JPH059373B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a novel modified crystalline aluminosilicate. More specifically, the present invention relates to a method for producing a modified crystalline aluminosilicate that has excellent performance as a catalyst, adsorption/separation agent, or the like. [Prior Art] Crystalline aluminosilicate is a porous material known as zeolite. Specifically, A-type, L-type, There are synthetic zeolites. Furthermore, regarding the synthetic zeolite, in recent years, zeolites such as ZSM-5 and ZSM-34, which have a skeleton structure different from that of natural zeolites, have been produced. In particular, ZSM-5, which is crystallized in the presence of a tetrapropylammonium compound, is attracting attention as a unique zeolite that can obtain crystalline phases over a wide range of silica/alumina skeleton molar ratios. In addition, since zeolite is porous and its crystal skeleton forms a regular cage structure, when it is used as a catalyst or adsorption/separation agent,
It is known that molecules exhibit shape selectivity for substances that participate in reactions and adsorption. That is, the size of molecules that can be adsorbed into or passed through the cage is regulated by the maximum entrance pore diameter of the cage. Furthermore, since zeolite has both acidic and basic properties, the degree of adsorption of molecules changes depending on the polarization of molecules passing through the pores. Furthermore, it is known that zeolite exhibits much higher catalytic activity than conventional solid acids such as silica-alumina by performing various modifications such as proton exchange and rare earth cation exchange. As mentioned above, zeolite has various excellent characteristics, and therefore it is an extremely important and widely used material in industrial use as a catalyst and adsorption/separation agent. This technology is currently being developed in the industrial field. Incidentally, in order to increase the selectivity and/or conversion rate in adsorption separation processes or catalytic reactions using zeolites, it has been proposed to modify zeolites. Therefore, such modification treatment mainly involves (a) adjusting the pore diameter of the zeolite more precisely according to the types and properties of the raw materials and products in order to increase the selectivity, and/or ( b) In order to increase the conversion rate, it consists of appropriately adjusting the acid sites of zeolite. As a representative example of the prior art related to the modification treatment, Japanese Patent Application Laid-Open No. 54-27528 discloses a method of modifying zeolite with a compound containing magnesium, phosphorus, and other elements. However, although this method shows a relatively high selectivity of p-ethyltoluene in the ethyltoluene synthesis (example) of 94 to 97%, it was difficult to obtain a high toluene conversion rate. The reason for these results is that the pore size is adjusted due to the improved selectivity, but on the other hand, the acid sites inside the pores are changed due to the decreased conversion rate of toluene. (Decrease)
It was a demonstration of what was being done. Furthermore, since the oxides of magnesium and phosphorus coat the inside of the pores of the zeolite, the shape selectivity is improved, but it is thought that the conversion rate is reduced. [Problems to be Solved by the Invention] The present invention aims to improve or solve the problems of the above-mentioned prior art. The purpose is to provide a method for producing aluminosilicate. A further object of the present invention is to provide a method for producing crystalline aluminosilicate with increased shape selectivity by adjusting the pore entrance diameter. Another object of the present invention is to provide a method for producing crystalline aluminosilicate that has high conversion and selectivity when used as a catalyst. A further object of the present invention is to provide a method for producing crystalline aluminosilicate that exhibits high selectivity without changing adsorption capacity when used as an adsorption/separation agent. In view of the current state of the art in this technical field regarding the production of modified crystalline aluminosilicate, the present inventors have conducted extensive research and development in order to achieve the above object. As a result, they discovered that by treatment with a heteropolyacid and/or its salt, it was possible to produce a crystalline aluminosilicate with a controlled pore entrance diameter and with almost no change in the melting point inside the pores. The invention was achieved. Therefore,
The present invention relates to a method for producing a novel modified crystalline aluminosilicate which has excellent performance as an adsorption/separation agent and a catalyst. [Structure of the Invention] The present invention is characterized in that a crystalline aluminosilicate is treated with a modifier containing one or more compounds selected from the group consisting of heteropolyacids and heteropolyacids. The present invention relates to a method for producing aluminosilicate. The crystalline aluminosilicate used in the present invention includes, for example, natural zeolites such as mordenite, chabasite, and erionite, and type X,
