WO2017094806A1

WO2017094806A1 - Method for producing propylene or aromatic hydrocarbon

Info

Publication number: WO2017094806A1
Application number: PCT/JP2016/085645
Authority: WO
Inventors: 光弘関口; 正嗣川瀬
Original assignee: 旭化成株式会社
Priority date: 2015-12-03
Filing date: 2016-11-30
Publication date: 2017-06-08
Also published as: TWI629101B; JPWO2017094806A1; TW201720522A; JP6505866B2

Abstract

A method for producing propylene or an aromatic hydrocarbon, wherein the production method includes a conversion reaction step in which a hydrocarbon raw material including a sulfur compound as an impurity and containing at least one C4-12 olefin is brought into contact with a zeolite-containing catalyst in a production reactor, and a catalyst regeneration step for burning off the carbonaceous substance adhered to the zeolite-containing catalyst; in the catalyst regeneration step, the temperature of the equipment and line through which the regeneration gas flows is maintained at or above the dew point temperature of the sulfuric acid contained in the regeneration gas flowing through the equipment and line.

Description

Propylene or aromatic hydrocarbon production method

The present invention relates to a method for producing propylene or aromatic hydrocarbon from a hydrocarbon raw material containing an olefin having 4 to 12 carbon atoms.

Zeolite-containing molded catalyst obtained by molding zeolite and a molding agent (hereinafter also referred to as “zeolite-containing catalyst” or “zeolite catalyst”) is catalytic conversion for obtaining propylene or aromatic hydrocarbons from hydrocarbon raw materials. Widely used as a catalyst for reactions. For example, Patent Document 1 discloses a method for producing propylene using a zeolite catalyst having a high SiO ₂ / Al ₂ O ₃ molar ratio. Here, the zeolite catalyst after the elapse of time used for the reaction is caused by the deterioration of the activity due to the adhesion of the carbonaceous material (hereinafter also referred to as “coking”). It is also necessary to try to activate the activity by removing and regenerating. Examples of the method for removing coke attached to the catalyst include a method for removing the coke by combustion using a gas containing oxygen.
In addition, when the hydrocarbon raw material is derived from fossil fuel, it is known to contain a sulfur compound as an impurity. For example, Patent Document 2 discloses a method for producing an olefin and hydrogen sulfide having a molecular weight lower than that of a raw material using an olefin-containing hydrocarbon raw material containing a sulfur-containing hydrocarbon, and a mixture after the reaction (hereinafter referred to as “reaction”). It is also referred to as “mixture.”) In which hydrogen sulfide is contained together with the olefin.

European Patent No. 109,060 European Patent 1,840,189

In the method of obtaining propylene or aromatic hydrocarbon from a hydrocarbon raw material using a zeolite-containing catalyst as described in

Patent Documents

1 and 2 above, the selectivity decreases or coking over the course of the reaction time. Deterioration may occur earlier than normal.
The present invention provides a method and apparatus for producing propylene or aromatic hydrocarbons from a hydrocarbon raw material by a conversion reaction step using a zeolite-containing catalyst, while suppressing such a decrease in catalyst performance with the passage of reaction time. An object of the present invention is to provide a method and an apparatus capable of producing propylene or an aromatic hydrocarbon.

Although it is considered that there are multiple causes for the reduction of the selectivity of the target product of the catalyst and the deterioration of coking, the present inventors have caused the foreign matter such as iron rust to enter the reactor and adhere to the catalyst. I found out that it was one. As a result of inferring that the source of iron rust etc. may be in the regeneration system piping and / or equipment, and as a result of further investigation, a part of the sulfur was adsorbed to the catalyst during the reaction, and the sulfur during the catalyst regeneration. It has been found that if it is released as an oxide and the temperature of the regeneration gas falls below the dew point of sulfuric acid, it will lead to corrosion of the piping and / or equipment.

It is known that sulfur derived from sulfur compounds contained in hydrocarbon raw materials mainly becomes hydrogen sulfide in a reaction under a reducing atmosphere. However, as a result of the study by the present inventors, the total amount of sulfur derived from the sulfur compound is not converted into hydrogen sulfide or the like and released as a component in the mixture after the reaction, but a part of it is released. It was found that it remained adsorbed on the zeolite-containing catalyst. In the regeneration of the catalyst using oxygen-containing gas, the sulfur adsorbed on the catalyst is released as sulfur oxide into the regeneration gas, so that in the piping system and apparatus through which the regeneration gas passes, We found a new problem that caused corrosion of manufacturing equipment. As a result, foreign matters such as iron rust and corroded metal fragments generated by the corrosion are mixed and deposited in the reaction system, particularly the reactor and catalyst, thereby reducing the selectivity of the target product, accelerating the deterioration of coking, and the amount of coke. Also found problems such as poor regeneration due to increase, generation of differential pressure in the reactor, drift of raw material gas, fluctuation of reaction results due to the drift, which hinders the production of propylene or aromatic hydrocarbons It was.
In addition, when the hydrocarbon raw material contains an olefin component having 4 to 12 carbon atoms of 20% by mass or more, the deterioration rate of the catalyst due to coking increases, so it is necessary to increase the regeneration frequency. It becomes easier to progress.
As a result of intensive studies to solve the above problems, the present inventors have determined the temperature of the line through which the regeneration gas flows and the equipment temperature in the catalyst regeneration process of the zeolite-containing catalyst used in the catalytic conversion reaction described above. It was concluded that maintaining the sulfuric acid dew point temperature or higher under the regeneration conditions of the above could protect the production equipment from acid corrosion by sulfur oxides, and based on this knowledge, the present invention was completed. .
At this time, the dew point temperature of sulfuric acid contained in the regeneration gas is obtained by a method of actually measuring the sulfuric acid concentration and the water pressure in the regeneration gas. Moreover, the dew point temperature (dew point estimated temperature) of sulfuric acid contained in the regeneration gas can be estimated by a method of estimating from the sulfur accumulation rate or the sulfur accumulation amount in the zeolite-containing catalyst. Further, as will be described later, by knowing the acid amount of the zeolite-containing catalyst in advance, the sulfur accumulation rate and sulfur accumulation amount in the catalyst are estimated, and the dew point temperature of sulfuric acid contained in the regeneration gas is estimated as described above. You can also
The “dew point temperature” in the present embodiment refers to both the above-described measured dew point temperature and the dew point estimated temperature estimated from the sulfur accumulation rate and the like.

That is, the present invention is as follows.
[1]
A process for producing propylene or aromatic hydrocarbons, comprising:
A conversion reaction step in which a hydrocarbon raw material containing a sulfur compound as an impurity and containing at least one olefin having 4 to 12 carbon atoms is contacted with a zeolite-containing catalyst in a production reactor;
A catalyst regeneration step of burning and removing the carbonaceous material adhering to the zeolite-containing catalyst,
In the catalyst regeneration step, the production method of maintaining the temperature of the line and the equipment through which the regeneration gas flows above the dew point temperature of sulfuric acid contained in the regeneration gas through the line and equipment.
[2]
A method for producing propylene, comprising:
A conversion reaction step in which a hydrocarbon raw material containing a sulfur compound as an impurity and containing at least one olefin having 4 to 12 carbon atoms is contacted with a zeolite-containing catalyst in a production reactor;
A catalyst regeneration step for burning and removing the carbonaceous material adhering to the zeolite-containing catalyst;
The reaction mixture obtained in the conversion reaction step includes a light fraction mainly containing hydrogen and a hydrocarbon having 1 to 3 carbon atoms, and a heavy fraction mainly containing at least one kind of hydrocarbon having 4 or more carbon atoms. A separation step of separating into
A recycling step in which part or all of the heavy fraction is recycled to the production reactor and used as the hydrocarbon feedstock,
In the catalyst regeneration step, the production method of maintaining the temperature of the line and the equipment through which the regeneration gas flows above the dew point temperature of sulfuric acid contained in the regeneration gas through the line and equipment.
[3]
The production method according to [1] or [2] above, wherein the regeneration gas is circulated and used.
[4]
The production reactor is an adiabatic fixed bed reactor of two or more, wherein the conversion reaction step and the catalyst regeneration step are switched in the reactor, and the production reactor according to the above [1] to [3] Any manufacturing method.
[5]
The production method according to any one of [1] to [4] above, wherein the hydrocarbon raw material contains 20% by mass or more of an olefin having 4 to 12 carbon atoms.
[6]
The production method according to any one of [1] to [5] above, wherein the catalyst regeneration step is performed at a frequency of once or more per month.
[7]
The production method according to any one of the above [1] to [6], wherein the zeolite-containing catalyst contains a zeolite having an intermediate pore diameter of 5 to 6.5 mm.
[8]
The production method according to any one of the above [1] to [7], wherein the zeolite-containing catalyst contains a group IB metal.
[9]
The production method according to any one of [1] to [8] above, wherein the zeolite-containing catalyst contains a porous refractory inorganic oxide.
[10]
The method according to any one of [1] to [9] above, wherein the zeolite-containing catalyst is heat-treated at a temperature of 500 ° C. or higher in the presence of water vapor prior to contact with the hydrocarbon raw material.
[11]
The production method according to any one of [1] to [10] above, wherein the catalyst regeneration step is started at a temperature lower than that of the conversion reaction step.
[12]
The production method according to any one of the above [1] to [11], further comprising a drying step of cooling the regeneration gas used in the catalyst regeneration step to remove water vapor in the regeneration gas.
[13]
[1] to [12], including a step of obtaining a dew point of sulfuric acid contained in the regeneration gas from a sulfuric acid concentration calculated from a correlation between an acid amount of the zeolite-containing catalyst and a catalyst accumulation rate or catalyst accumulation amount of sulfur. The manufacturing method in any one of.
[14]
An apparatus for producing propylene or aromatic hydrocarbons,
Switching between a conversion reaction step in which a hydrocarbon raw material and a catalyst are brought into contact with each other, and a catalyst regeneration step in which a carbonaceous material adhering to the catalyst is burned and removed by the conversion reaction step by bringing a gas containing oxygen into contact with the catalyst. Having at least one production reactor having the function of performing,
The production reactor includes a first piping system that feeds the hydrocarbon raw material into the production reactor and feeds a reaction mixture from the production reactor, and feeds the oxygen-containing gas into the production reactor. And a second piping system for delivering from the production reactor,
The second piping system is an apparatus for producing propylene or an aromatic hydrocarbon, comprising a dryer for removing water vapor in the regeneration gas.
[15]
Said 2nd piping system is an apparatus which manufactures the propylene or aromatic hydrocarbon of said [14] description further provided with the temperature measuring device which measures the temperature of the said regeneration gas.

According to the production method of the present invention, by suppressing the occurrence of corrosion in the production apparatus when producing propylene or aromatic hydrocarbon from an olefinic hydrocarbon raw material, the influence of foreign matters mixed due to the occurrence of corrosion is avoided. Propylene or aromatic hydrocarbons can be produced stably from olefinic hydrocarbon raw materials over a long period of time.

It is the schematic of an example of the manufacturing apparatus for enforcing the manufacturing method of the propylene or aromatic hydrocarbon which concerns on this invention. In the schematic diagram of an example of the manufacturing apparatus of FIG. 1, the line through which the regeneration gas flows is shown by a bold line. It is the schematic of an example of the manufacturing apparatus which installed the heat exchanger (dryer) on the line through which regeneration gas distribute | circulates. It is a figure which shows the relationship between sulfuric acid concentration and vapor pressure, and dew point temperature.

