Olefin oligomerization molecular sieve catalyst, its preparation method and application

Abstract

The application discloses an olefin polymerization molecular sieve catalyst and a preparation method and application thereof, and belongs to the field of molecular sieve catalysts. The olefin polymerization molecular sieve catalyst is an oxide molecular sieve composite catalyst, and the catalyst is a ZSM-5 molecular sieve containing an oxide. The oxide is any one of tin oxide, cerium oxide or zirconium oxide. Metal elements in the catalyst are connected with Si or Al elements through oxygen bridge bonds to form Si-O-M and Al-O-M bonds, and part of the metal elements exist in the form of one or more of metal oxide clusters or metal oxide particles. M represents a metal element. The catalyst is prepared by embedding the oxide into the molecular sieve and reacting with the molecular sieve lattice aluminum, so that the activation ability of the catalyst for olefins is improved. The catalyst is used to convert hexene into long-chain olefins with C12 and C18. The hexene polymerization activity is high, the stability of the catalyst is improved, the total selectivity of C12 and C18 can be kept above 80% after continuous reaction for more than 10 hours, and the catalyst has a wide application prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to an olefin catalytic condensation catalyst and its preparation method and application, belonging to the technical field of olefin synthesis. BACKGROUND

[0002] Long-chain olefins are widely used as an important organic chemical raw material and intermediate in the preparation of aviation kerosene, lubricating oil base oil, surfactants, pharmaceutical preparations, plasticizers, polyolefin resins, emulsifiers, and oil additives. At present, there is still a big gap between supply and demand of long-chain olefins in China, so domestic and foreign producers are constantly developing new technologies and improving existing technology to meet the huge market development potential of long-chain olefins. Coal-to-olefin process and catalytic cracking refinery are rich in low-carbon (C4~C6) olefins, and the conversion of olefins can improve enterprise efficiency.

[0003] The long-chain olefins of C12 and C18 generated by oligomerization of hexene (C6) have good application prospect and practical value. Compared with other methods, the C6 oligomerization method tends to generate single long-chain olefins of a specific carbon number, which can be used as the main raw material for copolymerization monomers, but the current technical bottleneck is that the product selectivity is low and the content of long-chain olefins of a specific carbon number is low. The condensation reaction is an oligomerization chemical reaction with olefin molecules as monomers, and the obtained products are named as dimers, trimers, and tetramers according to the number of monomers. In the condensation reaction, isomerization (double bond and skeleton), cracking (single molecule and double molecule), aromatization, hydrogen transfer, and other side reactions often occur. Chinese patent CN201810074798.2 uses strong acid type cationic resin for the carbon five / carbon six olefin condensation catalytic process of light gasoline, which has high activity and stability, but the catalyst preparation process is complex and needs to go through copolymerization-pore purification-sulfonation process. Chinese patent CN201310655027.X discloses a catalyst for the condensation of olefins into long-chain alpha-olefins, which is composed of carbon nanotubes and NiO loaded thereon, and the weight composition of NiO accounts for 0.5-30wt% of the content of the final catalyst, and the rest is carbon nanotubes. The technology has high catalytic activity and good selectivity, but the preparation scheme of carbon nanotubes is complex and needs acidification treatment, and the preparation process is complex.

[0004] The silicon-aluminum ratio of molecular sieve catalysts can be adjusted, and they have good hydrothermal stability and can be used as catalysts for olefin condensation. The B acid center of ZSM-5 molecular sieve can be used as the active center for olefin condensation catalysis, but its catalytic efficiency is low. At present, the activity of olefin condensation is mainly improved by synthesizing molecular sieves with different silicon-aluminum ratios and changing the molecular sieve configuration. Chinese patent CN202010696353.5 discloses a method and device for producing jet fuel components by olefin condensation, which uses ZSM-22 molecular sieve with a Si / Al ratio of 20-100, and the mass space velocity of hexene feed is 2h -1, reaction pressure 5 MPa, 200 DEG C, dimer selectivity 83.9%. But the application of conventional molecular sieve is greatly limited by its unchangeable Si and Al element skeleton components, resulting in insufficient active centers (especially lack of Lewis acid centers), and sometimes problems of relatively low catalytic activity and short service life.

[0005] Metal oxides have higher acidity, lower catalytic reaction temperature, and better selectivity for condensation products, but the structure is difficult to control during synthesis.

[0006] The present application aims at the current situation that coal chemical industry and petroleum chemical industry have high olefin content, gasoline production capacity is excessive, but the demand for jet fuel is growing, and the existing olefin condensation process has problems of short catalyst service life, poor applicability, damage to the environment and equipment, and low yield of jet fuel components, and provides a method for producing jet fuel (C12-C18) components by olefin condensation. SUMMARY

[0007] The present application aims to provide a method for catalytic condensation of olefins, using hexene as a raw material to obtain long-chain olefins with suitable chain length.

[0008] The present application uses oxide composite molecular sieve as a catalyst for olefin condensation reaction. The molecular sieve follows a carbonium ion reaction mechanism in the olefin condensation reaction. One molecule of olefin combines with the H proton of the B acid site of the molecular sieve to form a carbonium ion, which then condenses with another molecule of olefin to form a high-carbon number olefin. In the hexene condensation reaction, hexene will undergo hydrogen transfer, multi-step condensation and cracking, etc. after condensing to form dimers. Therefore, to obtain long-chain olefins with suitable chain length by olefin condensation, the occurrence of side reactions needs to be inhibited. The performance of conventional MFI configuration molecular sieve can be improved by designing it. The introduction of transition metal elements into the molecular sieve can change the physicochemical properties of the molecular sieve, such as acidity, pore structure, etc., thereby changing the performance of the molecular sieve. Based on a large number of experiments, it is found that the combination of Sn, Ce or Zr oxide and ZSM-5 molecular sieve can significantly improve the long-period operation stability of the olefin condensation reaction, the selectivity of C12 and C18 can reach more than 80%, and it can be maintained for at least 10 hours.

