阅读说明：本技术 分子筛催化剂及其制备方法和纤维素催化加氢生产生物乙醇的方法 (Molecular sieve catalyst, preparation method thereof and method for producing bioethanol by cellulose catalytic hydrogenation ) 是由 岑友良 王宝石 黄新龙 班新海 户勇 陈卫东 马天军 于 2021-01-05 设计创作，主要内容包括：本发明涉及生物乙醇制备技术领域,具体而言,涉及分子筛催化剂及其制备方法和纤维素催化加氢生产生物乙醇的方法。分子筛催化剂包括W掺杂的介孔硅基分子筛和负载于所述W掺杂的介孔硅基分子筛的具有加氢活性的金属。该分子筛催化剂的组成成分简单,能够高效催化纤维素水解加氢制备生物乙醇,且催化条件温和,易于实现。(The invention relates to the technical field of bioethanol preparation, in particular to a molecular sieve catalyst and a preparation method thereof, and a method for producing bioethanol by catalytic hydrogenation of cellulose. The molecular sieve catalyst comprises a W-doped mesoporous silicon-based molecular sieve and metal with hydrogenation activity loaded on the W-doped mesoporous silicon-based molecular sieve. The molecular sieve catalyst has simple components, can efficiently catalyze cellulose hydrolysis hydrogenation to prepare bioethanol, has mild catalysis conditions, and is easy to realize.)

1. A molecular sieve catalyst is characterized by comprising a W-doped mesoporous silicon-based molecular sieve and a metal with hydrogenation activity loaded on the W-doped mesoporous silicon-based molecular sieve.

2. The molecular sieve catalyst of claim 1, wherein the metal comprises at least one of Ru, Pd, Pt, Co, Cu, Fe, and Ni; preferably Pt.

3. The molecular sieve catalyst according to claim 1, characterized in that the metal loading is 2-3%, preferably 2%.

4. The molecular sieve catalyst according to any one of claims 1 to 3, wherein the W-doped mesoporous silicon-based molecular sieve is a molecular sieve having a Si/W molar ratio of more than 10;

preferably, the W-doped mesoporous silicon-based molecular sieve comprises any one of W-SBA-15, W-MCM-22, W-MCM-41, W-MCM-48, W-MCM-50, W-SBA-2, W-SBA-3, W-SBA-16, W-HMS, W-KIT-1 and W-KIT-6;

preferably, the content of W in the W-doped mesoporous silicon-based molecular sieve is 1-4.6%.

5. The molecular sieve catalyst of claim 4, wherein the molecular sieve catalyst has a Pt loading of 1-3%;

preferably, the molecular sieve catalyst comprises any one of W-SBA-15 loaded with 3% Pt, W-MCM-41 loaded with 2% Pt, and W-MCM-41 loaded with 1% Pt and 1% Cu.

6. The method of making a molecular sieve catalyst of any of claims 1 to 5, comprising: and loading the metal with hydrogenation activity on the W-doped mesoporous silicon-based molecular sieve.

7. The production method according to claim 6, wherein the method of supporting comprises a dipping method or a deposition method;

preferably, the step of loading comprises: enabling a metal raw material containing the metal to act on the W-doped mesoporous silicon-based molecular sieve so as to enable the metal to be loaded on the W-doped mesoporous silicon-based molecular sieve;

preferably, the metal raw material is a metal salt, preferably at least one of chloride, nitrate and sulfate;

preferably, the preparation step of the W-doped mesoporous silicon-based molecular sieve comprises: mixing a W-containing raw material with a silicon-containing raw material for forming the mesoporous silicon-based molecular sieve, aging, and then roasting to form the W-doped mesoporous silicon-based molecular sieve.

8. A method for producing bioethanol by catalytic hydrogenation of cellulose is characterized by comprising the following steps: the use of the molecular sieve catalyst of any of claims 1-5 to catalyze the production of bioethanol from cellulose.

9. The method for producing bioethanol by catalytic hydrogenation of cellulose according to claim 8, comprising: mixing the molecular sieve catalyst and the cellulose, and adding hydrogen to carry out hydrogenation reaction;

preferably, the cellulose is lignocellulose.

