Catalyst for directly producing green aromatic hydrocarbon from biomass synthesis gas as well as preparation method and application of catalyst

Abstract

The invention discloses a catalyst for directly producing green aromatic hydrocarbon from biomass synthesis gas, and a preparation method and application thereof, and belongs to the field of aromatic hydrocarbon production. The catalyst for directly producing the green aromatic hydrocarbon from the biomass synthesis gas comprises a zeolite molecular sieve and a transition metal modified Fe-based oxide M1M2-FeOx, the mass ratio of the M1M2-FeOx is 10-80%, and the mass ratio of the zeolite molecular sieve is 20-90%; m1 and M2 are transition metals; in the catalyst, transition metal is utilized to modify iron-based metal, so that various CO2 activation sites are formed, and CO2 adsorption activation is promoted; meanwhile, the iron-based metal active center and the zeolite molecular sieve acid center are matched with each other, so that the catalyst can be used in a reaction system for directly preparing the aromatic hydrocarbon from the biomass synthesis gas, and the catalyst has relatively high conversion rate and aromatic hydrocarbon selectivity in preparation of the aromatic hydrocarbon from the carbon dioxide-containing biomass synthesis gas, and has a good industrial application prospect.

Description

Technical Field

[0001] The present invention belongs to the field of aromatic hydrocarbon production, and in particular relates to a catalyst for directly producing green aromatic hydrocarbons from biomass synthesis gas, a preparation method and an application thereof. Background Art

[0002] Aromatics is not only an important platform chemical with wide applications in synthetic dyes, artificial resins, and pharmaceutical manufacturing, but also an indispensable component of transportation fuel, playing a key role in improving fuel octane number, flammability, and combustion efficiency. However, aromatics are currently mainly obtained through processes such as petroleum reforming and hydrogenation, gasoline cracking and hydrogenation, and are heavily dependent on fossil resources. With the advancement of the global "carbon tax" policy, the development of new ways to prepare aromatics using biomass as raw materials to replace traditional ways with high pollution and high carbon emissions has attracted great attention from countries around the world.

[0003] In recent years, synthesis gas (H 2 The rapid development of the technology of directly producing aromatics from biomass (CO / CO) has made the technology of preparing synthesis gas through pyrolysis / gasification of biomass and then preparing aromatics through C1 route very promising. However, due to the oxygen-rich characteristics of biomass raw materials (O element>40%), biomass synthesis gas has CO2-rich 2 The characteristics of the composition (accounting for 20-30%), and the gas composition obtained by different pyrolysis gasification technologies and biomass raw materials are very different, which makes it difficult to adapt many technologies that have been applied to coal-based syngas conversion. 2 The key to opening up this pathway is to directly and efficiently produce green aromatics from biomass synthesis gas.

[0004] The direct production of aromatics from syngas is mainly carried out on metal-molecular sieve bifunctional catalysts (such as NaFe-ZSM-5, ZnZrOx-ZSM-5, etc.). CO will first be converted into methanol / dimethyl ether, or olefins and other intermediates on the metal component, and these intermediates will then be aromatized at the acidic position of the molecular sieve to obtain aromatics. Therefore, the design and construction of efficient metal-molecular sieve catalysts has always been the focus of this research. Compared with coal-based syngas, biomass syngas is rich in CO 2 , which can be regarded as CO, CO 2 With H 2 Although some reports indicate that a small amount of CO is introduced into the syngas 2 The components can inhibit the water-gas shift (CO+H 2 O→CO 2 +H 2 ) side reaction, which is beneficial to increase the carbon yield of synthesis gas. 2 It will also compete with CO for adsorption on metal components, inhibiting the conversion of biomass to syngas. 2Hydrogenation can also directly prepare aromatics on a metal-zeolite bifunctional catalyst, that is, CO 2 through the reverse water-gas shift (CO 2 +H 2 →CO+H 2 O) reaction to generate CO, and then prepare aromatics through the syngas route. However, a large amount of CO components in biomass syngas will inhibit the progress of the reverse water-gas shift reaction, thus also resulting in the difficulty of converting CO 2 components. Therefore, developing a new type of metal-zeolite bifunctional catalyst to achieve the co-hydrogenation conversion of CO / CO 2 is the key to the efficient direct production of aromatics from biomass syngas. Summary of the Invention