Hereinafter, a mode for carrying out the present invention (hereinafter referred to as “the present embodiment”) will be described in detail with reference to the drawings as necessary. In addition, this invention is not limited to the following embodiment, It can implement by changing variously within the range of the summary. In the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. Further, positional relationships such as up, down, left and right are based on the positional relationships shown in the drawings unless otherwise specified. Further, the dimensional ratios in the drawings are not limited to the illustrated ratios.

The method for producing propylene or aromatic hydrocarbon in the present embodiment is as follows:
A conversion reaction step in which a hydrocarbon raw material containing a sulfur compound as an impurity and containing at least one olefin having 4 to 12 carbon atoms is contacted with a zeolite-containing catalyst in a production reactor;
A catalyst regeneration step of burning and removing the carbonaceous material adhering to the zeolite-containing catalyst,
In the catalyst regeneration step, the temperature of the line and the equipment through which the regeneration gas flows is maintained at or above the dew point temperature of sulfuric acid contained in the regeneration gas through the line and equipment.

[Propylene production reaction]
(1) Manufacturing apparatus The manufacturing method of propylene which is the 1st aspect in this embodiment is demonstrated.
FIG. 1 is a schematic diagram of an example of a production apparatus for carrying out the method for producing propylene in the present embodiment. The production apparatus shown in FIG. 1 includes a tank 1 containing a hydrocarbon feed, a reactor 4 for producing a reaction mixture containing propylene by catalytic conversion of the hydrocarbon feed, and heat exchange between the reaction mixture and the hydrocarbon feed.

Heat exchangers

2 and 3 to be performed, a heater (heater) 6 for heating the hydrocarbon raw material to a predetermined temperature, a heat exchanger (cooler) 10 for cooling the reaction mixture, a compressor 11 for compressing the reaction mixture, A heat exchanger (cooler) 12 for cooling the reaction mixture, a tank 13 for storing fractions condensed in the

heat exchangers

10 and 12, and a reaction mixture containing hydrogen and a fraction having 3 or less carbon atoms and 4 or more carbon atoms. A distillation column 14 that is separated into fractions, a heat exchanger (cooler) 15 that cools hydrogen and a fraction having 3 or less carbon atoms at the top of the distillation column 14, the cooling fraction is stored, and the tower of the distillation column 14 is stored. A tank 16 that recirculates to the top In are connected. Further, the line through which the regeneration gas flows in the catalyst regeneration step is shown by a thick line in FIG. 2 is excluded from the circulating line because the regeneration gas is only released and does not return to the reactor.
Further, a reactor 5 that regenerates the catalyst in parallel when the reactor 4 is subjected to the reaction, a heater 6 that heats the regeneration (combustion) gas to a predetermined temperature, and a heat exchanger that exchanges heat of the regeneration gas. 7. A compressor 8 for compressing the regeneration gas and a pressure holding valve 9 for purging the regeneration gas by a necessary amount are connected by piping.
FIG. 3 is a schematic diagram of an example of a manufacturing apparatus in which a heat exchanger (dryer) 17 is installed on a line through which the regenerative gas flows. The regenerative gas is cooled by the heat exchanger (dryer) 17. Remove water vapor in the regeneration gas. The heat exchanger (dryer) 17 is installed as necessary.

As shown in FIG. 1, when a conversion operation is performed in a part of the reactors 4 while a regeneration operation is performed in another part of the reactors 5 using a plurality of reactors, the reaction for performing the conversion reaction The reaction system and the regeneration system are separated by a double block bleeder so that the raw material hydrocarbon introduced into the reactor 4 and the oxygen introduced into the reactor 5 for performing the regeneration operation are not mixed to form an explosive mixture. Is preferable from the viewpoint of safety. That is, it is preferable to switch the conversion reaction step and the catalyst regeneration step in the production reactor. For example, the catalyst regeneration process is performed in the reactor 5 while performing the conversion reaction process in the reactor 4 in the first period, and the catalyst regeneration process is performed in the reactor 4 while performing the conversion reaction process in the reactor 5 in the second period. You may go. In addition, the catalyst regeneration process is performed in the reactor 5 while performing the conversion reaction process in the reactor 4 in the first period, and the catalyst regeneration process is performed in the reactor 4 while performing the conversion reaction process in the reactor 5 in the second period. And the conversion reaction step may be performed in the reactors 4 and 5 in the third period.
The reactors 4 and 5 need not be limited to a total of two, and may be a total of three or more. For example, the catalyst regeneration process is performed in the reactor 5 while performing the conversion reaction process in the reactors 4 and 4a (not shown) in the first period, and the conversion reaction process is performed in the reactors 4 and 5 in the second period. Alternatively, the catalyst regeneration step may be performed in the reactor 4a, and the catalyst regeneration step may be performed in the reactor 4 while performing the conversion reaction step in the reactors 4a and 5 in the third period.
When there is one reactor, the conversion reaction step may be performed in the first period, and the catalyst regeneration step may be performed in the same reactor in the second period.

As described above, the steps performed in the reactors 4 and 5 can vary between the conversion reaction step and the catalyst regeneration step depending on the period. In the following, the reactor 4 is used as a reactor for performing the conversion reaction step. The vessel 5 will be described as a reactor for performing the catalyst regeneration step.

The reactor 4 is a reactor for performing a conversion reaction step by bringing a hydrocarbon raw material into contact with a zeolite-containing catalyst. The reactor 4 contains a hydrocarbon raw material via the

heat exchangers

2 and 3, and the hydrocarbon raw material is catalytically converted by a zeolite-containing catalyst to obtain a reaction mixture containing propylene.
In addition, this heat exchanger 2 can heat the hydrocarbon raw material introduce | transduced into a manufacturing apparatus using the calorie | heat amount which the hydrocarbon fluid in the reactor 4 has. The reaction mixture containing propylene obtained in the reactor 4 is sent to the distillation column 14 while being compressed by the compressor 11 as necessary. At least a part of the specific fraction separated in the distillation column 14, specifically, at least a part of the heavy fraction mainly containing hydrocarbons having 4 or more carbon atoms described below is reacted by recycling. It is preferable to accommodate in container 4 and perform contact conversion. This aspect of recycling will be described later.

The distillation column 14 separates propylene as a light fraction from the reaction mixture containing propylene obtained in the reactor 4. The reaction mixture is separated into a light fraction mainly containing hydrogen and a hydrocarbon having 1 to 3 carbon atoms and a heavy fraction mainly containing at least one kind of hydrocarbon having 4 or more carbon atoms. In addition, there is an embodiment in which propylene is separated from the light fraction, but it is not limited to this embodiment.

As the reactor 4, any of a fixed bed type, moving bed type, fluidized bed type, and air flow type reactor can be used, and among them, an adiabatic fixed bed type reactor having a simple structure is preferable. When the reactor 4 is a moving bed type, a fluidized bed type or an air flow type, the method of cutting off the connection between the reaction system including the reactor 4 and the regeneration system including the reactor 5 is a double block bleeder. It may or may not be. As materials constituting the reactor 4 and the reactor 5, metal materials such as carbon steel and stainless steel are mainly preferred.

(2) Hydrocarbon raw material In the propylene production method of the present embodiment, the hydrocarbon raw material used for the reaction is a hydrocarbon raw material containing a sulfur compound as an impurity and containing at least one olefin having 4 to 12 carbon atoms. Use.
“Hydrocarbon feedstock” refers to a group consisting of hydrocarbons having 1 to 12 carbon atoms, such as normal paraffins having 1 to 12 carbon atoms, isoparaffins, olefins, cycloparaffins (naphthenes), and cycloparaffins having side chain alkyl groups. The raw material containing the at least 1 sort (s) of hydrocarbon chosen from these. In this specification, the term “olefin” is used as a term including linear, branched, and cyclic olefins and cycloparaffins. The olefin content in the hydrocarbon raw material is preferably 20% by mass or more and 30% by mass or more when the total amount of all hydrocarbons contained in the hydrocarbon raw material is 100% by mass. Is more preferable, and it is further more preferable that it is 40 mass% or more. If the olefin content is less than 20% by mass, the yield of propylene tends to be low.

In this embodiment, a hydrocarbon raw material containing a sulfur compound as an impurity is used. Specifically, when the entire hydrocarbon raw material is 100% by mass, a hydrocarbon raw material containing 0.1 mass ppm or more of one or more sulfur compounds is used. The hydrocarbon raw material may be a hydrocarbon raw material containing 0.001% by mass or more of one or more sulfur compounds in total, or a hydrocarbon raw material containing 0.01% by mass or more. The total content of sulfur compounds in the hydrocarbon raw material is preferably 5% by mass or less, more preferably 1% by mass or less, and further preferably 0.1% by mass or less. When the content of the sulfur compound in the hydrocarbon raw material exceeds 5% by mass, the action as a catalyst poison of the zeolite catalyst is large, and it tends to be difficult to perform a stable operation.

The sulfur compound contained in the hydrocarbon raw material is not particularly limited. For example, hydrogen sulfide, carbonyl sulfide, carbon disulfide, thiols such as methanethiol, sulfides such as dimethyl sulfide, disulfides such as dimethyl disulfide, thiophene, etc. Kind.

In order to suppress corrosion of the catalyst regeneration process line and equipment, it is possible to perform a desulfurization operation to reduce the amount of sulfur compounds contained in the hydrocarbon feed before being subjected to the conversion reaction process, but at the same time in the hydrocarbon feed Since the amount of the olefin component decreases, it is preferable not to perform the desulfurization operation.

Further, the hydrocarbon raw material may contain a small amount of oxygen-containing compounds such as tertiary butanol, methyl tertiary butyl ether, and methanol, and nitrogen-containing compounds.

The hydrocarbon raw material may contain diolefin (diene) compounds such as propadiene, butadiene and pentadiene, and acetylene compounds such as methylacetylene. These diolefin compounds and acetylene compounds are known to have high polymerizability and cause caulking deterioration of the catalyst. Therefore, it is preferable to reduce the contents of diolefin compounds and acetylene compounds as much as possible before conducting the catalytic conversion reaction by pretreatment such as distillation separation and partial hydrogenation.

Further, when the catalyst described later is used, if the total amount of diolefin compounds and acetylene compounds is 2.5% by mass or less with respect to the entire hydrocarbon raw material, the above-described pretreatment is not necessary, and It tends to be used as a reaction raw material. When more stable production of propylene is desired, the total amount of diolefin compounds and acetylene compounds is preferably 2% by mass or less based on the entire hydrocarbon raw material.

Further, the hydrocarbon raw material may be a mixture with a dilution gas. Examples of the diluent gas include inert gases such as hydrogen, methane, water vapor, and nitrogen, but it is preferable not to perform dilution with hydrogen. In other words, hydrogen can be used to suppress the coking deterioration of the catalyst, but at the same time, it can cause a hydrogenation reaction of the produced propylene, etc., and therefore it is also included in the mixture after the reaction (also called “reaction mixture”). There is a possibility that the olefin purity contained (propylene / (propylene + propane), etc.) is lowered.

As a hydrocarbon raw material, what is enumerated below can be used, for example.
(A) Partial hydrogenation of C4 and C5 fractions separated from products obtained by pyrolyzing petroleum hydrocarbons such as naphtha, and diolefins in the C4 and C5 fractions to olefins Distillate fraction;
(B) a fraction obtained by separating and removing part or all of butadiene and isobutene from the C4 fraction;
(C) a fraction obtained by separating and removing a part or all of isoprene and cyclopentadiene from the C5 fraction;
(D) C4 fraction and gasoline fraction separated from products obtained by fluid catalytic cracking (FCC) of petroleum hydrocarbons such as vacuum gas oil;
(E) C4 fraction and gasoline fraction separated from coker The hydrocarbon raw materials may be used alone or in admixture of two or more.

