SBA-15 molecular sieve catalyst for preparing n-butyronitrile and preparation method and application thereof

Abstract

The application belongs to the technical field of catalyst preparation, and particularly relates to an SBA-15 molecular sieve catalyst for preparing n-butyronitrile and a preparation method and application thereof. SBA-15 mesoporous molecular sieve is immersed in an aqueous solution of active metal salt for a period of time, taken out and dried, and used as a molecular sieve catalyst precursor. Aluminum isopropoxide is dissolved in ethanol, the above-mentioned molecular sieve catalyst precursor is added into the solution and mixed thoroughly, the molecular sieve catalyst precursor is taken out and washed and dried, and then calcination is carried out in air at 450-650 DEG C, and finally reduction is carried out in a hydrogen atmosphere at 300-600 DEG C.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of catalyst preparation, and particularly relates to an SBA-15 molecular sieve catalyst for preparing n-butyronitrile and a preparation method and application thereof. BACKGROUND

[0002] N-butyronitrile is an important chemical product, which can be used as an intermediate for the synthesis and preparation of drugs and as an additive of industrial products. At present, n-butyronitrile is mainly synthesized by the gas phase catalytic cyanation method of n-butanol or n-butyraldehyde. The supported catalyst has an ideal application prospect in the gas catalytic reaction based on the channel structure advantage of the carrier.

[0003] The mesoporous molecular sieve SBA-15 has a large pore size, which makes it have the prospect of being used as such a catalyst carrier. After loading a metal component with catalytic activity on the SBA-15 molecular sieve, it is used for the gas catalytic reaction. However, since the SBA-15 molecular sieve is composed of a silicon-oxygen structure and does not have acidity itself, the SBA-15 molecular sieve is relatively low in the aspect of its own acid catalytic activity, which also limits the application of the SBA-15 molecular sieve in the field of catalysts.

[0004] The doping modification of the SBA-15 molecular sieve by introducing aluminum elements can further improve the catalytic acidity and thermal stability of the SBA-15 molecular sieve itself. However, the applicant found in actual operation that the improvement of the supported catalyst based on the SBA-15 molecular sieve in the overall catalytic performance is still limited after the modification by introducing aluminum elements through the post-aluminum method. SUMMARY

[0005] To solve the above technical problems, the present application provides a preparation method of an SBA-15 molecular sieve catalyst for preparing n-butyronitrile,

[0006] (1) SBA-15 mesoporous molecular sieve is immersed in an aqueous solution of active metal salt for a period of time, taken out and dried, and used as a molecular sieve catalyst precursor;

[0007] (2) Aluminum isopropoxide is dissolved in ethanol, the molecular sieve catalyst precursor obtained in step (1) is added and fully mixed, the molecular sieve catalyst precursor is taken out and washed and dried, and then calcined in air at 450-650 DEG C and finally reduced in a hydrogen atmosphere at 300-600 DEG C.

[0008] As a preferred, in step (1), the metal elements in the active metal salt are composed of one or more of Cu, Cr, Co, Mo and Ni.

[0009] Further, the mass ratio of one or more of Cu, Cr, Co and Mo to Ni is 1-10:5-20.

[0010] As preferred: in step (1), the mass concentration of the active metal salt in the aqueous solution of the active metal salt is 5-25%.

[0011] As preferred: in step (1), the impregnation in the aqueous solution of the active metal salt is carried out at normal temperature (25℃, same below) for 8-15h.

[0012] As preferred: in step (1), the drying temperature is 100-120℃, and the drying time is 4-8h.

[0013] As preferred: in step (2), the stirring mixing after adding the molecular sieve catalyst precursor is carried out at normal temperature for 15-30h.

[0014] As preferred: in step (2), the drying temperature is 100-120℃, and the drying time is 10-20h.

[0015] As preferred: in step (2), the calcination time is 4-6h.

[0016] As preferred: in step (2), the reduction time in the hydrogen atmosphere is 3-5h.

[0017] The application further provides an SBA-15 molecular sieve catalyst for preparing n-butyronitrile, which is prepared by the above preparation method.

[0018] The application further provides a catalytic application of the above SBA-15 molecular sieve catalyst in the preparation of n-butyronitrile by the ammoniation of n-butanol.

