JP5294928B2 - Process for producing aromatic hydrocarbon and catalyst used in the process - Google Patents

Description

  The present invention relates to a production method for synthesizing an aromatic hydrocarbon from alcohol, olefin or paraffin, and an aromatic hydrocarbon having an increased ratio of paraxylene in xylene isomers contained in the synthesized aromatic hydrocarbon It is related with the manufacturing method. Moreover, it is related with the catalyst used for the said manufacturing method.

  Aromatic compounds such as benzene, toluene and xylene are useful as basic raw materials or solvents in the petrochemical industry, and paraxylene is particularly useful as a raw material for terephthalic acid.

As a method for producing such an aromatic compound, a method for producing from an alcohol, olefin or paraffin using a crystalline aluminosilicate or a crystalline gallosilicate as a catalyst is known. For example, a method of synthesizing aromatic hydrocarbons from ethanol in the presence of ZSM-5 catalyst modified with zinc, gallium or molybdenum (silica / alumina ratio: 80), crystalline alumino modified with gallium A method of synthesizing an aromatic hydrocarbon from ethylene in the presence of a silicate catalyst or a crystalline gallosilicate catalyst (Non-patent Document 2), a crystal having a control index of 1 to 12 containing zinc and gallium and a silica / alumina ratio of 12 or more And a method of synthesizing aromatic hydrocarbons from gaseous hydrocarbons composed of C2 to C12 hydrocarbons containing a high content of propane in the presence of a neutral zeolite catalyst (Patent Document 1).

However, in these methods, since xylene is obtained as a mixture of isomers such as a para isomer and a meta isomer, there is a problem that a load of a separation process of para xylene is large. That is, para-xylene (boiling point: 138.35 ° C.) and meta-xylene (boiling point: 139.10 ° C.) are very close to each other, and it is difficult to separate para-xylene and meta-xylene by distillation. For example, a method is known in which metaxylene is selectively extracted with a hydrogen fluoride-boron trifluoride mixture in advance, and the remaining paraxylene, orthoxylene, and ethylbenzene as a by-product are separated by precision distillation. However, this method requires the use of a highly hazardous hydrogen fluoride-boron trifluoride mixture. Other methods include a crystallization separation method in which para-xylene is selectively crystallized, or a method in which para-xylene is selectively adsorbed on an adsorbent such as molecular sieve and then desorbed using a desorbent. It has been known. However, these methods require complicated operations.

Therefore, in a method for producing aromatic hydrocarbons from alcohol, olefin or paraffin, an aromatic hydrocarbon mixture having a high ratio of paraxylene in xylene isomers contained in aromatic hydrocarbons synthesized by this production method is obtained. There is a need for a manufacturing method that can do this. Such attempts have already been reported. For example, in the reaction using ethylene as a raw material in the presence of a crystalline aluminosilicate catalyst modified with gallium, by reducing the reaction temperature and the space velocity of the ethylene raw material, Proton-type ZSM-5 catalyst poisoned with strong acid sites by pyridine in the reaction using an alcohol such as ethanol or an olefin such as propylene as a raw material is improved in the ratio of para-xylene (Non-patent Document 3). It has been reported that it is effective in obtaining an aromatic hydrocarbon mixture in which the ratio of para-xylene is increased (Non-patent Document 4). However, even with these methods, it cannot be said that the para-xylene selectivity in the xylene isomers is still high enough, and it was difficult to obtain high-purity para-xylene even by performing a precision distillation operation.

As another trial, a reaction example using a catalyst obtained by treating an acid-treated crystalline aluminosilicate with a silylating agent has been reported (Patent Document 2). By silylating the catalyst, the aromatic hydrocarbon yield is improved and the coke formation rate is reduced in the reaction of synthesizing lower olefins and aromatic hydrocarbons from non-aromatic hydrocarbons in the gasoline boiling range. However, there is no particular description regarding the selectivity of para-xylene in the xylene isomers.

Japanese Patent Laid-Open No. 60-25940 JP-A-10-151351

J. Phys. Chem., 2006, 110, 21816. Micropoor. Mesopor.Matter., 2001, 47, 253. Micropor. Mesopor. Mater., 2002, 51, 203. Appl. Catal., 1984, 9, 251.

