Preparation method of catalyst for directly preparing aviation kerosene from synthesis gas

Abstract

The invention relates to the field of a catalyst for directly preparing aviation kerosene from synthesis gas. The invention relates to a preparation method of a catalyst for directly preparing aviation kerosene from synthesis gas, which comprises the following steps of: soaking a ZSM-22 molecular sieve or a ZSM-23 molecular sieve in a strong alkali solution, washing in deionized water until the molecular sieve is neutral, filtering and drying to obtain a hierarchical pore molecular sieve; then uniformly mixing metal salt and the hierarchical pore molecular sieve, loading metal on the hierarchical pore molecular sieve by adopting a melt permeation method, drying the obtained solid product at normal temperature, and then roasting to obtain the metal / molecular sieve hierarchical pore catalyst, and finally, dispersing the metal / molecular sieve hierarchical pore catalyst in an ethanol solution of a mesoporous template agent, adding ammonia water to adjust the pH value to 8-9, adding an ethanol solution containing an organic silicon source, and stirring to completely react, so that the metal / molecular sieve hierarchical pore catalyst is coated with shell-layer mesoporous SiO2, thereby obtaining the metal / molecular sieve hierarchical pore catalyst. And washing, drying and roasting the product to obtain the catalyst for directly preparing the aviation kerosene from the synthesis gas.

Description

Technical Field

[0001] The present invention relates to the field of catalysts for directly preparing aviation fuel from synthesis gas. Background Art

[0002] The development of coal-based synthesis gas industry has great prospects and market.

[0003] For the production of liquid fuel from syngas, by coupling Fischer-Tropsch synthesis with isomerization to prepare a bifunctional catalyst, the high-carbon product is cleverly tailored in a relay manner, greatly improving the selectivity of liquid fuel. This new catalytic process route greatly simplifies the process flow, reduces process costs, and provides a new idea for the industrial production of aviation kerosene.

[0004] Invention patent CN 107573967 reported that after the diesel fraction raw oil was subjected to a hydrocracking catalyst reaction, the product was cooled, separated, and fractionated to obtain the aviation kerosene fraction. This method still uses petroleum-based products as raw materials to produce aviation kerosene. CN103801295A, CN102482595A, CN102719317A, etc. disclose methods for producing aviation kerosene from biomass, but the waste oil components are complex and the content of colloid components is relatively high, which easily leads to catalyst coking and is difficult to scale up industrially. Summary of the invention

[0005] The technical problem to be solved by the present invention is: how to provide a catalyst preparation method for producing aviation kerosene by one-step conversion of synthesis gas, wherein the aviation kerosene prepared by the method contains no sulfur and nitrogen, is green and environmentally friendly, and has high thermal stability.

[0006] The technical solution adopted by the present invention is: a method for preparing a catalyst for direct production of aviation kerosene from synthesis gas, characterized in that: the following steps are carried out Step 1: soak the ZSM-22 molecular sieve or ZSM-23 molecular sieve in a strong alkaline solution at 45-55°C to perform desiliconization and mesoporous treatment, then wash with deionized water until neutral, filter, and dry to obtain a multi-level pore molecular sieve; Step 2: uniformly mix the metal salt and the multi-level porous molecular sieve, load the metal on the multi-level porous molecular sieve by melt infiltration under vacuum conditions, dry the obtained solid product at room temperature, and then calcine to obtain a metal / molecular sieve multi-level porous catalyst; Step 3: Disperse the metal / molecular sieve multi-level porous catalyst in the ethanol solution of the mesoporous template, add ammonia water to adjust the pH value to 8-9, add the ethanol solution containing the organosilicon source at 45-55°C, stir to complete the reaction, and make the metal / molecular sieve multi-level porous catalyst covered with a shell layer of mesoporous SiO2, and then wash, dry and calcine the product to obtain a catalyst for direct production of aviation fuel from synthesis gas.

[0007] In step 1, the strong alkaline solution is 1-4 mol / L KOH or NaOH solution, and the soaking time is 2-6 hours.

[0008] In step 2, the metal salt is at least one of Fe(NO3)3·9H2O, FeCl3·6H2O, Co(NO3)2·6H2O, and CoCl2·6H2O, and the metal salt is calculated as a trivalent metal oxide, and the mass of the metal salt is 5-25% of the mass of the multi-level pore molecular sieve.