[0009] The present application provides an olefin condensation molecular sieve catalyst, which is a ZSM-5 molecular sieve containing an oxide, and the oxide is any one of tin oxide, cerium oxide or zirconium oxide.

[0010] The metal elements in the catalyst are connected to Si or Al elements through oxygen bridge bonds to form Si-O-M, Al-O-M bonds, and part of them exist in the form of metal oxide clusters or metal oxide particles, and M represents a metal element. The reaction mechanism of the tetravalent metal element entering the molecular sieve skeleton in the present application is as follows:

[0011]

[0012] Further, the weight ratio of the oxide to the molecular sieve in the catalyst is (0.01-0.3): 1.

[0013] The application provides a preparation method of the above olefin polymerization molecular sieve catalyst, and comprises the following steps:

[0014] (1) Preparation of the B-M-ZSM-5 molecular sieve catalyst: a silicon source, an aluminum source, a template agent, water, a tetravalent metal salt, an alkali metal compound mineralizer are mixed, rapidly stirred, and reacted at 90-200 DEG C for 6-48 h; after the reaction is completed, the product is cooled, washed with ethanol and water alternately until the pH value is 7-10, and then dried at 60-120 DEG C and calcined at 400-550 DEG C to obtain the B-M-ZSM-5 molecular sieve catalyst;

[0015] The B-M-ZSM-5 molecular sieve has a specific surface area greater than 400 m 2 / g and an external surface area greater than 100 m 2 / g; and the molar ratio of the silicon-aluminum oxide in the molecular sieve is 50-300.

[0016] The molar ratio of the raw materials is n (SiO2) : n (Al2O3) : n1: n (H2O) : n2: n3 = 1: (0.001-0.1) : (0.01-10) : (0.1-100) : (0.001-10) : (0.001-0.5), preferably 1: (0.002-0.01) : (0.1-1) : (1-20) : (0.005-5) : (0.01-0.1); wherein n (SiO2) represents the number of moles of SiO2 in the added silicon source, n (Al2O3) represents the number of moles of Al2O3 in the added aluminum source, n1 represents the number of moles of the template agent, n (H2O) represents the number of moles of water, n2 represents the number of moles of the tetravalent metal element, and n3 represents the number of moles of the alkali metal compound mineralizer.

[0017] (2) The B-M-ZSM-5 molecular sieve is calcined at 400-550 DEG C for 3-8 h, ammonium-exchanged with an aqueous solution of 1-10 mol / L ammonium chloride at 50-90 DEG C for 1-3 times, and then calcined at 400-550 DEG C for 3-8 h to obtain the H-M-ZSM-5 molecular sieve catalyst;

[0018] The H-M-ZSM-5 molecular sieve has an acid center number of 0.01-1.0 mmol / g, preferably 0.02-0.3 mmol / g.

[0019] (3) The H-M-ZSM-5 molecular sieve catalyst is ground and then activated in a gas atmosphere to obtain an olefin oligomerization molecular sieve catalyst. Specifically, the catalyst is ground and then activated in a N2, ethane, or propane gas atmosphere at 200-700℃ for 1-5h to obtain the olefin oligomerization molecular sieve catalyst. The olefin oligomerization molecular sieve catalyst has a specific surface area of greater than 400 m 2 / g, an external surface area of greater than 100 m 2 / g, and a molar ratio of silicon-aluminum oxide in the molecular sieve of 50-300.

[0020] Specifically, in step (1), the metal salt includes one of tin acetate, crystalline tin tetrachloride, cerium sulfate, cerium oxalate, cerium ammonium nitrate, zirconium acetate, and zirconium acetylacetone. Adding one kind of metal oxide facilitates the entry of the metal oxide into the molecular sieve framework, and adding multiple kinds of metal oxide is difficult to synthesize. The aluminum source is one of aluminum nitrate and aluminum sulfate. The alkali metal compound mineralizer is one of sodium chloride, sodium fluoride, potassium chloride, and potassium fluoride. The template agent is one of tetrapropylammonium hydroxide, tetraethylammonium hydroxide, tetraethylammonium fluoride, tetraethylammonium bromide, cetyltrimethylammonium bromide, and triethylamine. The silicon source is one of silica sol and tetraethyl orthosilicate.

[0021] The application provides application of the above-mentioned olefin oligomerization molecular sieve catalyst in a hexene oligomerization reaction to generate C12 and C18 long-chain olefins. The catalyst converts hexene into C12 and C18 long-chain olefins.

[0022] In the above-mentioned application, the reaction conditions are as follows: the reaction pressure is 0-4 MPa, the temperature is 120-300℃, and the olefin and the catalyst (mass space velocity WHSV is 0.1-10 h -1 ) are contacted to generate long-chain olefins with carbon numbers of C12 and C18. The total selectivity of C12 and C18 is maintained at more than 80% for more than 10 hours of continuous reaction.

[0023] The oligomerization reaction of olefins generally follows a carbonium ion mechanism on a molecular sieve, involves attack of a B acid site on an olefin molecule to form an ion pair, and the ion pair reacts with another olefin to generate a longer carbon chain.