(3) Zeolite-containing catalyst In the method for producing propylene in the present embodiment, a zeolite-containing catalyst is used as a catalyst for the catalytic conversion reaction. The above-mentioned hydrocarbon raw material is brought into contact with the zeolite-containing catalyst in the reactor 4 to perform a catalytic conversion reaction of the hydrocarbon raw material containing at least one kind of olefin having 4 to 12 carbon atoms contained in the hydrocarbon raw material. Thus, a reaction mixture containing propylene is obtained, and then propylene is separated from the obtained reaction mixture in the distillation column 14.

In the present embodiment, “zeolite” is crystalline porous aluminosilicate or metallosilicate, and includes phosphate-based porous crystals having the same or similar structure. The metallosilicate refers to a zeolite in which some or all of the aluminum atoms constituting the skeleton of the crystalline porous aluminosilicate are replaced with a substitutable element such as Ga, Fe, B, Cr, or Ti. .

Specifically, as a zeolite having a small pore diameter (structure having an oxygen 8-membered ring or less), chabazite (“CHA” in terms of a code that classifies zeolites determined by the International Zeolite Society) is used. ), Erionite (ERI), and A type (LTA).

Examples of zeolite having an intermediate pore size (oxygen 10-membered ring structure) include ferrierite (FER), MCM-22 (MWW), ZSM-11 (MEL), ZSM-5 (MFI), and AlPO4-11 (AEL). It is done. Moreover, as a zeolite with a large pore diameter (oxygen 12-membered ring structure), L type (LTL), X type (FAU), Y type (FAU), faujasite (FAU), β type (BEA), mordenite (MOR) ), ZSM-12 (MTW), and AlPO4-5 (AFI). Furthermore, UTD-1 (DON), CIT-5 (CFI), and VPI-5 (VFI) are mentioned as zeolites having a super-large pore diameter (structure having an oxygen 14-membered ring or more).

Among these, as the zeolite in the zeolite-containing catalyst, it is preferable to use an intermediate pore size zeolite having a pore size of 5 to 6.5 mm.

The intermediate pore size zeolite is not particularly limited and, for example, in addition to those described above, ZSM-8, ZSM-12, ZSM-18, ZSM-23, ZSM-35, ZSM- having a structure similar to ZSM-5 So-called pentasil-type zeolite such as 39 may be used. Among them, zeolites classified into the MFI structure by the framework structure type according to the IUPAC recommendation are preferable, and ZSM-5 is particularly preferable. P.P. A. Jacobs and J.M. A. Martens “Stud. Surf. Sci. Catal.” 33, P.M. 167-215 (1987, The Netherlands), zeolites similar to ZSM-5 and ZSM-11 can also be used.

The SiO ₂ / Al ₂ O ₃ molar ratio of the zeolite contained in the zeolite-containing catalyst is preferably 200 or more and 3,000 or less, and more preferably 500 or more and 2,000 or less. When the SiO ₂ / Al ₂ O ₃ molar ratio is 200 or more, the coking deterioration of the zeolite-containing catalyst due to coke accompanying the conversion reaction tends to be suppressed. When the coking deterioration of the zeolite-containing catalyst is suppressed, for example, the switching frequency to the regeneration system when switching between the reaction system reactor and the regeneration system reactor in the fixed bed two-column swing method is low. Therefore, regeneration (permanent) deterioration of the catalyst can be prevented. Here, regeneration (permanent) degradation is an irreversible effect that occurs when the catalyst is regenerated by water vapor generated by the combustion of coke, which promotes desorption of aluminum from the zeolite lattice at high temperatures and causes structural destruction. Refers to deterioration. In this regard, by using the above-described zeolite-containing catalyst, it is possible to simultaneously suppress the progress of regeneration (permanent) deterioration.

In addition, the method according to the present embodiment is performed after the hydrocarbon raw material in (d) or (e), the partial hydrogenation in (a), or the separation / removal in (b) or (c). Even when the hydrocarbon raw material contains 2.5% by mass or less of diolefin compounds, it can be used. However, when the diolefin compound is included in the hydrocarbon raw material, the coking deterioration is generally more remarkable than when the diolefin compound is not included, and the switching frequency between the reaction and the regeneration is further increased. There is a need to. In this case, if a zeolite having a SiO ₂ / Al ₂ O ₃ molar ratio of 200 or more is used, the coking deterioration of the catalyst due to the produced coke is suppressed, and diolefin compounds in the raw material can be reduced by pretreatment. Since it is not essential, it tends to be advantageous for industrial implementation. On the other hand, when the SiO ₂ / Al ₂ O ₃ molar ratio is 3,000 or less, there is a tendency that industrially stable quality zeolite can be produced. Incidentally, _SiO 2 / _Al 2 _{O 3} molar ratio of the zeolite can be adjusted by conventional means known in the art. Further, the SiO ₂ / Al ₂ O ₃ molar ratio of the zeolite can be determined by a known method. For example, the zeolite is completely dissolved in an alkaline aqueous solution or a hydrofluoric acid aqueous solution, and the resulting solution is subjected to plasma emission spectroscopy or the like. It can obtain | require by analyzing using.

As zeolites for zeolite-containing catalysts, metalloaluminosilicates in which some of the aluminum atoms constituting the zeolite skeleton are substituted with elements such as Ga, Fe, B, Cr, and all the aluminum atoms constituting the zeolite skeleton are as described above. Metallosilicates substituted with various elements can also be used. In that case, after converting the content of the element contained in the metalloaluminosilicate or metallosilicate into the number of moles of alumina, the SiO ₂ / Al ₂ O ₃ molar ratio is calculated.

As the zeolite of the zeolite-containing catalyst, in addition to proton type and ammonium type, zeolite that does not substantially contain protons can be used. Zeolite substantially free of protons is less susceptible to coking degradation than the proton type, and therefore it is not necessary to repeat the regeneration operation frequently. As a result, it becomes possible to produce propylene stably and efficiently over a long period of time.

“Substantially free of protons” means that the amount of protons (acid amount) in the zeolite determined by the liquid phase ion exchange / filter drop method is 0.02 mmol or less per gram of zeolite. Preferably, the amount of protons per gram of zeolite is 0.01 mmol or less. The above-mentioned “proton amount (acid amount) in zeolite determined by liquid phase ion exchange / filter droplet determination method” is a concept different from “acid amount in zeolite determined from pyridine desorption amount” described later.

Here, the liquid phase ion exchange / filter droplet method is defined as Intrazeolite Chemistry, “ACS Symp. Ser.”, 218, P369-382 (1983), The Chemical Society of Japan, [3], P.A. 521-527 (1989). Measurement of the proton content of zeolite using this method can be performed as follows.
The zeolite-containing catalyst calcined in air is subjected to ion exchange treatment using an aqueous NaCl solution, and then the catalyst is recovered by filtration and a filtrate is obtained. The recovered catalyst is washed with pure water, and the entire amount of the resulting washing solution is collected and mixed with the filtrate to obtain a mixed solution. The amount of protons in the obtained mixed solution is obtained by neutralization titration, and the value converted to the mass of zeolite contained in the zeolite-containing catalyst is defined as the amount of protons in the zeolite. It is known that ammonium ion type and polyvalent metal cation type zeolite (for example, rare earth metal cation type zeolite) generates protons by heat treatment. Therefore, prior to the measurement of the proton amount by the above method, the zeolite-containing catalyst needs to be calcined.

The zeolite of the zeolite-containing catalyst substantially free of protons is selected from the group consisting of metals belonging to Group IB of the periodic table (hereinafter also referred to as “Group IB metals”), that is, copper, silver, and gold. Zeolite containing at least one metal can be used. The group IB metal is preferably copper or silver, and more preferably silver. In this specification, “periodic table” means CRC Handbook of Chemistry and Physics, 75th edition [(David R. Lide et al., CRC Press Inc. published (1994-1995)], pages 1-15. The above-mentioned “contains a group IB metal” means that a group IB metal is included in a corresponding cation state, provided that the group IB metal is In addition to what is contained in the zeolite in the state of a cation, it may be further contained in a state other than the cation, for example, it may be contained in the state of an oxide. As an example of a method of containing the zeolite, a zeolite not containing a group IB metal is used, for example, ion exchange method, impregnation method, mixing And a method of treating by an ion exchange method, etc. When a group IB metal is contained in a zeolite by an ion exchange method, it is preferable to use a salt of a group IB metal. Examples of the salt include silver nitrate, silver acetate, silver sulfate, copper chloride, copper sulfate, copper nitrate, and gold chloride.

The amount of the group IB metal contained in the zeolite-containing catalyst as the group IB metal cation is preferably 0.005 to 5% by mass, and preferably 0.01 to 3% by mass with respect to the mass of the zeolite-containing catalyst. More preferred. Even if the content of the group IB metal is more than 5% by mass, the performance of the zeolite-containing catalyst is usually difficult to improve. The content of the group IB metal in the zeolite can be determined by, for example, X-ray fluorescence analysis.

In the zeolite contained in the zeolite-containing catalyst, the remaining ion exchange site exchanged with a group IB metal cation may be ion exchanged with a cation of at least one metal selected from alkali metals and alkaline earth metals. . The zeolite contained in the zeolite-containing catalyst is preferably ion-exchanged with a cation of at least one metal selected from alkali metals, more preferably a cation of at least one metal selected from the group consisting of sodium and potassium. Ion-exchanged with ions. That is, the zeolite contained in the zeolite-containing catalyst in the propylene production method of the present embodiment includes at least one metal selected from the group consisting of alkali metals and alkaline earth metals, and at least one metal selected from group IB metals. Zeolite containing both of these can be used.

Examples of the method of adding at least one metal selected from alkali metals and alkaline earth metals to zeolite include the same method as the method of adding a group IB metal to zeolite. The content of at least one metal selected from alkali metals and alkaline earth metals varies depending on the type of metal. For example, in the case of sodium, 0.01 to 0.4% by mass relative to the mass of the zeolite-containing catalyst. In the case of potassium, it is preferably in the range of 0.01 to 0.8% by mass with respect to the mass of the zeolite-containing catalyst.

When preparing the zeolite-containing catalyst, there is no particular limitation on the order and number of times of the method of containing at least one metal selected from alkali metals and alkaline earth metals in the zeolite and the method of containing a group IB metal. However, in any case, as described above, it is preferable that the metal-containing zeolite does not substantially contain protons. For example, when preparing a silver / sodium cation exchange type as a zeolite-containing catalyst, some silver cannot be supported as a silver cation if an alkali component is present in the zeolite-containing catalyst. It is preferable to convert. Specifically, the zeolite-containing molded catalyst formed as a proton type zeolite is exchanged with sodium type (non-proton type) (preferably using an aqueous solution of sodium nitrate), and then exchanged with silver cations (preferably, A method using an aqueous silver nitrate solution) is preferred.

If necessary, the zeolite-containing catalyst may contain IIb such as V, Cr, Mo, W, Mn, Pt, Pd, Fe, Ni, Zn, and Ga for the purpose of suppressing coking deterioration and improving the yield of propylene. , III, Vb, VIb, VIIb, and at least one metal selected from the group consisting of metals belonging to group VIII may be further contained.