Synthetic zeolites such as Y type and pentasil type. Furthermore, depending on the purpose of use, proton type, ammonium salt type, various metal salt types obtained by cation exchange, or those subjected to appropriate treatment such as dealumination can also be used. Further, in the present invention, part or all of the aluminum or silicon constituting the crystalline aluminosilicate is
Crystalline metallosilicates substituted with other metals such as gallium, germanium, beryllium, etc. can also be used. The crystalline aluminosilicate used in the present invention is
It may be in powder form or a molded article suitable for practical use. As the binder to be mixed during the molding, very common binders such as alumina sol and clay can be used. In the present invention, heteropolyacid is a general term for acids produced by condensation of two or more inorganic oxygen acids,
The central heteroatom of the heteropolyacid anion (~
It can take various forms depending on the combination of polyatoms (usually Mo, W, Nb, V, etc.) coordinated via oxygen. Various types of heteropolyacids can be used in the present invention. Specifically, 12-tungstophosphoric acid ( _H3PW12O40 ), 12-tungstosilicic acid _{( H4SiW12O40 )} , 12-molybdophosphoric acid ( _{H3PMo12O40 )} , ₁₂ - _{tungstophosphoric} acid ( _H3PMo12O40 ), Examples include germanic acid (H ₃ GeW ₁₂ O ₄₀ ), 12-molybdogermanic acid (H ₃ GeMo ₁₂ O ₄₀ ), and the like. Further, the heteropolyacid salts used in the present invention include ammonium salts, alkali metal salts, alkaline earth metal salts, and other metal salts of the above-mentioned heteropolyacids. These heteropolyacids or heteropolyacid salts are used after being dissolved in a solvent inert to the crystalline aluminosilicate and the heteropolyacid or heteropolyacid salts. From the viewpoint of industrial implementation, it is desirable to use one with high solubility. Examples of such preferred suitable solvents may include water, alcohols, ethers, ketones, and the like. The use of water is more preferred from the point of view of industrial practice. In the present invention, the modification treatment is carried out by bringing the crystalline aluminosilicate and the above modification agent into contact with each other by various known means such as dipping and spraying. The immersion temperature at that time may be any temperature that does not decompose the heteropolyacid or its salt. The temperature is preferably about 10 to 30°C for ease of processing. Of course, it is also possible to spray the modifier dissolved in a solvent directly onto the crystalline aluminosilicate at a temperature of about 200 to 300°C, at which the heteropolyacid or its salt does not decompose. The contact time of the modifier in this treatment is approximately 30 minutes to 50 minutes.
It is usually about 5 to 10 hours, preferably about 5 to 10 hours. In addition, the hydrogen ion concentration during contact treatment is
In order to prevent the heteropolyacid, which is strongly acidic, from deteriorating in quality, it is preferable to carry out the reaction in a low pH range. Note that the modifier is preferably applied in a proportion of about 5 to 50% by weight, for example, with respect to the crystalline aluminosilicate containing about 30% by weight of a binder such as alumina sol. After the above contact treatment, the crystalline aluminosilicate is separated and dried at a temperature of 150°C or less. The purpose of this drying is to remove the solvent used to dissolve the modifier. Then, it is fired in the presence of oxygen, air, or the like.
The firing is performed under conditions that do not alter the crystal structure of the crystalline aluminosilicate. For example, the firing temperature is about 400 to 650°C, and the firing time is about 1 to 20 hours. Without intending to be bound by theory, it is predicted that this calcination causes the metal in the heteropolyacid or heteropolyacid salt to exist primarily on the outer surface of the crystalline aluminosilicate in the form of a metal oxide. Ru. Note that this modification and firing process may be repeated several times. The crystalline aluminosilicate thus modified can be used in various forms such as powder, granules, and pellets depending on the purpose of use, and can be used for various purposes such as catalysts or adsorption/separation agents. EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these specific examples. Example 1 30% by weight of alumina sol was added as a binder to a proton-type crystalline aluminosilicate having a pentasil-type silica/alumina molar ratio of 50 and molded.
After drying at 110°C for 2 hours, it was fired at 520°C for 16 hours. Next, 12.5 g of this shaped and calcined crystalline aluminosilicate was added to 200 g of an 8% by weight aqueous solution of 12-tungstophosphoric acid, and immersed for 5 hours with gentle stirring. Analysis of the 12-tungstophosphoric acid concentration in the aqueous solution before and after immersion revealed that 12-
The amount of tungstophosphoric acid supported was 30% by weight based on the crystalline aluminosilicate containing 30% by weight of binder. After removing the solvent, it was dried at 110°C for 2 hours and then dried at 610°C for 5 hours in the presence of air.