[0024] The application provides application of the above-mentioned catalyst in a C3-C6 olefin oligomerization reaction to generate C6-C18 long-chain olefins.

[0025] The application has the following beneficial effects:

[0026] (1) The metal oxide in the application forms a metal-molecular sieve catalyst with good dispersity by interacting with the molecular sieve carrier, and the Si-O-M 4+The skeleton M in the ZSM-5 molecular sieve produces high-dispersed trivalent and tetravalent atoms, avoids generation of M oxide particles, cooperates with aluminum species in the molecular sieve to produce strong olefin activation capacity, and due to the introduction of the M metal, the acid distribution of the molecular sieve is changed;

[0027] (2) The application reduces the diffusion resistance of reactants and intermediate products in the catalyst through the synergistic effect of nanocrystals and mesopores, improves the accessibility of active sites of the catalyst, greatly improves the hexene condensation activity relative to that on pure molecular sieves, and improves the stability of the catalyst, so that the total selectivity of C12 and C18 can be maintained at more than 80% for more than 10 hours of continuous reaction, and the application prospect is wide. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 A scanning electron microscope (SEM) image of the ZSM-5 molecular sieve prepared in Example 2.

[0029] Figure 2 A scanning electron microscope (SEM) image of the Sn-ZSM-5 molecular sieve prepared in Example 2. DETAILED DESCRIPTION

[0030] The following examples are only preferred technical solutions of the application and are not intended to limit the application in any way. The application can have various modifications and changes for those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the application shall be included in the protection scope of the application. Example 1

[0031] (1) The silicon source TEOS, the aluminum source Al2(SO4)3·18H2O, the template agent TPAOH (tetrapropylammonium hydroxide), water, the tetravalent metal salt SnCl4·5H2O, and sodium chloride were mixed and rapidly stirred to obtain a co-mixture with a molar ratio of SiO2:Al2O3:TPAOH:H2O:SnO2:Na+=1:0.005:0.3:8:0.01:0.012. The mixture was stirred at room temperature for 48 h, then was loaded into a 100 mL hydrothermal kettle and crystallized at 120 ℃ for 48 h. The obtained product was filtered into neutral after stirring with water and ethanol for 5 min, was dried in a 100 ℃ oven for 12 h, and finally was calcined at 550 ℃ in an air atmosphere in a muffle furnace at a temperature increasing rate of 2 ℃ / min for 6 h to obtain Na-Sn-ZSM-5. The Na-Sn-ZSM-5 was mixed with a 1 M aqueous ammonium chloride solution at a solid-liquid ratio of 1 g:20 mL for ammonium exchange treatment, was centrifuged and washed with deionized water for 3 times after repeating 3 times, was dried at 100 ℃ overnight, and was calcined at 550 ℃ for 6 h to obtain H-Sn-ZSM-5. The specific surface area of the obtained H-Sn-ZSM-5 molecular sieve was 414 m 2 / g.

[0032] (2) Mix 1 g ZSM-5 with 1 g silica and load it into the isothermal section of the reaction tube, with a bed height of approximately 13 mm. Activate under a high-purity N2 atmosphere (50 mL / min) by purging at 400 °C for 2 h at atmospheric pressure. When the temperature drops to the reaction temperature of 240 °C, pressurize with high-purity N2 to a reaction pressure of 4 MPa, with an N2 flow rate of 50 mL / min and the liquid feed rate maintained at 0.03 mL / min. Continue the reaction for 12 h, and record the selectivity of α-olefins C12 and C18 at 4 h and 12 h of catalytic reaction. The results are shown in Table 1. Example 2

[0033] (1) The silicon source TEOS, the aluminum source Al2(SO4)3·18H2O, the template agent TPAOH, water, the tetravalent metal salt SnCl4·5H2O, and sodium chloride were mixed and stirred rapidly to obtain a molar ratio of SiO2:Al2O3:TPAOH:H2O:SnO2:Na + A mixture of 1:0.005:0.3:8:0.02:0.012 was prepared. The mixture was stirred at room temperature for 48 h, then transferred to a 100 mL hydrothermal reactor and crystallized at 120 °C for 48 h. The resulting product was added to water and ethanol, stirred for 5 min, filtered until neutral, and dried in a 100 °C oven for 12 h. Finally, the obtained solid powder was calcined in a muffle furnace at 550 °C in air atmosphere for 6 h at a heating rate of 2 °C / min to obtain Na-Sn-ZSM-5. Na-Sn-ZSM-5 was mixed with 1 M ammonium chloride aqueous solution at a solid-liquid ratio of 1 g:20 mL for ammonium exchange treatment. This process was repeated three times, followed by centrifugation, washing three times with deionized water, drying overnight at 100 °C, and calcining at 550 °C for 6 h to obtain H-Sn-ZSM-5. The specific surface area of ​​the prepared H-Sn-ZSM-5 molecule was 420 m². 2 / g.

[0034] (2) Mix 1 g of H-Sn-ZSM-5 with 1 g of silica and load it into the isothermal section of the reaction tube, with a bed height of approximately 13 mm. Activate under a high-purity N2 atmosphere (50 mL / min) by purging at 400 °C for 2 h at atmospheric pressure. When the temperature drops to the reaction temperature of 240 °C, pressurize with high-purity N2 to a reaction pressure of 4 MPa, with an N2 flow rate of 50 mL / min and the liquid feed rate controlled at 0.03 mL / min. Continue the reaction for 12 h, and record the selectivity of long-chain olefins C12 and C18 at 4 h and 12 h of catalytic reaction. The results are shown in Table 1.

