阅读说明：本技术 双金属氧化物催化剂及制备方法和应用 (Bimetallic oxide catalyst and preparation method and application thereof ) 是由 纪娜 李婷婷 刁新勇 王振娇 刘庆岭 宋春风 于 2019-09-12 设计创作，主要内容包括：本发明公开了一种双金属氧化物催化剂及制备方法和应用；催化剂结构为xSnO<Sub>2</Sub>-yMoO<Sub>3</Sub>,1≤x≤6,1≤y≤6；通过增加醇溶液加热处理方法合成不同比例双金属氧化物催化剂,用氨水调节含有活性组分Sn前体的可溶性盐溶液的pH,再加入含有金属Mo前体的可溶性盐,充分搅拌混匀后加入盐酸,加热后洗涤过滤再真空干燥得到白色产物,白色产物经过焙烧后变成墨绿色,研磨至粉末,通过醇溶液加热处理得到醇加热处理的xSnO<Sub>2</Sub>-yMoO<Sub>3</Sub>催化剂。催化剂有效增加催化剂表面的活性位点,进一步优化催化性能,为木质素高效转化利用提供了一种全新的方法。本发明催化剂具有原料廉价、反应过程绿色环境友好、催化剂制备简易等特点。(The invention discloses a bimetallic oxide catalyst and a preparation method and application thereof; the catalyst structure is xSnO 2 ‑yMoO 3 X is more than or equal to 1 and less than or equal to 6, and y is more than or equal to 1 and less than or equal to 6; synthesizing bimetallic oxide catalysts with different proportions by adding an alcoholic solution heating treatment method, adjusting the pH value of a soluble salt solution containing an active component Sn precursor by using ammonia water, adding a soluble salt containing a metal Mo precursor, fully stirring and uniformly mixing, adding hydrochloric acid, heating, washing, filtering, and drying in vacuum to obtain a white product, roasting the white product to obtain dark green, grinding the dark green into powder, and heating the alcoholic solution to obtain alcohol-heated xSnO 2 ‑yMoO 3 A catalyst. The catalyst effectively increases active sites on the surface of the catalyst, further optimizes the catalytic performance, and provides a brand new method for the efficient conversion and utilization of ligninThe method is carried out. The catalyst has the characteristics of cheap raw materials, green and environment-friendly reaction process, simple and easy preparation and the like.)

1. A bimetallic oxide catalyst for alcohol heating treatment has a structural formula of xSnO₂-yMoO₃Wherein x is more than or equal to 1 and less than or equal to 6, and y is more than or equal to 1 and less than or equal to 6.

2. A method for preparing the alcohol heat-treated double metal oxide catalyst according to claim 1, wherein the alcohol heat treatment is adopted, comprising the steps of:

a) preparing a soluble salt solution with the concentration of 0.033-0.200 mol/L and containing an active component Sn precursor, and adjusting the pH to 6-10 by using 25-28% by mass of ammonia water;

b) adding soluble salt with a corresponding concentration range of 0.033-0.200 mol/L of metal Mo precursor into the solution a) according to the proportion of 1/6-6/1 Sn/Mo, fully and uniformly mixing, adding hydrochloric acid, heating, washing, filtering and vacuum drying to obtain a white product;

c) calcining the white product obtained in claim b) in a muffle furnace to turn the calcined white product into blackish green, and grinding the blackish green white product into powder;

d) heating the powder-state dark green product in the step c) in an alcohol solution to obtain alcohol-heated xSnO₂-yMoO₃CatalysisAnd (3) preparing.

3. The method as set forth in claim 2, wherein the mass fraction of hydrochloric acid in b) is 36.0-38.0%, and the molar amount of hydrochloric acid added is 0.5-2 times (Sn + Mo); the heating condition is that the mixture is heated in an oven at the temperature of 30-100 ℃ for 0.5-2 h and then dried under the vacuum condition of 40-120 ℃ for 4-12 h.

4. The method as set forth in claim 2, wherein the calcination in c) is carried out at 100 ℃ to 500 ℃ for 2 hours to 10 hours and then at 300 ℃ to 800 ℃ for 5 hours to 10 hours at a temperature rise rate of 5 ℃/min.

5. The method as set forth in claim 2, wherein the alcohol solution selected in d) is one of methanol, absolute ethanol, n-propanol, isopropanol, n-butanol, or a mixture of several alcohols.

6. The method of claim 2, wherein the ratio of the mass of the catalyst to the mass of the alcohol solution is 1:20 to 1:60 g/mL.

