A catalyst for directly preparing ethylbenzene from ethane and benzene, a preparation method and application thereof

Abstract

This invention discloses a catalyst for the direct production of ethylbenzene from ethane and benzene. The catalyst is composed of a metal oxide and a molecular sieve in a mass ratio of 1:(0.25-1), wherein the metal oxide is a composite oxide of nickel and niobium, denoted as Ni. a Nb b O x In the formula a:b = 2-10, x represents the number of oxygen atoms required to satisfy the oxidation states of the metal elements Ni and Nb; the molecular sieve is a Ga-modified ZSM-5 molecular sieve, denoted as Ga / ZSM-5. This invention also discloses the preparation method and application of the catalyst. When used for the direct production of ethylbenzene from ethane and benzene, the catalyst provides a simple and easy-to-learn process with high benzene conversion and high ethylbenzene yield.

Description

A catalyst for the direct production of ethylbenzene from ethane and benzene, its preparation method and application Technical Field

[0001] This invention belongs to the field of ethylbenzene preparation technology, specifically relating to a catalyst for the direct production of ethylbenzene from ethane and benzene, its preparation method, and its application. Background Technology

[0002] Ethylbenzene is an important chemical raw material. Besides being used in the production of styrene, styrene homopolymers and copolymers (ABS, AS, etc.), it is used in the chemical industry to manufacture acetophenone, cellulose acetate, diethylbenzene (DEB), ethyl anthraquinone, ethylbenzenesulfonic acid, propylene oxide, and methylbenzyl alcohol. In pharmaceutical synthesis, it serves as an intermediate for antibiotics such as streptomycin and also has a partial presence in the artificial synthesis of fragrances. In recent years, my country's ethylbenzene production capacity has gradually increased, from 8.5 million tons in 2014 to 9.08 million tons in 2018, achieving a self-sufficiency rate of 70%. In 2019, China relied on imports for over 3 million tons of styrene. In 2020, apparent consumption was approximately 12.8236 million tons, making China the world's largest producer of ethylbenzene / styrene. In 2021, domestic styrene supply continued to grow significantly, with production reaching approximately 12.03 million tons and apparent consumption around 13.485 million tons.

[0003] Currently, ethylbenzene is mainly produced through the alkylation reaction of ethylene with benzene. However, the traditional industrial process of producing ethylene via naphtha cracking requires harsh reaction conditions and consumes a huge amount of energy. Furthermore, my country's energy endowment—rich in coal but poor in oil and gas—results in a large demand gap for ethylene, severely limiting ethylbenzene production. Therefore, starting from ethylene production, using inexpensive and abundant ethane as a raw material to prepare ethylene has become an important way to increase ethylene production. Coupled with the dehydrogenation of ethane to ethylene and the alkylation reaction of ethylene with benzene to produce ethylbenzene, this method holds promise as a new approach to optimize ethane resource utilization and ethylbenzene synthesis.

[0004] Traditional ethane dehydrogenation to ethylene production requires a high-temperature environment, resulting in high energy consumption and numerous side reactions. Furthermore, these processes are affected by coke deposition and poor catalyst stability. Therefore, developing new catalysts and opening up new, promising process routes for the direct production of ethylbenzene from ethylene instead of ethylene is of great significance for the development of my country's shale gas resources, reducing my country's dependence on imported oil, and the development of the ethylbenzene industry. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a catalyst for the direct production of ethylbenzene from ethane and benzene, its preparation method, and its application. The catalyst, in the one-step production of ethylbenzene from ethane and benzene, exhibits high benzene conversion, high ethylbenzene selectivity, and fewer byproducts such as toluene and trimethylbenzene.

[0006] A catalyst for the direct production of ethylbenzene from ethane and benzene, wherein the catalyst is composed of a metal oxide and a molecular sieve in a mass ratio of 1:(0.25-1), and the metal oxide is a composite oxide of nickel and niobium, denoted as Ni. a Nb b O x a:b=2-10, where x is the number of oxygen atoms required to satisfy the oxidation states of metal elements Ni and Nb; the molecular sieve is a Ga-modified ZSM-5 molecular sieve, denoted as Ga / ZSM-5.

[0007] Preferably, the silicon-aluminum ratio of the ZSM-5 molecular sieve is 25-120.