[0009] In step 2, the melting temperature of the melt infiltration method is 40-90°C, the calcination temperature is 350-500°C, and the calcination time is 3-10h.

[0010] In step three, the mesoporous template agent is at least one of hexadecyltrimethylammonium bromide and polyvinylpyrrolidone, and the organosilicon source is at least one of ethyl orthosilicate, (3-chloropropyl)trimethoxysilane, 3-aminopropyltriethoxysilane, and tetramethoxysilane.

[0011] In step 3, the thickness of the shell mesoporous SiO2 is 10-25nm.

[0012] In step three, the drying temperature is 60-80°C, the roasting temperature is 400-550°C, and the roasting time is 4-10h.

[0013] The beneficial effects of the present invention are as follows: the present invention removes silicon from ZSM-22 molecular sieve or ZSM-23 molecular sieve in an alkaline solution to form mesopores to obtain a multi-level porous molecular sieve, and then uses a melt infiltration method under vacuum conditions to load cobalt or iron onto the multi-level porous molecular sieve, and then coats the outer surface with a layer of mesoporous SiO2 to obtain a coated metal / molecular sieve catalyst. The FT reaction is carried out at the metal site to generate alkanes, and the alkane isomerization reaction is carried out on the molecular sieve. The two active sites are organically coordinated, and the product distribution is further adjusted by adjusting the thickness of the shell mesoporous SiO2, so that a highly selective and high-quality aviation kerosene product is obtained in one step. The thickness of the shell mesoporous SiO2 is adjusted to adjust the product distribution, which can improve and change the selectivity of C9-C16. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 XRD spectrum of ZSM-22 molecular sieve of Comparative Example 1; Figure 2 This is the XRD spectrum of the catalyst 5Co / ZSM-23@SiO2 prepared in Example 1. DETAILED DESCRIPTION

[0015] Comparative Example 1 Conventionally synthesized ZSM-22 molecular sieve with a silicon-aluminum ratio of 60 was not treated. Example 1

[0016] A method for preparing a catalyst for direct production of aviation fuel from syngas is carried out according to the following steps: Step 1: Soak 5 g of ZSM-22 molecular sieve in 20 ml of 2M KOH solution at 50°C for 3 h to perform desiliconization and mesoporous treatment, then wash with deionized water until neutral, filter, and dry at room temperature to obtain a multi-level pore molecular sieve; Step 2: Evenly mix 1.0 g of Co(NO3)3·6H2O and the multi-level porous molecular sieve prepared above, and load Co on the multi-level porous molecular sieve by melt infiltration at 60°C for 2 h under vacuum conditions. The obtained solid product is dried at room temperature and then calcined at 350°C for 10 h to obtain a metal / molecular sieve multi-level porous catalyst. Step 3: Disperse the metal / molecular sieve multi-level porous catalyst in 27.6g of hexadecylammonium bromide ethanol solution, adjust the Ph value to 8-9 with ammonia water, add 6ml of ethyl orthosilicate ethanol solution at 50°C, stir for 10h to complete the reaction, so that the metal / molecular sieve multi-level porous catalyst is coated with a shell layer of mesoporous SiO2, and then wash the product, dry it at 80°C, and calcine it at 400°C for 10h to obtain a synthesis gas direct production of aviation fuel catalyst (5Co / ZSM-22@SiO2), recorded as RD1. Example 2

[0017] A method for preparing a catalyst for direct production of aviation fuel from syngas is carried out according to the following steps: Step 1: Soak 5 g of ZSM-22 molecular sieve in 20 ml of 4 M KOH solution at 50°C for 2 h to perform desiliconization and mesoporous treatment, then wash with deionized water until neutral, filter, and dry at room temperature to obtain a multi-level pore molecular sieve; Step 2: 1.9 g Co(NO3)3·6H2O and the multi-level porous molecular sieve prepared above were mixed evenly, and Co was loaded on the multi-level porous molecular sieve by melt infiltration at 60°C for 2 h under vacuum conditions. The obtained solid product was dried at room temperature and then calcined at 400°C for 6 h to obtain a metal / molecular sieve multi-level porous catalyst; Step 3: Disperse the metal / molecular sieve multi-level porous catalyst in 10.2g of polyvinyl pyrrolidone ethanol solution, adjust the Ph value to 8-9 with ammonia water, add 6ml of ethyl orthosilicate ethanol solution at 50°C, stir for 10h to complete the reaction, so that the metal / molecular sieve multi-level porous catalyst is coated with a shell layer of mesoporous SiO2, and then wash the product, dry it at 60°C, and calcine it at 500°C for 10h to obtain a synthesis gas direct production of aviation fuel catalyst (10Co / ZSM-22@SiO2), recorded as RD2. Example 3