[0019] As preferred: the n-butanol gas and the ammonia gas are mixed in a molar ratio of 1:5, and then transmitted through a tubular reactor at a volume space velocity of 18h-1, the catalyst bed in the reaction cavity of the tubular reactor is filled with the SBA-15 molecular sieve catalyst, the temperature of the reaction cavity is set to 130℃, and the total gas pressure of the mixed gas of the n-butanol gas and the ammonia gas in the reaction cavity is maintained at 100kPa. -1

[0020] ​The beneficial effects of the present application are that the catalyst carrier SBA-15 molecular sieve of the present scheme has multi-level channels itself, which is beneficial to the timely diffusion of the generated product molecules, and on this basis, the present scheme hopes to further modify the SBA-15 molecular sieve with aluminum. Through post-aluminum modification, although the acid active sites of the SBA-15 molecular sieve are enriched, and the catalytic acidity of the molecular sieve itself is improved, in the modification process, part of the aluminum does not really enter the framework structure of the SBA-15 molecular sieve, and when this part of the non-framework aluminum remains in the molecular sieve channel or on the surface, the specific surface area and pore volume of the molecular sieve decrease, which may not have a great effect on the SBA-15 molecular sieve itself, but will also affect the loading of the metal active component on the molecular sieve in the subsequent impregnation operation, and finally the overall improvement of the catalytic effect is not ideal.

[0021] The present scheme first impregnates and loads the SBA-15 molecular sieve with a metal active component, hoping to load as many active ions as possible on the molecular sieve, and then performs post-aluminum modification. However, the post-aluminum operation needs to disperse the molecular sieve loaded with the metal active component into an aluminum source solution again, and generally, the dispersing solvent will cause a large amount of active metal ions loaded in the molecular sieve channel to be re-dissolved, resulting in a large loss of catalytically active metal components, and finally the overall catalytic effect cannot be effectively improved and may even further decrease.

[0022] However, in the present application, the overall catalytic effect is greatly improved, and for this, the applicant believes that on the one hand, the SBA-15 molecular sieve itself has a certain adsorption effect on active metal ions, and in the present scheme, isopropyl aluminum is used as an aluminum source to enter the molecular sieve, which has a certain complexation effect on the catalytic metal active ions therein, increases the stability of the active metal ions in the channel, and to some extent, inhibits the dissolution and separation. Finally, not only the post-aluminum doping is realized, but also the catalytically active metal originally loaded in the molecular sieve is well preserved, avoiding a large loss. DETAILED DESCRIPTION

[0023] A preparation method of an SBA-15 molecular sieve catalyst for preparing n-butyronitrile:

[0024] (1) SBA-15 mesoporous molecular sieve is immersed in an active metal salt aqueous solution with a solute mass concentration of 5-25% at room temperature for 8-15 h, taken out and dried at 100-120°C for 4-8 h, as a molecular sieve catalyst precursor,

[0025] Among them, the metal elements in the active metal salt are composed of one or more of Cu, Cr, Co, Mo and Ni, and the mass ratio of one or more of Cu, Cr, Co and Mo to Ni is 1-10:5-20.

[0026] (2) Dissolve aluminum isopropoxide in ethanol, then add the molecular sieve catalyst precursor obtained in step (1) into the solution, and stir the mixture at room temperature for 15-30 hours. Take out the molecular sieve catalyst precursor, wash it with deionized water, dry it at 100-120°C for 10-20 hours, calcine it in air at 450-650°C for 4-6 hours, and finally reduce it in hydrogen atmosphere at 300-600°C for 3-5 hours.

[0027] Use the SBA-15 molecular sieve catalyst prepared above to prepare n-butyronitrile by ammoniating n-butanol:

[0028] Both use the SBA-15 molecular sieve catalyst prepared above to fill the catalyst bed in the reaction cavity of the tubular reactor. Mix n-butanol gas and ammonia gas in a molar ratio of 1:5, and transport the mixture through the tubular reactor at a volume space velocity of 18h-1. The temperature of the reaction cavity is set to 130°C, the total gas pressure of the mixed gas of n-butanol gas and ammonia gas in the reaction cavity is maintained at 100kPa, the mixed gas transported out of the tubular reactor is cooled to room temperature, and the condensed liquid is collected as the n-butyronitrile product. -1

[0029] The scheme of the present application is further illustrated below in combination with examples. If not specifically stated, the raw materials and equipment used in the examples are all commonly used in the art; if not specifically stated, the methods used in the present application are all conventional methods in the art. In the following processes, the undisclosed conditions are all known conventional methods.

