ZSM-5 / MCM-41 molecular sieves with different sodium contents as well as controllable preparation method and application of ZSM-5 / MCM-41 molecular sieves

Abstract

The invention relates to the technical field of molecular sieves as well as preparation methods and application thereof, in particular to ZSM-5 / MCM-41 molecular sieves with different sodium contents as well as a controllable preparation method and application thereof, and the ZSM-5 / MCM-41 molecular sieves with different sodium contents are prepared by controlling the sodium content of a catalyst in one step by utilizing supergravity and ultrasonic means. The ZSM-5 / MCM-41 molecular sieves with different sodium contents prepared by the invention have good thermal stability and hydrothermal stability, and the activity of the catalyst is greatly improved; the catalyst is used in a reaction for preparing succinic acid through catalytic hydrogenation of maleic anhydride, the hydrothermal stability is high, the catalytic performance is excellent, the maleic anhydride conversion rate is high, the succinic acid selectivity is high, the stability can reach 900-1200 h, when the deactivated catalyst is regenerated subsequently and used for the reaction, the maleic anhydride conversion rate can still reach 100%, and the succinic acid selectivity and the catalyst stability are equivalent to those of a fresh agent.

Description

Technical Field

[0001] This invention relates to the field of molecular sieves, their preparation methods, and applications. It relates to ZSM-5 / MCM-41 molecular sieves with different sodium contents and their controllable preparation methods, and also includes the application of the ZSM-5 / MCM-41 molecular sieves with different sodium contents in the catalytic hydrogenation of maleic anhydride to succinic acid. Background Technology

[0002] The ZSM-5 molecular sieve with an MFI structure is composed of perpendicularly intersecting elliptical straight channels and nearly circular "Z"-shaped channels. ZSM-5 molecular sieve exhibits strong shape selectivity, is less prone to carbon deposition during the catalytic process of small molecule reactants, and possesses excellent thermal stability. As a catalytic cracking catalyst and additive component, it can improve the octane number of gasoline and the selectivity for low-molecular-weight olefins. ZSM-5 molecular sieve is currently one of the important active components for catalytic cracking catalysts, octane number enhancers, and additives for increasing the production of low-carbon olefins and propylene.

[0003] MCM-41 molecular sieves are among the most representative mesoporous molecules, featuring a regularly arranged hexagonal pore structure. The pore size can be adjusted by selecting surfactants, auxiliaries, and reaction conditions. They generally have advantages such as large specific surface area and uniform and tunable pore structure, making them highly promising for applications in industrial catalysis, biomedicine, adsorption separation, and other fields.

[0004] Molecular sieves are crystalline aluminosilicates composed primarily of SiO4 and AlO4 tetrahedra, linked by sharing an oxygen atom between two tetrahedra to form a three-dimensional framework with uniform molecular size (typically 0.25 nm–1 nm). Currently, the International Molecular Association (IZA) has identified over 200 molecular sieve structures. Among them, approximately 20 types, including Y (FAU), ZSM-5 (MFI), mordenite (MOR), beta (BEA), and MCM-22 (MWW), are widely used in industrial processes such as fluid catalytic cracking (FCC), alkylation, methanol-to-hydrocarbon (MTH), and hydroconversion. The success of molecular sieves in catalysis is mainly due to their excellent properties, including crystallinity, large internal surface area, superior hydrothermal stability, tunable acidity, and good shape selectivity. However, molecular sieve catalysts still suffer from a significant drawback: due to their small micropore size, they are often diffusion-limited, reducing their catalytic efficiency. Furthermore, this restricted mass transfer can lead to pore blockage by macromolecules or coke-like precipitates, resulting in catalyst deactivation. Therefore, researchers have designed micro-mesoporous materials that combine the advantages of mesoporous materials and microporous molecular sieves.

[0005] CN102795637B discloses a method for preparing a catalytic cracking catalyst. This method involves a molecular sieve exchange modification method that reduces the sodium oxide content in ZSM-5 type molecular sieves by using a low-temperature mixed acid to exchange molecular sieves and thereby eliminate ammonia nitrogen pollution. The molecular sieve exchange and washing process is carried out at low temperature with a mixed acid solution containing inorganic and organic acids. This method can reduce the sodium oxide content in the catalyst, avoid ammonia nitrogen pollution in the molecular sieve exchange and catalyst washing processes, and significantly reduce water consumption and wastewater treatment costs. The disadvantage is that while using inorganic and organic acids to exchange and wash the molecular sieves and catalyst to reduce sodium, it also significantly damages the crystal structure of the molecular sieves, resulting in poor crystallinity of the molecular sieves in the catalyst and reducing the thermal and hydrothermal stability of the catalyst.