A zeolite-containing catalyst is usually prepared by mixing porous refractory inorganic oxides such as alumina, silica, silica / alumina, zirconia, titania, diatomaceous earth, and clay with the above zeolite as a binder or a diluent for molding (matrix). The resulting mixture is molded, and the resulting molded body is used as a zeolite-containing molded body catalyst. When a matrix or binder is used, the content thereof is preferably in the range of 10 to 90% by mass, more preferably 20 to 50% by mass, based on the total mass of the zeolite and the matrix or binder.

The zeolite-containing catalyst can be heat-treated at a temperature of 500 ° C. or higher in the presence of water vapor prior to contact with the hydrocarbon raw material for the purpose of further improving resistance to coking deterioration. The heat treatment is preferably performed at a temperature of 500 ° C. or higher and 900 ° C. or lower and a water vapor partial pressure of 0.01 atmospheric pressure or higher.

(4) Conversion reaction step The propylene production method in the present embodiment comprises a hydrocarbon raw material containing a sulfur compound as an impurity and containing at least one olefin having 4 to 12 carbon atoms in a production reactor. A conversion reaction step in contact with the catalyst.
In the conversion reaction step, the above-described zeolite-containing catalyst is charged into the reactor, and a catalytic conversion reaction of a hydrocarbon raw material containing at least one olefin having 4 to 12 carbon atoms is performed.

The reaction temperature in the conversion reaction step is preferably 400 to 600 ° C, more preferably 500 to 580 ° C. The partial pressure of the hydrocarbon raw material is desirably low, and is usually 0.01 to 1 MPa, preferably 0.05 to 0.3 MPa. The weight hourly space velocity WHSV of the hydrocarbon feed relative to the mass of the zeolite-containing catalyst is preferably in the range of 1 to 100 hr ⁻¹ , more preferably 2 to 20 hr ⁻¹ . The contact time between the hydrocarbon raw material and the zeolite-containing catalyst is preferably 5 seconds or less, more preferably 1 second or less.
When each condition in the conversion reaction step is within the above range, the olefin having 4 to 12 carbon atoms in the raw material hydrocarbon is converted to propylene with high selectivity, and the paraffin present in the raw material hydrocarbon does not substantially react. It is in. Accordingly, the conversion reaction of olefins in the hydrocarbon feedstock is selectively promoted, and the conversion reaction of paraffin is suppressed. As a result, by-products such as methane, ethane, and propane due to the conversion reaction of paraffin are suppressed, and Propylene tends to be easily separated and purified.

The paraffin conversion reaction is a large endothermic reaction, and the olefin conversion reaction is a slightly endothermic reaction or an exothermic reaction, depending on the reaction conditions. Therefore, when the olefin in the hydrocarbon raw material is selectively reacted under the above conditions, there is an advantage that an adiabatic fixed bed reactor having a simple structure can be used because it is not necessary to supply reaction heat.

The method for controlling the production of the aromatic hydrocarbon component having 6 to 8 carbon atoms in the conversion reaction step is not particularly limited, but usually a method of reducing the conversion rate of the olefin in the hydrocarbon raw material is employed. Here, the olefin conversion means the butene-based olefin conversion represented by the following formula.
Olefin conversion rate (%) = {(concentration of olefin having 4 or more carbon atoms in hydrocarbon feed at reactor inlet−butene concentration in hydrocarbon component at reactor exit) / number of carbons in hydrocarbon feed at reactor entrance 4 or more olefin concentration} × 100
The olefin conversion is preferably 30 to 80% by mass, more preferably 40 to 75% by mass. When the olefin conversion rate is 30% by mass or more, a desired propylene yield tends to be obtained, and when it is 80% by mass or less, the production of by-produced aromatic hydrocarbons tends to be suppressed.

The means for reducing the olefin conversion is not particularly limited, but increases the weight hourly space velocity of the hydrocarbon feedstock; decreases the reaction temperature; or increases the SiO ₂ / Al ₂ O ₃ molar ratio of the zeolite in the zeolite-containing catalyst; Etc. can be used.

A zeolite containing at least one metal selected from the group consisting of metals belonging to Group IB of the Periodic Table and substantially free of protons has 6 to 6 carbon atoms compared to generally used H-type zeolite. Since the production of the aromatic hydrocarbon of 8 is suppressed, the olefin conversion rate can be further increased, and as a result, the yield of propylene tends to be improved.

(5) Separation step In the method for producing propylene in the present embodiment, the reaction mixture obtained in the conversion reaction step is divided into a light fraction mainly containing hydrogen and a hydrocarbon having 1 to 3 carbon atoms, and at least one kind. A separation step of separating the heavy fraction mainly containing hydrocarbons having 4 or more carbon atoms may be included. Propylene can be further separated from the light fraction.
The separation step can be performed by combining various known methods such as fractional distillation and extraction.

(6) Recycling process The method for producing propylene in the present embodiment may further include a recycling process in which a part or all of the heavy fraction described above is recycled to the production reactor and used as a hydrocarbon raw material.
As described above, olefins having 4 or more carbon atoms, aromatic hydrocarbons, and the like are present in the reaction mixture in addition to propylene. Therefore, in order to increase the yield of propylene per mass of the hydrocarbon raw material containing at least one olefin having 4 to 12 carbon atoms, which is a raw material for the conversion reaction step, hydrocarbons having 4 or more carbon atoms are mainly contained in the reaction mixture. The hydrocarbon raw material can be effectively utilized by separating a part or all of the heavy fraction contained therein, recycling it to the reactor, and reacting it again.

In the recycling process, a simpler recycling process can be established by using the raw material as it is without refining the heavy fraction.
Moreover, it exists in the tendency which can raise the production ratio of propylene by raising the recycle ratio in a recycle process. Further, when the recycle ratio is increased, it can be an effective means for increasing propylene purity.

The heavy fraction recycle ratio (ratio of the amount returned to the reactor 4 of the conversion reaction step with respect to the total amount of heavy fraction) can be 100% by mass (total amount), but preferably 10 to 95% by mass More preferably, it is 15 to 90% by mass. If the recycle ratio is less than 10% by mass, the contribution to improving the yield of propylene tends to be small. On the other hand, when the recycling ratio exceeds 95% by mass, there is a large accumulation of paraffin components contained in the raw material hydrocarbons and aromatic hydrocarbon components having 6 to 8 carbon atoms produced in the reactor, and the load on the reactor is reduced. It tends to be excessive. However, if the amount of paraffin and aromatic hydrocarbon components in the heavy fraction is within a range that allows accumulation, the entire amount can be recycled even temporarily.

The ratio of the hydrocarbon component having 9 or more carbon atoms in the heavy fraction is preferably 20% by mass or less, more preferably 15% by mass or less. When the ratio of the hydrocarbon component having 9 or more carbon atoms is 20% by mass or less, the ratio of the aromatic hydrocarbon component in the hydrocarbon component having 9 or more carbon atoms is small, and propylene tends to be obtained more efficiently.

When carrying out the recycling process, from the viewpoint of efficiently obtaining propylene, a calculated value obtained by dividing the amount of aromatic hydrocarbon component having 6 to 8 carbon atoms [mass%] produced by the reactor by the hydrocarbon partial pressure [MPa] is It is preferably 13 or less, more preferably 10 or less. When the above calculated value is 13 or less, the activity is not easily lowered by coking, and the ratio of olefin components in the component having 9 or more carbon atoms, which easily becomes an aromatic hydrocarbon component, is increased, and this component is recycled. Doing so tends to increase the yield of propylene. When the calculated value is greater than 13, that is, under reaction conditions where an aromatic hydrocarbon component is likely to be generated, the catalytic activity is likely to decrease due to coking. In addition, not only the yield of propylene is reduced by increasing the number of aromatic hydrocarbon components having 6 to 8 carbon atoms generated in the reactor, but also the aromatic hydrocarbon components and carbon atoms having 6 to 8 carbon atoms in the recycled material. The ratio of the aromatic hydrocarbon component of several 9 or more increases. As a result, accumulation in the reaction system and promotion of coking tend to be a problem.

Recycling the heavy fraction may increase the amount of sulfur accumulation in the zeolite-containing catalyst as compared to the case where it is not recycled. By maintaining the above, it is possible to prevent corrosion of the manufacturing apparatus due to acid.

(7) Example of using C4 fraction as hydrocarbon raw material Next, a fraction obtained by extracting and separating butadiene from C4 fraction obtained from a petroleum hydrocarbon steam cracking product (butane, isobutane, butene, isobutene, etc.) In the case of using mainly hydrocarbons having 4 carbon atoms and diolefin compounds of 2.5% by mass or less as hydrocarbon raw materials and recycling a part of heavy fractions to the production reactor. The method for producing propylene will be described in more detail with reference to FIG.

The reactor 4 is a reactor for performing a conversion reaction step by bringing a hydrocarbon raw material into contact with a zeolite-containing catalyst. The reactor 4 contains the hydrocarbon raw material via the

heat exchangers

2 and 3, and the hydrocarbon raw material is catalytically converted by a zeolite-containing catalyst to obtain a reaction mixture containing propylene. The reaction mixture (a mixture of hydrogen and a hydrocarbon having 1 or more carbon atoms) obtained in the reactor 4 passes through the

heat exchangers

2 and 3, is recovered by the heat exchanger 10, and then pressurized by the compressor 11. Then, it passes through the heat exchanger 12 again and is supplied to the distillation column 14.

In the distillation column 14, the reaction mixture is separated into a light fraction mainly containing hydrogen and a hydrocarbon having 1 to 3 carbon atoms and a heavy fraction mainly containing at least one kind of hydrocarbon having 4 or more carbon atoms. To do. The apparatus (C3 separator) used for separation is not limited to a distillation column, and for example, a flash drum (gas-liquid separator) or the like can be used. Propylene is recovered from the resulting light fraction. On the other hand, at least a part of the heavy fraction can be recycled to the reactor and used as a part of the propylene production raw material. By recycling the heavy fraction, butane contained in the raw material hydrocarbon is concentrated in the heavy fraction, but when the entire amount of the heavy fraction is recycled, butane is accumulated in the reactor. Therefore, it is preferable to control the accumulation of butane in the reactor by keeping the amount of heavy fraction recycled to the propylene production reactor part of the obtained heavy fraction.

When the initial hydrocarbon raw material contains water or contains an oxygen-containing compound as an impurity, the reaction mixture also contains water. Most of the water in the reaction mixture is separated to the bottom of the distillation column 14 (heavy fraction), but the water azeotroped with propylene in the light fraction is sent to the top of the tower 16 Concentrate with. Therefore, it is also possible to provide an extraction line at the bottom of the tank 16 and remove water therefrom.

When using a distillation tower as an apparatus used for separation, propylene or ethylene can be used as the refrigerant of the cooler 15.

The separated light fraction mainly containing hydrogen and hydrocarbons having 1 to 3 carbon atoms is separated from hydrogen and 1 to 3 carbon atoms using another distillation column or flash drum (gas-liquid separator), preferably a distillation column. It may be separated into a fraction mainly containing 2 hydrocarbons and a fraction mainly containing hydrocarbons having 3 carbon atoms, and may be carried out as follows. That is, a refinery system for an ethylene plant that purifies and separates hydrogen, methane, ethylene, propylene, C4 fraction, cracked gasoline (hydrocarbons having 5 or more carbon atoms), etc., obtained by pyrolyzing petroleum hydrocarbons such as naphtha. A light fraction mainly containing hydrogen and hydrocarbons having 1 to 3 carbon atoms separated in the distillation column 14 is introduced into hydrogen, methane (hydrocarbons having 1 carbon atom), ethylene and ethane (2 carbon atoms). Hydrocarbons), propylene and propane (hydrocarbons having 3 carbon atoms). Propylene may be separated from propane to be 99.9% polymer grade propylene or chemical grade propylene containing several percent propane.

