The method for producing ethylene according to any one of claims 4 to 6, wherein the catalyst is a catalyst contacted with a gas containing hydrogen of 0.001 MPa or more in absolute hydrogen partial pressure.