[0008] The method for preparing the catalyst for the direct production of ethylbenzene from ethane and benzene includes the following steps:

[0009] (1) Preparation of metal oxides:

[0010] (11) Add niobium oxalate C4H4NNbO9 to deionized water and stir until it is evenly dispersed. Add polyethylene glycol to it and stir until it dissolves.

[0011] (12) Add Ni(NO3)2·6H2O to the solution in step (11) while stirring, stir until the solution color is uniform, then add ammonia water and stir for 6-7 hours;

[0012] (13) Transfer to a hydrothermal autoclave and hydrothermally crystallize at 90-120℃ for 20-28 hours. After cooling, centrifuge to obtain powder. Wash the powder with deionized water and ethanol, dry it, and calcine it to obtain Ni metal oxide. a Nb b O x ;

[0013] (2) Preparation of molecular sieves:

[0014] ZSM-5 molecular sieve was impregnated with gallium nitrate solution in equal volume, stirred and allowed to stand for 4-6 hours, dried and calcined to obtain molecular sieve, labeled as Ga / ZSM-5.

[0015] (3) Preparation of catalyst:

[0016] The metal oxide obtained in step (1) and the molecular sieve obtained in step (2) are mixed, ground, and then pressed into tablets to obtain particles with a diameter of 0.425-0.850 mm.

[0017] Preferably, in step (1), the ratio of niobium oxalate ammonium, polyethylene glycol, and ammonia is (0.515-2.575) g: (6-10) g: (5-15) mL.

[0018] Preferably, the polyethylene glycol has a molecular weight of 400-4000; the ammonia solution has a concentration of 20-30 wt%; and the gallium nitrate solution has a concentration of 0.05-0.5 mol / L.

[0019] The ZSM-5 molecular sieve described in this invention is existing technology.

[0020] More preferably, the ZSM-5 molecular sieve in step (2) is prepared by the following method:

[0021] (21) Weigh TPABr and add it to the silica sol solution, stir well, add ethylamine solution dropwise, and stir well;

[0022] (22) Add aluminum nitrate aqueous solution to the solution in step (21), stir evenly, add seed crystals dropwise and continue stirring until the mixture becomes gel-like;

[0023] (23) Transfer to a hydrothermal autoclave and hydrothermally crystallize at 160-190℃ for 70-80h. After cooling, centrifuge to obtain powder. Wash the powder with deionized water, dry, and calcine to obtain ZSM-5 molecular sieve.

[0024] Preferably, in the preparation of ZSM-5 molecular sieve, the amount of silica sol is SiO2, the amount of water is the total amount of water required to prepare each solution, and the molar ratio of each raw material is as follows: SiO2: Al(NO3)3·9H2O: TPABr: ethylamine: H2O: seed crystal = 1: (0.0083-0.04): (0.15-0.18): (0.8-1.2): (16-20): 1%.

[0025] Preferably, the concentration of the silica sol solution is 30-35 wt%, and the concentration of the ethylamine solution is 60-70 wt%.

[0026] Preferably, the drying is carried out at 60-100℃ for 8-12 hours; the calcination is carried out at 400-600℃ for 4-6 hours.

[0027] A method for directly producing ethylbenzene from ethane and benzene involves: packing a catalyst into a fixed-bed reactor at atmospheric pressure, heating to the reaction temperature of 400-500℃, and then introducing ethane, oxygen, and benzene into the reactor to carry out the reaction. The space velocity of benzene is 0.5-0.8 h⁻¹. -1 The molar ratio of ethane, oxygen, and benzene is (10-15):(2-6):(2-4); the catalyst is the catalyst described in this invention.

[0028] Preferably, the temperature is increased to 400-500℃ at a heating rate of 2-5℃ / min.

[0029] More preferably, the space velocity of benzene is 0.5 h⁻¹.-1 The molar ratio of ethane, oxygen, and benzene is 12:4:3.

[0030] Advantages of this invention:

[0031] (1) In the preparation process of the catalyst of the present invention, the preparation of metal catalyst is relatively simple, and the process does not require concentrated acid or concentrated alkali, which is relatively safe. The processing time is short, the preparation process is easy to control, and non-precious metals are selected for preparation, resulting in low preparation cost and facilitating industrialization.

[0032] (2) After being uniformly mixed by mechanical grinding and then pressed into tablets, the distance between the metal oxide and the molecular sieve can be effectively shortened, the alkylation process of the intermediate product ethylene and benzene can be accelerated, and the selectivity of ethylbenzene can be improved.