When the light fraction separated by the distillation tower 14 is introduced into the purification system of the ethylene plant, it is preferable to connect the light fraction line before the base compound washing tower. Since the sulfur compound in the raw material may be contained in the light fraction, it is preferable to remove the sulfur compound with this washing tower.

The propylene or ethylene that can be used as the refrigerant of the refrigerator 15 may be propylene or ethylene obtained in an ethylene plant purification system.

Further, various types of compressors can be used as the compressor 11, but when a screw type compressor is used, lubricating oil may be mixed in the condensate of the reaction mixture in a small amount. In this case, since the mixed lubricating oil is recycled from the bottom of the distillation column 14 to the tank 1 and remains as an evaporation residue at the bottom of the heat exchanger 2, an extraction line is provided at the bottom of the heat exchanger 2, from which the lubricating oil is provided. It is also possible to remove. Further, the evaporation residue in the heavy fraction to be recycled can be similarly removed from the bottom of the heat exchanger 2.

Light fractions include a fraction mainly containing hydrogen and hydrocarbons having 1 to 2 carbon atoms (hereinafter also referred to as “C2-fraction”) and a fraction mainly containing hydrocarbons having 3 carbon atoms (hereinafter referred to as “C2 fraction”). , Also referred to as “C3 fraction”), and ethylene is recovered from the C2- fraction. In the case of selectively producing propylene, at least a part of the C2-fraction can be recycled to the reactor, and ethylene in the C2-fraction can be used as a part of the raw material. Since the C2-fraction contains hydrogen, methane, and ethane in addition to ethylene, hydrogen, methane, and ethane accumulate when the entire C2-fraction is recycled. Therefore, it is preferable to control the accumulation of hydrogen, methane, and ethane by limiting the amount of C2-fraction recycled to the reactor to a portion of the C2-fraction obtained.

On the other hand, propylene is recovered from the C3 fraction. However, if the reaction conditions and separation conditions are set appropriately, it can be used as it is as chemical grade propylene.

Furthermore, the heavy fraction includes a fraction mainly containing hydrocarbons having 4 carbon atoms (hereinafter also referred to as “C4 fraction”) and at least one hydrocarbon having 5 or more carbon atoms, as necessary. Can be separated into a fraction mainly containing (hereinafter also referred to as “C5 + fraction”). The timing of separating the C4 fraction from the fraction mainly containing at least one hydrocarbon having 4 or more carbon atoms (hereinafter also referred to as “C4 + fraction”) may be before or after recycling the C4 + fraction. . As the apparatus (C4 separator) used for the separation, for example, a distillation tower, a flash drum (gas-liquid separator) or the like can be used, but a distillation tower is preferably used. A part of the obtained C4 fraction and / or C5 + fraction can be recycled to the conversion reactor and used as part of the raw material hydrocarbon.

Another preferred embodiment of the recycle reaction system in the case of using a C4 + fraction as a hydrocarbon raw material is that a reaction mixture (a mixture of hydrogen and a hydrocarbon having 1 or more carbon atoms) is mixed with a C2 fraction and at least one carbon number of 3 It is separated into a fraction mainly containing the above hydrocarbons (hereinafter also referred to as “C3 + fraction”). As the apparatus (C2 separator) used for the separation, for example, a distillation tower, a flash drum (gas-liquid separator) or the like can be used, and a distillation tower is preferably used. Ethylene is recovered from the obtained C2 fraction. When propylene is selectively produced, as described above, at least a part of the C2- fraction is recycled to the propylene production reactor, and the C2- It is preferable to use ethylene in the raw material as part of the raw material.

On the other hand, the C3 + fraction is separated into a C3 fraction and a C4 + fraction. As an apparatus (C3 separator) used for separation, for example, a distillation column, a flash drum (gas-liquid separator), or the like can be used, and a distillation column is preferably used. Propylene is recovered from the C3 fraction, but can be used as it is as chemical grade propylene if the reaction conditions and separation conditions are set appropriately.

[Aromatic hydrocarbon production reaction]
The manufacturing method of the aromatic hydrocarbon which is the 2nd aspect in this embodiment is demonstrated.
(1) Production apparatus In the second aspect, an apparatus similar to the production apparatus in the first aspect described above can be used. However, in the production of aromatic hydrocarbons, the conversion rate of the olefin as a raw material is almost the same. Since it is 100%, the separation process, the recycling process, and the apparatus used therefor can be omitted.
(2) Hydrocarbon raw material As the hydrocarbon raw material used in the reaction, a hydrocarbon raw material containing a sulfur compound as an impurity and containing at least one olefin having 4 to 12 carbon atoms is used as in the first embodiment.
The definition of “hydrocarbon raw material”, preferable content of sulfur compounds, and preferable examples of usable hydrocarbon raw materials are the same as in the first embodiment. The olefin content in the hydrocarbon raw material is preferably 20% by mass or more and 30% by mass or more when the total amount of all hydrocarbons contained in the hydrocarbon raw material is 100% by mass. Is more preferable. When the olefin content is less than 20% by mass, in order to maintain the production amount of aromatic hydrocarbon, the paraffin conversion reaction must be promoted. In that case, the endothermic amount accompanying the paraffin conversion reaction is large. Therefore, in order to maintain the reaction temperature, there is an effect that the amount of heat supplied from the outside increases. Further, the fraction having 4 or more carbon atoms produced in the first embodiment can also be used as a raw material, and by doing so, the olefinic hydrocarbon raw material can be effectively used.

(3) Zeolite-containing catalyst In the second embodiment, the intermediate pore diameter zeolite used for the zeolite-containing catalyst is the same as the intermediate pore diameter zeolite described in detail in the first embodiment except for the points described below. Silicates or metallosilicates can also be used.

The SiO ₂ / Al ₂ O ₃ molar ratio of the zeolite is preferably 20 or more and 200 or less, more preferably 25 or more and 150 or less. When the SiO ₂ / Al ₂ O ₃ molar ratio is 20 or more, the stability against high-temperature steam tends to increase. That is, resistance to so-called regeneration degradation is increased, and when the manufacturing method of the present embodiment is industrially implemented, there is a tendency that regeneration degradation caused by repeated reaction / regeneration does not easily occur. When the SiO ₂ / Al ₂ O ₃ molar ratio is 200 or less, the decomposition activity tends to be high, and the aromatic hydrocarbon yield tends to be high.

As the zeolite of the zeolite-containing catalyst, the zeolite described in Japanese Patent No. 3,905,948 can be used. Such a zeolite has a high crystallinity and has a stable structure, so it is resistant to regeneration deterioration and can be used in a proton type.

In order to further increase the resistance to coking deterioration, a finer zeolite with a larger effective surface area can be used. However, such a zeolite tends to be unstable in crystal structure, has low hydrothermal stability, and is regenerated ( Permanent) deterioration is likely to occur. Therefore, when such a zeolite is used, it is substantially free of protons detailed in the propylene production reaction of the first embodiment, and is from the group consisting of Group IB metals of the periodic table, that is, copper, silver, and gold. It is preferable to use an IB metal type zeolite containing at least one selected metal.

The amount of the group IB metal contained in the zeolite-containing catalyst as the group IB metal cation is preferably 0.01 to 10% by mass, and preferably 0.1 to 5% by mass with respect to the mass of the zeolite-containing catalyst. More preferred. Even if the content of the group IB metal is more than 10% by mass, the performance of the zeolite-containing catalyst is usually difficult to improve.

The content of at least one metal selected from the alkali metal and alkaline earth metal that may be contained in the zeolite-containing catalyst zeolite varies depending on the type of metal. For example, in the case of sodium, the content of the zeolite-containing catalyst is The amount is preferably 0.01 to 2.0% by mass, and in the case of potassium, it is preferably in the range of 0.01 to 3.0% by mass with respect to the mass of the zeolite-containing catalyst.

The primary particle diameter of zeolite is preferably 0.02 to 3 μm. The primary particle size when the zeolite is used in the proton form is more preferably 0.3 to 3 μm. When the zeolite is used in the IB metal type, the hydrothermal stability is improved as compared with the proton type, so that it is possible to use a zeolite having a primary particle size of less than 0.3 μm.

There are various types of primary particle shapes of zeolite, and the primary particle diameter here means the average diameter of the widest part of each particle. These primary particles may exist alone or may be secondary aggregated.

Moisture generated when the primary particle size of zeolite is 0.02 μm or more to suppress the amount of carbonaceous matter accumulated on the catalyst during the conversion reaction and to burn and remove the carbonaceous matter with an oxygen-containing inert gas. There is a tendency to suppress permanent activity deterioration due to dealumination in a high temperature atmosphere in the presence of. In addition, when the primary particle diameter of zeolite is 3 μm or less, there is a tendency that a temporary decrease in activity due to carbonaceous matter accumulated on the catalyst during the conversion reaction is suppressed.

The primary particle diameter of zeolite in the present embodiment refers to the particle diameter of primary particles when a substantially fresh zeolite is observed with a scanning electron microscope, similarly to the SiO ₂ / Al ₂ O ₃ molar ratio. .

At the time of subjecting the zeolite-containing catalyst to the conversion reaction, the ratio of the surface acid points to the total acid points in the proton type is preferably 0.03 to 0.15, preferably 0.05 to 0.1. Is more preferable. By setting the ratio of the surface acid points to the total acid points to 0.03 or more, there is a tendency that a temporary decrease in activity due to carbonaceous matter accumulated on the catalyst during the conversion reaction is suppressed. In addition, by setting the ratio to 0.15 or less, the amount of carbonaceous matter that accumulates on the catalyst during the conversion reaction is suppressed, and the presence of moisture that occurs when the carbonaceous matter is burned and removed with an oxygen-containing inert gas. The permanent activity deterioration due to dealumination under a high-temperature atmosphere tends to be suppressed.
Here, a method for measuring the ratio of the surface acid points to the total acid points will be described later.

The zeolite-containing shaped catalyst contains at least one element selected from the group consisting of elements belonging to Groups IB, IIB, IIIB, and VIII of the Periodic Table from the viewpoint of obtaining high dehydrogenation ability. Is preferred. Among them, it is preferable to contain copper, zinc, gallium, indium, nickel, palladium, platinum metal, and / or a compound thereof (oxide, composite oxide, etc.), and to contain zinc and / or a compound of zinc. It is more preferable. As a method for incorporating a metal of an element belonging to Group IB, IIB, IIIB, or VIII of the periodic table and / or a compound thereof into a zeolite-containing molded catalyst, a general ion exchange method or impregnation support is used. Can be used. The amount of metal and / or compound of elements belonging to Group IB, IIB, IIIB, and VIII of the Periodic Table contained in the zeolite-containing molded catalyst is 0.1 to It is 25% by mass, preferably 2 to 20% by mass, and more preferably 5 to 20% by mass.

As the zeolite-containing catalyst, porous refractory inorganic oxides such as alumina, silica, silica / alumina, zirconia, titania, diatomaceous earth, and clay can be used as a binder or a molding diluent (matrix). Among these, alumina and silica are preferable, and alumina is more preferable. A mixture obtained by mixing a binder or a matrix and the above-mentioned zeolite is molded, and the obtained molded body can be used as a zeolite-containing molded body catalyst. When a matrix or binder is used, the content thereof is preferably in the range of 5 to 50% by mass, more preferably 10 to 50% by mass, based on the total mass of the zeolite and the matrix or binder.