  In the production method for synthesizing an aromatic hydrocarbon from alcohol, olefin or paraffin, the present invention is preferably a method in which the selectivity of para-xylene in the xylene isomer contained in the synthesized aromatic hydrocarbon is obtained by only precision distillation. It is an object of the present invention to provide a production method that is increased to a level at which high-purity para-xylene can be obtained only by a normal distillation step.

  As a result of intensive studies on catalyst design in order to achieve the above object, the present inventors have found that crystalline aluminosilicate and / or crystallinity in a reaction for synthesizing an aromatic hydrocarbon from alcohol, olefin and / or paraffin. By using a gallosilicate modified with silica as a catalyst, it was found that the proportion of paraxylene in the xylene isomer contained in the reaction product was extremely high, and the present invention was completed.

That is, the present invention
In the method of synthesizing the aromatic hydrocarbons from ethanol, the crystalline aluminosilicate and crystalline row UKaoru aromatic reaction in the presence of a catalyst a silicate selected from gallosilicate include compounds modified with silica hydrocarbons It is a manufacturing method.

The silicate is preferably a zeolite having an oxygen 10-membered ring structure.
The zeolite is preferably ZSM-5 or ZSM-11.

The catalyst preferably contains at least one metal selected from the group VIA, VIIA, VIII, IB, IIB, and IIIB.
The catalyst preferably contains at least one kind of metal such as zinc or gallium.
Moreover, it is preferable that content of the metal in the said catalyst is 0.1-30 mass%.

  Moreover, it is preferable that the silica which modifies the said catalyst is a silicalite.

The present invention relates to at least one selected from the group of compounds wherein at least one silicate selected from crystalline aluminosilicate and crystalline gallosilicate contains at least one metal selected from zinc and gallium and is modified with silica. It is a catalyst consisting of two compounds.

  From aromatic hydrocarbons synthesized by the production method of the present invention, high-purity para-xylene can be obtained only by precision distillation separation without performing extraction operation of meta-xylene with a hydrogen fluoride-boron trifluoride mixture. Is possible. If a process of decomposing ethylbenzene, which is a product having a boiling point close to that of para-xylene, into benzene and ethane using a known dealkylation reaction is used in combination, it is possible to eliminate precision distillation. Such a dealkylation technique is disclosed in US Pat. No. 5,475,179. For this reason, since the separation and purification load of para-xylene can be greatly reduced, the industrial significance of the present invention is great.

  In the present invention, alcohol, olefin or paraffin is used as a raw material. As the alcohol, an alcohol having 1 to 20 carbon atoms can be used, and the number of hydroxyl groups in one molecule is not particularly limited. However, in consideration of production cost and availability, methanol, ethanol, and isopropanol are used. Particularly preferred. As the olefin or paraffin, a hydrocarbon having 1 to 20 carbon atoms can be used. Here, the number of double bonds in one molecule of olefins is not particularly limited. For the same reason as mentioned above, monoolefins and dienes can be mentioned as preferred examples. Alcohol, olefin, and paraffin may be used alone or in combination of two or more compounds. Moreover, you may use combining these raw materials and organic compounds, such as a naphthene.

(catalyst)
In the present invention, a catalyst containing a compound obtained by modifying a silicate selected from crystalline aluminosilicate and crystalline gallosilicate with silica is used. This modification with silica is presumed to mainly modify the outer surface of the silicate and suppress the action of isomerization active sites of aromatic compounds present on the surface.
Examples of crystalline aluminosilicate and / or crystalline gallosilicate (hereinafter sometimes referred to as “main body side silicate”) include ZSM-5, ZSM-11, ZSM-57, ZSM-23, MCM-22, and the like. Zeolite having an oxygen 10-membered ring structure is preferred, and among them, ZSM-5 or ZSM-11 is more preferred, and ZSM-5 is particularly preferred. Zeolite as described above has a pore diameter substantially equal to the molecular diameter of the aromatic compound. For this reason, it is said that the cyclization reaction to an aromatic compound is accelerated and the yield of the aromatic compound tends to increase. Further, para-xylene having a relatively small molecular diameter is likely to diffuse out of the pores than ortho-xylene and meta-xylene, and is expected to be preferable for increasing the selectivity of para-xylene.