[0006] In summary, while current research reports on the effect of sodium content on catalyst activity, systematic studies on the impact of residual Na in the catalyst on catalytic hydrogenation activity are lacking. Excessive sodium content leads to poor catalytic performance and low product yield, while insufficient sodium content results in catalyst deactivation, carbon deposition, and a decrease in specific surface area, significantly affecting the catalyst's final stability. Na readily exists on the catalyst surface, covering active sites and clogging pores. Furthermore, excessive Na content can easily generate side reactions. Therefore, controlling the sodium content of the catalyst to achieve a good match between catalyst preparation and process technology is crucial. Summary of the Invention

[0007] This invention provides a controllable preparation method and application of ZSM-5 / MCM-41 molecular sieves with different sodium contents, overcoming the shortcomings of existing technologies. It effectively solves problems such as poor catalytic effect, low product yield, easy carbon deposition and deactivation of catalysts, short lifespan, and inability to achieve industrial application due to excessively high or low sodium content in existing preparation methods. The ZSM-5 / MCM-41 molecular sieves prepared using the controllable preparation method of this invention can produce molecular sieves with different sodium contents in a one-step process without post-processing, achieving precise control of the sodium content of ZSM-5 / MCM-41 molecular sieves. This method is energy-saving and environmentally friendly, improves preparation efficiency, reduces preparation cost, and simplifies the preparation process. Furthermore, when this catalyst is applied to the maleic anhydride catalytic hydrogenation reaction system, the yield of succinic acid increases, its stability improves, and its regeneration performance is good, demonstrating promising industrial application prospects.

[0008] One of the technical solutions of this invention is achieved through the following measures: a controllable preparation method of ZSM-5 / MCM-41 molecular sieves with different sodium contents, comprising at least the following steps: (1) Add silicon source, sodium aluminate and first template agent to the aqueous solution in sequence and stir until homogeneous to form solution a; add silicon source, ammonia and second template agent to the aqueous solution in sequence and stir until homogeneous to form solution b; (2) The solution a is slowly added dropwise to the solution b and mixed evenly by vigorous stirring to form a mixed gel A; (3) The obtained mixed gel A was transferred to a supergravity reactor, heated to carry out a crystallization reaction, and then dried and subjected to a first calcination treatment to obtain sodium-containing catalyst B; (4) Add the sodium-containing catalyst B to be treated to a certain amount of water, and then add ultrasonic treatment (i.e., add an ultrasonic generator to make it emit ultrasonic waves in the water) to adjust the sodium content in the water. Finally, filter, dry, and calcine the residue after ultrasonic treatment. Then use a flame photometer to test the sodium content of the prepared ZSM-5 / MCM-41 molecular sieve to obtain ZSM-5 / MCM-41 molecular sieves with different sodium contents.

[0009] Specifically, in the implementation of the present invention, the stirring temperature in step (2) is 10°C to 80°C and the stirring time is 2h to 24h. Preferably, the stirring temperature is 20°C to 60°C and the stirring time is 3h to 8h. In solution a, the molar ratio of SiO2:Al2O3:first template agent:H2O is 1:(0.03-0.1):(0.03-1):(36-100). In solution b, the molar ratio of SiO2: ammonia: second template agent: H2O is 1:(2.5-56):(0.1-1):(100-250). Optionally, the silicon source is any one or any combination of two or more of the following: tetraethyl orthosilicate, silica sol, silica powder, water glass, and sodium silicate nonahydrate. Optionally, the first template agent includes any one or any combination of two or more of n-butylamine, tetrapropylammonium hydroxide, and tetrabutylammonium hydroxide.

[0010] The first template agent is a template agent for ZSM-5 molecular sieve.

[0011] Optionally, the second template agent includes any one or any combination of two or more of hexadecyltrimethylammonium bromide and tetradecyltrimethylammonium bromide.

[0012] The second template agent is the template agent of MCM-41 molecular sieve.

[0013] Specifically, in step (3), the rotation speed of the hypergravity reactor is 100 rpm to 5000 rpm, the crystallization reaction temperature of the mixed gel A is 100°C to 300°C, and the crystallization reaction time is 17 h to 96 h. Preferably, the crystallization reaction temperature is 110°C to 180°C and the crystallization reaction time is 24 h to 72 h. Specifically, in step (3), the drying temperature is 50°C to 180°C and the drying time is 1h to 24h. Preferably, the drying temperature is 90°C to 150°C and the drying time is 3h to 12h. In the first calcination treatment, the solid product obtained by drying is heated to 430°C to 600°C and calcined for 3h to 10h to obtain sodium-containing catalyst B. The heating rate of the first calcination is controlled to be 1°C / min to 10°C / min. Preferably, the heating rate is controlled to be 2°C / min to 5°C / min. Specifically, in step (4), the mass ratio of sodium-containing catalyst B to water is 1:0.5 to 10, the intensity of ultrasound is 70 Hz to 140 Hz, the drying temperature is 50 ℃ to 180 ℃, and the drying time is 1 h to 24 h. Preferably, the drying temperature is 90 ℃ to 150 ℃ and the drying time is 3 h to 12 h. In the second calcination treatment, the solid product obtained by drying is heated to 430 ℃ to 600 ℃ and calcined for 3 h to 10 h to obtain ZSM-5 / MCM-41 molecular sieves with different sodium contents. The heating rate is controlled to be 1 ℃ / min to 10 ℃ / min. Preferably, the heating rate is controlled to be 2 ℃ / min to 5 ℃ / min.

[0014] The second technical solution of the present invention is achieved by the following measures: a controllable preparation method of ZSM-5 / MCM-41 molecular sieves with different sodium contents as described in the first technical solution.