[0030] Example 1

[0031] Preparation of SBA-15 molecular sieve catalyst:

[0032] (1) Immerse 2g of SBA-15 mesoporous molecular sieve in 30mL of a 10% mass concentration Ni(NO3)2 aqueous solution at room temperature for 10 hours, then filter out the molecular sieve and dry it at 110°C for 3 hours. Then immerse the molecular sieve in 30mL of a mixed aqueous solution of Cu(NO3)2 and Cr(NO3)3 (the mass concentration of Cu(NO3)2 is 3% and the mass concentration of Cr(NO3)3 is 3%) at room temperature for 5 hours, then filter out the molecular sieve and dry it at 110°C for 3 hours, as a molecular sieve catalyst precursor;

[0033] ​(2) 0.34 g aluminum isopropoxide was dissolved in 80 g ethanol, and the molecular sieve catalyst precursor obtained in step (1) was added thereto and stirred and mixed at room temperature for 20 h, after which the molecular sieve catalyst precursor was suction-filtered and washed with deionized water, and then dried at 100°C for 10 h, and then calcined at 550°C for 4 h in an air atmosphere, and then placed in a tube reactor and reduced at 450°C for 3 h in a hydrogen stream.

[0034] Example 2

[0035] Preparation of the SBA-15 molecular sieve catalyst, in step (1), the amount of SBA-15 mesoporous molecular sieve was increased to 2.2 g, and the rest of the operations were the same as in Example 1:

[0036] (1) 2.2 g of SBA-15 mesoporous molecular sieve was immersed in 30 mL of a 10% solute mass concentration Ni(NO3)2 aqueous solution at room temperature for 10 h, after which the molecular sieve was suction-filtered and dried at 110°C for 3 h, and then the molecular sieve was immersed in 30 mL of a mixed aqueous solution of Cu(NO3)2 and Cr(NO3)3 (wherein the mass concentration of Cu(NO3)2 was 3% and the mass concentration of Cr(NO3)3 was 3%) at room temperature for 5 h, after which the molecular sieve was suction-filtered and dried at 110°C for 3 h, and used as a molecular sieve catalyst precursor;

[0037] (2) 0.34 g aluminum isopropoxide was dissolved in 80 g ethanol, and the molecular sieve catalyst precursor obtained in step (1) was added thereto and stirred and mixed at room temperature for 20 h, after which the molecular sieve catalyst precursor was suction-filtered and washed with deionized water, and then dried at 100°C for 10 h, and then calcined at 550°C for 4 h in an air atmosphere, and then placed in a tube reactor and reduced at 450°C for 3 h in a hydrogen stream.

[0038] Blank Example 1

[0039] Preparation of the SBA-15 molecular sieve catalyst, no aluminum modification was performed on the molecular sieve catalyst, and the rest of the operations were the same as in Example 2:

[0040] (1) 2.2 g of SBA-15 mesoporous molecular sieve was immersed in 30 mL of a 10% solute mass concentration Ni(NO3)2 aqueous solution at room temperature for 10 h, after which the molecular sieve was suction-filtered and dried at 110°C for 3 h, and then the molecular sieve was immersed in 30 mL of a mixed aqueous solution of Cu(NO3)2 and Cr(NO3)3 (wherein the mass concentration of Cu(NO3)2 was 3% and the mass concentration of Cr(NO3)3 was 3%) at room temperature for 5 h, after which the molecular sieve was suction-filtered and dried at 110°C for 3 h, and used as a molecular sieve catalyst precursor;

[0041] (2) The molecular sieve catalyst precursor obtained in step (1) is calcined in air at 550°C for 4h, and then placed in a tube reactor for reduction treatment in a hydrogen stream at 450°C for 3h.

