A composite mesoporous molecular sieve catalyst and its application in the preparation of arabinose

Abstract

The present invention belongs to the technical field of catalyst synthesis, and specifically relates to a composite mesoporous molecular sieve catalyst and its application in the preparation of arabinose. The catalyst of the present invention uses mesoporous molecular sieve SBA-15 as a carrier and metal oxides such as tin, aluminum, cobalt, and cerium as active ingredients, and can be used to catalyze the hydrolysis reaction of crop straw, residues, etc. x O y / SBA‑15 catalyst not only has the advantages of solid acid and the acidity characteristics of Lewis acid, but also does not contain SO4 2‑ ions, has excellent catalytic performance, and can be recycled for multiple times. The mesoporous molecular sieve SBA-15 is prepared by the following steps: 1) mixing the template with tetraethyl orthosilicate and hydrochloric acid to obtain a reactant; 2) reacting the reactant for 12-24 hours to obtain a solid product, washing, drying, and roasting to obtain the mesoporous molecular sieve SBA-15. The catalyst prepared by the present invention is used in the catalytic hydrolysis reaction of corn husks, and arabinose can be directly obtained, with a high yield of the target product and good application prospects.

Description

Technical Field

[0001] The invention belongs to the technical field of catalyst synthesis, and in particular relates to a composite mesoporous molecular sieve catalyst and an application thereof in the preparation of arabinose. Background Art

[0002] In its natural state, arabinose usually exists in cellulose, hemicellulose, resin, and gum arabic in a chemical state. The arabinose content in different plant tissues is different. Plants with higher arabinose content include corn husk, beet pulp, wheat bran, and larch wood. Common extraction methods include acid and alkaline hydrolysis, microbial enzymatic hydrolysis, and microbial impurity removal.

[0003] The hydrolysis method mainly uses acid or alkali to degrade polysaccharides containing arabinose in plant tissues and release them in the form of monosaccharides (arabinose). The main principle is that by hydrolyzing cellulose and hemicellulose, a hydrolyzate containing arabinose and other monosaccharide components can be obtained, and then after separation and purification, high-purity arabinose can be obtained. However, this method requires chromatography separation, which is difficult to separate, requires high equipment investment, has low industrial feasibility, and waste pollutes the environment. At the same time, the acid hydrolysis method has difficulties in treating the "three wastes", and the catalyst contains SO 4 2- It causes serious environmental pollution; the degradation efficiency of alkaline hydrolysis is not high.

[0004] The microbial enzymatic hydrolysis method is to mix the sediments such as filter dregs with water and enzymes at 40-80°C for 3-24 hours, filtrate them, and refine them by activated carbon and ion exchange, and then evaporate and concentrate them to make arabinose crystals. In the enzymatic hydrolysis reaction, the yield of arabinose can be increased by mixing two or more enzymes with different activities, that is, arabinose, arabino-xylan, arabinogalactan decomposing enzymes and pectinase are used to obtain arabinose with high yield. In addition, impregnation enzymes that can destroy plant cells can be added to the reaction to increase the yield of arabinose.

[0005] The essence of the microbial impurity removal method is to use certain microorganisms to degrade monosaccharides such as xylose and glucose in the hemicellulose hydrolysate, but not to absorb arabinose, thereby reducing the content of impurities in the hydrolysate and simplifying the purification process. The purification method using microbial fermentation to remove impurities can improve the subsequent separation of arabinose.

[0006] Although microbial and enzyme methods can simplify production processes and reduce production costs, as well as reduce the discharge of acid, alkali and salt-containing waste liquids and reduce environmental pollution, representing the direction of green chemistry, these two methods also have certain problems. The price of enzymes is relatively high, and the catalytic efficiency of existing enzymes is relatively low.