[0005] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a catalyst, a preparation method and an application for directly producing green aromatics from biomass syngas, and solve the problems in the prior art.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] The catalyst for directly producing green aromatics from biomass syngas includes: zeolite molecular sieve and transition metal-modified Fe-based oxide M1M2-FeOx; the mass ratio of M1M2-FeOx is 10-80%, and the mass ratio of zeolite molecular sieve is 20-90%;

[0008] M1 and M2 are transition metals.

[0009] Further, M1 and M2 are selected from any two of Cu, Zn, Ni, Co, Mn, Cr, Nb, Mo, Zr.

[0010] Further, the molar ratio of M1, M2 to Fe element is 1:(0.001-0.4):(0.001-0.4).

[0011] Further, the topological structure of the zeolite molecular sieve is one of MFI, FAU, TON.

[0012] The preparation method of the above-mentioned catalyst for directly producing green aromatics from biomass syngas includes the following steps:

[0013] Add iron salt to the mixed solution of water and ethylene glycol and stir to dissolve to obtain solution A;

[0014] In solution A, successively add ethylenediamine, polyvinylpyrrolidone, anhydrous sodium acetate, and M1, M2 metal salts, and stir to dissolve to obtain solution B;

[0015] Perform a hydrothermal reaction on Solution B. After cooling to room temperature, separate the solid, wash and dry it to obtain M1M2-FeOx;

[0016] Mold and screen M1M2-FeOx and zeolite molecular sieve respectively, and then mix them to obtain the catalyst.

[0017] Furthermore, when preparing Solution A, the volume ratio of water to ethylene glycol is between (0 - 5.8):1.

[0018] Furthermore, when preparing Solution B, the molar ratio of the iron salt, ethylenediamine, polyvinylpyrrolidone, anhydrous sodium acetate, M1 and M2 metal salts is 1:(5 - 10):(0.01 - 0.08):(3 - 6):(0.001 - 0.4):(0.001 - 0.4).

[0019] Furthermore, the iron salt is one or more of ferric chloride, ferric nitrate, ferric sulfate, ferric acetate, iron acetylacetonate; the M1 and M2 metal salts are one of chloride salts, nitrate salts, and acetate salts.

[0020] Application of the above catalyst for directly producing green aromatics from biomass syngas in the preparation of aromatics.

[0021] Furthermore, the process of preparing aromatics includes:

[0022] Load the catalyst into a fixed-bed reactor, introduce hydrogen at atmospheric pressure and in-situ reduce it at 350 - 500 °C for 4 - 12 h, then switch to biomass syngas, raise the pressure to 2.0 - 6.0 MPa, and at a reaction temperature of 280 - 400 °C and a gas hourly space velocity of 500 - 10000 h -1 under the conditions of, directly prepare green aromatics from biomass syngas;

[0023] The biomass syngas is a mixture of CO, CO 2 and H 2 ; the molar ratio of CO / CO 2 in the biomass syngas is (1:10) - (10:1), and the molar ratio of (CO + CO 2 ) / H 2 is (2:1) - (1:3).

[0024] Advantages of the present invention:

[0025] The bifunctional catalyst of the present invention includes two parts: transition metal modified iron-based oxide and zeolite molecular sieve; the transition metal modifies the iron-based metal to form a variety of CO 2 activation sites, promoting the adsorption and activation of CO 2 ; meanwhile, the iron-based metal active center and the zeolite molecular sieve acid center match each other, in biomass syngas (CO / CO2 / H 2 )In the reaction system for directly preparing aromatics, under appropriate reaction conditions, the single-pass conversion rate of CO / CO 2 and the proportion of aromatics in all products (excluding H 2 O) are both significantly increased. In addition, after continuous reaction for 48 hours, the reaction activity of the catalyst remains stable, showing good prospects for industrial application. Specific Embodiments