[0018] A method for preparing a catalyst for direct production of aviation fuel from syngas is carried out according to the following steps: Step 1: Soak 5 g of ZSM-23 molecular sieve in 20 ml of 2M KOH solution at 50°C for 3 h to perform desiliconization and mesoporous treatment, then wash with deionized water until neutral, filter, and dry at room temperature to obtain a multi-level pore molecular sieve; Step 2: Evenly mix 1.3 g Fe(NO3)3·9H2O, 1.0 g Co(NO3)3·6H2O and the multi-level porous molecular sieve prepared above, and load Co and Fe on the multi-level porous molecular sieve by melt infiltration at 60°C for 2 h under vacuum conditions. The obtained solid product is dried at room temperature and then calcined at 400°C for 6 h to obtain a metal / molecular sieve multi-level porous catalyst. Step 3: Disperse the metal / molecular sieve multi-level porous catalyst in 12.8g of hexadecylammonium bromide ethanol solution, adjust the Ph value to 8-9 with ammonia water, add 4ml of ethyl orthosilicate and 4ml of (3-chloropropyl)trimethoxysilane ethanol solution at 50°C, stir for 10h to complete the reaction, so that the metal / molecular sieve multi-level porous catalyst is coated with a shell layer of mesoporous SiO2, and then wash the product, dry it at 60°C, and calcine it at 500°C for 6h to obtain a synthesis gas direct production of aviation fuel catalyst (5Fe5Co / ZSM-23@SiO2), recorded as RD3. Example 4

[0019] A method for preparing a catalyst for direct production of aviation fuel from syngas is carried out according to the following steps: Step 1: Soak 5 g of ZSM-23 molecular sieve in 20 ml of 2M NaOH solution at 50°C for 3 h to perform desiliconization and mesoporous treatment, then wash with deionized water until neutral, filter, and dry at room temperature to obtain a multi-level pore molecular sieve; Step 2: 3.17 g of CoCl2·6H2O and the multi-level porous molecular sieve prepared above were mixed evenly, and Co was loaded on the multi-level porous molecular sieve by melt infiltration at 90°C for 2 h under vacuum conditions. The obtained solid product was dried at room temperature and then calcined at 500°C for 3 h to obtain a metal / molecular sieve multi-level porous catalyst; Step 3: Disperse the metal / molecular sieve multi-level porous catalyst in 12.8g of hexadecylammonium bromide ethanol solution, adjust the Ph value to 8-9 with ammonia water, add 3ml of tetramethoxysilane ethanol solution at 50°C, stir for 10h to complete the reaction, so that the metal / molecular sieve multi-level porous catalyst is coated with a shell layer of mesoporous SiO2, and then wash the product, dry it at 70°C, and calcine it at 550°C for 4h to obtain a synthesis gas direct production of aviation fuel catalyst (20Co / ZSM-23@SiO2), recorded as RD4. Example 5

[0020] A method for preparing a catalyst for direct production of aviation fuel from syngas is carried out according to the following steps: Step 1: Soak 5 g of ZSM-22 molecular sieve in 20 ml of 1 M NaOH solution at 50°C for 6 h to perform desiliconization and mesoporous treatment, then wash with deionized water until neutral, filter, and dry at room temperature to obtain a multi-level pore molecular sieve; Step 2: Evenly mix 4.2 g of FeCl3·6H2O and the multi-level porous molecular sieve prepared above, and load Fe on the multi-level porous molecular sieve by melt infiltration at 40°C for 2 h under vacuum conditions, dry the obtained solid product at room temperature, and then calcine at 500°C for 3 h to obtain a metal / molecular sieve multi-level porous catalyst; Step 3: Disperse the metal / molecular sieve multi-level porous catalyst in 12.8g of hexadecylammonium bromide ethanol solution, adjust the Ph value to 8-9 with ammonia water, add 6.3g of polyvinyl pyrrolidone ethanol solution at 50°C, stir for 10h to complete the reaction, so that the metal / molecular sieve multi-level porous catalyst is coated with a shell layer of mesoporous SiO2, and then wash the product, dry it at 60°C, and calcine it at 500°C for 6h to obtain a synthesis gas direct production of aviation fuel catalyst (25Fe / ZSM-22@SiO2), recorded as RD5.