[0007] In addition to the above methods, K Toeda et al. invented a method for extracting arabinose from rice hull and beet pulp using high pressure steam. The use of high pressure steam can release arabinose from crop residues, and the addition of phosphoric acid solution to the high pressure steam can increase the yield of L-arabinose (Toeda K, Kawabata Y. Production of arabinose from corn hull and beet pulp by high pressure steaming [J]. Nippon Shokuhin Kogyo Gakkaishi, 2002, 49 (8): 551-554.). However, this method has high requirements on equipment and is not easy to implement.

[0008] In view of the problems existing in the existing process, the present invention uses mesoporous molecular sieve SBA-15 as a carrier and metal oxides such as aluminum, tin, cobalt, cerium, etc. as active ingredients to obtain a catalyst, which is used to catalyze the hydrolysis of crop straw, residues, etc. to prepare arabinose, and by adjusting the catalyst components, it is expected to achieve a significant improvement in catalytic activity and reaction efficiency. Summary of the invention

[0009] The purpose of the present invention is to provide a composite SnO with mesoporous molecular sieve SBA-15 as carrier and metal oxides such as tin, aluminum, cobalt, cerium, etc. as active ingredients. 2 -M x O y / SBA-15 catalyst can be used to catalyze the hydrolysis reaction of crop straw, residues, etc. 2 -M x O y / SBA-15 catalyst not only has the advantages of solid acid and the acidity characteristics of Lewis acid, but also does not contain SO 4 2- Ions have excellent catalytic properties and can be used repeatedly.

[0010] The present invention also provides a method for preparing the above catalyst, using an impregnation method to prepare SnO 2 -Al 2 O 3 / SBA-15、SnO 2 -Co 3 O 4 / SBA-15 and SnO 2 -CeO 2 / SBA-15 three two-component composite catalysts, and explored the effects of catalysts with different active components on the hydrolysis of crop residues to produce arabinose.

[0011] The present invention also provides the use of the catalyst in preparing arabinose by hydrolyzing crop straws, residues and the like.

[0012] Based on the above purpose, the present invention adopts the following technical solutions:

[0013] A composite SnO 2 -M x O y / Mesoporous molecular sieve catalyst, with metal tin and metal M as main active ingredients and mesoporous molecular sieve as carrier.

[0014] Specifically, the mesoporous molecular sieve is SBA-15 or MCM-41.

[0015] Specifically, the metal M is aluminum, cobalt or cerium.

[0016] Specifically, the mesoporous molecular sieve SBA-15 is prepared by the following steps:

[0017] 1) Dissolve the template in water, then add tetraethyl orthosilicate and hydrochloric acid, stir and mix, and react at a temperature of 35-40° C. for 12-24 hours to obtain a reactant;

[0018] 2) The reactants are reacted at 100-120° C. for 12-24 hours to obtain a solid product, which is then washed, dried, and calcined to remove the template agent or the template agent is washed away by solvent reflux to obtain the mesoporous molecular sieve SBA-15.

[0019] Specifically, the template in step 1) is a triblock surfactant P123 (polyoxyethylene-polyoxypropylene-polyoxyethylene).

[0020] Specifically, in the reaction process of step 1), hydrochloric acid is calculated as HCl, and the molar ratio of each raw material is: tetraethyl orthosilicate: template: HCl: H 2 O=1: (0.01-0.02): (5-6): (130-140).

[0021] Furthermore, the present invention also provides a method for preparing a catalyst for catalyzing the hydrolysis of crop residues to produce arabinose, comprising the following steps:

[0022] a. Preparation of SnCl 4 aqueous solution, and add metal oxide for ultrasonic treatment for 1 to 2 hours, the ultrasonic temperature is 20 to 50°C, and then the impregnation treatment is carried out for 12 to 24 hours to obtain an impregnation solution, and then solid-liquid separation is performed to obtain a solid mixture;

[0023] b. Add the mesoporous molecular sieve and the solid mixture of step a into a soluble metal salt solution, mix thoroughly, and obtain a solid product by atmospheric distillation and concentration, and then dry, roast, wash, dry, and grind to finally obtain a catalyst.