[0035] In the appendix Figure 1The SEM image of the HZSM-5 molecular sieve prepared in this embodiment is given, showing that the HZSM-5 has a smooth surface and a particle size of about 150~300 nm.

[0036] Appendix Figure 2 The image shows a scanning electron microscope (SEM) image of H-Sn-ZSM-5 molecular sieve. The comparison reveals that the addition of Sn did not have a significant effect on the grain size of the sample, but it caused a significant change in the morphology of the catalyst's outer surface, making the surface abnormally rough. Example 3

[0037] (1) The silicon source TEOS, the aluminum source Al2(SO4)3·18H2O, the template agent TPAOH, water, the tetravalent metal salt SnCl4·5H2O, and sodium chloride were mixed and stirred rapidly to obtain a molar ratio of SiO2:Al2O3:TPAOH:H2O:SnO2:Na + A mixture of 1:0.005:0.3:8:0.03:0.012 was prepared. The mixture was stirred at room temperature for 48 h, then transferred to a 100 mL hydrothermal reactor and crystallized at 120 °C for 48 h. The resulting product was then mixed with water and ethanol, stirred for 5 min, filtered until neutral, and dried in a 100 °C oven for 12 h. Finally, the resulting solid powder was calcined in a muffle furnace at 550 °C in air for 6 h at a heating rate of 2 °C / min to obtain Na-Sn-ZSM-5. Na-Sn-ZSM-5 was then mixed with 1 M ammonium chloride aqueous solution at a solid-liquid ratio of 1 g:20 mL for ammonium exchange treatment. This process was repeated three times, followed by centrifugation, washing three times with deionized water, drying overnight at 100 °C, and calcining at 550 °C for 6 h to obtain H-Sn-ZSM-5. The specific surface area of ​​the prepared H-Sn-ZSM-5 molecule was 406 m². 2 / g.

[0038] (2) Mix 1 g H-Sn-ZSM-5 with 1 g silica and load it into the isothermal section of the reaction tube, with a bed height of approximately 13 mm. Activate under a high-purity N2 atmosphere (50 mL / min) by purging at 400 °C for 2 h at atmospheric pressure. When the temperature drops to the reaction temperature of 240 °C, pressurize with high-purity N2 to a reaction pressure of 4 MPa, with an N2 flow rate of 50 mL / min and the liquid feed rate controlled at 0.03 mL / min. Continue the reaction for 12 h, and record the selectivity of long-chain olefins C12 and C18 at 4 h and 12 h of catalytic reaction. The results are shown in Table 1.

[0039] Examples 1-3 provide the effects of using Al2(SO4)3·18H2O as the aluminum source and Sn content of 0.03, 0.02, and 0.01, respectively, and compare them with Comparative Example 1. Example 4

[0040] (1) The silicon source TEOS, aluminum source NaAlO2, template agent TPAOH, water, tetravalent metal salt SnCl4·5H2O, and sodium chloride were mixed and stirred rapidly to obtain a co-mixture with a molar ratio of SiO2:Al2O3:TPAOH:H2O:SnO2:Na + =1:0.005:0.3:8:0.01:0.012. The mixture was stirred at room temperature for 48 h, and then was loaded into a 100 mL hydrothermal kettle and crystallized at 120 °C for 48 h. The obtained product was added with water and ethanol, stirred for 5 min, and then filtered into a neutral state. The product was dried in a 100 °C oven for 12 h, and finally the obtained solid powder was calcined in a muffle furnace at 550 °C in an air atmosphere at a temperature increasing rate of 2 °C / min for 6 h to obtain Na-Sn-ZSM-5. The Na-Sn-ZSM-5 was mixed with a 1 M aqueous solution of ammonium chloride at a solid-liquid ratio of 1 g:20 mL for ammonium exchange treatment. After repeated 3 times, the product was centrifuged and washed with deionized water 3 times, dried at 100 °C overnight, and calcined at 550 °C for 6 h to obtain H-Sn-ZSM-5. The prepared H-Sn-ZSM-5 had a specific surface area of 415 m 2 / g.

[0041] (2) 1 g of H-Sn-ZSM-5 was mixed with 1 g of silicon oxide and loaded into a reaction tube constant temperature section with a bed height of about 13 mm. Under a high-purity N2 (50 mL / min) atmosphere, the product was activated at 400 °C under normal pressure for 2 h. When the temperature decreased to the reaction temperature of 240 °C, the product was pressurized to a reaction pressure of 4 MPa with high-purity N2, and the N2 flow rate was 50 mL / min. The liquid feeding amount was controlled to be 0.03 mL / min. The continuous reaction was carried out for 12 h. The selectivity of long-chain olefins C12 and C18 at 4 h and 12 h of the catalytic reaction was recorded, and the results are shown in Table 1. Example 5

[0042] (1) The silicon source TEOS, aluminum source NaAlO2, template agent TPAOH, water, tetravalent metal salt SnCl4·5H2O, and sodium chloride were mixed and stirred rapidly to obtain a co-mixture with a molar ratio of SiO2:Al2O3:TPAOH:H2O:SnO2:Na += 1 : 0.005 : 0.3 : 8 : 0.02 : 0.012. Stirring at room temperature for 48 h, then loading into a 100 mL autoclave for crystallization at 120 °C for 48 h. The obtained product was added with water and ethanol, stirring for 5 min, then filtered to neutral, dried in an oven at 100 °C for 12 h, and finally the obtained solid powder was calcined in a muffle furnace at 550 °C in air atmosphere with a heating rate of 2 °C / min for 6 h to obtain Na-Sn-ZSM-5. The Na-Sn-ZSM-5 was mixed with 1 M aqueous solution of ammonium chloride at a solid-liquid ratio of 1 g:20 mL for ammonium exchange treatment, repeated 3 times, then centrifuged and washed with deionized water 3 times, dried at 100 °C overnight, and calcined at 550 °C for 6 h to obtain H-Sn-ZSM-5.