[0033] (3) The catalyst prepared is simple and easy to learn when used to directly produce ethylbenzene from ethane and benzene. It has a high benzene conversion rate, a high ethylbenzene yield, and a shortened process route. The co-feeding of oxidant can effectively avoid the formation of coke on the catalyst surface, improve the diffusion performance of coke precursor in zeolite channels, inhibit the polymerization reaction in molecular sieve micropores, and improve the ethylbenzene yield while also improving the thermal stability of its catalytic reaction. Attached Figure Description

[0034] Figure 1 is a transmission electron microscope image of the metal oxide in Example 1;

[0035] Figure 2 is a transmission electron microscope image of the metal oxide in Example 2;

[0036] Figure 3 is a scanning electron microscope image of the ZSM-5 molecular sieve prepared in Example 1;

[0037] Figure 4 shows the XRD pattern of the metal oxide in Example 1;

[0038] Figure 5 shows the XRD patterns of ZSM-5 molecular sieve in Example 1 and its metal impregnation.

[0039] Figure 6 shows the evaluation results of the catalysts provided in Examples 1-2;

[0040] Figure 7 shows the evaluation results of the catalysts obtained in Examples 1, 5, and 6. Detailed Implementation

[0041] Example 1

[0042] A catalyst for the direct production of ethylbenzene from ethane and benzene, wherein the catalyst comprises a metal oxide and a molecular sieve in a mass ratio of 1:1, and the metal oxide is a composite oxide of nickel and niobium, denoted as Ni. 34 Nb6O 49The molecular sieve is a Ga-modified ZSM-5 molecular sieve, denoted as Ga / ZSM-5; the silicon-to-aluminum ratio of the ZSM-5 molecular sieve is 40.

[0043] The catalyst for the direct production of ethylbenzene from ethane and benzene was prepared by the following method:

[0044] (1) Preparation of metal oxides:

[0045] (11) Add 0.918g of ammonium niobate C4H4NNbO9 to deionized water and stir until evenly dispersed. Add 8g of polyethylene glycol with a molecular weight of 4000 and stir until dissolved.

[0046] (12) Add 5g Ni(NO3)2·6H2O to the solution in step (11) while stirring, stir until the solution color is uniform, then add 10ml of 25wt% ammonia water and stir to mix evenly.

[0047] (13) Transfer to a hydrothermal autoclave and hydrothermally crystallize at 100°C for 24 hours. After cooling, centrifuge to obtain powder. Wash the powder with deionized water and ethanol, dry at 80°C for 8 hours, and calcine at 450°C for 4 hours to obtain Ni metal oxide. 34 Nb6O 49 ;

[0048] (2) Preparation of molecular sieves:

[0049] (21) Weigh TPABr and add it to a 30wt% silica sol solution, stir well, add 65wt% ethylamine solution dropwise, and stir well;

[0050] (22) Add aluminum nitrate aqueous solution to the solution in step (21), stir evenly, add seed crystals dropwise and continue stirring until the mixture becomes gel-like; wherein, the amount of silica sol is SiO2, the amount of water is the total amount of water required to prepare each solution, and the molar ratio of each raw material is as follows: SiO2: Al(NO3)3·9H2O: TPABr: ethylamine: H2O: seed crystals = 1:0.025:0.15:1:17:1%;

[0051] (23) Transfer to a hydrothermal autoclave and hydrothermally crystallize at 170°C for 72 hours. After cooling, centrifuge to obtain powder. Wash the powder with deionized water, dry at 80°C for 8 hours, and calcine at 550°C for 6 hours to obtain ZSM-5 molecular sieve.

[0052] (24) ZSM-5 molecular sieve was impregnated with 0.5 mol / L gallium nitrate solution in equal volume, stirred and allowed to stand for 6 h, dried at 80 °C for 8 h, and calcined at 500 °C for 4 h to obtain molecular sieve, labeled as Ga / ZSM-5.

[0053] (3) Preparation of catalyst:

[0054] The metal oxide obtained in step (1) and the molecular sieve obtained in step (2) are mixed, ground, and then pressed into tablets to obtain particles with a diameter of 0.425-0.850 mm.

[0055] Example 2

[0056] The molecular weight of polyethylene glycol is 400, and other parameters are the same as in Example 1.