[0042] Comparative Example 1

[0043] The preparation of the SBA-15 molecular sieve catalyst is first to modify the SBA-15 molecular sieve by doping aluminum, and then to impregnate and load metal active ingredients on the molecular sieve, and the rest of the operations are the same as in Example 2:

[0044] (1) 0.34g aluminum isopropoxide is dissolved in 80g ethanol, 2.2g SBA-15 mesoporous molecular sieve is added thereto and stirred and mixed at room temperature for 20h, the molecular sieve is then filtered out and washed with deionized water, and then dried at 100°C for 10h, and then calcined in air at 550°C for 4h to obtain the SBA-15 molecular sieve modified by doping aluminum;

[0045] (2) The SBA-15 molecular sieve modified by doping aluminum obtained in step (1) is immersed in 30mL of a 10% Ni(NO3)2 aqueous solution at room temperature for 10h, the molecular sieve is then filtered out and dried at 110°C for 3h, and then immersed in 30mL of a mixed aqueous solution of Cu(NO3)2 and Cr(NO3)3 (wherein the mass concentration of Cu(NO3)2 is 3% and the mass concentration of Cr(NO3)3 is 3%) at room temperature for 5h, the molecular sieve is then filtered out and dried at 110°C for 3h, and then calcined in air at 550°C for 4h, and then placed in a tube reactor for reduction treatment in a hydrogen stream at 450°C for 3h.

[0046] Comparative Example 2

[0047] The preparation of the SBA-15 molecular sieve catalyst is first to modify the SBA-15 molecular sieve by doping aluminum, and then to impregnate and load metal active ingredients on the molecular sieve, and the rest of the operations are the same as in Example 2:

[0048] (1) 2.2g SBA-15 mesoporous molecular sieve is immersed in 30mL of a 10% Ni(NO3)2 aqueous solution at room temperature for 10h, the molecular sieve is then filtered out and dried at 110°C for 3h, and then immersed in 30mL of a mixed aqueous solution of Cu(NO3)2 and Cr(NO3)3 (wherein the mass concentration of Cu(NO3)2 is 3% and the mass concentration of Cr(NO3)3 is 3%) at room temperature for 5h, the molecular sieve is then filtered out and dried at 110°C for 3h, and then calcined in air at 550°C for 4h to obtain the molecular sieve catalyst precursor;

[0049] (2) 0.22 g of anhydrous aluminum chloride was dissolved in 80 g of ethanol, and the molecular sieve catalyst precursor obtained in step (1) was added thereto and stirred and mixed at normal temperature for 20 h, after which the molecular sieve catalyst precursor was suction-filtered and washed with deionized water, and then dried at 100°C for 10 h, and then calcined at 550°C for 4 h in an air atmosphere, and then reduced at 450°C for 3 h in a hydrogen stream in a tube reactor.

[0050] Example 3

[0051] In the preparation of the SBA-15 molecular sieve catalyst, the amount of SBA-15 mesoporous molecular sieve in step (1) was increased to 2.3 g, and the rest of the operations were the same as in Example 1:

[0052] (1) 2.3 g of SBA-15 mesoporous molecular sieve was immersed in 30 mL of a 10% solute mass concentration Ni(NO3)2 aqueous solution at normal temperature for 10 h, after which the molecular sieve was suction-filtered and dried at 110°C for 3 h, and then the molecular sieve was immersed in 30 mL of a mixed aqueous solution of Cu(NO3)2 and Cr(NO3)3 (wherein the mass concentration of Cu(NO3)2 was 3% and the mass concentration of Cr(NO3)3 was 3%) at normal temperature for 5 h, after which the molecular sieve was suction-filtered and dried at 110°C for 3 h, and used as a molecular sieve catalyst precursor;

[0053] (2) 0.34 g of aluminum isopropoxide was dissolved in 80 g of ethanol, and the molecular sieve catalyst precursor obtained in step (1) was added thereto and stirred and mixed at normal temperature for 20 h, after which the molecular sieve catalyst precursor was suction-filtered and washed with deionized water, and then dried at 100°C for 10 h, and then calcined at 550°C for 4 h in an air atmosphere, and then reduced at 450°C for 3 h in a hydrogen stream in a tube reactor.