[0043] (2) 1 g of H-Sn-ZSM-5 was mixed with 1 g of silicon oxide and loaded into the constant temperature section of the reaction tube with a bed height of about 13 mm. Under a high-purity N2(gas flow rate: 50 mL / min) atmosphere, the sample was activated at 400 °C under atmospheric pressure for 2 h. When the temperature decreased to the reaction temperature of 240 °C, the sample was pressurized to a reaction pressure of 4 MPa with high-purity N2(gas flow rate: 50 mL / min), and the liquid feeding amount was controlled to be 0.03 mL / min. The continuous reaction was carried out for 12 h, and the selectivity of long-chain olefins C12 and C18 at 4 h and 12 h of the catalytic reaction was recorded. The results are shown in Table 1. Example 6

[0044] (1) The silicon source TEOS, the aluminum source NaAlO2, the template agent TPAOH, water, the tetravalent metal salt SnCl4·5H2O, and sodium chloride were mixed and stirred rapidly to obtain a co-mixture with a molar ratio of SiO2:Al2O3:TPAOH:H2O:SnO2:Na + = 1 : 0.005 : 0.3 : 8 : 0.02 : 0.012. Stirring at room temperature for 48 h, then loading into a 100 mL autoclave for crystallization at 120 °C for 48 h. The obtained product was added with water and ethanol, stirring for 5 min, then filtered to neutral, dried in an oven at 100 °C for 12 h, and finally the obtained solid powder was calcined in a muffle furnace at 550 °C in air atmosphere with a heating rate of 2 °C / min for 6 h to obtain Na-Sn-ZSM-5. The Na-Sn-ZSM-5 was mixed with 1 M aqueous solution of ammonium chloride at a solid-liquid ratio of 1 g:20 mL for ammonium exchange treatment, repeated 3 times, then centrifuged and washed with deionized water 3 times, dried at 100 °C overnight, and calcined at 550 °C for 6 h to obtain H-Sn-ZSM-5. The prepared H-Sn-ZSM-5 had a specific surface area of 423 m 2 / g.

[0045] (2) Mix 1 g of H-Sn-ZSM-5 with 1 g of silica and load it into the isothermal section of the reaction tube, with a bed height of approximately 13 mm. Activate under a high-purity N2 atmosphere (50 mL / min) by purging at 400 °C for 2 h at atmospheric pressure. When the temperature drops to the reaction temperature of 240 °C, pressurize with high-purity N2 to a reaction pressure of 4 MPa, with an N2 flow rate of 50 mL / min and the liquid feed rate controlled at 0.03 mL / min. Continue the reaction for 12 h, and record the selectivity of long-chain olefins C12 and C18 at 4 h and 12 h of catalytic reaction. The results are shown in Table 1.

[0046] Examples 4-6 provide the effects of different Sn contents (0.01, 0.02, and 0.03) when the Al source is NaAlO2, and compare them with Comparative Example 2. Example 7

[0047] (1) The silicon source TEOS, the aluminum source Al2(SO4)3·18H2O, the template agent TPAOH, water, the tetravalent metal salt ZrOCl2·8H2O, and sodium fluoride were mixed and stirred rapidly to obtain a molar ratio of SiO2:Al2O3:TPAOH:H2O:ZrO2:Na + A mixture of 1:0.005:0.3:8:0.01:0.012 was prepared. The mixture was stirred at room temperature for 48 h, then transferred to a 100 mL hydrothermal reactor and crystallized at 120 °C for 48 h. The resulting product was then mixed with water and ethanol, stirred for 5 min, filtered until neutral, and dried in a 100 °C oven for 12 h. Finally, the resulting solid powder was calcined in a muffle furnace at 550 °C in air for 6 h at a heating rate of 2 °C / min to obtain Na-Zr-ZSM-5. Na-Zr-ZSM-5 was then mixed with 1 M ammonium chloride aqueous solution at a solid-liquid ratio of 1 g:20 mL for ammonium exchange treatment. This process was repeated three times, followed by centrifugation, washing three times with deionized water, drying overnight at 100 °C, and calcining at 550 °C for 6 h to obtain H-Zr-ZSM-5. The specific surface area of ​​the prepared H-Zr-ZSM-5 was 408 m². 2 / g.

[0048] (2) Mix 1 g of H-Zr-ZSM-5 with 1 g of silica and load it into the isothermal section of the reaction tube, with a bed height of approximately 13 mm. Activate under a high-purity N2 atmosphere (50 mL / min) by purging at 400 °C for 2 h at atmospheric pressure. When the temperature drops to the reaction temperature of 240 °C, pressurize with high-purity N2 to a reaction pressure of 4 MPa, with an N2 flow rate of 50 mL / min and the liquid feed rate controlled at 0.03 mL / min. Continue the reaction for 12 h, and record the selectivity of long-chain olefins C12 and C18 at 4 h and 12 h of catalytic reaction. The results are shown in Table 1. Example 8