  The silica / alumina ratio of the crystalline aluminosilicate is not particularly limited, but is usually preferably 5 to 700, more preferably 10 to 200, and particularly preferably 15 to 100. When the silica / alumina ratio is high, the water resistance of the crystalline aluminosilicate is reduced when water is by-produced by the reaction or when the catalyst deactivated by the coke accumulation is calcined and regenerated in the air. On the other hand, when the silica / alumina ratio is low, the catalytic activity is low. The silica / gallia ratio of the crystalline gallosilicate is not particularly limited, but is usually preferably about 5 to 700, more preferably 10 to 200, and particularly preferably 15 to 100.

A commercially available crystalline aluminosilicate and / or crystalline gallosilicate may be used, but it can also be synthesized by a known method. The particle diameter of crystalline aluminosilicate and / or crystalline gallosilicate is not particularly limited, but those having an average particle diameter of 0.2 μm to 10 μm are usually used from the viewpoint of handling and availability. The particle size distribution is not particularly limited, but it is preferable to use crystalline aluminosilicate and / or crystalline gallosilicate having a narrow particle size distribution in order to control the film thickness at the time of silica coating. When an aluminosilicate having a wide particle size distribution is used, the proportion of fine powder and coarse particles increases. In this case, there is a possibility that the silica film thickness of the fine powder becomes relatively high and the silica film thickness of the coarse particles becomes relatively low. In such a case, there is a possibility that the catalyst performance of the fine powder and the coarse particle part is different.

The crystal structure of the silica that modifies the crystalline aluminosilicate (hereinafter sometimes referred to as “modified silica”) is not particularly limited, and either amorphous silica or crystalline silica can be used. Crystalline silica is preferred, and silicalite is more preferred.
The modified silica is presumed to have an effect of mainly suppressing the isomerization reaction. Specifically, it is considered that the action of the isomerization active site which is supposed to exist on the outer surface of the main body side silicate is suppressed. Crystalline silica, particularly silicalite, is presumed to have a higher effect of suppressing the isomerization reaction than amorphous silica. Specifically, silicalite-1 and silicalite-2. The structure is desirably the same as that of the main body side silicate. For example, when the main crystalline aluminosilicate is ZSM-5, silicalite-1 is preferably used as a modifier, and when the crystalline aluminosilicate is ZSM-11, silicalite-2 is preferably used as a modifier. When these modifiers are used, the selectivity for para-xylene tends to be higher.

  The modification of crystalline aluminosilicate and / or crystalline gallosilicate with silicalite is performed by using crystalline aluminosilicate and / or crystalline gallosilicate in advance as a raw material liquid for hydrothermal synthesis of silicalite at room temperature. It can be carried out by suspending it in The raw material liquid for synthesizing silicalite contains a silica source, a structure-directing agent, and distilled water, and further contains an alcohol such as ethyl alcohol as necessary. As a silica source, colloidal silica such as alkoxysilane such as tetramethoxysilane or tetraethoxysilane, Aerosil (registered trademark, manufactured by Evonik Degussa), Snowtex (registered trademark, manufactured by Nissan Chemical Industries, Ltd.) can be used. Among these, alkoxysilane and aerosil are preferable because a raw material with a small amount of aluminum impurities can be easily obtained. As the structure directing agent, known compounds such as tetrapropylammonium can be used for synthesizing silicalite-1, and tetrabutylammonium can be used for synthesizing silicalite-2.

During the synthesis of silicalite, the raw material liquid may be allowed to stand. However, in order to uniformly modify crystalline aluminosilicate and / or crystalline gallosilicate with silicalite, it is preferable to stir the raw material liquid. The reaction temperature is preferably 60 ° C to 200 ° C, more preferably 100 ° C to 190 ° C, and particularly preferably 120 ° C to 190 ° C. The time required for the reaction is appropriately selected depending on the reaction temperature. Usually, it is 12 hours to 7 days.
The amount of the modified silica with respect to the crystalline aluminosilicate is preferably from 3 to 200 mass%, more preferably from 10 to 150 mass%, particularly preferably from 20 to 100 mass%. The modification of the crystalline aluminosilicate with silica may be performed once or about 2 to 5 times.