[0057] Example 3

[0058] The silicon-aluminum ratio of ZSM-5 molecular sieve is 30, that is, when preparing ZSM-5 molecular sieve, SiO2: Al(NO3)3·9H2O=1:0.033, and other parameters are the same as in Example 1.

[0059] Example 4

[0060] The silicon-aluminum ratio of ZSM-5 molecular sieve is 50, that is, when preparing ZSM-5 molecular sieve, SiO2: Al(NO3)3·9H2O=1:0.02, and other parameters are the same as in Example 1.

[0061] Example 5

[0062] The silicon-aluminum ratio of ZSM-5 molecular sieve is 80, that is, when preparing ZSM-5 molecular sieve, SiO2: Al(NO3)3·9H2O=1:0.0125, and other parameters are the same as in Example 1.

[0063] Example 6

[0064] The silicon-aluminum ratio of ZSM-5 molecular sieve is 120, that is, when preparing ZSM-5 molecular sieve, SiO2: Al(NO3)3·9H2O=1:0.0083, and other parameters are the same as in Example 1.

[0065] Example 7

[0066] In step (24), ZSM-5 molecular sieve was impregnated with an equal volume of gallium nitrate solution of 0.2 mol / L, and the rest was the same as in Example 1.

[0067] Example 8

[0068] Commercially available ZSM-5 molecular sieve with a silicon-to-aluminum ratio of 40 was used, and other procedures were the same as in Example 1.

[0069] Example 9

[0070] A catalyst for the direct production of ethylbenzene from ethane and benzene, the catalyst comprising a metal oxide and a molecular sieve in a mass ratio of 1:0.25, wherein the metal oxide is a composite oxide of nickel and niobium, denoted as Ni4Nb2O9; the molecular sieve is a Ga-modified ZSM-5 molecular sieve, denoted as Ga / ZSM-5; and the silicon-to-aluminum ratio of the ZSM-5 molecular sieve is 25.

[0071] The catalyst for the direct production of ethylbenzene from ethane and benzene was prepared by the following method:

[0072] (1) Preparation of metal oxides:

[0073] (11) Add 2.575g of ammonium niobate C4H4NNbO9 to deionized water and stir until evenly dispersed. Add 6g of polyethylene glycol with a molecular weight of 2000 and stir until dissolved.

[0074] (12) Add 5g Ni(NO3)2·6H2O to the solution in step (11) while stirring, stir until the solution color is uniform, then add 5ml 20wt% ammonia water and stir to mix evenly.

[0075] (13) Transfer to a hydrothermal autoclave and hydrothermally crystallize at 90°C for 28 hours. After cooling, centrifuge to obtain powder. Wash the powder with deionized water and ethanol, dry at 60°C for 12 hours, and calcine at 400°C for 6 hours to obtain metal oxide Ni4Nb2O9.

[0076] (2) Preparation of molecular sieves:

[0077] (21) Weigh TPABr and add it to a 35wt% silica sol solution, stir well, add 60wt% ethylamine solution dropwise, and stir well;

[0078] (22) Add aluminum nitrate aqueous solution to the solution in step (21), stir evenly, add seed crystals dropwise and continue stirring until the mixture becomes gel-like; wherein, the amount of silica sol is SiO2, the amount of water is the total amount of water required to prepare each solution, and the molar ratio of each raw material is as follows: SiO2: Al(NO3)3·9H2O: TPABr: ethylamine: H2O: seed crystals = 1:0.04:0.18:0.8:16:1%;

[0079] (23) Transfer to a hydrothermal autoclave and hydrothermally crystallize at 160°C for 80 h. After cooling, centrifuge to obtain powder. Wash the powder with deionized water, dry at 60°C for 12 h, and calcine at 400°C for 6 h to obtain ZSM-5 molecular sieve.

[0080] (24) ZSM-5 molecular sieve was impregnated with 0.05 mol / L gallium nitrate solution in equal volume, stirred and allowed to stand for 4 h, dried at 60 °C for 12 h, and calcined at 400 °C for 6 h to obtain molecular sieve, labeled as Ga / ZSM-5.

[0081] (3) Preparation of catalyst:

[0082] The metal oxide obtained in step (1) and the molecular sieve obtained in step (2) are mixed, ground, and then pressed into tablets to obtain particles with a diameter of 0.425-0.850 mm.