[0015] The third technical solution of the present invention is achieved through the following measures: the application of a ZSM-5 / MCM-41 molecular sieve with different sodium contents in the catalytic hydrogenation of maleic anhydride to succinic acid.

[0016] This invention provides the application of ZSM-5 / MCM-41 molecular sieves with different sodium contents in the catalytic hydrogenation of maleic anhydride to succinic acid. The specific steps for evaluating the performance of this catalyst are as follows: The ZSM-5 / MCM-41 molecular sieve, after being tableted, extruded, or pulverized, is sieved to obtain particles with a size of 0.5 cm to 2 cm, and loaded into a fixed-bed reactor. The catalyst is fixed in the reaction section of the reactor using alumina ceramic balls. Maleic anhydride and solvent are used as raw materials, mixed and fed into the reactor using a plunger pump, with hydrogen as the carrier gas. The reaction temperature is controlled at 80°C to 300°C, the reaction pressure at 0 MPa to 5 MPa, and the mass hourly space velocity (based on maleic anhydride) at 0.5-3 h⁻¹. -1 Hydrogen flow rate = 30 ml / min - 100 ml / min. Liquid phase products were sampled at fixed time intervals, and their composition was analyzed using gas chromatography.

[0017] In this invention, the solvent is not strictly controlled and is a commonly used organic solvent selected from any one of tetrahydrofuran, acetone, dioxane, benzene, toluene, γ-butyrolactone, propyl ether, isopropyl ether, butyl ether, isobutyl ether, ethyl acetate, isopropyl acetate, isoamyl acetate, diethyl succinate, dimethyl succinate, etc.

[0018] After reacting for a period of time, the ZSM-5 / MCM-41 molecular sieve can be sieved to obtain regenerated material. The specific steps are as follows: The ZSM-5 / MCM-41 molecular sieve after reaction is placed in a reactor and regenerated under a reducing atmosphere. The regeneration temperature is 300℃ to 600℃ and the regeneration time is 2h to 8h. Then, the performance of the catalyst is evaluated.

[0019] Optionally, the reducing atmosphere includes hydrogen, nitrogen, or a mixture of hydrogen and nitrogen.

[0020] This invention provides a controllable preparation method for ZSM-5 / MCM-41 molecular sieves with different sodium contents. Utilizing centrifugal force and ultrasound, the method achieves one-step controllable preparation of ZSM-5 / MCM-41 molecular sieves with varying sodium contents. This method features a simple preparation process, precise control of the sodium content of the ZSM-5 / MCM-41 molecular sieve, good product morphology, and strong reproducibility. The ZSM-5 / MCM-41 molecular sieve exhibits good crystallinity and moderate acid strength and amount. Furthermore, the ZSM-5 / MCM-41 molecular sieve possesses excellent thermal and hydrothermal stability, significantly improving the activity of the catalyst (i.e., the ZSM-5 / MCM-41 molecular sieve). This catalyst is used in the catalytic hydrogenation of maleic anhydride to succinic acid. It exhibits strong hydrothermal stability, excellent catalytic performance, high maleic anhydride conversion (≥98%), high succinic acid selectivity (≥99%), and stability for 900-1200 hours. When the deactivated catalyst is regenerated and used in the reaction, the maleic anhydride conversion can still reach 100%, and the succinic acid selectivity and catalyst stability are comparable to those of the fresh catalyst. Detailed Implementation

[0021] This invention is not limited to the following embodiments, and specific implementation methods can be determined according to the technical solutions and actual conditions of this invention. Unless otherwise specified, all chemical reagents and chemical products mentioned in this invention are well-known and commonly used chemical reagents and chemical products in the prior art; unless otherwise specified, all percentages in this invention are mass percentages; unless otherwise specified, all solutions in this invention are aqueous solutions with water as the solvent, for example, hydrochloric acid solution is an aqueous solution of hydrochloric acid.

[0022] The present invention will be further described below with reference to embodiments:

Example 1

[0023] (2) Preparation of solution b1: First, add 104.17g tetraethyl orthosilicate, 21.29g ammonia and 18.2g hexadecyltrimethylammonium bromide to 900g deionized water in sequence, and stir evenly at 20°C to form solution b1 (in solution b1, the molar ratio of SiO2: ammonia: second template agent: H2O is 1:2.5:0.1:100).

[0024] (3) Finally, the b1 solution was slowly added dropwise to the a1 solution, and the mixture was stirred vigorously at 30°C for 5 hours to form a gel solution A1. The resulting mixed gel A1 was transferred to a high-gravity reactor and reacted at 100 rpm and a crystallization temperature of 170°C for 48 hours. After that, it was dried at 120°C for 6 hours and finally calcined at 550°C for 6 hours to obtain the sodium-containing catalyst B1.

[0025] (4) Add 10g of sodium-containing catalyst B1 to 10g of deionized water, then add an ultrasonic generator to make it emit ultrasonic waves in the water. The intensity of the ultrasonic waves is 70Hz. Adjust the sodium content in the water. Finally, filter the residue after ultrasonication, dry it at 120℃ for 6h, and then calcine it at 550℃ for 6h. Use a flame photometer to test the sodium content of the prepared ZSM-5 / MCM-41 molecular sieve to obtain 0.9% Na-ZSM-5 / MCM-41 molecular sieve.