The zeolite-containing catalyst used in the method for producing aromatic hydrocarbons in the present embodiment has a temperature of 500 ° C. or higher in the presence of water vapor prior to contact with the hydrocarbon raw material for the purpose of further improving resistance to coking deterioration. Heat treatment is preferable. The heat treatment is preferably performed under conditions of a temperature of 500 ° C. or more and 900 ° C. or less and a water vapor partial pressure of 0.01 atm or more.

In the case of containing a mixture of zinc and its compound and alumina, the above heat treatment stabilizes the zinc component in the catalyst as zinc aluminate, and also has the effect of greatly suppressing the scattering loss of zinc in the reaction atmosphere. Can bring. This effect is extremely advantageous when industrial production of aromatic hydrocarbons is carried out. In addition, the zinc aluminate as used in this specification is JCPDS 5-0669NBS Circ. , 539, Vol. II, which has the same X-ray diffraction pattern as the pattern shown in 38 (1953).

(4) Conversion Reaction Step In the second aspect, the conditions for the conversion reaction are the same as the conditions for the conversion reaction described in detail in the first aspect, except as described below.
The reaction conditions in the method for producing aromatic hydrocarbons in the present embodiment vary depending on the light hydrocarbon raw material, particularly the amount ratio of olefin and paraffin in the raw material, but a temperature of 300 to 650 ° C., more preferably 400 to 600 ° C. Thus, the weight hourly space velocity WHSV of the hydrocarbon raw material relative to the mass of the hydrocarbon partial pressure of the atmospheric pressure to 30 atm and the zeolite-containing catalyst is preferably 0.1 to 50 hr ⁻¹ . The hydrocarbon raw material may be a mixture with a dilution gas. As the diluent gas, hydrogen, methane, water vapor, nitrogen, carbon dioxide, carbon monoxide, or the like can be used. The content of the diluent gas in the hydrocarbon raw material is preferably 20% by volume or less, and more preferably 10% by volume or less.

As a reactor for producing aromatic hydrocarbons, any of a fixed bed type, a moving bed type, a fluidized bed type and an air flow type reactor can be used. Is preferred.

[Catalyst regeneration process]
In the method for producing propylene or aromatic hydrocarbon in the present embodiment, a catalyst regeneration step is performed in which the carbonaceous material adhering to the zeolite-containing catalyst is removed by combustion. Hereinafter, the catalyst regeneration step will be described. The catalyst regeneration step is common to the first embodiment and the second embodiment.
Zeolite-containing catalysts cause coking degradation when used for long-term conversion reactions. In that case, the coke on the catalyst is burned and removed at a temperature of 400 to 700 ° C. in a normal gas or a mixed gas composed of oxygen and an inert gas (hereinafter also referred to as “regenerated gas”), thereby reducing coking deterioration. The generated catalyst can be regenerated (hereinafter, this treatment is also referred to as “regeneration treatment”).

The catalyst regeneration step is preferably started at a temperature lower than that of the conversion reaction step described above. Specifically, in the regeneration process, after the supply of raw materials is stopped, the system is replaced by nitrogen purge for a while to prevent rapid combustion of carbonaceous matter adhering to the catalyst and, consequently, rapid increase in the temperature of the catalyst layer. Therefore, it is preferable to slightly lower the catalyst layer temperature. After starting the circulation of the regeneration gas, it is preferable to gradually increase the regeneration temperature and the oxygen concentration while measuring the catalyst layer temperature and the O ₂ , CO, and CO ₂ concentrations in the outlet gas.

The temperature of the catalyst layer before the regeneration treatment is preferably 400 to 450 ° C. Further, it is preferable to start the regeneration process at an oxygen concentration of about 0.2 to 2% by volume.

Recycled gas can be recycled using the compressor 8 shown in FIG. At that time, in order to prevent accumulation of water vapor, carbon monoxide, and carbon dioxide generated by combustion of carbonaceous matter attached to the catalyst, the regeneration gas is appropriately purged from the pressure holding valve 9.

Also, the temperature of the catalyst layer is slightly lowered, and the regeneration process is started with the oxygen concentration being low. During the regeneration process, the oxygen concentration is monitored while nitrogen and air or oxygen gas is kept constant. Replenish. When most of the carbonaceous matter adhering to the catalyst burns, the temperature of the catalyst layer is lowered, so that the catalyst layer temperature is increased to near the conversion reaction temperature. Thereafter, if no significant heat generation is observed, the oxygen concentration is increased, and the regeneration process is performed so that the carbonaceous residue remains as little as possible.

During the regeneration process, the sulfur component adhering to the zeolite-containing catalyst moves into the regeneration gas in the form of SO _X. When water vapor generated by carbonaceous combustion and SO _X associate with each other, it becomes an acid gas, which may cause acid corrosion of the equipment.

In the manufacturing method of the present embodiment, the temperature of the line and equipment through which the regeneration gas flows is adjusted to be equal to or higher than the dew point of sulfuric acid contained in the regeneration gas. However, if the temperature of the line and equipment through which the regenerative gas circulates is raised too much, the regenerative gas cannot be put into the compressor 8 due to device restrictions. It is set within that range.

In the production method of the present embodiment, when the raw material contains 20% by mass or more of olefin, the coke generation rate is increased. Therefore, the catalyst regeneration step is preferably performed at least once a month, preferably at least once every 20 days, more preferably at least once every 10 days.

The dew point temperature of sulfuric acid contained in the regeneration gas can be obtained by taking the sulfuric acid concentration C _H2SO4 on the horizontal axis and selecting the moisture pressure P _H2O in FIG. 4 and reading the vertical axis.
The sulfuric acid concentration C _H2SO4 can be obtained by sampling the regeneration gas, cooling it at 5 ° C., measuring the amount of condensed water, and titrating the condensed water with a base. It can also be measured using a sulfuric acid gas detector tube, ion chromatography or the like.
The moisture pressure P _H2O can also be obtained by directly measuring the regeneration gas with a moisture meter, a dew point meter or the like.
Further, by measuring the sulfur accumulation rate and accumulation amount of the zeolite-containing catalyst used in the conversion reaction step, the maximum concentration of sulfuric acid in the regenerated gas due to the release of sulfur accumulated in the catalyst can be calculated from the following

formula

1 or 1 ′. It is also possible to use as the sulfuric acid concentration C _H2SO4 by estimating.

FIG. 4 is the same as the diagram described on page 237 of the revised sulfuric acid handbook [published by the sulfuric acid association (1977)].

In addition, it is possible to lower the minimum management temperature of the line and the equipment by lowering the dew point by collecting the water vapor and sulfuric acid components with a heat exchanger (dryer) described later. As described separately, when the aqueous sulfuric acid solution is recovered from the regeneration gas with a dryer, the control temperature of the regeneration line after the dryer is the dew point of sulfuric acid obtained by measuring the water pressure and sulfuric acid concentration at the outlet of the dryer. It can be temperature.

By maintaining the temperature of the line and the equipment through which the regeneration gas circulates at or above the dew point temperature of sulfuric acid contained in the regeneration gas, it becomes possible to reduce acid corrosion of the production apparatus due to sulfur oxides.
The holding temperature of the line through which the regenerative gas circulates and the equipment is preferably a dew point temperature of + 10 ° C. or more, more preferably a dew point temperature of + 20 ° C. or more, taking into account measurement errors and followability to rapid temperature changes. More preferably, it is dew point temperature +30 degreeC or more. By setting the temperature of the line and the device through which the regeneration gas flows to the above holding temperature, the regeneration line and the device are prevented from being corroded, and accordingly, foreign matters such as iron rust are mixed into the reactor.

Measure the temperature of the line and equipment through which the regeneration gas circulates with a resistance temperature detector, thermocouple, infrared radiation thermometer, non-contact thermometer, remote indicator thermometer, etc. In this embodiment, the temperature of the line and equipment through which the regeneration gas circulates refers to the skin temperature of the line and equipment that comes into contact with the gas. It shall be measured in contact with the skin part.

The temperature of the line through which the regenerative gas circulates and the temperature of the device are not particularly limited, and examples thereof include heating using a heat exchanger, a heater, a steam trace, and the like. Moreover, it is preferable that the line and apparatus through which the regeneration gas flows are kept warm by a heat insulating material.
However, in any part of the line and equipment through which the regeneration gas circulates, it is possible to partially not warm or keep warm as long as the sulfuric acid dew point temperature is maintained.

Further, it may further include a drying step of cooling the regeneration gas used in the catalyst regeneration step to remove water vapor in the regeneration gas. Cooling the regeneration gas and condensing and separating water vapor in the gas and a part or all of the sulfuric acid component associated therewith is an effective means for lowering the dew point temperature of sulfuric acid contained in the regeneration gas. Therefore, a heat exchanger (dryer) 17 for condensing and separating water vapor and the like in the gas may be provided on the line through which the regeneration gas flows. In this case, the temperature of the apparatus for condensing and separating water vapor in the gas is a temperature effective for condensing and separating water vapor, for example, the lower limit is about 1 ° C. or higher, preferably about 5 ° C. or higher, and the upper limit is Is preferably controlled at about 230 ° C. or lower, preferably about 160 ° C. or lower, more preferably about 120 ° C. or lower. The heat exchanger (dryer) 17 is installed at the place where the regeneration gas is appropriately purged by the pressure-holding valve 9 in FIG. 1 and before the regeneration gas is introduced into the heater 6, preferably before the compressor 8. FIG. 3 shows an apparatus schematic diagram of an example when a heat exchanger (dryer) 17 is installed. Moreover, it is preferable to use the material of the heat exchanger (dryer) 17 having higher SO _X resistance than the equipment on the line through which other regeneration gas flows.
In addition, the heat exchanger (dryer) 17 for performing the said drying process is not contained in the apparatus through which the regeneration gas distribute | circulates maintaining the temperature more than the dew point temperature of a sulfuric acid. Furthermore, in the heat exchanger 17, since water vapor and a part or all of the sulfuric acid component accompanying it are removed, the dew point temperature of sulfuric acid is lowered. In this case, the line and equipment after the heat exchanger 17 need only be equal to or higher than the sulfuric acid dew point temperature of the regeneration gas, and it is not necessary to maintain the same temperature as the line before the heat exchanger 17.
However, when the regenerated gas is recycled, it may be necessary to heat the heater 6 so that a load is not applied to the heater 6.

In addition, as shown in the following examples, a zeolite or catalyst containing a zeolite or catalyst containing a first- or second-order correlation equation between the acid amount of the zeolite-containing catalyst and the sulfur catalyst accumulation rate or the sulfur catalyst accumulation amount is prepared. From the value of the acid amount of the catalyst, the catalyst accumulation rate of sulfur and the amount of catalyst accumulation of sulfur can be estimated from the correlation equation. In this case, the catalyst accumulation rate and the catalyst accumulation amount of sulfur are the values obtained from the first-order or second-order correlation approximation formula, and the higher value is used depending on the line through which the regeneration gas flows and the acid of the equipment. It is an effective means for preventing corrosion.
The correlation equation under the example conditions in this specification is shown in the following test examples.

Here, the acid amount of the zeolite-containing catalyst is the amount of pyridine desorbed at 500 to 900 ° C. by the temperature-programmed desorption method, and is expressed as the amount of desorption per 1 g of the zeolite-containing catalyst. The acid amount of the zeolite-containing catalyst can be measured, for example, as follows.
An SUS column having an inner diameter of 6 mm and an overall length of 220 mm is packed with 0.1 to 1 g of catalyst. The catalyst has a length of 1 to 5 mm if it is molded into a pellet, and is packed by compression molding to 20 to 30 mesh if it is a powder. As an acid amount measuring apparatus, an apparatus in which a gas chromatography GC-14A manufactured by Shimadzu Corporation and a data processing apparatus CR-4A are connected to the rear of a SUS column is used. Nitrogen is flowed at 60 cc / min as a carrier gas, and the SUS column is heated to 180 ° C. by a tubular electric furnace having an inner diameter of 20 mmφ and a length of 150 mm. Next, a fixed amount (1 μcc) of pyridine is continuously injected from the injection port at a fixed period (2 to 5 minutes) using an autosampler microsyringe.