[0083] Example 10

[0084] A catalyst for the direct production of ethylbenzene from ethane and benzene, wherein the catalyst comprises a metal oxide and a molecular sieve in a mass ratio of 1:1, and the metal oxide is a composite oxide of nickel and niobium, denoted as Ni. 20 Nb2O 25 The molecular sieve is a Ga-modified ZSM-5 molecular sieve, denoted as Ga / ZSM-5; the silicon-to-aluminum ratio of the ZSM-5 molecular sieve is 25.

[0085] The catalyst for the direct production of ethylbenzene from ethane and benzene was prepared by the following method:

[0086] (1) Preparation of metal oxides:

[0087] (11) Add 0.515g of ammonium niobate C4H4NNbO9 to deionized water and stir until evenly dispersed. Add 10g of polyethylene glycol with a molecular weight of 2000 and stir until dissolved.

[0088] (12) Add 5g Ni(NO3)2·6H2O to the solution in step (11) while stirring, stir until the solution color is uniform, then add 15ml of 30wt% ammonia water and stir to mix evenly.

[0089] (13) Transfer to a hydrothermal autoclave and hydrothermally crystallize at 120°C for 20 hours. After cooling, centrifuge to obtain powder. Wash the powder with deionized water and ethanol, dry at 100°C for 8 hours, and calcine at 600°C for 4 hours to obtain Ni metal oxide. 20 Nb2O 25 ;

[0090] (2) Preparation of molecular sieves:

[0091] (21) Weigh TPABr and add it to a 35wt% silica sol solution, stir well, then add a 70wt% ethylamine solution dropwise and stir well.

[0092] (22) Add aluminum nitrate aqueous solution to the solution in step (21), stir evenly, add seed crystals dropwise and continue stirring until the mixture becomes gel-like; wherein, the amount of silica sol is SiO2, the amount of water is the total amount of water required to prepare each solution, and the molar ratio of each raw material is as follows: SiO2: Al(NO3)3·9H2O: TPABr: ethylamine: H2O: seed crystals = 1:0.04:0.18:1.2:20:1%;

[0093] (23) Transfer to a hydrothermal autoclave and hydrothermally crystallize at 190°C for 70 h. After cooling, centrifuge to obtain powder. Wash the powder with deionized water, dry at 100°C for 8 h, and calcine at 600°C for 4 h to obtain ZSM-5 molecular sieve.

[0094] (24) ZSM-5 molecular sieve was impregnated with 0.05 mol / L gallium nitrate solution in equal volume, stirred and allowed to stand for 5 h, dried at 100 °C for 8 h, and calcined at 600 °C for 4 h to obtain molecular sieve, labeled as Ga / ZSM-5.

[0095] (3) Preparation of catalyst:

[0096] The metal oxide obtained in step (1) and the molecular sieve obtained in step (2) are mixed, ground, and then pressed into tablets to obtain particles with a diameter of 0.425-0.850 mm.

[0097] I. Electron Microscopy Examination

[0098] Transmission electron microscopy was performed on the metal oxides obtained in step (1) of Examples 1 and 2, and the results are shown in Figures 1 and 2.

[0099] As shown in Figure 1, the use of polyethylene glycol with a molecular weight of 4000 can induce a large number of nanoparticles to self-assemble as a large amount of NiO nanoparticles accumulate, forming a relatively complete rod-shaped morphological structure.

[0100] As shown in Figure 2, when polyethylene glycol with a molecular weight of 400 is used, due to the low degree of polymerization of polyethylene glycol, the self-assembly process between nanoparticles cannot be successfully induced, resulting in the particles not aggregating with each other, but the morphology is relatively regular and complete, with a particle size of about 20~30nm, and all sample particles are well dispersed.

[0101] Scanning electron microscopy was performed on the ZSM-5 molecular sieve prepared in step (2) of Example 1, and the results are shown in Figure 3. As can be seen from Figure 3, the surface morphology of the ZSM-5 molecular sieve matrix is ​​relatively regular, exhibiting a hexagonal plate-like structure. The overall structure is relatively complete, with a particle size of approximately 200~350 nm. All sample particles are well dispersed and have uniform size.