7. The method as set forth in claim 2, wherein the blackish green powder product ground after the calcination in d) is heated in an alcohol solution at 60 ℃ to 120 ℃ for 4 hours to 12 hours.

8. The bimetallic oxide, xSnO, of claim 1₂-yMoO₃Application to hydrodeoxygenation in lignin model compounds.

9. The application of claim 8, which comprises the following steps:

a) fully mixing a lignin model compound, a catalyst, an internal standard substance and a reaction solvent, adding the mixture into a reaction kettle, replacing gas in the kettle with gas for three times before the reaction starts, and filling the pressure in the kettle to a target pressure of 2-7 MPa at normal temperature;

b) heating the reaction kettle to 250-300 ℃, wherein the stirring speed is 800-1200r/min, and the stirring time is 2-7 h;

c) after the reaction is finished, the temperature is reduced, the pressure is released, the kettle is opened, solid components in the kettle are filtered, and meanwhile, liquid products are obtained and used for gas chromatography analysis.

The reaction solvent in a) is one of n-pentane, n-hexane, n-heptane, decalin and methylcyclohexane, or the solvents are mixed in any proportion, the internal standard substance is n-dodecane, and the used gas is hydrogen.

10. The method as claimed in claim 8, wherein the concentration of the lignin model compound in the a) in the reaction solvent is 0.042-0.375 mol/L; the mass ratio of the lignin to the catalyst is 1: 1-10: 1.

Technical Field

The invention relates to the technical field of catalysts, in particular to a preparation method and application of a bimetallic oxide catalyst subjected to alcohol heating treatment; in particular to a preparation method of a brand-new bimetallic oxide catalyst and application thereof in a lignin model compound.

Background

Energy is the foundation of the survival and development of the current society and is also an important index for measuring the comprehensive national power and the living standard of people. With the development of economy and the increase of world population, the demand of human beings for energy is increasing, and in recent years, the burning of traditional fossil fuels causes not only the continuous exhaustion of non-renewable resources, but also serious environmental pollution. Therefore, the development of clean renewable energy becomes the research center of the majority of researchers, and among the renewable energy, biomass is considered as one of the fossil fuel substitutes which hopefully relieve the energy crisis, and has the characteristics of being renewable, low in cost, carbon neutral, high in productivity and the like.

The biomass is composed of cellulose, hemicellulose and lignin. The lignin accounts for about 15-30% of the biomass by weight and 40% by energy, is a three-dimensional amorphous polymer consisting of methoxy phenylpropane structures, is a compound which is formed by connecting a plurality of units with different benzene ring structures through C-C bonds and C-O bonds and has a three-dimensional high molecular structure, has a stable chemical structure, is easy to be polymerized into a macromolecular compound again in a degradation process, and is not widely used for industrial production due to the characteristics of complex structure and difficulty in being decomposed into small molecular structures.

In previous reports, lignin can be converted to phenolic compounds by hydrogenation, oxidation, hydrolysis, thermal, photochemical and electrochemical conversion, among others. Among them, Hydrodeoxygenation (HDO) is a fast, efficient, green method for catalytic conversion of lignin derivatives.

At present, catalysts applied to hydrogenation and deoxidation of lignin model compounds are various, and can be divided into homogeneous catalysts and heterogeneous catalysts according to phase states of a reaction system, and the homogeneous catalysts are difficult to separate and regenerate, but the homogeneous catalysts are very important to a large-scale production process, so that a great deal of research is mainly focused on catalytic conversion of the heterogeneous catalysts on lignin. The catalyst can be classified into an acid catalyst, a basic catalyst, a metal catalyst and the like according to the property of the catalyst, and the metal catalyst can be classified into a traditional metal catalyst, a novel noble metal catalyst and a transition metal catalyst. The conventional sulfide, phosphide and nitride metal catalysts are easy to deactivate due to loss of active components, carbon deposit, water poisoning and the like, which is an important reason that they cannot be widely used in industrial production, and although the single metal oxide catalysts have stable properties and simple preparation processes, the catalytic effect and single selectivity of the products are not high.