On the other hand, the carrier gas that has passed through the SUS column is analyzed using an FID type detector, and a chromatogram of changes in pyridine concentration over time, in which peaks periodically appear. As the number of injections increases, the amount of pyridine adsorbed on the sample approaches saturation, and the amount of non-adsorbed pyridine obtained increases accordingly. When the amount of change in pyridine concentration change is 5% or less, it is determined that the amount of pyridine adsorption is saturated.

After it is judged that the saturated adsorption of pyridine on the catalyst is completed under the above conditions, the temperature is raised at a rate of 15 ° C./min using a tubular electric furnace. Here, the gas flow path between the SUS column and the FID type detector is heated by a ribbon heater or the like except for a portion in the electric furnace, and the outside is covered with a heat insulating material and kept at 200 ° C. The temperature detection of the catalyst part is performed at the position of the temperature detection end closely attached to the outside of the catalyst packing part of the SUS column. Pyridine desorbed from the catalyst until the temperature detection end reaches 900 ° C. is detected by an FID type detector, and the desorption amount is converted using a calibration curve of pyridine. The ratio of the surface acid points to the total acid points was determined by changing the pyridine to 4-methylquinoline and determining the amount of 4-methylquinoline desorption measured by the same method as described above. It is expressed as a ratio of the elimination amount of 4-methylquinoline (μmol / g-cat) to g-cat).

The catalyst accumulation rate of sulfur can be determined by, for example, compressing and molding the used catalyst, then performing X-ray fluorescence analysis using an X-RAY SPECTROMETER RIX 3000 apparatus manufactured by Rigaku Denki Co., Ltd., and measuring the mass% of elemental sulfur. Can be sought.

[Manufacturing equipment]
Propylene or aromatic hydrocarbon production apparatus in the present embodiment,
Switching between a conversion reaction step in which a hydrocarbon raw material and a catalyst are brought into contact with each other, and a catalyst regeneration step in which a carbonaceous material adhering to the catalyst is burned and removed by the conversion reaction step by bringing a gas containing oxygen into contact with the catalyst. Having at least one production reactor having the function of performing,
The production reactor includes a first piping system that feeds the hydrocarbon raw material into the production reactor and feeds a reaction mixture from the production reactor, and feeds the oxygen-containing gas into the production reactor. And a second piping system for delivering from the production reactor,
Said 2nd piping system is an apparatus which manufactures a propylene or aromatic hydrocarbon provided with the drier which removes the water vapor | steam in the said regeneration gas.

Here, at least one production reactor may be provided, and production may be performed using a plurality of production reactors.
When the reactor 4 performs the production reaction of propylene or aromatic hydrocarbon and the reactor 5 performs the catalyst regeneration step, the first piping system feeds the hydrocarbon raw material into the production reactor, and 1 has a function of feeding the reaction mixture from the production reactor, the tank 1 containing the hydrocarbon raw material in FIG. 1, the reactor 4 for producing a reaction mixture containing propylene by catalytic conversion of the hydrocarbon raw material, Heat exchangers 2 and 3 for performing heat exchange between the reaction mixture and the hydrocarbon raw material, a heater (heater) 6 for heating the hydrocarbon raw material to a predetermined temperature, a heat exchanger (cooler) 10 for cooling the reaction mixture, a reaction A compressor 11 that compresses the mixture, a heat exchanger (cooler) 12 that cools the compressed reaction mixture, a tank 13 that stores fractions condensed in the heat exchangers 10 and 12, and a hydrogen and carbon number of the reaction mixture A distillation column 14 that separates into the following fraction and a fraction having 4 or more carbon atoms; a heat exchanger (cooler) 15 that cools hydrogen and a fraction having 3 or less carbon atoms at the top of the distillation column 14; The apparatus of the tank 16 which stores a part and recirculate | refluxs to the tower top of the distillation tower 14 is shown with the piping which connects these apparatuses, and the piping which connects the tank 1 from the tower bottom part of the distillation tower 14. The second piping system has a function of sending a gas containing oxygen into the production reactor and sending out the regeneration gas from the production reactor. The reactor 5, the heat exchanger 7 in FIG. It is shown by the compressor 8, the heater 6, the pressure-holding valve 9, and piping which connects these apparatuses.
The second piping system may further include a temperature measuring device that measures the temperature of the regeneration gas.

Here, the production reactor, the dryer, the temperature measuring device, etc. in the production apparatus are the same as those described in the production method.

<Test Example 1> Measurement 1 of sulfur accumulation rate of catalyst for propylene production reaction
H-type ZSM-5 zeolite having a SiO ₂ / Al ₂ O ₃ ratio of 1068 was mixed with colloidal silica, Snowtex ST-N manufactured by Nissan Chemical Industries, Ltd., adjusted for moisture, and extruded. The obtained molded body was dried at 120 ° C. for 6 hours and then calcined at 550 ° C. for 6 hours to obtain a zeolite-containing molded body catalyst (containing 30% by mass of SiO ₂ binder, 1.6 mmφ). The obtained zeolite-containing molded catalyst was dispersed in a 1N nitric acid aqueous solution (10 cc / g-molded catalyst) and subjected to an ion exchange treatment at room temperature for 1 hour. Next, filtration, washing with water, and drying were performed to prepare an H exchange type ZSM-5 / SiO ₂ molded body catalyst.
The obtained H exchange type ZSM-5 / SiO ₂ molded catalyst was dispersed in a 1N sodium nitrate aqueous solution (10 cc / g-zeolite molded product), and the ion exchange treatment for 1 hour at room temperature was repeated three times. Next, filtration, washing with water, and drying were performed to prepare a Na exchange type ZSM-5 / SiO ₂ molded body catalyst. This was dispersed in a 0.00145N silver nitrate aqueous solution (10 cc / g-molded catalyst) and subjected to ion exchange treatment at room temperature for 2 hours. Next, the catalyst A was prepared by filtration, washing with water and drying. The Ag content of catalyst A measured by fluorescent X-ray analysis was 0.084% by mass.

Catalyst A was charged into a Hastelloy C reactor having an inner diameter of 27.2 mm and steamed for 5 hours under conditions of a temperature of 650 ° C., a steam flow rate of 218 g / hr, and a nitrogen flow rate of 220 NL / hr. The amount of the catalytic acid after the steaming treatment was determined by a pyridine temperature-programmed desorption method and found to be 21 μmol / g-cat.

After the steaming treatment, 60 g of catalyst A was charged into a Hastelloy C reactor having an inner diameter of 27.2 mmφ. A raw material containing 30 mass ppm of sulfur (C3 fraction 6 mass%, C4 olefin 46 mass%, C4 paraffin 45 mass%, C5 fraction 3 mass%, dienes 0.04 mass%) is used as a hydrocarbon raw material, and reaction The reaction was carried out for 48 hours under the conditions of a temperature of 550 ° C., a raw material supply amount of 435 g / hr, and 0.1 MPaG. The catalyst accumulation rate of sulfur after the propylene production reaction of catalyst A was 0.5 wt% from the result of fluorescent X-ray analysis, and the sulfur accumulation amount per 1 g of catalyst was 0.05 mg / g-cat.

<Test Example 2> Measurement of sulfur accumulation rate of catalyst for propylene production reaction 2
The same operation as in Test Example 1 was carried out except that H-type ZSM-5 zeolite having a SiO ₂ / Al ₂ O ₃ ratio of 308 was used to obtain catalyst B containing 0.087% by mass of Ag.
The amount of catalyst acid after the steaming treatment was determined by a pyridine temperature-programmed desorption method. As a result, it was 44 μmol / g-cat, the catalyst accumulation rate of the catalyst B after the reaction was 1 wt%, and the sulfur per gram of catalyst. The accumulated amount was 0.1 mg / g-cat.

<Test Example 3> Measurement of sulfur accumulation rate of catalyst for aromatic hydrocarbon production reaction H-type ZSM-5 zeolite was synthesized by the method described in Example 1 of Japanese Patent No. 3,905,948. The obtained zeolite had a SiO ₂ / Al ₂ O ₃ ratio of 42.
To 2 kg of the zeolite powder, 1.3 kg of zinc nitrate hexahydrate and alumina sol were blended so that zeolite / alumina = 8/2. The mixture was appropriately mixed and kneaded while adjusting the moisture, and extruded to 1/16 inch × 5 to 10 mm. The obtained extruded catalyst was dried at 120 ° C. for 12 hours and calcined at 500 ° C. for 6 hours to obtain Catalyst C.

The steaming treatment was performed on the catalyst C in the same manner as in Test Example 1 except that the steaming time was 3 hours. The amount of the catalytic acid after the steaming treatment was determined by a pyridine temperature programmed desorption method and found to be 294 μmol / g-cat.

After the steaming treatment, 100 g of the catalyst C was charged into a Hastelloy C reactor having an inner diameter of 27.2 mmφ.
Using the raw material of Table 1 containing 764 ppm by mass of sulfur, the reaction was carried out for 48 hours under the conditions of a reaction temperature of 515 ° C., a raw material supply amount of 600 g / hr, and a reaction pressure of 0.5 MPaG. The catalyst accumulation rate of sulfur in catalyst C after the reaction was 5.9%, and the sulfur accumulation amount per gram of catalyst was 13 mg / g-cat.
Further, in this test example, the temporal change in the amount of accumulated sulfur was followed. The sulfur accumulation amount after 3 hours from the start of raw material supply was 11 mg / g-cat, and reached 6 mg after 6 hours.

From the results of Test Examples 1 to 3, when the acid amount of the zeolite-containing catalyst is x (μmol / g-cat) and the catalyst accumulation rate of sulfur accumulated in the zeolite-containing catalyst is y (wt%), the conditions of this test example Below, it was found that the relationship between x and y is expressed by a linear correlation equation of y = 0.020x.
Further, assuming that the acid amount of the zeolite-containing catalyst is x (μmol / g-cat) and the catalyst accumulation amount of sulfur accumulated in the zeolite-containing catalyst is z (mg / g-cat), under the conditions of this example, x It was found that the relationship between z and z is expressed by a quadratic correlation formula of z = 0.0002x ² -0.004x.

[Example 1]
(Production of aromatic hydrocarbons)
Catalyst D was obtained by using the same method as in Test Example 3 using H-type ZSM-5 zeolite (SiO ₂ / Al ₂ O ₃ ratio = 80).
The same steaming treatment as in Test Example 3 was performed on the catalyst D. The amount of the catalytic acid after the steaming treatment was determined by a pyridine temperature programmed desorption method and found to be 244 μmol / g-cat.