[0026] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0027] A catalyst for directly producing green aromatics from biomass syngas includes transition metal-modified Fe-based oxides (M1M2-FeOx) and zeolite molecular sieves; the mass ratio of M1M2-FeOx is 10-80%, and the mass ratio of zeolite molecular sieves is 20-90%;

[0028] M1 and M2 are transition metals selected from any two of Cu, Zn, Ni, Co, Mn, Cr, Nb, Mo, and Zr; the molar ratio of the transition metals M1, M2 to the Fe element is (0.001-0.4):(0.001-0.4):1; the topological structure of the zeolite molecular sieve is one of MFI, FAU, and TON.

[0029] The preparation process of this catalyst includes:

[0030] (1) Using a mixed solution of water and ethylene glycol as a solvent, adding an iron salt to the solvent and stirring to dissolve at room temperature to obtain solution A;

[0031] (2) In solution A, successively add ethylenediamine, polyvinylpyrrolidone, sodium acetate anhydrous, and M1 and M2 metal salts, and stir to dissolve at room temperature to obtain solution B.

[0032] (3) Transfer solution B to a polytetrafluoroethylene high-temperature hydrothermal autoclave, perform hydrothermal reaction for 12 hours, cool to room temperature, separate the solid, wash the solid with deionized water and absolute ethanol, and finally place the solid in a vacuum oven at 60°C and dry overnight to obtain M1M2-FeOx.

[0033] (4) Shape and screen M1M2-FeOx and zeolite molecular sieves separately, and then mix them to obtain a catalyst for directly producing aromatics from biomass syngas.

[0034] In step (1), the volume ratio of water to ethylene glycol is between (0 - 5.8):1; the iron metal salt in step (1) is one or more of ferric chloride, ferric nitrate, ferric sulfate, ferric acetate, and iron acetylacetonate; in step (1), 0.02 - 0.2 mol of iron salt is dissolved in 0.2 L of a mixed solution of water and ethylene glycol.

[0035] In step (2), the molar ratio of iron salt, ethylenediamine, polyvinylpyrrolidone, anhydrous sodium acetate, M1 and M2 metal salts is 1:(5 - 10):(0.01 - 0.08):(3 - 6):(0.001 - 0.4):(0.001 - 0.4). In step (2), the M1 and M2 metal salts are one of chloride salts, nitrate salts, and acetate salts.

[0036] The hydrothermal reaction temperature in step (3) is 170 - 220 °C.

[0037] In step (4), any one of the zeolite molecular sieves HZSM-5, HY, and HZSM-22 is used. In step (4), M1M2-FeOx and the zeolite molecular sieve are respectively formed and sieved into 20 - 100 mesh particles.

[0038] This catalyst can be used for directly preparing aromatics from biomass syngas; the steps for preparing aromatics specifically include:

[0039] Load the catalyst into a fixed-bed reactor, introduce hydrogen at normal pressure and in-situ reduce it at 350 - 500 °C for 4 - 12 h, then switch to the feed gas (biomass syngas), raise the pressure to 2.0 - 6.0 MPa, and at a reaction temperature of 280 - 400 °C and a gas hourly space velocity of 500 - 10000 h -1 under the conditions of, directly prepare green aromatics from biomass syngas.

[0040] Among them, the biomass syngas is a mixed gas of CO, CO 2 and H 2 ; the molar ratio of CO / CO 2 in the biomass syngas is (1:10)-(10:1), and the molar ratio of (CO + CO 2 ) / H 2 is (1:2)-

[0041] (3:1); the aromatics are C6 - C13 monocyclic aromatics.

[0042] More preferably, the molar ratio of CO / CO 2 in the biomass syngas is (1:2)-(2:1),

[0043] (CO + CO 2 ) / H 2 is (1:1)-(2:1);

[0044] More preferably, the reduction temperature is 400 °C, the gas hourly space velocity is 5000 h -1 , the reduction time is 6 h; the reaction temperature is 360 °C, the gas hourly space velocity is 2500 h -1 , and the reaction pressure is 4.0 MPa.