[0054] Example 4

[0055] In the preparation of the SBA-15 molecular sieve catalyst, the loading concentration of the nickel salt in step (1) was increased to 15%, and the rest of the operations were the same as in Example 2:

[0056] (1) 2.2 g of SBA-15 mesoporous molecular sieve was immersed in 30 mL of a 15% solute mass concentration Ni(NO3)2 aqueous solution at normal temperature for 10 h, after which the molecular sieve was suction-filtered and dried at 110°C for 3 h, and then the molecular sieve was immersed in 30 mL of a mixed aqueous solution of Cu(NO3)2 and Cr(NO3)3 (wherein the mass concentration of Cu(NO3)2 was 3% and the mass concentration of Cr(NO3)3 was 3%) at normal temperature for 5 h, after which the molecular sieve was suction-filtered and dried at 110°C for 3 h, and used as a molecular sieve catalyst precursor;

[0057] (2) The molecular sieve catalyst precursor obtained in step (1) is dissolved in 80 g of ethanol, 0.34 g of aluminum isopropoxide is added to the solution, and the mixture is stirred at room temperature for 20 h. The molecular sieve catalyst precursor is filtered out and washed with deionized water. The mixture is dried at 100°C for 10 h, calcined at 550°C in air for 4 h, and then reduced at 450°C in a hydrogen stream for 3 h in a tube reactor.

[0058] Example 2

[0059] The SBA-15 molecular sieve catalyst is prepared without aluminum doping modification, and the remaining operations are the same as in Example 4.

[0060] (1) 2.2 g of SBA-15 mesoporous molecular sieve is immersed in 30 mL of a 15% Ni(NO3)2 aqueous solution at room temperature for 10 h. The molecular sieve is filtered out and dried at 110°C for 3 h. The molecular sieve is then immersed in a mixed aqueous solution of Cu(NO3)2 and Cr(NO3)3 (the mass concentration of Cu(NO3)2 is 3%, and the mass concentration of Cr(NO3)3 is 3%) at room temperature for 5 h. The molecular sieve is filtered out and dried at 110°C for 3 h as a molecular sieve catalyst precursor.

[0061] (2) The molecular sieve catalyst precursor obtained in step (1) is calcined at 550°C in air for 4 h, and then reduced at 450°C in a hydrogen stream for 3 h in a tube reactor.

[0062] Example 3

[0063] The SBA-15 molecular sieve catalyst is prepared by first doping aluminum modification to the SBA-15 molecular sieve, and then impregnating and loading metal active ingredients on the molecular sieve. The remaining operations are the same as in Example 4.

[0064] (1) 0.34 g of aluminum isopropoxide is dissolved in 80 g of ethanol, and 2.2 g of SBA-15 mesoporous molecular sieve is added to the solution. The mixture is stirred at room temperature for 20 h. The molecular sieve is filtered out and washed with deionized water. The mixture is dried at 100°C for 10 h, calcined at 550°C in air for 4 h, and then reduced at 450°C in a hydrogen stream for 3 h in a tube reactor.

[0065] (2) The aluminum-modified SBA-15 molecular sieve obtained in step (1) is immersed in 30 mL of a 15% mass concentration Ni(NO3)2 aqueous solution at room temperature for 10 h, the molecular sieve is filtered out and dried at 110°C for 3 h, then the molecular sieve is immersed in a mixed aqueous solution of Cu(NO3)2 and Cr(NO3)3 (wherein the mass concentration of Cu(NO3)2 is 3% and the mass concentration of Cr(NO3)3 is 3%) at room temperature for 5 h, the molecular sieve is filtered out and dried at 110°C for 3 h, then the molecular sieve is calcined at 550°C in an air atmosphere for 4 h, and then the molecular sieve is placed in a tube reactor and reduced at 450°C in a hydrogen stream for 3 h.

[0066] Comparative Example 4

[0067] The preparation of the SBA-15 molecular sieve catalyst, in the post-aluminum operation of step (2), aluminum chloride is used as the aluminum source and deionized water is used as the solvent, and the remaining operations are the same as in Example 4:

[0068] (1) 2.2 g of SBA-15 mesoporous molecular sieve is immersed in 30 mL of a 15% mass concentration Ni(NO3)2 aqueous solution at room temperature for 10 h, the molecular sieve is filtered out and dried at 110°C for 3 h, then the molecular sieve is immersed in a mixed aqueous solution of Cu(NO3)2 and Cr(NO3)3 (wherein the mass concentration of Cu(NO3)2 is 3% and the mass concentration of Cr(NO3)3 is 3%) at room temperature for 5 h, the molecular sieve is filtered out and dried at 110°C for 3 h, and the molecular sieve is used as a molecular sieve catalyst precursor;

[0069] (2) 0.32 g of anhydrous aluminum chloride is dissolved in 80 g of deionized water, then the molecular sieve catalyst precursor obtained in step (1) is added thereto and stirred and mixed at room temperature for 20 h, the molecular sieve catalyst precursor is filtered out and washed with deionized water, then the molecular sieve catalyst precursor is dried at 100°C for 10 h, calcined at 550°C in an air atmosphere for 4 h, and then placed in a tube reactor and reduced at 450°C in a hydrogen stream for 3 h.