After the steaming treatment, 60 g of the catalyst D was charged into a Hastelloy C reactor having an inner diameter of 27.2 mmφ.
Ethyl mercaptan was added to the raw material of Test Example 1 to make the sulfur content 210 mass ppm, the reaction temperature was 515 ° C., the raw material supply amount (W [T / hr]) = 0.00018 T / hr, the reaction pressure was 0 The aromatic hydrocarbon was produced for 48 hours under the condition of 0.5 MPaG (sulfur concentration in the raw material (Sr [wtppm]) = 210 wtppm). After stopping the supply of the raw materials at a reaction time (Treat [hr]) = 48 hours, the temperature of the catalyst layer was lowered to 450 ° C. while replacing the system by nitrogen purge. Thereafter, 1 vol% oxygen / 99 vol% nitrogen gas is regenerated pressure (P [MPaG]) = 0.5 MPaG, regenerated gas amount (Q “Nm ³ /hr”)=8.4×10 ⁻³ Nm ³ / hr Then, combustion removal (regeneration) of coke adhered to the catalyst was started. While measuring the concentration of CO, CO ₂ and O ₂ in the outlet gas, the regeneration temperature and the oxygen concentration are gradually increased, and finally the regeneration time (Tregene [hr]) = 10 hours, the processing temperature 550 ° C., Regeneration was completed at an oxygen concentration of 5 vol%.
From the amount of water recovered by cooling the regeneration gas at 5 ° C., the average _{H 2} O concentration _{(C H2 O)} is 1.4 mol%, the water pressure _{(P H2 O:} corresponding to the vapor pressure of Figure 4) is 63mmHg met It was. From the result of neutralization titration of the condensed water with sodium hydroxide, the sulfuric acid concentration ( _{CH 2 SO 4} ) in the regeneration gas was 0.6 mol%. Using FIG. 4, it was found that the dew point temperature of sulfuric acid was about 150 ° C.
Further, as a result of extracting a part of the zeolite-containing catalyst after completion of the aromatic hydrocarbon production reaction and performing fluorescent X-ray analysis, the sulfur adsorption amount (accumulated amount) on the catalyst was 9.8 mg / g-cat. . The sulfuric acid concentration in the regeneration gas obtained from Equation 1 ′ is 0.49 mol%. When the water pressure measured above (P _H2O : corresponding to the vapor pressure in FIG. 4) 63 mmHg is used, the dew point estimated temperature of sulfuric acid that can be read from FIG. 4 is about 150 ° C.
When the acid amount of this catalyst D: 244 μmol / g-cat is applied to the second-order correlation equation obtained from the above test example, the amount of sulfur accumulated in the catalyst is estimated to be 11 mg / g-cat.
Based on this value, the sulfuric acid concentration in the regeneration gas obtained from Equation 1 ′ is 0.55 mol%. The moisture pressure measured above (P _H2O : corresponding to the vapor pressure in FIG. 4) is 63 mmHg, and the estimated dew point temperature of sulfuric acid that can be read from FIG. 4 is about 150 ° C. This value was in good agreement with the value obtained by actually measuring the water pressure and sulfuric acid concentration of the regeneration gas and the value calculated by actually measuring the sulfur accumulation amount of the catalyst.
This cycle operation of 48 hours reaction / 10 hours regeneration was repeated 10 times under the above conditions.
During the regeneration process, the temperature of the line through which the regeneration gas circulates and the equipment were monitored with a thermocouple and a temperature controller along the outside of the pipe, and kept at 180 ° C. After 10 cycles of operation, no acid corrosion was observed on the equipment of material SUS304.

[Example 2]
A dryer made of material SUS316L is installed in the line through which the regenerative gas flows (position corresponding to 17 in FIG. 3), and the temperature of the line through which the regenerative gas flows before the drier and the equipment is kept at 180 ° C. The reaction / regeneration cycle operation is performed in the same manner as in Example 1 except that the water vapor is condensed and separated at 5 ° C. and the temperature of the line and equipment through which the regeneration gas after the dryer flows is maintained at 130 ° C. It was. After 10 cycles of operation, no acid corrosion of the equipment was observed.

[Comparative Example 1]
The reaction / regeneration cycle operation was performed in the same manner as in Example 1 except that the temperature of the line through which the regeneration gas circulated during the regeneration process and the temperature of the equipment were kept at 40 ° C. After 10 cycle operations, the generation of scale containing sulfide on the inner wall of the line was observed.

[Example 3]
(Production of propylene)
60 g of the catalyst A after the steaming treatment was charged into a Hastelloy reactor having an inner diameter of 27.2 mmφ. A raw material containing 340 ppm by mass of sulfur (C3 fraction 6 mass%, C4 olefin 46 mass%, C4 paraffin 45 mass%, C5 fraction 3 mass%, dienes 0.04 mass%) is used as a hydrocarbon raw material, and reaction The reaction was carried out for 48 hours under conditions of a temperature of 550 ° C., a raw material supply amount of 360 g / hr, and 0.1 MPaG. The obtained reaction product was cooled to 10 ° C. using a heat exchanger at the reactor outlet, and then introduced into a gas-liquid separation drum to separate a fraction of C5 or higher.
Subsequently, the raw material containing 340 ppm by mass of sulfur was supplied to the reactor at 290 g / hr, and the fraction of C5 or more separated as described above was supplied at 70 g / h to carry out a propylene production reaction for 24 hr.
Subsequently, the same regeneration operation as in Example 1 was performed except that the regeneration pressure (P [MPaG]) was set to 0.1 MPaG.
Average _{H 2} O concentration of the regeneration gas purged from pressure holding valve 9 was measured with a hygrometer _{(C H2 O)} is 0.7 mol%, the water pressure was 10 mmHg. Further, the regeneration gas is passed through an aqueous sodium hydroxide solution, and the aqueous sodium hydroxide solution is subjected to ion chromatography (Tosoh IC2010, conductivity detector, column: TSKgel guard column SuperIC-AZ TSKgel Super IC-AZ (4.6 × 150 mm), eluent: 7.5 mM with sodium bicarbonate + 1.1 mM sodium carbonate), it was measured sulfur concentration in the regeneration gas, sulfuric acid concentration in the regeneration gas _{(C H2 SO4)} in 0.04 mol% there were. Using FIG. 4, it was found that the dew point temperature of sulfuric acid was about 80 ° C.
Further, the catalyst accumulation rate of sulfur after the propylene production reaction of the catalyst A is 0.5 wt% from the result of Test Example 1. The sulfuric acid concentration in the regeneration gas obtained from Equation 1 was 0.037 mol%, and the dew point estimated temperature of sulfuric acid that can be read from FIG.
Further, the sulfuric acid concentration obtained using Equation 1 from the amount of catalytic acid (21 μmol / g-cat) is 0.031 mol%, and the dew point estimated temperature of sulfuric acid is calculated to be about 80 ° C.
This 72 hour reaction / 10 hour regeneration cycle operation was repeated 5 times under the above conditions.
During the regeneration process, the temperature of the line and equipment through which the regeneration gas circulates was maintained at 130 ° C. After five cycles of operation, no acid corrosion of the equipment was observed.
From this example, by simply measuring the water concentration in the regeneration gas and the amount of catalytic acid, the estimated dew point temperature of sulfuric acid can be predicted, which can be a cumbersome operation, and without any sampling of gas, by a simple method. It was found that the estimated dew point temperature of sulfuric acid can be predicted.

This application is based on a Japanese patent application (Japanese Patent Application No. 2015-236785) filed with the Japan Patent Office on December 3, 2015, the contents of which are incorporated herein by reference.

The production method of the present invention can produce a target product safely and stably, and is useful in the field of methods for producing propylene or aromatic hydrocarbons.

1, 13, 16 ...

tank

2, 3 ... heat exchanger 4, 5 ... reactor 6 ...

heater

7, 10, 12, 15 ...

heat exchanger

8, 11, ...・ Compressor 9 ... Pressure holding valve 14 ... Distillation tower 17 ... Heat exchanger (dryer)

Claims

A process for producing propylene or aromatic hydrocarbons, comprising:
A conversion reaction step in which a hydrocarbon raw material containing a sulfur compound as an impurity and containing at least one olefin having 4 to 12 carbon atoms is contacted with a zeolite-containing catalyst in a production reactor;
A catalyst regeneration step of burning and removing the carbonaceous material adhering to the zeolite-containing catalyst,
In the catalyst regeneration step, the production method of maintaining the temperature of the line and the equipment through which the regeneration gas flows above the dew point temperature of sulfuric acid contained in the regeneration gas through the line and equipment.
A method for producing propylene, comprising:
A conversion reaction step in which a hydrocarbon raw material containing a sulfur compound as an impurity and containing at least one olefin having 4 to 12 carbon atoms is contacted with a zeolite-containing catalyst in a production reactor;
A catalyst regeneration step for burning and removing the carbonaceous material adhering to the zeolite-containing catalyst;
The reaction mixture obtained in the conversion reaction step includes a light fraction mainly containing hydrogen and a hydrocarbon having 1 to 3 carbon atoms, and a heavy fraction mainly containing at least one kind of hydrocarbon having 4 or more carbon atoms. A separation step of separating into
A recycling step in which part or all of the heavy fraction is recycled to the production reactor and used as the hydrocarbon feedstock,
In the catalyst regeneration step, the production method of maintaining the temperature of the line and the equipment through which the regeneration gas flows above the dew point temperature of sulfuric acid contained in the regeneration gas through the line and equipment.
The production method according to claim 1 or 2, wherein the regeneration gas is used in a circulating manner.
The production reactor is an adiabatic fixed bed reactor of two or more units, and the conversion reaction step and the catalyst regeneration step are performed in the reactor while being switched. The manufacturing method of description.
The production method according to any one of claims 1 to 4, wherein the hydrocarbon raw material contains 20 mass% or more of an olefin having 4 to 12 carbon atoms.
The production method according to any one of claims 1 to 5, wherein the catalyst regeneration step is performed at least once a month.
The production method according to any one of claims 1 to 6, wherein the zeolite-containing catalyst contains a zeolite having an intermediate pore diameter of 5 to 6.5 mm.
The production method according to any one of claims 1 to 7, wherein the zeolite-containing catalyst contains a group IB metal.
The production method according to any one of claims 1 to 8, wherein the zeolite-containing catalyst contains a porous refractory inorganic oxide.
The production method according to any one of claims 1 to 9, wherein the zeolite-containing catalyst is heat-treated at a temperature of 500 ° C or higher in the presence of water vapor prior to contact with the hydrocarbon raw material.
The production method according to any one of claims 1 to 10, wherein the catalyst regeneration step is started at a temperature lower than that of the conversion reaction step.
The production method according to any one of claims 1 to 11, further comprising a drying step of cooling the regeneration gas used in the catalyst regeneration step to remove water vapor in the regeneration gas.
The method according to any one of claims 1 to 12, further comprising a step of obtaining a dew point of sulfuric acid contained in the regeneration gas from a sulfuric acid concentration calculated from a correlation between an acid amount of the zeolite-containing catalyst and a catalyst accumulation rate or catalyst accumulation amount of sulfur. The manufacturing method of 1 item | term.
An apparatus for producing propylene or aromatic hydrocarbons,
Switching between a conversion reaction step in which a hydrocarbon raw material and a catalyst are brought into contact with each other, and a catalyst regeneration step in which a carbonaceous material adhering to the catalyst is burned and removed by the conversion reaction step by bringing a gas containing oxygen into contact with the catalyst. Having at least one production reactor having the function of performing,
The production reactor includes a first piping system that feeds the hydrocarbon raw material into the production reactor and feeds a reaction mixture from the production reactor, and feeds the oxygen-containing gas into the production reactor. And a second piping system for delivering from the production reactor,
The second piping system is an apparatus for producing propylene or an aromatic hydrocarbon, comprising a dryer for removing water vapor in the regeneration gas.
The apparatus for producing propylene or aromatic hydrocarbons according to claim 14, wherein the second piping system further includes a temperature measuring device for measuring the temperature of the regeneration gas.