10. The method for producing bioethanol by catalytic hydrogenation of cellulose according to claim 9, wherein the reaction process conditions are as follows: the reaction time is 1-8h, the reaction temperature is 180-230 ℃, the hydrogen pressure in the reaction system is 2-8MPa, and the mass ratio of the molecular sieve catalyst to the cellulose is as follows: 0.01-0.5: 1;

preferably, the reaction temperature is 200-: 0.1-0.3:1.

Technical Field

The invention relates to the technical field of bioethanol preparation, in particular to a molecular sieve catalyst and a preparation method thereof, and a method for producing bioethanol by catalytic hydrogenation of cellulose.

Background

Bioethanol is a high-quality renewable clean energy source, can be added into gasoline fuel to replace part of petroleum-based fuel, can reduce pollutant emission, and has been widely used internationally. At present, fuel ethanol is mainly prepared by fermenting sugar-containing grains as raw materials, but the dependence breaks the balance of grain supply and demand in the world. The method for producing fuel ethanol by using various lignocelluloses such as agricultural and forestry wastes with wide sources as raw materials has a very wide prospect, and is also a focus of research in the technical field of biochemical engineering in recent years.

At present, the main process for preparing ethanol from cellulose is a biological fermentation method, namely a technology for hydrolyzing cellulose to generate fermentable monosaccharide and further generating fuel ethanol through microbial fermentation, but the production period of the method is long, and the concentration of ethanol in the product is low. The method for preparing bioethanol by hydrolysis and hydrogenation by a chemical method from cellulose biomass is regarded as a novel utilization way for cellulose conversion, a large amount of hydroxyl groups of glucose units in cellulose are reserved in the conversion process, the atom economy in the whole process is high, and a strong industrial utilization prospect is shown. However, the components of the catalyst used in the process of preparing bioethanol by hydrolysis hydrogenation in the prior art are too complex (for example, CN 108623436 a), and include a first active component, a first auxiliary agent, a first carrier, a second active component, a second auxiliary agent, a second carrier, and the like; meanwhile, the reaction temperature needs to be controlled in a segmented manner in the reaction process, the final temperature is as high as 350 ℃, and the adverse factors limit the application of cellulose hydrolysis hydrogenation to prepare bioethanol.

In view of this, the invention is particularly proposed.

Disclosure of Invention

The invention aims to provide a molecular sieve catalyst, a preparation method thereof and a method for producing bioethanol by cellulose catalytic hydrogenation. The embodiment of the invention provides a novel molecular sieve catalyst which is simple in composition, can efficiently catalyze cellulose hydrolysis hydrogenation to prepare bioethanol, is mild in catalysis condition and is easy to implement.

The invention is realized by the following steps:

in a first aspect, the present invention provides a molecular sieve catalyst, which includes a W-doped mesoporous silicon-based molecular sieve and a metal having hydrogenation activity supported on the W-doped mesoporous silicon-based molecular sieve.

In alternative embodiments, the metal comprises at least one of Ru, Pd, Pt, Co, Cu, Fe, and Ni; preferably Pt.

In an alternative embodiment, the metal loading is 2-3%, preferably 2%. The loading represents the mass content of the metal in the molecular sieve catalyst.

In an alternative embodiment, the W-doped mesoporous silicon-based molecular sieve is a molecular sieve having a Si/W molar ratio greater than 10;

preferably, the W-doped mesoporous silicon-based molecular sieve comprises any one of W-SBA-15, W-MCM-22, W-MCM-41, W-MCM-48, W-MCM-50, W-SBA-2, W-SBA-3, W-SBA-16, W-HMS, W-KIT-1 and W-KIT-6;

preferably, the content of W in the W-doped mesoporous silicon-based molecular sieve is 1-4.6%.

In alternative embodiments, the molecular sieve catalyst has a Pt loading of 1-3%; for example, the molecular sieve catalyst includes any one of W-SBA-15Pt (noted as: 3% Pt/W-SBA-15) supporting 3% Pt, W-MCM-41 (noted as 2% Pt/W-MCM-41) supporting 2% Pt, and W-MCM-41 (noted as 1% Pt 1% Cu/W-MCM-41) supporting 1% Pt and 1% Cu.

In a second aspect, the present invention provides a method of making a molecular sieve catalyst as set forth in any preceding embodiment, comprising: and loading the metal with hydrogenation activity on the W-doped mesoporous silicon-based molecular sieve.