Time firing was performed. The acidity (corresponding to the number of acid sites) of the obtained modified crystalline aluminosilicate was measured according to the BENESI method. That is, a sample is dispersed in a predetermined amount of benzene, and paranitrodiphenylamine (pKa = -
2.48) and benzeneazodiphenylamine (pKa=+1.5) with n-butylamine. From the obtained titer, acidity was determined using the following formula. Acidity (pKa = 2.48) = Titration amount of n-butylamine (milliequivalent) when using para-nitrodiphenylamine / Grams of sample (g)
Acidity (pKa=+1.5) = Titration amount of n-butylamine (milliequivalents) in the case of benzeneazodiphenylamine/grams of sample (g
) The results obtained are shown in Table 1. Examples 2 to 5 In place of the 12-tungstophosphoric acid modifier used in Example 1, 12-molybdophosphoric acid was used in Example 2, 12-tungstosilicic acid was used in Example 3, and 12-tungstosilicic acid was used in Example 4. A modified crystalline aluminosilicate was prepared in the same manner as in Example 1, except that ammonium storate was used, and potassium 12-molybdophosphate was used in Example 5. The acidity of each modified crystalline aluminosilicate obtained was measured, and the results are shown in Table 1. Comparative Example 1 According to the method described in JP-A No. 54-27528,
I performed the following operations. The crystalline aluminosilicate obtained by adding a binder, molding and firing in the same manner and under the same conditions as in Example 1 was immersed in a 40% by weight aqueous magnesium acetate solution for 16 hours. The amount of magnesium acetate supported was 5% by weight of magnesium metal relative to the crystalline aluminosilicate containing the binder. Next, the crystalline aluminosilicate supporting magnesium acetate was dried and calcined in the same manner as in Example 1. The acidity of the obtained crystalline aluminosilicate was measured by the same method as in Example 1, and the results are shown in Table 1. Comparative Example 2 A crystalline aluminosilicate (not modified) was obtained by adding a binder, molding and firing in the same manner and under the same conditions as in Example 1, and its acidity was measured.
The results obtained are shown in Table 1.

[Table] The values were within reach.
Example 6 Using the crystalline aluminosilicate modified with 12-tungstophosphoric acid obtained in Example 1 as a catalyst, p-ethyltoluene was synthesized using toluene and ethylene as raw materials. The reaction was carried out using an atmospheric pressure flow reactor having a stainless steel (or glass) reaction tube with an inner diameter of 15 mm and a length of 400 mm, with a portion of the tube serving as a preheating section for the raw materials. The reaction tube was then heated by an electric tube furnace. Catalyst loading amount is 6.2g, its particle size is 20~42
It was a mess. The center temperature of the catalyst layer was 400°C. The molar ratio of toluene/ethylene is 5, hydrogen/
The molar ratio of ethylene is 3, and the weight hourly space velocity is
It was 10hr ^-1 . The reaction product was analyzed by gas chromatography. The results of the reaction obtained are shown in Table 2. Examples 7 and 8 Instead of the crystalline aluminosilicate modified with 12-tungstophosphoric acid, in Example 7, the crystalline aluminosilicate modified with 12-molybdophosphoric acid obtained in Example 2 was used as a catalyst. In Example 8, toluene and ethylene were prepared in the same manner and under the same conditions as in Example 6, except that the crystalline aluminosilicate catalyst modified with potassium 12-molybdophosphate obtained in Example 5 was used. A synthesis reaction of p-ethyltoluene was carried out using as a raw material. The results obtained are shown in Table 2. Comparative Examples 3 and 4 In Comparative Example 3, the magnesium acetate obtained in Comparative Example 1 was supported, and the dried and calcined crystalline aluminosilicate was used as a catalyst, and in Comparative Example 4, the molding obtained in Comparative Example 2, A synthetic reaction of p-ethyltoluene using toluene and ethylene as raw materials was carried out in the same manner and under the same conditions as in Example 6, except that calcined (unmodified) crystalline aluminosilicate was used as a catalyst. The results obtained are shown in Table 2.