[0024] Specifically, the SnCl 4 The mass fraction of the aqueous solution is 1.0 to 10%, preferably 4 to 6%.

[0025] Specifically, the metal oxide is Al 2 O 3 、Co 3 O 4 and CeO 2 One or more of, preferably Co 3 O 4 .

[0026] Specifically, the amount of the metal oxide added in step a is, based on the molar ratio of Sn to the metal element M in the metal oxide, Sn:M=(0.1-0.3):1, preferably 0.2:1, and M is Al, Co or Ce.

[0027] Specifically, the soluble metal salt solution in step b is one or more of aluminum nitrate solution, aluminum chloride solution, cobalt nitrate solution, cobalt chloride solution, cerium nitrate solution and cerium chloride solution, preferably aluminum nitrate solution; the concentration (mass fraction) of the soluble metal salt solution is 2-3%, preferably 2.5%.

[0028] Specifically, in step b, the mass ratio of the mesoporous molecular sieve, the solid mixture and the soluble metal salt solution is 1:(0.01-0.3):(2.0-10.0).

[0029] Specifically, the mesoporous molecular sieve in step b is SBA-15 or MCM-41.

[0030] Further preferably, the present invention also provides a composite SnO 2 -M x O y / A method for preparing an SBA-15 catalyst, wherein the catalyst is used for catalyzing the hydrolysis of crop residues to produce arabinose, and the preparation method comprises the following steps:

[0031] (1) Preparation of mesoporous molecular sieve SBA-15 carrier:

[0032] Dissolve the template in water, then add tetraethyl orthosilicate and hydrochloric acid, stir and mix, and react at a temperature of 35-40° C. for 12-24 hours to obtain a reactant;

[0033] The reactants are then reacted at 100-120°C for 12-24h to obtain a solid product, which is then washed and dried at 80-100°C for 12-24h, and finally calcined at 500-600°C for 2-5h to remove the template or the template is washed away by solvent reflux to obtain a mesoporous molecular sieve SBA-15 carrier;

[0034] (2) Preparation of catalyst:

[0035] a. Preparation of SnCl 4 The aqueous solution is added with metal oxide and ultrasonically treated for 1-2 hours at a temperature of 20-50°C. The impregnation treatment is performed for 12-24 hours to obtain an impregnation solution, and then solid-liquid separation is performed to obtain a SnCl 4 A solid mixture;

[0036] b. Mesoporous molecular sieve SBA-15, containing SnCl 4 The solid mixture is added to a soluble metal salt solution, mixed thoroughly, and distilled and concentrated under normal pressure to obtain a concentrated product. The concentrated product is dried at 100-110°C for 8-12 hours, then roasted at 200-300°C for 30-35 hours, cooled to room temperature, washed, dried, and ground to finally obtain SnO 2 -M x O y / SBA-15 catalyst.

[0037] Specifically, the template in step (1) is a triblock surfactant P123 (polyoxyethylene-polyoxypropylene-polyoxyethylene).

[0038] Specifically, in step (1), hydrochloric acid is calculated as HCl, and the molar ratio of each raw material is: tetraethyl orthosilicate: template: HCl: H 2 O=1: (0.01-0.02): (5-6): (130-140).

[0039] Specifically, the molar ratio of metal elements in the catalyst obtained in step (2) is Sn:M=(0.1-0.2):1, and M is one of Al, Co or Ce, preferably Al.

[0040] Specifically, in step (2), SnCl 4 The aqueous solution concentration is 1.0-10%, preferably 4-6%; the metal oxide is Al 2 O 3 、Co 3 O 4 and CeO 2 One or more of, preferably Co 3 O 4 .

[0041] Specifically, the soluble metal salt solution in step (2) is one or more of aluminum nitrate solution, aluminum chloride solution, cobalt nitrate solution, cobalt chloride solution, cerium nitrate solution and cerium chloride solution, preferably cobalt nitrate solution; the concentration (mass fraction) of the soluble metal salt solution is 2-3%, preferably 2.5%.