The modification of the crystalline aluminosilicate and / or crystalline gallosilicate with amorphous silica is carried out by dissolving the amorphous silica raw material in a solvent and then adding the crystalline aluminosilicate and / or crystalline gallosilicate, and then obtaining the suspension The solvent in the solvent can be distilled off, and the dried powder can be fired under the flow of a gas containing oxygen.
As a raw material for amorphous silica, it is desirable to use an organosilicon compound having a molecular size larger than the pores of crystalline aluminosilicate and / or crystalline gallosilicate. Specific examples of the organosilicon compound include phenylmethylpolysiloxane, dimethylpolysiloxane, diphenylpolysiloxane, phenylmethylsiloxane, diphenylsiloxane and the like. Further, polysiloxane obtained by copolymerizing at least two kinds of monomers such as phenylmethylsiloxane, dimethylsiloxane, and diphenylsiloxane can also be used.

The solvent can be used without particular limitation as long as it is a solvent in which the silica raw material is dissolved and crystalline aluminosilicate and / or crystalline gallosilicate is not dissolved. Since operation at a lower temperature at the time of distilling off the solvent is easier, usually a low-polarity nonpolar solvent such as hexane or toluene is preferably used.
The organosilicon compound becomes amorphous silica by firing under a gas stream containing oxygen such as air. The firing temperature is preferably 300 to 800 ° C, more preferably 500 to 650 ° C.
The amount of modification of amorphous silica with respect to crystalline aluminosilicate is preferably 3 to 200% by mass, more preferably 10 to 150% by mass, and particularly preferably 20 to 100% by mass.
In some cases, the modification with amorphous silica cannot sufficiently suppress the isomerization active site. Therefore, when amorphous silica is used as a modifier, it is desirable to perform coking treatment after carrying out modification with amorphous silica and further circulating a hydrogen / toluene mixed gas through the catalyst at a high temperature of about 450 ° C. .

In the method for producing aromatic hydrocarbons of the present invention, for example, the amount of paraffin produced as a by-product and the selectivity of the aromatic compound can be further improved, so that VIA groups such as molybdenum and chromium, rhenium, etc. Contains at least one metal selected from group VIIA, group VIII such as cobalt, nickel and platinum, group IB such as copper and silver, group IIB such as zinc and cadmium, and group IIIB such as gallium and indium It is desirable to keep it. Among the above, zinc or gallium is particularly preferable. Particularly preferred is zinc.
Such a metal-containing catalyst has a feature that the isomer selectivity of an aromatic compound obtained is extremely high as described later.

The above metals can be introduced mainly by using a metal compound such as a metal nitrate as a reaction raw material. The catalyst of the present invention may contain only a metal or may be contained as a compound. The content is preferably 0.1 to 30% by mass, more preferably 0.5 to 20% by mass, and particularly preferably 0.8 to 12% by mass in terms of metal atoms with respect to the solid component after modification. 1-6 mass% is the most preferable.
For the introduction of the metal, a known method such as an ion exchange method or an impregnation method can be adopted without limitation using a metal salt such as nitrate as a raw material. The modification with metal may be performed on crystalline aluminosilicate and / or crystalline gallosilicate whose outer surface is modified with silica, or the metal may be contained in crystalline aluminosilicate and / or crystalline gallosilicate. Then, it may be modified with silicalite.
The above catalysts can be used in combination of two or more. Further, the above catalyst can be used in combination with other useful components as long as the object of the present invention is not impaired.

(Aromatic hydrocarbon production method)
The reaction temperature in the reaction for synthesizing the aromatic hydrocarbon from alcohol, olefin and / or paraffin is preferably 300 ° C to 700 ° C, more preferably 350 ° C to 600 ° C, and particularly preferably 380 ° C to 550 ° C. If the reaction temperature is too low, the reaction rate decreases, olefin intermediates may remain, and the yield of aromatic compounds may decrease. If the reaction temperature is too high, the xylene selectivity in the aromatic compound may decrease.
The reaction pressure when synthesizing the aromatic hydrocarbon is preferably atmospheric pressure to 2 MPa, more preferably atmospheric pressure to 0.9 MPa, and particularly preferably atmospheric pressure to 0.5 MPa.
In the method for producing aromatic hydrocarbons of the present invention, xylene is produced. In particular, para bodies are obtained with extremely high selectivity.