In alternative embodiments, the method of loading includes a dipping method or a deposition method;

preferably, the step of loading comprises: enabling a metal raw material containing the metal to act on the W-doped mesoporous silicon-based molecular sieve so as to enable the metal to be loaded on the W-doped mesoporous silicon-based molecular sieve;

preferably, the metal raw material is a metal salt, preferably at least one of chloride, nitrate and sulfate;

preferably, the preparation step of the W-doped mesoporous silicon-based molecular sieve comprises: mixing a W-containing raw material with a silicon-containing raw material for forming the mesoporous silicon-based molecular sieve, aging, and then roasting to form the W-doped mesoporous silicon-based molecular sieve.

In a third aspect, the present invention provides a method for producing bioethanol by catalytic hydrogenation of cellulose, comprising: catalyzing cellulose to produce bioethanol using the molecular sieve catalyst of any of the preceding embodiments.

In an alternative embodiment, the method comprises the following steps: mixing the molecular sieve catalyst and the cellulose, and adding hydrogen to carry out hydrogenation reaction;

preferably, the cellulose is lignocellulose.

In an alternative embodiment, the reaction process conditions are: the reaction time is 1-8h, the reaction temperature is 180-230 ℃, the hydrogen pressure in the reaction system is 2-8MPa, and the mass ratio of the molecular sieve catalyst to the cellulose is as follows: 0.01-0.5: 1;

preferably, the reaction temperature is 200-: 0.1-0.3:1.

The invention has the following beneficial effects: the embodiment of the invention provides a W-doped mesoporous silicon-based molecular sieve and takes the molecular sieve loaded with metal with hydrogenation activity as a catalyst, so that more catalytic active sites can be provided, the dosage and catalytic conditions of the catalyst are reduced, the catalytic efficiency is improved, and the yield of subsequent bioethanol is improved. Meanwhile, the mesoporous silicon-based molecular sieve provides a diffusion channel for reactant molecules and catalytic active sites, and the contact of the reactant and more catalytic active sites is realized, so that the catalytic efficiency is further improved. In addition, the W-doped mesoporous silicon-based molecular sieve is in close contact with two catalytic active sites of metal, so that the reaction rate is increased, and the yield of the bioethanol is further increased. And the molecular sieve catalyst has high hydrothermal stability, is convenient to recycle and can be repeatedly used.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.

The embodiment of the invention provides a molecular sieve catalyst, which comprises a W-doped mesoporous silicon-based molecular sieve and metal with hydrogenation activity loaded on the W-doped mesoporous silicon-based molecular sieve. The W-doped mesoporous silicon-based molecular sieve is matched with metal, so that the catalytic performance of a molecular sieve catalyst can be improved, the using amount of the catalyst is reduced, and the efficiency of the molecular sieve for catalyzing cellulose to produce bioethanol can be improved.

Specifically, the mesoporous structure in the W-doped mesoporous silicon-based molecular sieve can provide a diffusion channel for reactant molecules and catalytically active sites, so that the reactant is in contact with more catalytically active sites, and the reaction rate and efficiency are further improved. Meanwhile, the specific use of W for doping can further improve the performance of the molecular sieve catalyst, and if other elements are used for doping or mesoporous silicon base is replaced by other substances, the performance of the molecular sieve catalyst can be obviously reduced.

Further, the W-doped mesoporous silicon-based molecular sieve is a molecular sieve with the Si/W molar ratio of more than 10; specifically, the W-doped mesoporous silicon-based molecular sieve comprises any one of W-SBA-15, W-MCM-22, W-MCM-41, W-MCM-48, W-MCM-50, W-SBA-2, W-SBA-3, W-SBA-16, W-HMS, W-KIT-1 and W-KIT-6, and the content of W in the W-doped mesoporous silicon-based molecular sieve is 1-4.6%. The specific W-doped mesoporous silicon-based molecular sieve is adopted to further improve the performance of the molecular sieve catalyst.

Further, the metal includes at least one of Ru, Pd, Pt, Co, Cu, Fe, and Ni; preferably Pt. And the metal loading is 2-3%, preferably 2%. The adoption of the metal as a technology with hydrogenation activity and the loading capacity can be beneficial to ensuring the performance of the molecular sieve catalyst, so that the molecular sieve catalyst still has good catalytic performance even on the basis of the bottom consumption, and meanwhile, when the subsequent cellulose is catalyzed to produce the bioethanol, other catalysts do not need to be additionally adopted to promote the catalysis.