[0102] II. XRD Detection

[0103] The metal oxide prepared in step (1) of Example 1 was subjected to XRD detection, and the results are shown in Figure 4. As can be seen from Figure 4, the diffraction peaks of the metal oxide at 37.3°, 43.3°, 62.8°, 75.5° and 79.4° correspond to the structural characteristic peaks of the NiO standard card (PDF#44-1159). However, no characteristic diffraction peaks of niobium oxide were observed in the spectrum, indicating that the very small niobium oxide particles are well dispersed on the NiO surface, or that niobium ions are well dispersed in the NiO lattice.

[0104] XRD analysis was performed on the ZSM-5 molecular sieve and Ga / ZSM-5 molecular sieve obtained in steps (2) and (3) of Example 1, respectively. The results are shown in Figure 5. As can be seen from Figure 5, the characteristic diffraction peaks of ZSM-5 molecular sieve (2θ is 7.9°, 8.8°, 23.1°, 24.0° and 24.4°) prove that they all have complete zeolite MFI type topology, and the crystal structure of the molecular sieve was not destroyed after metal impregnation chemical modification.

[0105] III. Catalytic Performance Testing

[0106] A method for the direct production of ethylbenzene from ethane and benzene is as follows: A catalyst is packed into a fixed-bed reactor at atmospheric pressure, and the temperature is increased to 400°C at a heating rate of 5°C / min. Ethane, oxygen, and benzene are then introduced into the reactor to carry out the reaction, wherein the space velocity of benzene is 0.5 h⁻¹. -1 The molar ratio of ethane, oxygen, and benzene is 12:4:3; the catalyst is the catalyst described in this invention; after stable operation, the reaction product stream enters the Zhongke Huifen GC-6890A gas chromatograph through an insulated pipeline. The raw material conversion rate and product selectivity are calculated based on the carbon atom conservation method. The evaluation results are shown in Figures 6 and 7, where B, T, EB, Styrene, STB, DEB, and OBS represent benzene, toluene, ethylbenzene, styrene, mesitylene, diethylbenzene, and other products, respectively.

[0107] (1) The catalysts used were those provided in Examples 1-2, where PEG400 and PEG4000 represent the catalysts obtained in Examples 2 and 1, respectively. The evaluation results are shown in Figure 6. As shown in Figure 6, the high degree of polymerization of polyethylene glycol enables spontaneous and orderly assembly between metal nanoparticles, resulting in a catalyst with a high specific surface area and less amorphous NiNb oxide, which significantly improves the yield of ethylbenzene, with a benzene conversion rate of 32.3% and an ethylbenzene selectivity of 84.62%. It can be seen that when using high molecular weight polyethylene glycol as a binder template, the prepared catalyst has a high benzene conversion rate and ethylbenzene selectivity when used for the direct production of ethylbenzene from ethane and benzene. Increasing the molecular weight of polyethylene glycol can significantly improve the yield of ethylbenzene.

[0108] (2) The catalysts used were those obtained in Examples 1, 5, and 6, and the evaluation results are shown in Figure 7. As shown in Figure 7, reducing the silica-alumina ratio of the molecular sieve, i.e., increasing the acidity of the molecular sieve, strengthens the alkylation process of benzene with the intermediate product ethylene, and significantly increases the yield of ethylbenzene. Among them, compared with Example 1, the yield of ethylbenzene in Example 6 decreased the most significantly, with the conversion rate of the catalytic reaction decreasing from 32.3% to 8.51%, and its selectivity also decreasing significantly from 84.62% to 61.24%. As for the conversion rate of benzene and the selectivity of ethylbenzene in Example 5, the decrease in values ​​was relatively small. It can be seen that the reason for this performance result may be that the lower acid site density of the molecular sieve catalyst is not conducive to the deep alkylation reaction. The catalyst composed of ZSM-5 with a silica-alumina ratio of 40 in Example 1 has a higher product yield, with an ethylbenzene selectivity of 84.62% and a benzene conversion rate of 32.3%.

Claims

1. A catalyst for the direct production of ethylbenzene from ethane and benzene, characterized in that: The catalyst is composed of a metal oxide and a molecular sieve in a mass ratio of 1:(0.25-1), wherein the metal oxide is a composite oxide of nickel and niobium, denoted as Ni. a Nb b O x a:b=2-10, where x is the number of oxygen atoms required to satisfy the oxidation states of metal elements Ni and Nb; the molecular sieve is a Ga-modified ZSM-5 molecular sieve, denoted as Ga / ZSM-5.