Without extraction of meta-xylene by HF-BF _3, in order to obtain high-purity para-xylene only precision distillation, paralogs / meta isomer ratio after the reaction is preferably 500 or more, 1000 or more More preferably, it is particularly preferably 2000 or more. Of course, it is most preferable that the meta-body is not by-produced, so the upper limit value is infinite, but if it is deliberately defined, it is 100,000.
Since para-xylene and ortho-xylene can be separated by precision distillation, there is no particular limitation on the para-ortho-ratio ratio, but in order to reduce the precision distillation load or eliminate the need for precision distillation, it must be 1000 or more. Is desirable.
The method for producing an aromatic compound of the present invention often produces ethylbenzene. Ethylbenzene and paraxylene are compounds with close boiling points, but can be separated by precision distillation.
On the other hand, if ethylbenzene can be dealkylated, precision distillation is not necessary, and para-xylene can be purified by a normal distillation operation.

Examples are shown below, but the present invention is not limited to these Examples.
Example 1
<1> Preparation of ZSM-5 In an autoclave container having an inner bag of 1 L of Teflon (registered trademark), 66.7 g (0.32 mol) of tetraethoxysilane and 3.0 g (0.008 mol) of aluminum nitrate nonahydrate Then, 3.2 g (0.08 mol) of sodium hydroxide, 32.0 g (0.12 mol) of tetrapropylammonium bromide and 519.0 g (28.8 mol) of distilled water were added, and the mixture was stirred at room temperature for 30 minutes. Then, it was made to react at 180 degreeC for 3 days, stirring an autoclave. After completion of hydrothermal synthesis, the autoclave was cooled and the solid matter was filtered. The obtained solid was washed 5 times with 500 ml of distilled water and then calcined in the air at 600 ° C. for 5 hours to obtain ZSM-5.
The obtained ZSM-5 was dissolved in hydrogen fluoride and then analyzed with an ICP emission spectrometer. As a result, the silica-alumina ratio was 60. Moreover, the average particle diameter of ZSM-5 was 5 micrometers.

<2> Preparation of Crystalline Aluminosilicate Modified with Silicalite-1 (Catalyst of the Present Invention) In a 200 ml Teflon (registered trademark) container, 4.16 g (0.020 mol) of tetraethoxysilane, 20% tetrapropylammonium Add 5.1 g (0.005 mol) of hydroxide, 11.0 g (0.239 mol) of ethyl alcohol, 54.0 g (3.00 mol) of distilled water and 4 g of ZSM-5 obtained above, and add 30 g at room temperature. Stir for minutes. Thereafter, a Teflon (registered trademark) container was placed in an autoclave and allowed to react at 180 ° C. for 1 day while stirring. After completion of hydrothermal synthesis, the autoclave was cooled and the solid matter was filtered. The obtained solid was washed 5 times with 500 ml of distilled water.
The obtained solid was transferred to a 200 ml Teflon (registered trademark) container, tetraethoxysilane 4.16 g (0.020 mol), 20% tetrapropylammonium hydroxide 5.1 g (0.005 mol), ethyl alcohol 11.0 g. (0.239 mol) and 54.0 g (3.00 mol) of distilled water were added, followed by stirring at room temperature for 30 minutes. Thereafter, a Teflon (registered trademark) container was placed in an autoclave and allowed to react at 180 ° C. for 1 day while stirring. After completion of hydrothermal synthesis, the autoclave was cooled and the solid matter was filtered. The obtained solid was washed 5 times with 500 ml of distilled water, dried at 120 ° C. for 3 hours, and further calcined at 600 ° C. for 5 hours in air.

Example 2 Preparation of Zinc-modified Silicalite-1 Modified ZSM-5 (Catalyst of the Present Invention) 100 g of distilled water was added to 0.0728 g (0.245 μmol) of zinc nitrate hexahydrate, and an aqueous zinc nitrate solution was added. Was prepared. Thereto was added 0.8 g of ZSM-5 catalyst modified with silicalite-1 obtained in Example 1 to obtain a slurry. Water was distilled off from the slurry under reduced pressure at 70 ° C. The obtained solid was dried at 120 ° C. for 3 hours, and further calcined in air at 600 ° C. for 5 hours to obtain zinc-modified silicalite-1-modified ZSM-5.
The zinc content was 2% by mass as a result of analysis with an ICP emission spectrometer after dissolving the catalyst with hydrogen fluoride.