[0049] (1) The silicon source TEOS, aluminum source Al2(SO4)3·18H2O, template agent TPAOH, water, tetravalent metal salt Zr(NO3)4, sodium fluoride were mixed, and rapid stirring was performed to obtain a co-mixture with a molar ratio of SiO2:Al2O3:TPAOH:H2O:ZrO2:Na + =1:0.005:0.3:8:0.01:0.012. After stirring at room temperature for 48 h, 100 mL of a hydrothermal kettle was filled and crystallized at 120°C for 48 h. The obtained product was added with water and ethanol, stirred for 5 min, and then filtered to neutral in a 100°C oven and dried for 12 h. Finally, the obtained solid powder was calcined in a muffle furnace at 550°C in an air atmosphere at a temperature rising rate of 2°C / min for 6 h to obtain Na-Zr-ZSM-5. The Na-Zr-ZSM-5 was mixed with 1 M aqueous ammonium chloride solution at a solid-liquid ratio of 1 g:20 mL for ammonium exchange treatment, repeated 3 times, centrifuged, washed with deionized water 3 times, dried at 100°C overnight, and calcined at 550°C for 6 h to obtain H-Zr-ZSM-5. The prepared H-Zr-ZSM-5 had a specific surface area of 406 m 2 / g.

[0050] (2) 1 g of H-Zr-ZSM-5 was mixed with 1 g of silicon oxide and loaded into the constant temperature section of the reaction tube with a bed height of about 13 mm. Under a high-purity N2 (50 mL / min) atmosphere, activation was performed at 400°C under normal pressure for 2 h. When the temperature decreased to the reaction temperature of 240°C, high-purity N2 was filled to a reaction pressure of 4 MPa, the N2 flow rate was 50 mL / min, and the liquid feeding amount was controlled to be 0.03 mL / min. Continuous reaction was performed for 12 h, and the selectivity of long-chain olefins C12 and C18 at 4 h and 12 h of the catalytic reaction was recorded, and the results are shown in Table 1. Example 9

[0051] (1) The silicon source TEOS, aluminum source Al2(SO4)3·18H2O, template agent TPAOH, water, tetravalent metal salt Ce(NO3)3·6H2O, and sodium fluoride were mixed, and rapid stirring was performed to obtain a co-mixture with a molar ratio of SiO2:Al2O3:TPAOH:H2O:CeO2:Na +=1:0.005: 0.3: 8: 0.01: 0.012 of the co-mixture. Stir at room temperature for 48 h, then load into a 100 mL autoclave for crystallization at 120 °C for 48 h. The obtained product is filtered to neutrality after stirring in water and ethanol for 5 min, dried in an oven at 100 °C for 12 h, and finally calcined at 550 °C in air for 6 h in a muffle furnace at a heating rate of 2 °C / min to obtain Na-Ce-ZSM-5. The Na-Ce-ZSM-5 is treated by ammonium exchange with 1 M aqueous ammonium chloride solution at a solid-liquid ratio of 1 g:20 mL, repeated 3 times, then washed with deionized water 3 times, dried at 100 °C overnight, and calcined at 550 °C for 6 h to obtain H-Ce-ZSM-5. The prepared H-Ce-ZSM-5 has a specific surface area of 419 m 2 / g.

[0052] (2) 1 g of H-Ce-ZSM-5 is mixed with 1 g of silicon oxide and loaded into the constant temperature section of a reaction tube with a bed height of about 13 mm. Under a high-purity N2 (50 mL / min) atmosphere, activation is performed at 400 °C under atmospheric pressure for 2 h. When the temperature drops to the reaction temperature of 240 °C, the high-purity N2 is pressurized to a reaction pressure of 4 MPa, the N2 flow rate is 50 mL / min, and the liquid feeding amount is controlled to be 0.03 mL / min. Continuous reaction is performed for 12 h, and the selectivity of long-chain olefins C12 and C18 at 4 h and 12 h of the catalytic reaction is recorded, and the results are shown in Table 1. Example 10

[0053] (1) The silicon source TEOS, the aluminum source Al2(SO4)3·18H2O, the template TPAOH, water, the tetravalent metal salt Ce(NO3)3·6H2O, and sodium fluoride are mixed and stirred rapidly to obtain a co-mixture with a molar ratio of SiO2:Al2O3:TPAOH:H2O:CeO2:Na + =1:0.005: 0.3: 8: 0.02: 0.012 of the co-mixture. Stir at room temperature for 48 h, then load into a 100 mL autoclave for crystallization at 120 °C for 48 h. The obtained product is filtered to neutrality after stirring in water and ethanol for 5 min, dried in an oven at 100 °C for 12 h, and finally calcined at 550 °C in air for 6 h in a muffle furnace at a heating rate of 2 °C / min to obtain Na-Ce-ZSM-5. The Na-Ce-ZSM-5 is treated by ammonium exchange with 1 M aqueous ammonium chloride solution at a solid-liquid ratio of 1 g:20 mL, repeated 3 times, then washed with deionized water 3 times, dried at 100 °C overnight, and calcined at 550 °C for 6 h to obtain H-Ce-ZSM-5.

[0054] (2) 1 g H-Ce-ZSM-5 was mixed with 1 g of silica and loaded into the constant temperature section of the reactor tube with a bed height of about 13 mm. Under a high-purity N2 (50 mL / min) atmosphere, activation was performed at 400 °C for 2 h at normal pressure. When the temperature decreased to the reaction temperature of 240 °C, high-purity N2 was used to pressurize to a reaction pressure of 4 MPa, and the N2 flow rate was 50 mL / min. The liquid feed amount was controlled to be maintained at 0.03 mL / min. Continuous reaction was performed for 12 h, and the selectivity of long-chain olefins C12 and C18 at 4 h and 12 h of the catalytic reaction was recorded. The results are shown in Table 1.