At present, numerous researches show that an alloy catalytic system of noble metals Ru, Rh, Pd, Pt and Re and non-noble metals Cu, Ni, Fe and Mo has high-efficiency application in catalytic conversion of a lignin model compound, but harsh conditions such as high temperature and high pressure are required, excessive hydrogenation of benzene rings can be caused, aromatic compounds with high purity are difficult to obtain, but the aromatic compounds have irreplaceable important function in the chemical industry, so that the search for a catalyst which is high in efficiency, stable and low in price and can not cause excessive hydrogenation of reaction products becomes a research hotspot of lignin conversion in recent years. MoO₃The catalyst is a catalyst with high attraction and rich content on the earth surface, can be widely applied to hydrodeoxygenation of lignin derivatives, and has simple preparation process and easy operation. From the research results of the current literatures, the conversion rate of the traditional single-metal MoO3 catalyst on lignin model compounds and the single selectivity of the product are not high, the products mainly comprise benzene and phenol, the contents of the two products are relatively close, the requirement on the reaction temperature is high, and the requirement on the reaction temperature is mainly concentrated above 320-350 ℃. There is currently little interest in SnO₂And MoO₃The synergistic research of the bimetallic oxide in the catalytic conversion of lignin model compounds and the mode of using alcoholic solution for heating treatment to change the surface active center of the catalyst so as to further improveAnd (4) researching the catalytic performance.

Disclosure of Invention

In order to solve the problems in the prior art, the invention adds a second metal oxide SnO₂Improving the MoO of the traditional metal oxide₃The catalytic performance, the method of adding corresponding alcohol solution for treatment and the like obviously reduce the reaction condition, improve the conversion rate of reactants and the single selectivity of target products, which is the innovation of the invention, thereby solving the problems that the metal catalyst in the prior art is easy to inactivate, the reaction condition is high, the process is complex, the conversion rate of the reactants is low, the selectivity of the target products is not high and the like.

The technical scheme of the invention is as follows:

a bimetallic oxide catalyst with the structural formula of xSnO₂-yMoO₃Wherein x is more than or equal to 1 and less than or equal to 6, and y is more than or equal to 1 and less than or equal to 6.

The method comprises the steps of synthesizing bimetallic oxide catalysts with different proportions by introducing an alcohol solution heating treatment method, adjusting the pH of a soluble salt solution containing an active component Sn precursor by using ammonia water, adding a soluble salt containing a metal Mo precursor, fully and uniformly stirring, adding hydrochloric acid, heating, washing, filtering and drying in vacuum to obtain a white product, roasting the white product to obtain dark green, grinding the dark green product to powder, and heating the alcohol solution to obtain alcohol-heated xSnO₂-yMoO₃A catalyst.

The invention relates to a bimetallic oxide catalyst, a preparation method and application thereof

The preparation method of the bimetallic oxide catalyst comprises the following steps:

a) preparing a soluble salt solution with the concentration of 0.033-0.200 mol/L and containing an active component Sn precursor, and adjusting the pH to 6-10 by using 25-28% by mass of ammonia water;

b) adding soluble salt with a corresponding concentration range of 0.033-0.200 mol/L of metal Mo precursor into the solution a) according to the proportion of 1/6-6/1 Sn/Mo, fully and uniformly mixing, adding hydrochloric acid, heating, washing, filtering and vacuum drying to obtain a white product;

c) roasting the white product obtained in the step b) in a muffle furnace, wherein the roasted white product is blackish green, and grinding the blackish green white product to be in a powder state;

d) heating the powder-state dark green product in the step c) in an alcohol solution to obtain alcohol-heated xSnO₂-yMoO₃A catalyst.

The mass fraction of the hydrochloric acid in the b) is 36.0-38.0 percent, the molar concentration of the hydrochloric acid is about 12mol/L through conversion, and the molar amount of the hydrochloric acid added is 0.5-2 times (Sn + Mo); the heating condition is that the mixture is heated and treated for 0.5 to 2 hours in an oven at the temperature of between 30 and 100 ℃, and then dried and treated for 4 to 12 hours under the condition of vacuum at the temperature of between 40 and 120 ℃;

the roasting condition in c) is roasting for 2 to 10 hours at the temperature of between 100 and 500 ℃, and then roasting for 5 to 10 hours at the temperature of between 300 and 800 ℃, wherein the heating rate is 5 ℃/min;

the alcohol solution selected in the step d) is one of methanol, absolute ethyl alcohol, n-propyl alcohol, isopropyl alcohol and n-butyl alcohol, or a mixed solution of a plurality of alcohols, the mass ratio of the catalyst to the alcohol solution is 1: 20-1: 60g/mL, and the roasted and ground dark green powder product is heated in the alcohol solution at the temperature of 60-120 ℃ for 4-12 hours.