[0026] The 0.9% Na-ZSM-5 / MCM-41 molecular sieve and 30wt% Al2O3 support obtained after calcination were pressed into tablets or extruded into strips, crushed and sieved, and catalyst particles with a particle size of 0.8cm to 2.0cm were separated for use in the following application experiments.

[0027] Catalyst application: In a fixed-bed reactor, 5g of the above-mentioned catalyst particles were packed into the middle of the reaction tube; the reactants, maleic anhydride and solvent, entered through the inlet of the fixed-bed reactor at a mass ratio of 1:1, and contacted the catalyst bed under the action of hydrogen to undergo a catalytic hydrogenation reaction of maleic anhydride. The reaction conditions were: reaction temperature 150℃, pressure 1MPa (H2), WHSV = 1.0h. -1 (Total space velocity), hydrogen flow rate = 30 ml / min.

[0028] Liquid products were collected at fixed time intervals, and their composition was analyzed by gas chromatography. The catalytic hydrogenation of maleic anhydride to succinic acid yielded a maleic anhydride conversion rate of 98.12%, a succinic acid selectivity of 98.16%, and a catalyst stability of 900 h.

[0029]

Example 2

[0030] (2) Preparation of solution b2: First, add 104.17g tetraethyl orthosilicate, 21.29g ammonia and 36.45g hexadecyltrimethylammonium bromide to 900g deionized water in sequence, and stir evenly at 20°C to form solution b2 (in solution b2, the molar ratio of SiO2: ammonia: second template agent: H2O is 1:3:0.2:100).

[0031] The subsequent steps are the same as in (3) of Example 1, to obtain sodium-containing catalyst B2.

[0032] (4) Add 10g of sodium-containing catalyst B2 to 20g of deionized water, then add an ultrasonic generator to make it emit ultrasonic waves in the water. The intensity of the ultrasonic waves is 70Hz. Adjust the sodium content in the water. Finally, filter the residue after ultrasonication, dry it at 120℃ for 6h, and then calcine it at 550℃ for 6h. Use a flame photometer to test the sodium content of the prepared ZSM-5 / MCM-41 molecular sieve to obtain 0.85% Na-ZSM-5 / MCM-41 molecular sieve.

[0033] The calcined 0.85% Na-ZSM-5 / MCM-41 molecular sieve and 30wt% Al2O3 support were pressed into tablets or extruded into strips, crushed and sieved to separate catalyst particles with a particle size of 0.8cm to 2.0cm for use in the following application experiments.

[0034] Catalyst application: In a fixed-bed reactor, 5g of the above-mentioned catalyst particles were packed into the middle of the reaction tube; the reactants, maleic anhydride and solvent, entered through the reactor inlet at a mass ratio of 1:1, and contacted the catalyst bed under the action of hydrogen to undergo a catalytic hydrogenation reaction of maleic anhydride. The reaction conditions were: reaction temperature 150℃, pressure 2MPa (H2), and WHSV = 1.0h.-1 (Total space velocity), hydrogen flow rate = 30 ml / min.

[0035] Liquid phase products were collected at fixed time intervals, and their composition was analyzed by gas chromatography. The catalytic hydrogenation of maleic anhydride to succinic acid yielded a maleic anhydride conversion rate of 99.12%, a succinic acid selectivity of 99.21%, and a catalyst stability of 900 h.

[0036]

Example 3

[0037] (2) Preparation of solution b3: First, add 104.17g tetraethyl orthosilicate, 29.80g ammonia and 18.23g hexadecyltrimethylammonium bromide to 900g deionized water in sequence, and stir evenly at 20°C to form solution b3 (in solution b3, the molar ratio of SiO2: ammonia: second template agent: H2O is 1:3.5:0.1:100).

[0038] The subsequent steps are the same as in (3) of Example 1, to obtain sodium-containing catalyst B3.

[0039] (4) Add 10g of sodium-containing catalyst B3 to 30g of deionized water, then add an ultrasonic generator to make it emit ultrasonic waves in the water. The intensity of the ultrasonic waves is 70Hz. Adjust the sodium content in the water. Finally, filter the residue after ultrasonication, dry it at 120℃ for 6h, and then calcine it at 550℃ for 6h. Use a flame photometer to test the sodium content of the prepared ZSM-5 / MCM-41 molecular sieve to obtain 0.75% Na-ZSM-5 / MCM-41 molecular sieve.

[0040] The calcined 0.75% Na-ZSM-5 / MCM-41 molecular sieve and 30wt% Al2O3 support were pressed into tablets or extruded into strips, crushed and sieved to separate catalyst particles with a particle size of 0.8cm to 2.0cm for use in the following application experiments.

[0041] Catalyst application: In a fixed-bed reactor, 5g of the above-mentioned catalyst particles were packed into the middle of the reaction tube; the reactants, maleic anhydride and solvent, entered through the reactor inlet at a mass ratio of 1:1, and contacted the catalyst bed under the action of hydrogen to undergo a catalytic hydrogenation reaction of maleic anhydride. The reaction conditions were: reaction temperature 160℃, pressure 2MPa (H2), and WHSV = 1.0h. -1 (Total space velocity), hydrogen flow rate = 30 ml / min.