[0070] Example 5

[0071] The preparation of the SBA-15 molecular sieve catalyst, in step (1), the loading concentrations of the copper salt and the chromium salt are both increased to 5%, and the remaining operations are the same as in Example 4:

[0072] (1) 2.2 g of SBA-15 mesoporous molecular sieve was immersed in 30 mL of a 15% mass concentration Ni(NO3)2 aqueous solution at room temperature for 10 h, the molecular sieve was filtered out and dried at 110°C for 3 h, then the molecular sieve was immersed in 30 mL of a mixed aqueous solution of Cu(NO3)2 and Cr(NO3)3 (wherein the mass concentration of Cu(NO3)2 is 5%, the mass concentration of Cr(NO3)3 is 5%) at room temperature for 5 h, the molecular sieve was filtered out and dried at 110°C for 3 h, serving as a molecular sieve catalyst precursor;

[0073] (2) 0.34 g of aluminum isopropoxide was dissolved in 80 g of ethanol, then the molecular sieve catalyst precursor obtained in step (1) was added and stirred and mixed at room temperature for 20 h, the molecular sieve catalyst precursor was filtered out and washed with deionized water, then dried at 100°C for 10 h, calcined at 550°C for 4 h in an air atmosphere, and then placed in a tubular reactor for reduction treatment at 450°C for 3 h in a hydrogen gas stream.

[0074] Example 6

[0075] In the preparation of the SBA-15 molecular sieve catalyst, cobalt salt and molybdenum salt were used instead of copper salt and chromium salt in step (1), and the rest of the operations were the same as in Example 5:

[0076] (1) 2.2 g of SBA-15 mesoporous molecular sieve was immersed in 30 mL of a 15% mass concentration Ni(NO3)2 aqueous solution at room temperature for 10 h, the molecular sieve was filtered out and dried at 110°C for 3 h, then the molecular sieve was immersed in 30 mL of a mixed aqueous solution of Cu(NO3)2 and Cr(NO3)3 (wherein the mass concentration of Cu(NO3)2 is 5%, the mass concentration of Cr(NO3)3 is 5%) at room temperature for 5 h, the molecular sieve was filtered out and dried at 110°C for 3 h, serving as a molecular sieve catalyst precursor; 24 24 (1) 2.2 g of SBA-15 mesoporous molecular sieve was immersed in 30 mL of a 15% mass concentration Ni(NO3)2 aqueous solution at room temperature for 10 h, the molecular sieve was filtered out and dried at 110°C for 3 h, then the molecular sieve was immersed in 30 mL of a mixed aqueous solution of Cu(NO3)2 and Cr(NO3)3 (wherein the mass concentration of Cu(NO3)2 is 5%, the mass concentration of Cr(NO3)3 is 5%) at room temperature for 5 h, the molecular sieve was filtered out and dried at 110°C for 3 h, serving as a molecular sieve catalyst precursor;

[0077] (2) 0.34 g of aluminum isopropoxide was dissolved in 80 g of ethanol, then the molecular sieve catalyst precursor obtained in step (1) was added and stirred and mixed at room temperature for 20 h, the molecular sieve catalyst precursor was filtered out and washed with deionized water, then dried at 100°C for 10 h, calcined at 550°C for 4 h in an air atmosphere, and then placed in a tubular reactor for reduction treatment at 450°C for 3 h in a hydrogen gas stream.

[0078] Blank Example 3

[0079] In the preparation of the SBA-15 molecular sieve catalyst, no aluminum modification was performed on the molecular sieve catalyst, and the rest of the operations were the same as in Example 6:

[0080] ​(1) 2.2 g of SBA-15 mesoporous molecular sieve was immersed in 30 mL of 15% Ni(NO3)2 aqueous solution at room temperature for 10 h. The molecular sieve was then filtered out and dried at 110 °C for 3 h. The molecular sieve was then immersed in 30 mL of Co(NO3)2 and (NH4)6Mo7O at room temperature. 24 A mixed aqueous solution (in which the mass concentration of Co(NO3)2 is 5% and the mass concentration of (NH4)6Mo7O is 5%) 24 After 5 hours in a solution containing 5% by mass, the molecular sieve was filtered out and dried at 110℃ for 3 hours to serve as a precursor for the molecular sieve catalyst.