[0021] The catalyst was ion exchanged with 1 M NH4Cl at 80°C for 3 h, filtered and washed until neutral, and then calcined at 500°C for 10 h before being used in the synthesis gas conversion reaction. Catalyst evaluation conditions: CO / H2=2, P=2MPa, GHSV=2000ml·g -1 ·h -1 , 270℃.

[0022] Table 1 Catalyst evaluation results

[0023] The CO conversion rate and the selectivity of hydrocarbon products can be calculated using the following formula: CO conversion rate: X co (%) =

[0024] Product selectivity: S i =

[0025] in, N co,in is the mole number of CO in the feed gas; N co,out is the molar number of CO in the tail gas; i, j are the carbon numbers of different hydrocarbons in the product (j = 1, 2, 3, ...); W i is the mass of hydrocarbons.

Claims

1. A method for preparing a catalyst for direct production of aviation kerosene from synthesis gas, characterized in that: Follow the steps below Step 1: soak the ZSM-22 molecular sieve or ZSM-23 molecular sieve in a strong alkaline solution at 45-55°C to perform desiliconization and mesoporous treatment, then wash with deionized water until neutral, filter, and dry to obtain a multi-level pore molecular sieve; Step 2: uniformly mix the metal salt and the multi-level porous molecular sieve, load the metal on the multi-level porous molecular sieve by melt infiltration under vacuum conditions, dry the obtained solid product at room temperature, and then calcine to obtain a metal / molecular sieve multi-level porous catalyst; Step 3: Disperse the metal / molecular sieve multi-level porous catalyst in the ethanol solution of the mesoporous template, add ammonia water to adjust the pH value to 8-9, add the ethanol solution containing the organosilicon source at 45-55°C, stir to complete the reaction, and make the metal / molecular sieve multi-level porous catalyst covered with a shell layer of mesoporous SiO2, and then wash, dry and calcine the product to obtain a catalyst for direct production of aviation fuel from synthesis gas.

2. The method for preparing a catalyst for direct production of aviation kerosene from synthesis gas according to claim 1, characterized in that: In step 1, the strong alkaline solution is 1-4 mol / L KOH or NaOH solution, and the soaking time is 2-6 hours.

3. The method for preparing a catalyst for direct production of aviation kerosene from synthesis gas according to claim 1, characterized in that: In step 2, the metal salt is at least one of Fe(NO3)3·9H2O, FeCl3·6H2O, Co(NO3)2·6H2O, and CoCl2·6H2O, and the metal salt is calculated as a trivalent metal oxide, and the mass of the metal salt is 5-25% of the mass of the multi-level pore molecular sieve.

4. The method for preparing a catalyst for direct production of aviation kerosene from synthesis gas according to claim 1, characterized in that: In step 2, the melting temperature of the melt infiltration method is 40-90°C, the calcination temperature is 350-500°C, and the calcination time is 3-10h.

5. The method for preparing a catalyst for direct production of aviation kerosene from synthesis gas according to claim 1, characterized in that: In step three, the mesoporous template agent is at least one of hexadecyltrimethylammonium bromide and polyvinylpyrrolidone, and the organosilicon source is at least one of ethyl orthosilicate, (3-chloropropyl)trimethoxysilane, 3-aminopropyltriethoxysilane, and tetramethoxysilane.

6. The method for preparing a catalyst for direct conversion of syngas to aviation kerosene according to claim 1, characterized in that: In step 3, the thickness of the shell mesoporous SiO2 is 10-25nm.

7. The method for preparing a catalyst for direct production of aviation kerosene from synthesis gas according to claim 1, characterized in that: In step three, the drying temperature is 60-80°C, the roasting temperature is 400-550°C, and the roasting time is 4-10h.

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