Specifically, the loading amount of Pt in the molecular sieve catalyst is 1-3%, that is, the mass content of Pt in the molecular sieve catalyst is 1-3%, but it is still ensured that the loading amount of the metal is 2-3%, that is, the loaded metal may be a simple metal, or a metal combination formed by a plurality of metals, such as a combination of Pt and Cu, and the like.

Further, the molecular sieve catalyst comprises any one of 3% Pt/W-SBA-15, 2% Pt/W-MCM-41 and 1% Pt 1% Cu/W-MCM-41. The yield of the bioethanol obtained by catalyzing cellulose by the molecular sieve catalyst is up to 90%.

The embodiment of the invention also provides a preparation method of the molecular sieve catalyst, which comprises the following steps: and loading the metal with hydrogenation activity on the W-doped mesoporous silicon-based molecular sieve.

Specifically, an impregnation method or a deposition method is adopted for loading, and the impregnation method or the deposition method is adopted to enable the W-doped mesoporous silicon-based molecular sieve and two catalytic active sites of metal to be in close contact, so that the reaction rate can be increased, and the yield of bioethanol can be increased.

It should be noted that the specific processes and operating conditions of the dipping method or the deposition method are conventional in the art, and the embodiments of the present invention will not be described in detail.

Specifically, the step of loading comprises: enabling a metal raw material containing the metal to act on the W-doped mesoporous silicon-based molecular sieve so as to enable the metal to be loaded on the W-doped mesoporous silicon-based molecular sieve;

preferably, the metal raw material is a metal salt, preferably at least one of chloride, nitrate and sulfate. In the preparation process of the molecular sieve catalyst, the metal is not in a metal state and is reduced in a hydrogen atmosphere or hydrogen with certain concentration before use.

The W doping in the W-doped mesoporous silicon-based molecular sieve is realized without adopting a deposition or impregnation method, but adopts a direct synthesis method to dope W, namely the W doping is realized while the mesoporous silicon-based molecular sieve is prepared, instead of performing the W doping after the mesoporous silicon-based molecular sieve is formed, the direct synthesis method can improve the dispersion degree of W in the mesoporous molecular sieve, and the molecular sieve catalyst provides more catalytic active sites, so that the catalytic performance of the molecular sieve catalyst is improved.

Specifically, a W-containing raw material and a silicon-containing raw material for forming the mesoporous silicon-based molecular sieve are mixed, aged and then roasted to form the W-doped mesoporous silicon-based molecular sieve. For example, taking W-SBA-15 as an example, P123 is dissolved in acid to form a solution A, raw materials containing W are dissolved in water to form a solution B, tetraethyl orthosilicate and the solution A are added into the solution B at the same time, then aging is carried out, and then the aged product is roasted to obtain W-SBA-15.

The embodiment of the invention also provides a method for producing bioethanol by catalytic hydrogenation of cellulose, which comprises the following steps: catalyzing cellulose to produce bioethanol using the molecular sieve catalyst of any of the preceding embodiments.

Specifically, after the molecular sieve catalyst and the cellulose are mixed, hydrogen is added for hydrogenation reaction; wherein the cellulose is lignocellulose. The lignocellulose has high cellulose content, can form a large amount of bioethanol, and improves the yield of the bioethanol.

Further, the reaction process conditions are as follows: the reaction time is 1-8h, the reaction temperature is 180-230 ℃, the hydrogen pressure in the reaction system is 2-8MPa, and the mass ratio of the molecular sieve catalyst to the cellulose is as follows: 0.01-0.5: 1; preferably, the reaction temperature is 200-: 0.1-0.3:1. The yield of the bioethanol can be further improved by adopting the reaction conditions.

The features and properties of the present invention are described in further detail below with reference to examples.

Example 1

This embodiment provides a method for preparing a W-doped mesoporous silica-based molecular sieve (W-SBA-15), including:

9.6g P123 was dissolved in 300mL of 2mol/L hydrochloric acid, and after P123 was completely dissolved, 20.4g of tetraethyl orthosilicate and 1.20g of Na were added dropwise₂WO₄Heating the aqueous solution in water bath at 40 ℃ for 24h to form milky white gel; and then transferring the gel into a stainless steel kettle with a polytetrafluoroethylene substrate, aging for 24h at 100 ℃, cooling, filtering, drying for 8h at 100 ℃, and roasting for 6h at 540 ℃ to obtain the W-SBA-15 molecular sieve, wherein the W content is 1.02%.