[0042] Specifically, in step (2), the mass ratio of the mesoporous molecular sieve SBA-15, the solid mixture and the soluble metal salt solution is 1: (0.01-0.3): (2.0-10.0).

[0043] Furthermore, the present invention also provides the use of the catalyst in catalyzing the hydrolysis of crop residues to produce arabinose.

[0044] Further preferably, the present invention also provides a method for preparing arabinose by hydrolyzing crop residues using the catalyst, which specifically comprises the following steps:

[0045] (1) Drying and crushing the crop residues, taking the crushed product with a mesh size of 20 to 80, mixing it with a catalyst, dispersing it in water, and reacting it at a temperature of 160 to 200° C. for 160 to 220 minutes at a reaction pressure of 0.7 to 1.6 MPa;

[0046] (2) After the reaction, cool with water for 1-2 hours, and then filter to obtain the degradation liquid and waste residue.

[0047] Specifically, the crop residues are corn husks or corn stalks.

[0048] Specifically, the amount of catalyst added is 10-50% of the amount of the crop residue, preferably 15-30%; the amount of water added is 1-50 times the amount of the residue.

[0049] Specifically, after the reaction, high performance liquid chromatography-evaporative light scattering detection (HPLC-ELSD) is used to determine the sugar components and contents in the degradation solution after the reaction.

[0050] Compared with the prior art, the present invention has the following advantages:

[0051] 1. The present invention provides a composite SnO with mesoporous molecular sieve SBA-15 as carrier and metal oxides such as tin, aluminum, cobalt, cerium, etc. as active ingredients. 2 -M x O y / SBA-15 catalyst can be used to catalyze the hydrolysis reaction of crop straw, residues, etc. 2 -M x O y / SBA-15 catalyst not only has the advantages of solid acid and the acidity characteristics of Lewis acid, but also does not contain SO 4 2- Ions have excellent catalytic properties and can be recycled many times. After deactivation, they can be regenerated and used again. The process is green and environmentally friendly.

[0052] 2. The catalyst prepared by the present invention is used in catalyzing the hydrolysis reaction of corn husks to directly produce arabinose with a high yield of the target product and has good application prospects. DETAILED DESCRIPTION

[0053] In order to make the technical purpose, technical scheme and beneficial effects of the present invention clearer, the technical scheme of the present invention is further described below in conjunction with specific embodiments, but the embodiments are intended to explain the present invention and cannot be understood as limiting the present invention. If no specific technology or conditions are specified in the embodiments, the technology or conditions described in the literature in the field or the product instructions are used. The raw materials used in the present invention are all common commercial products or can be prepared using conventional techniques in the field.

[0054] Example 1

[0055] Embodiment 1 provides a SnO 2 -Al 2 O 3 / The preparation method of SBA-15 catalyst, the specific steps are as follows:

[0056] (1) Preparation of mesoporous molecular sieve SBA-15 carrier:

[0057] The triblock surfactant P123 (polyoxyethylene-polyoxypropylene-polyoxyethylene, P123 is a common template for preparing SBA-15) is dissolved in deionized water as a template, and then tetraethyl orthosilicate (TEOS) and 38% (mass fraction) hydrochloric acid are added, and the reaction is continued at a temperature of 40° C. with continuous and vigorous stirring for 24 hours to obtain a reactant;

[0058] The reactants were transferred into a high-pressure hydrothermal reactor lined with polytetrafluoroethylene, and crystallized at 100°C for 24 hours to obtain a solid product. After being fully washed, the solid product was dried at 100°C for 24 hours, and finally calcined at 550°C for 5 hours to remove the template (P123), thereby obtaining a mesoporous molecular sieve SBA-15 carrier.

[0059] In step (1), hydrochloric acid is calculated as HCl, and the molar ratio of each raw material is: TEOS: P123: HCl: H 2 O=1:0.017:5.88:136.