[Table] Example 9 (Competitive adsorption test) Ortho, meta, and para isomers of xylene were each dissolved in 1,3,5-triisopropylbenzene at a concentration of 4% by weight. To the solution, 1 g of sodium pentasil-type crystalline aluminosilicate (silica/alumina molar ratio: 50) modified with 12-tungstophosphoric acid, obtained in the same manner as in Example 1, was added to reach sufficient equilibrium. like 24
Soaked for more than an hour. From the results of gas chromatographic analysis of the composition of the 1,3,5-triisopropylbenzene solution before and after immersion, the xylene adsorption capacity (mg/g-aluminosilicate) and para-xylene selectivity (mol%) were determined.
was calculated. The results obtained are shown in Table 3. Example 10 and Comparative Example 5 Instead of the Na-type crystalline aluminosilicate modified with 12-tungstophosphoric acid of Example 9,
In Example 10, 12 obtained in the same manner as in Example 2
- Crystalline aluminosilicate (Na type) modified with molybdophosphoric acid was used, and in Comparative Example 5, crystalline aluminosilicate (without modification treatment) that was molded and calcined in the same manner as in Comparative Example 2 was used. A xylene competitive adsorption test was conducted in the same manner and under the same conditions as in Example 9, except that silicate (Na type) was used. The results obtained are shown in Table 3.

〔Effect of the invention〕

(1) As shown in Table 1, the acidity of the modified crystalline aluminosilicate produced by the method of the present invention in Examples 1 to 5 was pKa = -2.48 and
For both cases of pKa=+1.5, the acidity was almost the same as that of the unmodified crystalline aluminosilicate of Comparative Example 2, and no change (decrease) in acidity was observed due to modification. Furthermore, the acidity of the crystalline aluminosilicate according to the present invention (Examples 1 to 5) was more than twice as high as that of the crystalline aluminosilicate modified with magnesium acetate of Comparative Example 1. These results indicate that the acid sites (acid sites are closely related to catalytic activity, etc.) in the pores of the crystalline aluminosilicate obtained by the method of the present invention are
This indicates that the material undergoes almost no change during the modification treatment and maintains the performance (for example, catalytic activity when used as a catalyst) as before the modification treatment even after the modification treatment. (2) As shown in Table 2, the p-ethyltoluene selectivity when using the crystalline aluminosilicate treated by the method of the present invention was compared to when using the untreated product shown as Comparative Example 4. Approximately 2
The value was about 95%, which is twice as high as that when the magnesium acetate treated product shown as Comparative Example 3 was used. Further, the toluene conversion rate of the crystalline aluminosilicate treated by the method of the present invention was more than twice that of the magnesium acetate treated product (Comparative Example 3). Furthermore, regarding the total yield of p-ethyltoluene, the crystalline aluminosilicate treated by the method of the present invention is more than twice that of the magnesium acetate treated product (Comparative Example 3), and the yield of the untreated product (Comparative Example 3). It was about 1.5 times that of 4). That is, the conversion rate and selectivity in a catalytic reaction using the crystalline aluminosilicate obtained by the production method of the present invention as a catalyst are higher than those in the conventional method. Furthermore, considering the results in Tables 1 and 3, the crystalline aluminosilicate obtained by the production method of the present invention has a structure in which the pore entrance diameter can be adjusted without reducing the acidity inside the pores. It can be seen that it is something that (3) As shown in Table 3, compared to untreated crystalline aluminosilicate, crystalline aluminosilicate modified by the method of the present invention has p- The selectivity of xylene is improved. This result shows that the manufacturing method of the present invention can control only the pore entrance diameter without changing the volume inside the pores. Furthermore, it can be seen that the crystalline aluminosilicate obtained by the production method of the present invention has improved shape selectivity compared to conventional products. That is, the crystalline aluminosilicate modified according to the present invention can control the diffusion of reactants or adsorbed substances into the pores and the diffusion of reaction products or desorbed substances to the outside of the pores. . (4) The acidity of crystalline aluminosilicate hardly changes due to the modification of the production method of the present invention (Table 1), and the adsorption capacity also does not change (Table 3). It is thought that this occurs on the outer surface of the aluminosilicate, and therefore,
It is believed that the outer surface is inactivated by denaturation. This is suggested by the fact that the selectivity of p-ethyltoluene in Table 2 is significantly different between the untreated product (Comparative Example 4) and the treated products (Examples 6 to 8). Therefore, when the modified crystalline aluminosilicate obtained by the production method of the present invention is used as an adsorption/separation agent or a catalyst in various catalytic reactions, it can suppress undesirable reactions occurring on the outer surface. As described above, the crystalline aluminosilicate produced by the method of the present invention exhibits excellent performance when used as an adsorption/separation agent or a catalyst for adhesion reactions.

Claims (1)

[Claims] 1. A method for producing a modified crystalline aluminosilicate, which comprises treating the crystalline aluminosilicate with a modifier containing one or more compounds selected from the group consisting of heteropolyacids and heteropolyacid salts.