Example 2

This example provides a method for preparing a molecular sieve catalyst (3% Pt/W-SBA-15), which includes, for example, the following steps:

weighing 2.0g of the W-SBA-15 molecular sieve prepared in the example 1, adding 30mL of chloroplatinic acid solution, adding 0.6g of sodium borohydride for reduction, stirring for 2h, centrifugally separating out solids, and drying at 90 ℃ for 10h to obtain the 3% Pt/W-SBA-15 catalyst, wherein the mass fraction of Pt is 3%.

Example 3

This embodiment provides a method for preparing a W-doped mesoporous silica-based molecular sieve (W-MCM-41), comprising:

10.4g of ammonium tungstate was dissolved in 100mL of water to prepare solution A; 8.1g of cetylpyridinium bromide was mixed with 60mL of HCl (5mol/L) to form solution B. Then 14.8g of tetraethyl orthosilicate and solution A were added simultaneously to solution B, and after the resulting gel had been aged at 50 ℃ for 22 hours, the solid product was centrifuged, washed with distilled water and dried. Roasting for 4 hours at 600 ℃ in air atmosphere to obtain the MCM-41 molecular sieve with the W content of 4.6 percent.

Example 4

This example provides a method for preparing a molecular sieve catalyst (2% Pt/W-MCM-41), which is an example of an impregnation method, and comprises:

weighing 2g of dried W-MCM-41, adding 20mL of chloroplatinic acid solution, soaking at room temperature for 12h, drying in an oven at 80 ℃ for 10h, taking out, and roasting in a muffle furnace at 300 ℃ for 4h to obtain the 2% Pt/W-MCM-41 catalyst.

Example 5

The embodiment provides a method for producing bioethanol by catalytic hydrogenation of cellulose, which comprises the following steps:

0.2g of the 3% Pt/W-SBA-15 catalyst prepared in example 1, 2.0g of cellulose and 70mL of water were put in a 100mL autoclave, the autoclave was sealed, and then charged with H₂Replacing gas in the kettle for 3 times, and then adding H₂Pressurizing to 5 MPa. Starting stirring to 600rpm, heating the reaction kettle to 200 ℃ at a heating rate of 10 ℃/min, starting timing, and reacting for 2 hours. The yield of the product ethanol is 89.3%.

Example 6 example 23

Examples 6-23 each provide a process for the catalytic hydrogenation of cellulose to bioethanol, which process operates substantially identically to the process for the catalytic hydrogenation of cellulose to bioethanol provided in example 5, except for the temperature, pressure, time, mass ratio of molecular sieve catalyst to cellulose, and the molecular sieve catalyst used, as described in the following table:

the molecular sieve catalysts of examples 6 to 13 were prepared in the same manner as in example 2, and the molecular sieve catalysts of examples 14 to 23 were prepared in the same manner as in example 3, except that the metal salt was replaced with a metal salt of the corresponding metal.

Comparative example

The following comparative examples each provide a process for the catalytic hydrogenation of cellulose to bioethanol, which is substantially identical to the process for the catalytic hydrogenation of cellulose to bioethanol provided in example 5, except that the reaction temperature, pressure, time, mass ratio of molecular sieve catalyst to cellulose, and molecular sieve catalyst used are different, as shown in the following table:

wherein the preparation method of the molecular sieve is the same as that provided in embodiment 2 of the invention, wherein SiO is₂-A is commercial white carbon black, SiO₂B is the treated silica sol. From the above table, even if the reaction conditions of catalytic hydrogenation are all within the protection range of the embodiment of the present invention, the ethanol yield may be significantly different by using different catalysts. For example, the temperature, pressure and time of comparative examples 1 to 6 are within the ranges defined in the examples of the present invention, and are mainly different from the examples of the present invention in that the yield of ethanol produced by the catalysts is significantly reduced, particularly, in comparative examples 3 to 7, the content of metal in the catalysts is significantly higher than that of the examples of the present invention, but the yield of ethanol is significantly reduced, which further illustrates that the molecular sieve catalysts provided in the examples of the present invention can catalyze the production of bioethanol well, and improve the yield of bioethanol.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.