2. The catalyst for the direct production of ethylbenzene from ethane and benzene according to claim 1, characterized in that: The silicon-aluminum ratio of the ZSM-5 molecular sieve is 25-120.

3. The method for preparing the catalyst for the direct production of ethylbenzene from ethane and benzene as described in claim 1 or 2, characterized in that: Includes the following steps: (1) Preparation of metal oxide: (11) Add niobium ammonium oxalate C4H4NNbO9 to deionized water and stir until it is evenly dispersed. Add polyethylene glycol and stir until dissolved. (12) Add Ni(NO3)2·6H2O to the solution in step (11) while stirring. Stir until the solution color is uniform. Then add ammonia water and stir for 6-7 hours. (13) Transfer to a hydrothermal autoclave and hydrothermally crystallize at 90-120℃ for 20-28 hours. After cooling, centrifuge to obtain powder. Wash the powder with deionized water and ethanol, dry it, and calcine it to obtain metal oxide Ni. a Nb b O x (2) Preparation of molecular sieve: ZSM-5 molecular sieve is impregnated with gallium nitrate solution in equal volume, stirred and left to stand for 4-6 hours, dried and calcined to obtain molecular sieve, labeled as Ga / ZSM-5; (3) Preparation of catalyst: The metal oxide obtained in step (1) and the molecular sieve obtained in step (2) are mixed, ground and pressed into tablets to obtain particles with a diameter of 0.425-0.850 mm.

4. The method for preparing the catalyst for the direct production of ethylbenzene from ethane and benzene according to claim 3, characterized in that: In step (1), the ratio of niobium oxalate ammonium, polyethylene glycol and ammonia is (0.515-2.575) g: (6-10) g: (5-15) mL.

5. The method for preparing the catalyst for the direct production of ethylbenzene from ethane and benzene according to claim 4, characterized in that: The polyethylene glycol has a molecular weight of 400-4000; the ammonia solution has a concentration of 20-30 wt%; and the gallium nitrate solution has a concentration of 0.05-0.5 mol / L.

6. The method for preparing the catalyst for the direct production of ethylbenzene from ethane and benzene according to claim 3, characterized in that: The ZSM-5 molecular sieve in step (2) is prepared by the following method: (21) TPABr is weighed and added to the silica sol solution, stirred evenly, and ethylamine solution is added dropwise and stirred evenly; (22) Aluminum nitrate aqueous solution is added to the solution in step (21), stirred evenly, seed crystals are added dropwise and stirred until the mixture becomes gel-like; (23) It is transferred to a hydrothermal autoclave and hydrothermally crystallized at 160-190℃ for 70-80h. After cooling, it is centrifuged to obtain powder. The powder is washed with deionized water, dried, and calcined to obtain ZSM-5 molecular sieve.

7. The method for preparing the catalyst for the direct production of ethylbenzene from ethane and benzene according to claim 6, characterized in that: In the preparation of ZSM-5 molecular sieve, the amount of silica sol is SiO2, and the amount of water is the total amount of water required to prepare each solution. The molar ratio of each raw material is as follows: SiO2: Al(NO3)3·9H2O: TPABr: Ethylamine: H2O: Seed crystal = 1: (0.0083-0.04): (0.15-0.18): (0.8-1.2): (16-20): 1%.

8. The method for preparing the catalyst for the direct production of ethylbenzene from ethane and benzene according to claim 7, characterized in that: The concentration of the silica sol solution is 30-35 wt%, and the concentration of the ethylamine solution is 60-70 wt%.

9. The method for preparing the catalyst for the direct production of ethylbenzene from ethane and benzene according to claim 8, characterized in that: The drying process was carried out at 60-100℃ for 8-12 hours; the calcination process was carried out at 400-600℃ for 4-6 hours.

10. A method for directly producing ethylbenzene from ethane and benzene, characterized in that: The catalyst is packed into a fixed-bed reactor under atmospheric pressure, and the temperature is raised to the reaction temperature of 400-500 °C. Ethane, oxygen, and benzene are then introduced into the reactor to carry out the reaction, where the space velocity of benzene is 0.5-0.8 h⁻¹. -1 The molar ratio of ethane, oxygen, and benzene is (10-15):(2-6):(2-4); the catalyst is the catalyst described in claim 1 or 2.

Images