The alcohol heat treatment of the invention is carried out on the bimetallic oxide xSnO₂-yMoO₃Use of hydrodeoxygenation in lignin model compounds:

the hydrogenation reaction of the lignin model compound is carried out in an intermittent high-pressure reaction kettle, a reaction internal standard substance is a thermostable organic substance n-dodecane, and a reaction solvent can dissolve a substrate, a reaction product and the like. The method comprises the following specific steps:

a) fully mixing a lignin model compound, a catalyst, an internal standard substance and a reaction solvent, adding the mixture into a reaction kettle, replacing gas in the kettle with gas for three times before the reaction starts, and filling the pressure in the kettle to a target pressure of 2-7 MPa at normal temperature;

b) heating the reaction kettle to 250-300 ℃, wherein the stirring speed is 800-1200r/min, and the stirring time is 2-7 h;

c) after the reaction is finished, the temperature is reduced, the pressure is released, the kettle is opened, solid components in the kettle are filtered, and meanwhile, liquid products are obtained and used for gas chromatography analysis.

The reaction solvent in a) is one of n-pentane, n-hexane, n-heptane, decalin and methylcyclohexane, or the solvents are mixed in any proportion, the internal standard substance is n-dodecane, and the used gas is hydrogen;

the concentration of the lignin model compound in the a) in the reaction solvent is 0.042-0.375 mol/L; the mass ratio of the lignin to the catalyst is (1:1) - (10: 1);

the temperature rise rate in the step b) is 5 ℃/min.

Predecessors about monometallic oxide MoO₃The hydrodeoxygenation result in the lignin model compound shows that the conversion rate is mostly concentrated at 70-80% when guaiacol is used as a reaction substrate, the main products are benzene and phenol, the yield of the benzene and the phenol is close to each other and is about 30%, and a pure-phase dominant product is difficult to obtain by improving the reaction conditions, so that the method is not favorable for large-scale production and application, the reaction temperature is required to be above 320-350 ℃, the reaction time is long, and the energy consumption is large. However, the results of this study show that the addition of a second metal oxide SnO₂After the alcohol solution is heated, the conditions required by the reaction are reduced, and the conversion rate of the guaiacol and the yield of the phenol respectively reach 100.0 percent and 92.8 percent under the optimal reaction conditions, compared with the traditional single metal oxide MoO₃The conversion rate of the substrate and the selectivity of a single product are greatly improved in the hydrodeoxygenation of the lignin model compound.

The catalyst is prepared from non-noble metal salt raw materials, and has the advantages of low cost, simple preparation process, and less time and material consumption.

The preparation of the catalyst of the invention not only introduces the second metal oxide SnO₂The hydrodeoxygenation effect of the catalyst is improved, and a brand new technical method, namely an alcoholic solution is used for heating the roasted catalyst, so that the performance of the prepared catalyst is further optimized. And the conventional metal oxide MoO in the literature₃Compared with the hydrodeoxygenation effect in the lignin model compound, the catalyst prepared by the method has the advantages of conversion rate of the lignin model compound and aromatic compoundsThe single selectivity of the method is improved to a large extent, and meanwhile, the reaction conditions are reduced, and the energy is saved.

The reaction solvent in the invention is a conventional organic solvent, and is environment-friendly and pollution-free.

The mass of the catalyst used in the invention is smaller than the proportion of the reaction substrate, the using amount of the catalyst is less, and the activity of the prepared catalyst is higher.

The catalyst system has good cyclicity and water resistance, and can be repeatedly used.

Drawings

FIG. 1 shows n-butanol treatment 1SnO in example 13 of the present invention₂-1MoO₃The catalyst takes normal hexane as a solvent to analyze the result of GC-MS spectrum analysis in guaiacol conversion.

FIG. 2 shows Anhydrous ethanol treatment 1SnO in example 14 of the present invention₂-1MoO₃The catalyst takes normal hexane as a solvent to analyze the result of GC-MS spectrum analysis in guaiacol conversion.

FIG. 3 shows the treatment of 1SnO with anhydrous ethanol in example 15 of the present invention₂-2MoO₃The catalyst takes normal hexane as a solvent to analyze the result of GC-MS spectrum analysis in guaiacol conversion.

FIG. 4 shows Anhydrous ethanol treatment of 1SnO in example 17 of the present invention₂-2MoO₃The catalyst takes n-pentane as a solvent to analyze the result of GC-MS spectrum analysis in guaiacol conversion.

Detailed Description

The invention will be described in more detail with reference to the following figures and embodiments, but the scope of the invention is not limited thereto.