[0060] (2) Preparation of catalyst:

[0061] a. Take a certain amount of SnCl 4 ·5H 2 O is dissolved in water to obtain a solution a with a mass fraction of 5%, wherein the total mass of solution a is 76 g;

[0062] b. Add 2.17 g of active A1 to solution a. 2O 3 (purchased from Shandong Aowei New Material Technology Co., Ltd.), ultrasonically treated at 20-50°C for 1 h, and then immersed for 24 h to obtain solution b;

[0063] c. Centrifuge solution b to separate solid and liquid to obtain solid, which is SnCl 4 and Al 2 O 3 The mixture is set aside;

[0064] d. 20g mesoporous molecular sieve SBA-15, 5g SnCl 4 and Al 2 O 3 The impregnated mixture was added to 100 g of aluminum nitrate solution (the mass fraction of aluminum nitrate was 2.5%), mixed thoroughly, and then distilled and concentrated under normal pressure to obtain a mixture c;

[0065] The mixture c was heated to 100°C for drying for 12 h, then calcined at 200°C for 35 h, cooled to room temperature, washed, dried, and ground to obtain SnO 2 -Al 2 O 3 / SBA-15 catalyst.

[0066] The molar ratio of metal elements in the solid catalyst obtained in step (2) is Sn:M(Al)=0.2:1.

[0067] Example 2

[0068] Embodiment 2 provides a SnO 2 -Co 3 O 4 / Preparation method of SBA-15 catalyst, the difference between Example 2 and Example 1 is that A1 2 O 3 Replaced with Co 3 O 4 , replace aluminum nitrate with cobalt nitrate solution, and finally obtain SnO 2 -Co 3 O 4 / SBA-15 catalyst.

[0069] Example 3

[0070] Embodiment 3 provides a SnO 2 -CeO 2 / Preparation method of SBA-15 catalyst, the difference between Example 3 and Example 1 is that A1 2 O 3 Replaced by CeO 2 , replace aluminum nitrate with cerium nitrate solution, and finally obtain SnO2 -CeO 2 / SBA-15 catalyst.

[0071] Test Example 1

[0072] (I) Experimental Example 1: Crop residue (corn husk) was used as the reaction raw material. The pretreatment of the reaction raw material was as follows: the corn husk was dried and crushed, and the 20-80 mesh corn husk crushed material was taken as the experimental raw material for standby. The cellulose content of corn husk was 16.40%, and the hemicellulose content was 47.68% (see the literature "Wang Yabo, Liu Zhanying, Lan Hui, Li Yongli, Liu Yanxin. Preparation of bacterial protein feed by yeast fermentation of corn husk [J]. China Feed, 2017 (04): 31-33+37. DOI: 10.15906 / j.cnki.cn11-2975 / s.20170408.").

[0073] (II) Catalytic hydrolysis of crop residues (corn husks) to produce arabinose

[0074] After multiple tests and comparisons, the inventors obtained the optimal reaction conditions for hydrolyzing corn husk to produce arabinose. The specific method steps are as follows:

[0075] (1) Accurately weigh 5.0 g of crushed corn husk, 0.5 g of catalyst and 120 mL of distilled water; mix them evenly in a beaker, transfer them to a polytetrafluoroethylene tank, place them in a high-pressure tank, and then place them in an oven at 160° C. for 160 min, with a reaction pressure of about 0.7 MPa;

[0076] (2) After the reaction, the high-pressure tank was taken out, cooled with running water for 1 hour, and then filtered to obtain the degradation liquid and waste residue.

[0077] (3) The sugar components and contents in the degradation solution after the reaction were determined by high performance liquid chromatography-evaporative light scattering detection (HPLC-ELSD). A Waters Amide column (4.6×250 mm 3.5 μm) was used for separation, with 1% ammonia water and acetonitrile as the mobile phase (i.e., the volume ratio of ammonia water to acetonitrile was 1:99), and an evaporative light scattering detector was used for detection.