[0045] The preparation method of the catalyst for directly producing green aromatics from biomass syngas is illustrated by the following examples and comparative examples; the raw material sources in the examples and comparative examples are as follows:

[0046] Ferric chloride, Aladdin Biochemical Technology Co., Ltd., ACS grade;

[0047] Ethylene glycol, Shanghai Macklin Biochemical Co., Ltd., AR grade;

[0048] Ethylenediamine, Guangdong Daxiao Chemical Co., Ltd., AR grade;

[0049] Polyvinylpyrrolidone, Shanghai Macklin Biochemical Co., Ltd., AR grade;

[0050] Sodium acetate anhydrous, Shanghai Macklin Biochemical Co., Ltd., AR grade;

[0051] Copper acetate anhydrous, Shanghai Macklin Biochemical Co., Ltd., purity 98%;

[0052] Zinc acetate anhydrous, Shanghai Macklin Biochemical Co., Ltd., AR grade;

[0053] Cobalt acetate anhydrous, Shanghai Macklin Biochemical Co., Ltd., AR grade;

[0054] Nickel acetate anhydrous, Shanghai Macklin Biochemical Co., Ltd., AR grade;

[0055] HZSM-5 zeolite molecular sieve, self-made, Si / Al = 50 - 75; the self-making process is as follows: using one or more of aluminum nitrate, aluminum isopropoxide, and sodium meta-aluminate as the aluminum source, tetraethyl orthosilicate as the silicon source, and tetrapropylammonium hydroxide as the template agent, adding them to water in a certain proportion and dissolving; then, condensing and refluxing at 70 °C for 30 h, transferring to a hydrothermal autoclave, and standing hydrothermally at 170 °C for 3 days; finally, after separating the solid, washing, drying, and calcining to obtain the HZSM-5 molecular sieve.

[0056] HZSM-22 zeolite molecular sieve, Tianjin Nanhua Catalyst Co., Ltd., Si / Al = 40 - 50

[0057] Example 1

[0058] S1. Add ferric chloride to a mixed solution of 0.2 L of water and ethylene glycol (volume ratio is 0.1), and stir to dissolve at room temperature.

[0059] S2. Subsequently, add ethylenediamine, polyvinylpyrrolidone, anhydrous sodium acetate, anhydrous copper acetate, and anhydrous zinc acetate in sequence, and stir to dissolve at room temperature; among them, the molar ratio of ferric chloride, ethylenediamine, polyvinylpyrrolidone, anhydrous sodium acetate, anhydrous copper acetate, and anhydrous zinc acetate is 1:7.5:0.02:4.3:0.07:0.002.

[0060] S3. After all are dissolved, transfer the solution to a polytetrafluoroethylene high-temperature hydrothermal autoclave, carry out hydrothermal reaction at 200 °C for 12 hours, cool to room temperature, separate the solid, wash the solid with deionized water and anhydrous ethanol, and finally place the solid in a vacuum dryer at 60 °C overnight to obtain 7Cu0.2ZnFeOx, and then form and screen it into 20 - 40 mesh particles.

[0061] S4. Finally, mix HZSM-5 zeolite molecular sieve (20 - 40 mesh) with 7Cu0.2ZnFeOx particles (20 - 40 mesh) to obtain the catalyst, among which the mass ratios of 7Cu0.2ZnFeOx and HZSM-5 in the catalyst are 40% and 60% respectively.

[0062] Example 2

[0063] The difference between Example 2 and Example 1 is only that:

[0064] The molar ratio of ferric chloride to anhydrous copper acetate and anhydrous zinc acetate is 1:0.07:0.01.

[0065] Example 3

[0066] The difference between Example 3 and Example 1 is only that:

[0067] The molar ratio of ferric chloride to anhydrous copper acetate and anhydrous zinc acetate is 1:0.07:0.05.

[0068] Example 4

[0069] The difference between Example 4 and Example 1 is only that:

[0070] The molar ratio of ferric chloride to anhydrous copper acetate and anhydrous zinc acetate is 1:0.03:0.01.