[0055] Examples 7-10 provide the influence of the aluminum source Al2(SO4)3·18H2O and the metals Zr, Ce (0.01, 0.02), and are compared with Comparative Example 2.

[0056] Comparative Example 1 (no metal oxide added, aluminum source Al2(SO4)3·18H2O)

[0057] (1) The silica source TEOS, the aluminum source Al2(SO4)3·18H2O, the template TPAOH, water, and sodium chloride were mixed and rapidly stirred to obtain a co-mixture with a molar ratio of SiO2:Al2O3:TPAOH:H2O:Na+=1:0.005:0.3:8:0.012. After stirring at room temperature for 48 h, the mixture was loaded into a 100 mL hydrothermal kettle for crystallization at 120 °C for 48 h. The obtained product was added with water and ethanol, stirred for 5 min, and then filtered to neutral in a 100 °C oven for drying for 12 h. Finally, the obtained solid powder was calcined in a muffle furnace at 550 °C in an air atmosphere at a temperature increasing rate of 2 °C / min for 6 h to obtain Na-ZSM-5. The Na-ZSM-5 was mixed with a 1 M aqueous ammonium chloride solution at a solid-liquid ratio of 1 g:20 mL for ammonium exchange treatment. After repeating 3 times, the product was centrifuged and washed with deionized water 3 times, dried at 100 °C overnight, and calcined at 550 °C for 6 h to obtain H-ZSM-5.

[0058] (2) 1 g H-ZSM-5 was mixed with 1 g of silica and loaded into the constant temperature section of the reactor tube with a bed height of about 13 mm. Under a high-purity N2 (50 mL / min) atmosphere, activation was performed at 400 °C for 2 h at normal pressure. When the temperature decreased to the reaction temperature of 240 °C, high-purity N2 was used to pressurize to a reaction pressure of 4 MPa, and the N2 flow rate was 50 mL / min. The liquid feed amount was controlled to be maintained at 0.03 mL / min. Continuous reaction was performed for 12 h, and the selectivity of long-chain olefins C12 and C18 at 4 h and 12 h of the catalytic reaction was recorded. The results are shown in Table 1.

[0059] Comparative Example 2 (no metal oxide added, aluminum source NaAlO2)

[0060] (1) Mix silicon source TEOS, aluminum source NaAlO2, template agent TPAOH, water, and sodium chloride, and stir rapidly to obtain a molar ratio of SiO2:Al2O3:TPAOH:H2O:Na + A mixture of 1:0.005:0.3:8:0.012 was prepared. The mixture was stirred at room temperature for 48 h, then transferred to a 100 mL hydrothermal reactor and crystallized at 120 °C for 48 h. The resulting product was mixed with water and ethanol, stirred for 5 min, filtered until neutral, and dried in a 100 °C oven for 12 h. Finally, the resulting solid powder was calcined in a muffle furnace at 550 °C in air for 6 h at a heating rate of 2 °C / min to obtain Na-ZSM-5. Na-ZSM-5 was then mixed with a 1 M ammonium chloride aqueous solution at a solid-liquid ratio of 1 g:20 mL for ammonium exchange treatment. This process was repeated three times, followed by centrifugation, washing three times with deionized water, drying overnight at 100 °C, and calcining at 550 °C for 6 h to obtain H-ZSM-5.

[0061] (2) Mix 1 g of H-ZSM-5 with 1 g of silica and load it into the isothermal section of the reaction tube, with a bed height of approximately 13 mm. Activate under a high-purity N2 atmosphere (50 mL / min) by purging at 400 °C for 2 h at atmospheric pressure. When the temperature drops to the reaction temperature of 240 °C, pressurize with high-purity N2 to a reaction pressure of 4 MPa, with an N2 flow rate of 50 mL / min and the liquid feed rate controlled at 0.03 mL / min. Continue the reaction for 12 h, and record the selectivity of α-olefins C12 and C18 at 4 h and 12 h of catalytic reaction. The results are shown in Table 1.

[0062] Table 1. Catalytic reaction results of catalysts in Examples 1-11 and Comparative Examples 1-2

[0063]

[0064] In Table 1, 4h and 12h represent reaction times of 4 hours and 12 hours, respectively, and the C12+C18 data represent the sum of the selectivity of C12 and C8.

[0065] Examples 1-3 provide the effects of using Al2(SO4)3·18H2O as the aluminum source and Sn content of 0.01, 0.02, and 0.03, respectively, and compare them with Comparative Example 1. The experimental results show that the selectivity of C12 and C18 is greatly improved, and increases with the increase of Sn content.

[0066] Examples 4-6 provide the effects of different Sn contents (0.01, 0.02, and 0.03) on the Al source NaAlO2, and compare them with Comparative Example 2. The experimental results show that the selectivity of C12 and C18 is greatly improved, and increases with the increase of Sn content.

[0067] Examples 7-10 provide: the influence of the aluminum source Al2(SO4)3·18H2O, and two other metals Zr (0.01), Ce (0.01, 0.02) in addition to Sn, and comparison with Comparative Example 2. The experimental results show that the selectivity of C12 and C18 is greatly improved, and different metal sources have no obvious effect on the selectivity of the product.

[0068] From Table 1 we find that by introducing transition metals (Sn, Zr, Ce) into the molecular sieve by one-pot method, the selectivity of 1-hexene oligomerization C12-C18 can be improved compared with pure molecular sieve, and increases with the increase of the content of transition metal, and still can maintain high C12-C18 selectivity after 12h of reaction.