[0078] During the reaction, the experimental group 1 was set to use the prepared SnO 2 -Al 2 O 3 / SBA-15 catalyst is used to extract arabinose after raw material hydrolysis;

[0079] Experimental group 2 was prepared using SnO 2 -Co 3 O 4 / SBA-15 catalyst is used to extract arabinose after raw material hydrolysis;

[0080] Experimental group 3 was prepared using SnO 2 -CeO 2 / SBA-15 catalyst is used to extract arabinose after raw material hydrolysis;

[0081] A blank control group was set up, in which SnCl 4 and Al 2 O 3 The mixture is directly added to the raw material for reaction without loading treatment.

[0082] (III) Calculation of results

[0083] 1. Arabinose yield:

[0084]

[0085] 2. Corn husk conversion rate:

[0086]

[0087] The conversion rate of the raw material and the yield of arabinose in the reaction product were determined according to the above two formulas. The specific results are shown in Table 1.

[0088] Table 1 Comparison of catalytic effects of different catalysts

[0089]

[0090] As shown in Table 1 above, by comparing the blank control group with Example 1, the composite SnO 2 -M x O y / SBA-15 catalyst can improve the yield of arabinose; compared with Examples 1-3, SnO 2 -Co 3 O 4 / SBA-15 catalyst has better catalytic performance.

[0091] Test Example 2

[0092] Experimental Example 2 Based on Experimental Example 1, SnO 2 -Co 3 O 4 The inventors have found that as the molar ratio of Sn / Co increases, the surface area and acid density of the corresponding catalyst also increase. When the molar ratio of Sn / Co is 0.2, SnO 2 -Co 3 O 4 / SBA-15 has a larger specific surface area and stronger acid density. As the Sn / Co element molar ratio is greater than 0.2, although the specific surface area of ​​the catalyst gradually increases, the corresponding acid density gradually decreases.

[0093] In Experimental Example 2, the method of Part (II) of Experimental Example 1 was used to catalyze the hydrolysis of crop residues (corn husks) to prepare arabinose. The difference was that in step (1), the mass / volume ratio of corn husks to water was 1:24 (5 g / 120 mL), the amount of catalyst was 0.2 g, the reaction temperature was 180° C., and the reaction time was 170 min.

[0094] The results were measured and calculated using the method in Part (III) of Experimental Example 1. The arabinose yield was 35.8% and the corn bran conversion rate was 93.5%.

[0095] In summary, by optimizing the loading amount in the catalyst and the reaction conditions for catalytic degradation of crop residues (corn husks), both the arabinose yield and the corn husk raw material conversion rate can be improved.

[0096] Test Example 3

[0097] Experimental Example 3 Based on Experimental Example 1, SnO 2 -Co 3 O 4 The service life of SBA-15 catalyst is further studied.

[0098] The specific operation is as follows: based on the method of Experimental Example 1, a continuous reaction method is adopted. After the first reaction, 10% (mass percentage) of the initial catalyst amount is added to make up for the catalyst loss during the separation process such as filtration. 2 -Co 3 O 4 / SBA-15 catalyst was applied, and the changes in the yield of each product after multiple applications were tested. The specific reaction conditions and substrate dosage were the same as those in Experimental Example 1. The test results are shown in Table 2.

[0099] Table 2

[0100]

[0101] From the above data, it can be seen that the catalyst was seriously deactivated after being used for 5 times. The main reason for the deactivation was that humus coated the catalyst surface and pores.

[0102] The deactivated catalyst was re-calcined by the calcination method in Example 1 to achieve regeneration, and then the above method was continued to be applied, and the changes in the yield of each product after multiple applications were tested. The specific reaction conditions and substrate dosage were the same as those in Experimental Example 1. The test results are shown in Table 3.

[0103] Table 3

[0104]

[0105]

[0106] It can be seen from the results in Table 3 that the catalyst can recover most of its activity after calcination and regeneration, and can still be reused.