[0042] Liquid phase products were collected at fixed time intervals, and their composition was analyzed by gas chromatography. The catalytic hydrogenation of maleic anhydride to succinic acid yielded a maleic anhydride conversion rate of 100%, a succinic acid selectivity of 99.25%, and a catalyst stability of 950 h.

[0043]

Example 4

[0044] (2) Preparation of solution b4: First, add 100g of silica sol, 42.58g of ammonia, 1.45g of mesoporous MCM-41 seed crystal and 36.45g of hexadecyltrimethylammonium bromide to 1280g of deionized water in sequence, and stir evenly at 20°C to form solution b4 (the molar ratio of SiO2: ammonia: second template agent: H2O in solution b4 is 1:5:0.2:150).

[0045] (3) Finally, the b4 solution was slowly added dropwise to the a4 solution, and the mixture was stirred vigorously at 30°C for 5 hours to form a gel solution A4. The resulting mixed gel A4 was transferred to a high-gravity reactor and reacted at a rotation speed of 300 rpm and a crystallization temperature of 170°C for 48 hours. After that, it was dried at 120°C for 6 hours and finally calcined at 550°C for 6 hours to obtain the sodium-containing catalyst B4.

[0046] (4) Add 10g of sodium-containing catalyst B4 to 20g of deionized water, then add an ultrasonic generator to make it emit ultrasonic waves in the water. The intensity of the ultrasonic waves is 70Hz. Adjust the sodium content in the water. Finally, filter the residue after ultrasonication, dry it at 120℃ for 6h, and then calcine it at 550℃ for 6h. Use a flame photometer to test the sodium content of the prepared ZSM-5 / MCM-41 molecular sieve to obtain 0.65% Na-ZSM-5 / MCM-41 molecular sieve.

[0047] The calcined 0.65% Na-ZSM-5 / MCM-41 molecular sieve and 30wt% Al2O3 support were pressed into tablets or extruded into strips, crushed and sieved to separate catalyst particles with a particle size of 0.8cm to 2.0cm for use in the following application experiments.

[0048] Catalyst application: In a fixed-bed reactor, 5g of the above-mentioned catalyst particles were packed into the middle of the reaction tube; the reactants, maleic anhydride and solvent, entered through the reactor inlet at a mass ratio of 1:1, and contacted the catalyst bed under the action of hydrogen to undergo a catalytic hydrogenation reaction of maleic anhydride. The reaction conditions were: reaction temperature 170℃, pressure 2MPa (H2), and WHSV = 1.0h. -1 (Total space velocity), hydrogen flow rate = 30 ml / min.

[0049] Liquid phase products were collected at fixed time intervals, and their composition was analyzed by gas chromatography. The catalytic hydrogenation of maleic anhydride to succinic acid yielded a maleic anhydride conversion rate of 100%, a succinic acid selectivity of 97.52%, and a catalyst stability of 950 h.

[0050]

Example 5

[0051] (2) Preparation of solution b5: First, add 40.00g of silica sol, 190.74g of ammonia and 72.89g of hexadecyltrimethylammonium bromide to 872.00g of deionized water in sequence, and stir evenly at 20°C to form solution b5 (in solution b5, the molar ratio of SiO2: ammonia: second template agent: H2O is 1:56:1:250).

[0052] (3) Finally, the b5 solution was slowly added dropwise to the a5 solution, and the mixture was stirred vigorously at 30°C for 5 hours to form a gel solution A5. The resulting mixed gel A5 was transferred to a high-gravity reactor and reacted at a rotation speed of 500 rpm and a crystallization temperature of 170°C for 48 hours. After that, it was dried at 120°C for 6 hours and finally calcined at 550°C for 6 hours to obtain the sodium-containing catalyst B5.

[0053] (4) Add 10g of sodium-containing catalyst B5 to 50g of deionized water, then add an ultrasonic generator to make it emit ultrasonic waves in the water. The intensity of the ultrasonic waves is 70Hz. Adjust the sodium content in the water. Finally, filter the residue after ultrasonication, dry it at 120℃ for 6h, and then calcine it at 550℃ for 6h. Use a flame photometer to test the sodium content of the prepared ZSM-5 / MCM-41 molecular sieve to obtain 0.45% Na-ZSM-5 / MCM-41 molecular sieve.

[0054] The calcined 0.45% Na-ZSM-5 / MCM-41 molecular sieve and 30wt% Al2O3 support were pressed into tablets or extruded into strips, crushed and sieved to separate catalyst particles with a particle size of 0.8cm to 2.0cm for use in the following application experiments.

[0055] Catalyst application: In a fixed-bed reactor, 5g of the above-mentioned catalyst particles were packed into the middle of the reaction tube; the reactants, maleic anhydride and solvent, entered through the reactor inlet at a mass ratio of 1:1, and contacted the catalyst bed under the action of hydrogen to undergo a catalytic hydrogenation reaction of maleic anhydride. The reaction conditions were: reaction temperature 160℃, pressure 1.5MPa (H2), and WHSV = 1.0h. -1 (Total space velocity), hydrogen flow rate = 50 ml / min.