[0071] Example 5

[0072] The difference between Example 5 and Example 1 is only that:

[0073] The molar ratio of ferric chloride to anhydrous copper acetate and anhydrous zinc acetate is 1:0.01:0.01.

[0074] Example 6

[0075] The difference between Example 6 and Example 2 is only that:

[0076] The mass percentages of M1M2FeOx and HZSM-5 in the catalyst are 20% and 80% respectively.

[0077] Example 7

[0078] The difference between Example 7 and Example 1 is only that:

[0079] The HZSM-5 zeolite molecular sieve is replaced by HZSM-22.

[0080] Example 8

[0081] The difference between Example 8 and Example 1 is only that:

[0082] Anhydrous zinc acetate is replaced by anhydrous cobalt acetate.

[0083] Example 9

[0084] The difference between Example 9 and Example 1 is only that:

[0085] Anhydrous zinc acetate is replaced by anhydrous nickel acetate.

[0086] Comparative Example 1

[0087] The difference between Comparative Example 1 and Example 1 is only that:

[0088] Anhydrous copper acetate and anhydrous zinc acetate are not added.

[0089] Comparative Example 2

[0090] The difference between Comparative Example 2 and Example 1 is only that:

[0091] Anhydrous acetic acid is not added.

[0092] Comparative Example 3

[0093] The difference between Comparative Example 3 and Example 1 is only that:

[0094] Anhydrous copper acetate is not added.

[0095] Experimental verification

[0096] The catalysts prepared in Examples 1-9 and Comparative Examples 1-3 were applied to the reaction of preparing aromatics from biomass syngas; the experimental process was as follows:

[0097] Weigh 1.0 g of the catalyst and load it into a fixed-bed reactor. In situ reduction was carried out under hydrogen at 400 °C and normal pressure for 6 h. Then, the pressure of the reactor was increased to 4.0 MPa, the reaction temperature was 360 °C, and the gas hourly space velocity was 2500 h -1The reaction is carried out under the condition that the ratio of (CO + CO 2 ) / H 2 in the biomass syngas used is 1:2, and the ratio of CO / CO 2 is 1:1. After the reaction is stabilized, the tail gas obtained from the reaction is collected with an air bag, and the liquid components are collected by cold trapping. Finally, qualitative and quantitative analysis is carried out using gas chromatography. The carbon balance is maintained above 92% before and after the reaction.

[0098] After 48 hours of stable reaction, the CO conversion rates, CO 2 conversion rates and the proportion of aromatics in the products of Examples 1-9 and Comparative Examples 1-2 are shown in Table 1 below:

[0099] Table 1 Reaction performance of different catalysts for the production of aromatics from biomass syngas

[0100]

[0101] Among them, C 5+ * represents C 5+ hydrocarbons without aromatics.

[0102] It can be seen from the test results in Table 1 that:

[0103] 1) Examples 1 and Comparative Examples 1-3 show that the simultaneous introduction of Cu and Zn promoters into the Fe-based oxide to form a Cu-Zn-Fe interface is beneficial to improving the competitive adsorption of CO and CO 2 on the Fe-based metal active sites and promoting the co-conversion of CO and CO 2 molecules.

[0104] 2) Examples 1-5 show that reducing the Cn / Zn promoter ratio can inhibit the formation of CH 4 by-products; while an appropriate Cu / Zn ratio can not only further improve the CO and CO 2 conversion rates on the catalyst, but also be beneficial to the formation of aromatics.

[0105] 3) Examples 2 and 6 show that an appropriate mass ratio of Fe-based oxide to zeolite molecular sieve in the catalyst can improve the selectivity of aromatics in the product.

[0106] 4) Examples 1 and 7 show that the HZSM-5 zeolite molecular sieve with the MFI topological structure is beneficial to promoting the conversion of CO molecules and the production of aromatics.