[0081] (2) The molecular sieve catalyst precursor obtained in step (1) is calcined at 550°C for 4 hours in an air atmosphere, and then placed in a tubular reactor for reduction treatment at 450°C for 3 hours in a hydrogen gas stream.

[0082] Comparative Example 5

[0083] The preparation of the SBA-15 molecular sieve catalyst involved first modifying the SBA-15 molecular sieve with aluminum doping, then impregnating the molecular sieve with a loaded metal active component. All other operations were the same as in Example 6.

[0084] (1) Dissolve 0.34g aluminum isopropoxide in 80g ethanol, then add 2.2g SBA-15 mesoporous molecular sieve and stir and mix at room temperature for 20h. After filtering out the molecular sieve and washing it thoroughly with deionized water, dry it at 100℃ for 10h and calcine it at 550℃ for 4h in air atmosphere to obtain the SBA-15 molecular sieve modified with aluminum doping.

[0085] (2) The SBA-15 molecular sieve modified with aluminum doping obtained in step (1) was immersed in 30 mL of Ni(NO3)2 aqueous solution with a solute mass concentration of 15% for 10 h at room temperature. The molecular sieve was then filtered out and dried at 110 °C for 3 h. The molecular sieve was then immersed in 30 mL of Co(NO3)2 and (NH4)6Mo7O at room temperature. 24 A mixed aqueous solution (in which the mass concentration of Co(NO3)2 is 5% and the mass concentration of (NH4)6Mo7O is 5%) 24 After 5 hours in a 5% (mass concentration) solution, the molecular sieve is filtered out and dried at 110℃ for 3 hours. Then, it is calcined at 550℃ in an air atmosphere for 4 hours and then placed in a tubular reactor for reduction treatment at 450℃ in a hydrogen gas stream for 3 hours.

[0086] The SBA-15 molecular sieve catalysts prepared in the above-described examples, comparative examples, and blank control examples were used to fill the catalyst bed in the reaction chamber of the tubular reactor. After thoroughly mixing n-butanol gas and ammonia gas at a molar ratio of 1:5, the mixture was allowed to run for 18 hours. -1The volume space velocity of the mixed gas of n-butanol gas and ammonia gas was transported through the tubular reactor, the temperature of the reaction cavity was set to 130°C, the total gas pressure of the mixed gas of n-butanol gas and ammonia gas when the mixed gas was introduced into the reaction cavity was 100 kPa, the reaction was continuously carried out for 1 hour, during which the mixed gas transported out of the tubular reactor was analyzed on-line by gas chromatography and then cooled to room temperature, and the liquid substance condensed was collected.

[0087] The above analysis results are shown in Table 1, wherein,

[0088] The n-butanol conversion rate = (the total amount of n-butanol in the raw material gas introduced - the total amount of n-butanol in the liquid substance condensed collected) ÷ the total amount of n-butanol in the raw material gas introduced × 100%;

[0089] The n-butyronitrile selectivity = the total number of moles of n-butyronitrile in the liquid substance condensed collected ÷ (the total number of moles of n-butanol in the raw material gas introduced - the total number of moles of n-butanol in the liquid substance condensed collected) × 100%;

[0090] The yield = the n-butyronitrile selectivity × the n-butanol conversion rate × 100%.

[0091] Table 1

[0092] n-Butanol conversion / % n-Butyronitrile selectivity / % Yield / % Example 1 94.7 95.4 90.3 Example 2 96.2 97.4 93.7 Blank Example 1 87.2 84.1 73.3 Comparative Example 1 91.6 90.6 83.0 Comparative Example 2 85.7 84.3 72.2 Example 3 95.1 95.3 90.6 Example 4 96.8 97.9 94.8 Blank Example 2 82.4 83.1 68.5 Comparative Example 3 88.0 86.7 76.3 Comparative Example 4 77.2 75.4 58.2 Example 5 98.4 98.5 96.9 Example 6 97.6 98.0 95.6 Blank Example 3 85.7 87.2 74.7 Comparative Example 5 90.3 89.4 80.7

[0093] In the above table, blank control example 1, blank control example 2 and blank control example 3 are not subjected to post-alumina modification of SBA-15 molecular sieve, and the catalytically active metal is directly loaded on the molecular sieve. In contrast, comparative example 1, comparative example 3 and comparative example 5 are subjected to post-alumina modification of SBA-15 molecular sieve, and then the catalytically active metal is loaded, and the final catalytic effect is improved, but the improvement is limited.