[0056] Liquid phase products were collected at fixed time intervals, and their composition was analyzed by gas chromatography. The catalytic hydrogenation of maleic anhydride to succinic acid yielded a maleic anhydride conversion rate of 100%, a succinic acid selectivity of 99.23%, and a catalyst stability of 1000 h.

[0057]

Example 6

[0058] (2) Preparation of solution b6: First, add 100.00g of silica sol, 42.58g of ammonia and 36.45g of cetyltrimethylammonium bromide to 1280.00g of deionized water in sequence, and stir evenly at 20°C to form solution b6 (in solution b6, the molar ratio of SiO2: ammonia: second template agent: H2O is 1:5:0.2:150).

[0059] The subsequent steps are the same as in (3) of Example 5, to obtain sodium-containing catalyst B6.

[0060] (4) Add 10g of sodium-containing catalyst B6 to 50g of deionized water, then add an ultrasonic generator to make it emit ultrasonic waves in the water. The intensity of the ultrasonic waves is 70Hz. Adjust the sodium content in the water. Finally, filter the residue after ultrasonication, dry it at 120℃ for 6h, and then calcine it at 550℃ for 6h. Use a flame photometer to test the sodium content of the prepared ZSM-5 / MCM-41 molecular sieve to obtain 0.3% Na-ZSM-5 / MCM-41 molecular sieve.

[0061] The calcined 0.3% Na-ZSM-5 / MCM-41 molecular sieve and 30wt% Al2O3 support were pressed into tablets or extruded into strips, crushed and sieved to separate catalyst particles with a particle size of 0.8cm to 2.0cm for use in the following application experiments.

[0062] Catalyst application: In a fixed-bed reactor, 5g of the above-mentioned catalyst particles were packed into the middle of the reaction tube; the reactants, maleic anhydride and solvent, entered through the reactor inlet at a mass ratio of 1:1, and contacted the catalyst bed under the action of hydrogen to undergo a catalytic hydrogenation reaction of maleic anhydride. The reaction conditions were: reaction temperature 160℃, pressure 1.5MPa (H2), and WHSV = 1.0h. -1 (Total space velocity), hydrogen flow rate = 50 ml / min.

[0063] Liquid phase products were collected at fixed time intervals, and their composition was analyzed by gas chromatography. The catalytic hydrogenation of maleic anhydride to succinic acid yielded a maleic anhydride conversion rate of 100%, a succinic acid selectivity of 99.32%, and a catalyst stability of 1110 h.

[0064]

Example 7

[0065] (2) Preparation of solution b7: First, add 104.17g tetraethyl orthosilicate, 21.29g ammonia and 36.45g hexadecyltrimethylammonium bromide to 900g deionized water in sequence, and stir evenly at 20°C to form solution b7 (in solution b7, the molar ratio of SiO2: ammonia: first template agent: H2O is 1:3:0.2:100).

[0066] The subsequent steps are the same as in (3) of Example 5, to prepare sodium-containing catalyst B7.

[0067] (4) Add 10g of sodium-containing catalyst B7 to 50g of deionized water, then add an ultrasonic generator to make it emit ultrasonic waves in the water. The intensity of the ultrasonic waves is 140Hz. Adjust the sodium content in the water. Finally, filter the residue after ultrasonication, dry it at 120℃ for 6h, and then calcine it at 550℃ for 6h. Use a flame photometer to test the sodium content of the prepared ZSM-5 / MCM-41 molecular sieve to obtain 0.2% Na-ZSM-5 / MCM-41 molecular sieve.

[0068] The calcined 0.2% Na-ZSM-5 / MCM-41 molecular sieve and 30wt% Al2O3 support were pressed into tablets or extruded into strips, crushed and sieved to separate catalyst particles with a particle size of 0.8cm to 2.0cm for use in the following application experiments.

[0069] Catalyst application: In a fixed-bed reactor, 5g of the above-mentioned catalyst particles were packed into the middle of the reaction tube; the reactants, maleic anhydride and solvent, entered through the reactor inlet at a mass ratio of 1:1, and contacted the catalyst bed under the action of hydrogen to undergo a catalytic hydrogenation reaction of maleic anhydride. The reaction conditions were: reaction temperature 160℃, pressure 1.5MPa (H2), and WHSV = 1.0h. -1 (Total space velocity), hydrogen flow rate = 50 ml / min.

[0070] Liquid phase products were collected at fixed time intervals, and their composition was analyzed by gas chromatography. The catalytic hydrogenation of maleic anhydride to succinic acid yielded a maleic anhydride conversion rate of 100%, a succinic acid selectivity of 99.53%, and a catalyst stability of 1115 h.

[0071]

Example 8

[0072] (2) The deactivated catalyst particles that were sieved were placed into the reactor and regenerated by passing N2 gas through it. The regeneration temperature was 550℃ and the regeneration time was 6h. The regenerated catalyst particles were used in the following application experiments.