[0107] 5) Examples 1 and 8, 9 show that selecting appropriate types and ratios of promoters M1 and M2 (two of Cu, Zn, Ni, Co, Mn, Cr, Nb, Mo, Zr) can improve the conversion of the raw material gas and the selectivity of aromatics. Generally speaking, the catalyst provided by the present invention for directly producing aromatics from biomass syngas has CO and CO2 It has the characteristics of high co - conversion rate and excellent selectivity for aromatics. The catalyst preparation process is simple and has good industrial application prospects.

[0108] In the description of this specification, the descriptions referring to terms such as "one embodiment", "example", "specific example", etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0109] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art of this industry should understand that the present invention is not limited by the above - mentioned embodiments. The above - mentioned embodiments and the descriptions in the specification only illustrate the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed.

Claims

1. A catalyst for direct production of green aromatics from biomass synthesis gas, characterized in that: include: Zeolite molecular sieve and transition metal modified Fe-based oxide M1M2-FeOx; the mass proportion of M1M2-FeOx is 10-80%, and the mass proportion of zeolite molecular sieve is 20-90%; The M1 and M2 are transition metals.

2. The catalyst for direct production of green aromatics from biomass synthesis gas according to claim 1, characterized in that: M1 and M2 are selected from any two of Cu, Zn, Ni, Co, Mn, Cr, Nb, Mo, and Zr.

3. The catalyst for direct production of green aromatics from biomass synthesis gas according to claim 1, characterized in that: The molar ratio of M1, M2 to Fe element is 1:(0.001~0.4):(0.001~0.4).

4. The catalyst for direct production of green aromatics from biomass synthesis gas according to claim 1, characterized in that: The topological structure of the zeolite molecular sieve is one of MFI, FAU and TON.

5. The method for preparing a catalyst for direct production of green aromatics from biomass synthesis gas according to any one of claims 1 to 4, characterized in that: The following steps are involved: Adding iron salt to a mixed solution of water and ethylene glycol and stirring to dissolve, to obtain solution A; In solution A, ethylenediamine, polyvinyl pyrrolidone, anhydrous sodium acetate, and metal salts M1 and M2 are added in sequence, and stirred to dissolve to obtain solution B; Solution B is subjected to a hydrothermal reaction, and after cooling to room temperature, a solid is separated, and M1M2-FeOx is obtained after washing and drying; The M1M2-FeOx and the zeolite molecular sieve are formed and sieved separately, and then mixed to obtain a catalyst.

6. The method for preparing a catalyst for direct production of green aromatics from biomass synthesis gas according to claim 5, characterized in that: When preparing solution A, the volume ratio of water to ethylene glycol is between (0-5.8):

1.

7. The method for preparing a catalyst for direct production of green aromatics from biomass synthesis gas according to claim 5, characterized in that: When preparing solution B, the molar ratio of the iron salt, ethylenediamine, polyvinyl pyrrolidone, anhydrous sodium acetate, M1 and M2 metal salts is 1: (5-10): (0.01-0.08): (3-6): (0.001-0.4): (0.001-0.4).

8. The method for preparing a catalyst for direct production of green aromatics from biomass synthesis gas according to claim 5, characterized in that: The iron salt is one or more of ferric chloride, ferric nitrate, ferric sulfate, ferric acetate, and ferric acetylacetonate; the metal salts M1 and M2 are one of chloride, nitrate, and acetate.

9. Use of the catalyst for direct production of green aromatics from biomass synthesis gas as claimed in any one of claims 1 to 4 in the preparation of aromatics.

10. The use according to claim 9, characterized in that: The process of preparing aromatics includes: The catalyst is loaded into a fixed bed reactor, hydrogen is introduced at normal pressure to reduce the reactor in situ at 350-500°C for 4-12h, and then the biomass synthesis gas is switched to increase the pressure to 2.0-6.0MPa. The reaction temperature is 280-400°C and the gas volume space velocity is 500-10000h -1 Under the conditions of , green aromatics can be directly prepared from biomass syngas; The biomass synthesis gas is a mixture of CO, CO2 and H2; the molar ratio of CO / CO2 in the biomass synthesis gas is (1:10)-(10:1), and the molar ratio of (CO+CO2) / H2 is (2:1)-(1:3).

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