[0107] The above content is a detailed description of the present invention in combination with specific implementation cases, and it cannot be determined that the content of the present invention is limited to the above description. For ordinary technicians in the technical field to which the present invention belongs, all related deductions and substitutions made without departing from the concept of the present invention should be regarded as the protection scope of the present invention.

Claims

1. A composite SnO2-M x O y / Application of mesoporous molecular sieve catalyst in catalyzing hydrolysis of crop residues to produce arabinose, characterized in that: The specific steps for application are as follows: 1) After drying and crushing the crop residues, take the 20-80 mesh crushed material and mix it with the catalyst and disperse it in water, react at 160-200℃ for 160-220min, and the reaction pressure is 0.7-1.6MPa; 2) After the reaction, cool with water for 1-2 hours, and then filter to obtain the degradation liquid and waste residue; The catalyst has metal tin and metal M as main active ingredients and a mesoporous molecular sieve as a carrier; the mesoporous molecular sieve is SBA-15; the metal M is aluminum, cobalt or cerium; The catalyst is prepared by the following steps: (1) Preparation of mesoporous molecular sieve SBA-15 carrier: Dissolve the template in water, then add tetraethyl orthosilicate and hydrochloric acid, stir and mix, and react at a temperature of 35-40° C. for 12-24 hours to obtain a reactant; The reactants are then reacted at 100-120°C for 12-24h to obtain a solid product, which is then washed and dried at 80-100°C for 12-24h, and finally calcined at 500-600°C for 2-5h to remove the template or the template is washed away by solvent reflux to obtain a mesoporous molecular sieve SBA-15 carrier; (2) Preparation of catalyst: a. Prepare a SnCl4 aqueous solution, add a metal oxide and perform ultrasonic treatment for 1-2 hours at a temperature of 20-50°C, perform an impregnation treatment for 12-24 hours to obtain an impregnation solution, and then perform solid-liquid separation to obtain a solid mixture containing SnCl4; b. Add the mesoporous molecular sieve SBA-15 and the solid mixture containing SnCl4 into the soluble metal salt solution, mix them thoroughly, and distill and concentrate them under normal pressure to obtain a concentrated product. The concentrated product is dried at 100-110°C for 8-12h, then calcined at 200-300°C for 30-35h, cooled to room temperature, washed, dried, and ground to finally obtain SnO2-M x O y / SBA-15 catalyst; The template agent in step (1) is a polyoxyethylene-polyoxypropylene-polyoxyethylene triblock surfactant; During the reaction of step (1), hydrochloric acid is calculated as HCl, and the molar ratio of each raw material is: tetraethyl orthosilicate: template: HCl: H2O=1: (0.01-0.02): (5-6): (130-140); The amount of the metal oxide added in step a is, based on the molar ratio of Sn to the metal element M in the metal oxide, Sn:M=(0.1-0.3):1; the metal oxide is one of Al2O3, Co3O4 and CeO2; the metal element in the soluble metal salt is the same as the metal element in the metal oxide; In step b, the mass ratio of the mesoporous molecular sieve SBA-15, the solid mixture and the soluble metal salt solution is 1: (0.01-0.3): (2.0-10.0).

2. The use according to claim 1, characterized in that: The crop residues are corn husks or corn stalks; the amount of catalyst added is 10 to 50% of the amount of the crop residues; and the amount of water added is 1 to 50 times the amount of the residues.

3. The use according to claim 1, characterized in that: The mass fraction of the SnCl4 aqueous solution in step a is 1.0-10%.

4. The use according to claim 1, characterized in that: The soluble metal salt solution in step b is one of aluminum nitrate solution, aluminum chloride solution, cobalt nitrate solution, cobalt chloride solution, cerium nitrate solution and cerium chloride solution.

5. The use according to claim 1, characterized in that: The molar ratio of metal elements in the catalyst obtained in step (2) is Sn:M=(0.1-0.2):1, and M is one of Al, Co or Ce.

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