[0073] Application of the regenerated catalyst: In a fixed-bed reactor, 5g of the above-mentioned catalyst particles were packed into the middle of the reaction tube; maleic anhydride and solvent were introduced into the reactor inlet at a mass ratio of 1:1, and a coupled modification reaction was carried out in contact with the catalyst bed. The reaction conditions were: reaction temperature 500℃, pressure 0.5 MPa (N2), WHSV = 1.0h. -1 (Total airspeed).

[0074] After the reaction was completed, the samples were collected and separated for chromatographic analysis. The results of the methanol-coupled light hydrocarbon reforming reaction to produce low-carbon olefins while also taking into account aromatics were obtained: the yield of ethylene + propylene + butene was 55.4%, and the reaction time reached 850 h when the methanol conversion rate was 100%.

[0075]

Example 9

[0076] (2) The deactivated catalyst particles that were sieved were placed into the reactor and regenerated by passing H2 gas through it. The regeneration temperature was 550℃ and the regeneration time was 5h. The regenerated catalyst particles were used in the following application experiments.

[0077] Catalyst application: In a fixed-bed reactor, 5g of the above-mentioned catalyst particles were packed into the middle of the reaction tube; the reactants, maleic anhydride and solvent, entered through the reactor inlet at a mass ratio of 1:1, and contacted the catalyst bed under the action of hydrogen to undergo a catalytic hydrogenation reaction of maleic anhydride. The reaction conditions were: reaction temperature 150℃, pressure 2MPa (H2), and WHSV = 1.0h. -1 (Total space velocity), hydrogen flow rate = 30 ml / min.

[0078] Liquid products were collected at fixed time intervals, and their composition was analyzed by gas chromatography. The catalytic hydrogenation of maleic anhydride to succinic acid yielded a maleic anhydride conversion rate of 98.56%, a succinic acid selectivity of 98.67%, and a catalyst stability of 860 h.

[0079]

Example 10

[0080] (2) The deactivated catalyst particles that were sieved were placed into the reactor and regenerated by passing H2 gas through it. The regeneration temperature was 480℃ and the regeneration time was 5h. The regenerated catalyst particles were used in the following application experiments.

[0081] Catalyst application: In a fixed-bed reactor, 5g of the above-mentioned catalyst particles were packed into the middle of the reaction tube; the reactants, maleic anhydride and solvent, entered through the reactor inlet at a mass ratio of 1:1, and contacted the catalyst bed under the action of hydrogen to undergo a catalytic hydrogenation reaction of maleic anhydride. The reaction conditions were: reaction temperature 160 ℃, pressure 2MPa (H2), WHSV = 1.0h. -1 (Total space velocity), hydrogen flow rate = 30 ml / min.

[0082] Liquid products were collected at fixed time intervals, and their composition was analyzed by gas chromatography. The catalytic hydrogenation of maleic anhydride to succinic acid yielded a maleic anhydride conversion rate of 99.51%, a succinic acid selectivity of 99.01%, and a catalyst stability of 900 h.

[0083] Comparative Example 1 The preparation of solutions a1, b1 and gel A1 is the same as that in Example 1. The difference from Example 1 is that the obtained mixed gel A1 is transferred to a crystallization vessel, crystallized in an oven, reacted at 170°C for 48 hours, dried at 120°C for 6 hours, and finally calcined at 550°C for 6 hours to obtain sodium-containing catalyst B1.

[0084] The subsequent steps are the same as in (4) of Example 5, and 1.2% Na-ZSM-5 / MCM-41 molecular sieve can be obtained. The calcined molecular sieve and 30wt% Al2O3 support are pressed into tablets or extruded into strips, crushed and sieved, and catalyst particles with a particle size of 0.8cm to 2.0cm are sieved out for use in the following application experiments.

[0085] Catalyst application: In a fixed-bed reactor, 5g of the above-mentioned catalyst particles were packed into the middle of the reaction tube; the reactants, maleic anhydride and solvent, entered through the reactor inlet at a mass ratio of 1:1, and contacted the catalyst bed under the action of hydrogen to undergo a catalytic hydrogenation reaction of maleic anhydride. The reaction conditions were: reaction temperature 150℃, pressure 1MPa (H2), and WHSV = 1.0h. -1 (Total space velocity), hydrogen flow rate = 30 ml / min.

[0086] Liquid phase products were collected at fixed time intervals, and their composition was analyzed by gas chromatography. The catalytic hydrogenation of maleic anhydride to succinic acid yielded a maleic anhydride conversion rate of 98.21%, a succinic acid selectivity of 98.24%, and a catalyst stability of 600 h.

[0087] In summary, as demonstrated by the above examples and comparative examples, the ZSM-5 / MCM-41 molecular sieves with different sodium contents described in this invention exhibit strong hydrothermal stability and excellent catalytic performance in the catalytic hydrogenation of maleic anhydride to succinic acid. These results in high maleic anhydride conversion (≥98%), high succinic acid selectivity (≥99%), and stability for 900-1200 hours. In contrast, the 1.2% Na-ZSM-5 / MCM-41 molecular sieve in the comparative example also shows relatively high maleic anhydride conversion and succinic acid selectivity, but its catalyst stability is significantly lower than that of the ZSM-5 / MCM-41 molecular sieves with different sodium contents described in this invention. Furthermore, when the deactivated catalyst of this invention is subsequently regenerated and used in the reaction, its maleic anhydride conversion still reaches 100%, and its succinic acid selectivity and catalyst stability are comparable to those of the fresh catalyst.