[0069] It is apparent to those skilled in the art that the application is not limited to the details of the foregoing exemplary embodiments, and that the application can be implemented in other particular forms without departing from the spirit or essential characteristics of the application. Therefore, the embodiments should be considered in all respects as illustrative and not restrictive, and the scope of the application should be defined by the appended claims rather than the above description, and it is intended to include all changes falling within the meaning and range of equivalents of the claims.

[0070] Furthermore, it should be understood that although the present specification is described in terms of embodiments, not every implementation embodies an independent technical solution, and the description of the specification is only for the sake of clarity, and those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be appropriately combined to form other embodiments that those skilled in the art can understand.

Claims

1. A process for the preparation of an olefin oligomerization molecular sieve catalyst characterized by: The catalyst is ZSM-5 molecular sieve containing oxide, and the oxide is any one of tin oxide, cerium oxide or zirconium oxide; The metal elements in the catalyst are connected with Si or Al elements through oxygen bridge bonds to form Si-O-M, Al-O-M bonds, and part of the metal elements exist in the form of one or more of metal oxide clusters or metal oxide particles, and M represents a metal element; The preparation method of the olefin polymerization molecular sieve catalyst comprises the following steps: (1) Preparation of B-M-ZSM-5 molecular sieve catalyst: a silicon source, an aluminum source, a template agent, water, a tetravalent metal salt, an alkali metal compound mineralizer are mixed, rapidly stirred, and reacted at 90-200°C for 6-48h, and then the product is cooled, washed with ethanol and water alternately until the pH value is 7-10, and then dried at 60-120°C and calcined at 400-550°C to obtain the B-M-ZSM-5 molecular sieve catalyst; (2) The B-M-ZSM-5 molecular sieve is calcined at 400-550°C for 3-8h, ammonium exchanged with 1-10 mol / L ammonium chloride aqueous solution at 50-90°C for 1-3 times, and then calcined at 400-550°C for 3-8h to obtain the H-M-ZSM-5 molecular sieve catalyst; The number of acid centers of the H-M-ZSM-5 molecular sieve is 0.01-1.0 mmol / g; (3) The H-M-ZSM-5 molecular sieve catalyst is ground and then activated in a gas atmosphere to obtain the olefin polymerization molecular sieve catalyst: the catalyst is ground and then activated in N2, ethane and propane gas atmosphere at 200-700°C for 1-5h to obtain the olefin polymerization molecular sieve catalyst.

2. The process for preparing an olefin oligomerization molecular sieve catalyst according to claim 1, characterized by: The weight ratio of the oxide in the catalyst to the molecular sieve is (0.01-0.3):

1.

3. The process for preparing an olefin oligomerization molecular sieve catalyst according to claim 1, characterized in that: The B-M-ZSM-5 molecular sieve obtained in step (1) has a specific surface area greater than 400 m 2 / g, an external surface area greater than 100 m 2 / g; and a molar ratio of silicon-alumina oxide in the molecular sieve is between 50 and 300.

4. The process for preparing an olefin oligomerization molecular sieve catalyst according to claim 1, characterized by: In step (1), the molar ratio of the raw materials is n(SiO2):n(Al2O3):n1:n(H2O):n2:n3=1:(0.001-0.1):(0.01-10):(0.1-100):(0.001-10):(0.001-0.5), wherein n(SiO2) represents the number of moles of SiO2 in the added silicon source, n(Al2O3) represents the number of moles of Al2O3 in the added aluminum source, n1 represents the number of moles of the template agent, n(H2O) represents the number of moles of water, n2 represents the number of moles of the tetravalent metal element, and n3 represents the number of moles of the alkali metal compound mineralizer.

5. The process for preparing an olefin oligomerization molecular sieve catalyst according to claim 4, characterized by: The molar ratio of the raw materials is n(SiO2):n(Al2O3):n1:n(H2O):n2:n3=1:(0.002-0.01):(0.1-1):(1-20):(0.005-5):(0.01-0.1).

6. The process for preparing an olefin oligomerization molecular sieve catalyst according to claim 1, characterized by: The olefin oligomerization molecular sieve catalyst obtained in step (3) has a specific surface area greater than 400 m 2 / g, an external surface area greater than 100 m 2 / g; and a molar ratio of silicon-alumina oxide in the molecular sieve is between 50 and 300.

7. The process for preparing an olefin oligomerization molecular sieve catalyst according to Claim 1, characterized by: In step (1), the tetravalent metal salt includes one of tin acetate, crystalline tin tetrachloride, cerium sulfate, cerium oxalate, cerium ammonium nitrate, zirconium acetate, zirconium acetylacetone; the aluminum source is one of aluminum nitrate and aluminum sulfate; the alkali metal compound mineralizer is one of sodium chloride, sodium fluoride, potassium chloride, potassium fluoride; the template agent is one of tetrapropylammonium hydroxide, tetraethylammonium hydroxide, tetraethylammonium fluoride, tetraethylammonium bromide, cetyltrimethylammonium bromide, triethylamine; the silicon source is one of silica sol and tetraethyl orthosilicate.

8. The application of an olefin-modified molecular sieve catalyst prepared by the method of claim 1 or 2 in the hexene-modified reaction to generate C12 and C18 long-chain olefins, characterized in that: The reaction pressure is 0-4 MPa, and the temperature is 120-300 ℃; the olefins are contacted with the catalyst to produce long-chain olefins with carbon number C12 and C18, and the mass space velocity WHSV is 0.1-10 h -1 ; the total selectivity of C12 and C18 is kept above 80% for more than 10 hours of continuous reaction.

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