[0094] In contrast, in examples 1 to 6, the SBA-15 mesoporous molecular sieve is first subjected to catalytically active metal impregnation and loading, and then subjected to post-alumina modification. During the impregnation and loading, as many catalytically active metal ions as possible are loaded in the molecular sieve channels, and the loss of these metal ions is well inhibited during the post-alumina process, and the final catalytic performance is still significantly improved.

[0095] In Comparative Example 2, although the support is also impregnated first and then subjected to post-alumination, since the conventional aluminum source inorganic aluminum chloride is used, the complexation and stabilization effect of isopropyl alcohol on the catalytically active metal ions in the molecular sieve is lost, and in the post-alumination modification, the active metal ions in the molecular sieve are subjected to a large amount of elution from the molecular sieve due to the impact from the solvent, resulting in a significant decline in the overall catalytic effect of the final product, which is even worse than the blank control example. In Comparative Example 4, on the basis of using the conventional aluminum source inorganic aluminum chloride, the solvent in the post-alumination process is deionized water, and the solubility of deionized water for the catalytically active metal ions is much higher than that of ethanol, which further increases the elution degree of the active metal in the molecular sieve in the post-alumination process, resulting in a more obvious decline in the overall catalytic effect of the final product.

Claims

1. A method for preparing an SBA-15 molecular sieve catalyst for the preparation of n-butyronitrile, characterized in that: The preparation method is as follows: (1) After immersing SBA-15 mesoporous molecular sieve in an aqueous solution of active metal salt for a period of time, it is taken out and dried to serve as a precursor for molecular sieve catalyst. (2) Dissolve aluminum isopropoxide in ethanol, then add the molecular sieve catalyst precursor obtained in step (1) and mix thoroughly. Stir and mix at room temperature for 15-30 h. Take out the molecular sieve catalyst precursor, wash and dry it, calcine it in air at 450-650 °C, and finally reduce it in a hydrogen atmosphere at 300-600 °C. In step (1), the immersion conditions are: immersion in the aqueous solution of the active metal salt at room temperature for 8 to 15 hours, and the drying conditions are: drying temperature of 100 to 120°C and drying time of 4 to 8 hours.

2. The method for preparing SBA-15 molecular sieve catalyst for preparing n-butyronitrile as described in claim 1, characterized in that: In the active metal salt described in step (1), the metal element is composed of one or more of Cu, Cr, Co, and Mo, along with Ni.

3. The method for preparing SBA-15 molecular sieve catalyst for preparing n-butyronitrile as described in claim 2, characterized in that: The mass ratio of one or more of the elements Cu, Cr, Co, and Mo to Ni is 1–10:5–20.

4. The method for preparing the SBA-15 molecular sieve catalyst for preparing n-butyronitrile as described in claim 1, characterized in that: In step (2), the drying temperature is 100-120℃ and the drying time is 10-20h.

5. An SBA-15 molecular sieve catalyst for preparing n-butyronitrile, prepared by the method according to any one of claims 1 to 4.

6. The catalytic application of the SBA-15 molecular sieve catalyst prepared by the method described in claim 5 in the amination of n-butanol to n-butyronitrile.

7. The application of the SBA-15 molecular sieve catalyst as described in claim 6, characterized in that: The method for preparing n-butanol by amination of n-butanol is as follows: n-butanol gas and ammonia gas are mixed thoroughly at a molar ratio of 1:5, and then subjected to a reaction for 18 hours. -1 The volume hourly space velocity (VHSV) is transported through the tubular reactor, and the catalyst bed in the reaction chamber of the tubular reactor is filled with the SBA-15 molecular sieve catalyst. The temperature of the reaction chamber is set to 130°C, and the total pressure of the mixture of n-butanol gas and ammonia gas in the reaction chamber is maintained at 100 kPa.