[0088] The above technical features constitute the embodiments of the present invention, which have strong adaptability and implementation effect. Unnecessary technical features can be added or removed according to actual needs to meet the needs of different situations.

Claims

1. A method for controllable preparation of ZSM-5 / MCM-41 molecular sieves with different sodium contents, characterized in that, The method comprises the following steps: (1) adding a silicon source, sodium metaaluminate and a first template agent into an aqueous solution in sequence and stirring to form an a solution; adding a silicon source, ammonia and a second template agent into an aqueous solution in sequence and stirring to form a b solution; (2) slowly adding the a solution into the b solution and mixing uniformly by means of vigorous stirring to form a mixed gel A; (3) transferring the mixed gel A into a high gravity reactor, performing a crystallization reaction by heating, and then performing drying and a first calcination treatment to obtain a sodium-containing catalyst B; (4) adding the sodium-containing catalyst B into a certain amount of water, then performing ultrasonic treatment to regulate the sodium content in the water, and finally filtering, drying and performing a second calcination treatment on the remaining substance after the ultrasonic treatment to obtain a ZSM-5 / MCM-41 molecular sieve with different sodium contents.

2. The process for the controlled preparation of ZSM-5 / MCM-41 molecular sieves with different sodium contents according to claim 1, characterized in that, The stirring temperature in step (2) is 10-80°C, and the stirring time is 2-24 hours.

3. The process for the controlled preparation of ZSM-5 / MCM-41 molecular sieves with different sodium contents according to claim 2, characterized in that, The stirring temperature in step (2) is preferably 20-60°C, and the stirring time is preferably 3-8 hours.

4. The process for the controlled preparation of ZSM-5 / MCM-41 zeolites with different sodium contents according to any one of claims 1 to 3, characterized in that, In the solution a, the molar ratio of SiO2:Al2O3:first template agent:H2O is 1:(0.03-0.1):(0.03-1):(36-100); or / and, in the solution b, the molar ratio of SiO2:ammonia:second template agent:H2O is 1:(2.5-56):(0.1-1):(100-250); or / and, the silicon source is any one or any combination of two or more of tetraethyl orthosilicate, silica sol, silicon powder, water glass and sodium silicate; or / and, the first template agent comprises any one or any combination of two or more of n-butylamine, tetrapropylammonium hydroxide and tetrabutylammonium hydroxide; or / and, the second template agent comprises any one or any combination of two or more of cetyltrimethylammonium bromide and tetradecyltrimethylammonium bromide.

5. The process for the controlled preparation of ZSM-5 / MCM-41 zeolites with different sodium contents according to any one of claims 1 to 4, characterized in that, In step (3), the rotation speed of the high gravity reactor is 100-5000 rpm, the crystallization reaction temperature for the mixed gel A is 100-300°C, and the crystallization reaction time is 17-96 hours; or / and, in step (3), the drying temperature is 50-180°C, and the drying time is 1-24 hours; or / and, in the first calcination treatment, the dried solid product is heated to 430-600°C and calcined for 3-10 hours to obtain the sodium-containing catalyst B; wherein the control heating rate of the first calcination treatment is 1-10°C / min.

6. The process for the controlled preparation of ZSM-5 / MCM-41 molecular sieves with different sodium contents according to claim 5, characterized in that, In step (3), the crystallization reaction temperature is preferably 110-180°C, and the reaction time is preferably 24-72 hours; or / and, in step (3), the drying temperature is preferably 90-150°C, and the drying time is preferably 3-12 hours; or / and, the control heating rate of the first calcination treatment is preferably 2-5°C / min.

7. The process for the controlled preparation of ZSM-5 / MCM-41 zeolites with different sodium contents according to any one of claims 1 to 6, characterized in that, In step (4), the mass ratio of the sodium-containing catalyst B to water is 1:0.5 to 10, the intensity of ultrasonic treatment is 70 Hz to 140 Hz, the drying temperature is 50°C to 180°C, and the drying time is 1 h to 24 h; or / and, in the second calcination treatment, the dried solid product is heated to 430°C to 600°C and calcined for 3 h to 10 h to obtain the ZSM-5 / MCM-41 molecular sieve with different sodium contents; wherein the heating rate of the second calcination is 1°C / min to 10°C / min.

8. The process for the controlled preparation of ZSM-5 / MCM-41 molecular sieves with different sodium contents according to claim 7, characterized in that, In step (4), preferably, the drying temperature is 90°C to 150°C, and the drying time is 3 h to 12 h; or / and, preferably, the heating rate of the second calcination is 2°C / min to 5°C / min. 9.A ZSM-5 / MCM-41 molecular sieve with different sodium contents, which is prepared by the method according to any one of claims 1 to 8. 10.The ZSM-5 / MCM-41 molecular sieve with different sodium contents according to claim 9 is used in the reaction of catalytic hydrogenation of maleic anhydride to produce succinic acid.