Comparative Example 1 Preparation of Zinc-modified ZSM-5 ZSM-5 prepared in <1> of Example 1 instead of using the ZSM-5 catalyst modified with silicalite-1 prepared in Example 1 ZSM-modified ZSM-5 was prepared in the same manner as in Example 2 except that was used.
The zinc content was 2% by mass as a result of analysis with an ICP emission spectrometer after dissolving the catalyst with hydrogen fluoride.

(Example 3)
0.3 g of the zinc-modified silicalite-1 modified ZSM-5 catalyst prepared in Example 2 was charged into a SUS tubular reactor having a diameter of 3/8 inch and a total length of 300 mm. The reactor was connected to a flow reactor, and the temperature was raised under a nitrogen flow. After the internal temperature of the reactor reached 400 ° C., the flow of nitrogen was stopped, and ethyl alcohol was allowed to flow through the reactor at a rate of 1.78 g / hour to start the reaction. The product after 20 minutes from the start of the reaction was analyzed by an on-line gas chromatograph. The line from the outlet of the reactor to the gas chromatograph was kept at 250 ° C., and the product was circulated as a gas. The ethanol conversion was 100%.
The product was analyzed by an absolute calibration curve method using a gas chromatograph equipped with a flame ionization detector.

Table 1 shows the analysis results of the product.

(Comparative Example 2)
The reaction was conducted in the same manner as in Example 3 except that the zinc-modified ZSM-5 catalyst prepared in Comparative Example 1 was used instead of the zinc-modified silicalite-1 modified ZSM-5 catalyst prepared in Example 2. Went. The ethanol conversion was 100%. The results obtained by quantifying the obtained product in the same manner as in Example 3 are shown in Table 1.

From the results shown in Table 1, it can be seen that by using the catalyst of the present invention, an aromatic hydrocarbon having an extremely high ratio of para-xylene in the xylene isomer can be produced.

Paraxylene is a very useful compound derived from terephthalic acid and used as a raw material for polyester fibers or films.
According to the method for producing aromatic hydrocarbons of the present invention, it is possible to produce a product having a very high ratio of para-xylene in the xylene isomer, and it is easy to take out para-xylene from the xylene isomer. The catalyst according to the present invention is useful as a catalyst for synthesizing para-xylene.

Claims (10)

In the method of synthesizing the aromatic hydrocarbons from ethanol, the crystalline aluminosilicate and crystalline row UKaoru aromatic reaction in the presence of a catalyst a silicate selected from gallosilicate include compounds modified with silica hydrocarbons Production method. The process for producing an aromatic hydrocarbon according to 請 Motomeko 1 Ru zeolites der with the silicate oxygen 10-membered ring structures. The method for producing an aromatic hydrocarbon according to claim 1, wherein the silicate is ZSM-5 or ZSM-11. Group wherein the catalyst VIA, VIIA Group, VIII group, IB group, IIB group and the IIIB group of any one of 請 Motomeko 1 to claim 3 you containing at least one kind of metal selected from the metals A process for producing aromatic hydrocarbons. The process for producing an aromatic hydrocarbon according to any one of claims 1 to請 Motomeko 3 you comprising at least one kind of metal the catalyst is selected from zinc, and gallium. The process for producing an aromatic hydrocarbon according to 請 Motomeko 4 or claim 5 the content of the metal is Ru der than 30 wt% 0.1 wt% of the catalyst. The method for producing an aromatic hydrocarbon according to any one of claims 1 to 6, wherein the silica is silicalite. The method for producing an aromatic hydrocarbon according to any one of claims 1 to 7, wherein the aromatic hydrocarbon contains para-xylene. The method for producing an aromatic hydrocarbon according to any one of claims 1 to 8, wherein the reaction is performed at a temperature of 380 ° C to 550 ° C and a pressure of atmospheric pressure to 0.5 MPa. Compound der least one kind of silicate modified with silica selected from crystalline aluminosilicate and crystalline gallosilicate is, and contains at least one kind of metal selected from zinc, and gallium, including xylene from ethanol Catalyst for producing aromatic hydrocarbons .