阅读说明：本技术 一种负载型金属氧化物催化剂及其制备方法和应用 (Supported metal oxide catalyst and preparation method and application thereof ) 是由 谭猗生 武应全 解红娟 张涛 杨国辉 于 2020-06-03 设计创作，主要内容包括：本发明公开一种负载型金属氧化物催化剂及其制备方法和应用,属于催化剂制备及应用领域。催化剂由载体(ThO<Sub>2</Sub>、La<Sub>2</Sub>O<Sub>3</Sub>中的一种与ZrO<Sub>2</Sub>组成复合载体)、活性组分(CuO、ZnO、Cr<Sub>2</Sub>O<Sub>3</Sub>)、碱性助剂(K<Sub>2</Sub>O、CaO、MgO、BaO中的一种或两种)组成。催化剂采用浸渍法负载活性组分和助剂后经干燥、焙烧制得。该催化剂用于乙醇缩合制备正丁醇,在固定床反应装置上进行,反应压力1~5MPa,乙醇通过液体压力泵进入装置反应器,载气空速为1000~3000 h<Sup>-1</Sup>,反应温度250~400 <Sup>o</Sup>C。本发明催化剂制备方法简单,成本低廉,乙醇转化率高达97%以上,正丁醇选择性高达95.5%以上,更具产业化的应用前景。(The invention discloses a supported metal oxide catalyst and a preparation method and application thereof, belonging to the field of catalyst preparation and application. Catalyst carrier (ThO) 2 、La 2 O 3 And ZrO 2 Constituting a composite carrier), active components (CuO, ZnO, Cr 2 O 3 ) Alkali assistant (K) 2 One or two of O, CaO, MgO and BaO). The catalyst is prepared by loading active components and an auxiliary agent by an impregnation method, drying and roasting. The catalyst is used for preparing n-butanol through ethanol condensation, the reaction is carried out on a fixed bed reaction device, the reaction pressure is 1-5 MPa, ethanol enters a device reactor through a liquid pressure pump, and the air speed of carrier gas is 1000-3000 h ‑1 The reaction temperature is 250-400 DEG C o C. The preparation method of the catalyst is simple and has the advantages ofThe method is low in cost, the conversion rate of ethanol is up to more than 97%, the selectivity of n-butyl alcohol is up to more than 95.5%, and the method has industrial application prospects.)

1. A supported metal oxide catalyst is characterized by comprising a carrier, an active component and an alkaline assistant;

the carrier is as follows: ThO₂、La₂O₃And ZrO₂Forming a composite carrier, wherein: ZrO in a weight ratio of the corresponding oxides₂Ratio to other carriers 5: 1-10: 1;

the active components are CuO, ZnO and Cr₂O₃；

The alkaline auxiliary agent is K₂In O, CaO, MgO, BaOOne or two of (1).

2. The supported metal oxide catalyst of claim 1, wherein: the weight percentage of each component is as follows:

carrier: 65 to 88 percent of the total weight of the steel,

CuO：8%~25%，

ZnO：0.5%~9%，

Cr₂O₃：1.4%~11%，

alkaline auxiliary agent: 0.5 to 5 percent.

3. The supported metal oxide catalyst of claim 1, wherein: when two alkaline assistants are selected, the weight ratio of the two is 1.5-11: 1.

4. a method for preparing a supported metal oxide catalyst according to any one of claims 1 to 3, characterized by comprising the steps of:

(1) ZrO was weighed separately₂、ThO₂Or La₂O₃Uniformly mixing, grinding to below 300 meshes, forming, and crushing to 20-30 meshes for later use;

(2) weighing soluble salts of Cu, Zn and Cr, dissolving the soluble salts in deionized water to prepare a solution with the total metal ion concentration of 1.2-2.5M, and mixing the solution with a carrier/CuO = 2.6-11: 1, soaking for 3-12 h, ultrasonically evaporating to dryness, and drying by 80-110^oCDrying for 5-15 h under the condition, and roasting for 3-9 h at the temperature of 350-600 ℃ to prepare a precursor A;

(3) weighing soluble salts of alkaline auxiliary agent components, dissolving the soluble salts in deionized water to prepare a solution with the total metal ion concentration of 0.03-1M, adding a precursor A, soaking for 3-12 h, ultrasonically evaporating to dryness, and 80-110%^oAnd C, drying for 5-15 h, and roasting for 3-9 h at the temperature of 350-600 ℃ to obtain the supported metal oxide catalyst.

5. The method of preparing a supported metal oxide catalyst according to claim 4, characterized in that: the soluble salt of Cu is one of copper nitrate trihydrate or copper acetate monohydrate.

6. The method of preparing a supported metal oxide catalyst according to claim 4, characterized in that: the soluble salt of Zn is one of zinc nitrate hexahydrate and zinc acetate.

7. The method of preparing a supported metal oxide catalyst according to claim 4, characterized in that: the soluble salt of Cr is one of chromium nitrate nonahydrate or chromium acetate.

8. The method of preparing a supported metal oxide catalyst according to claim 4, characterized in that: in the soluble salt of the alkaline auxiliary agent component, when potassium is selected, the soluble salt of the potassium is one of potassium carbonate or KOH; when selecting magnesium, the soluble salt of magnesium is magnesium nitrate; when calcium is selected, the soluble salt of the calcium is calcium nitrate; when barium is selected, the soluble salt of barium is barium nitrate.

9. Use of a supported metal oxide catalyst according to any one of claims 1 to 3 in the preparation of n-butanol by the condensation of ethanol.

10. Use according to claim 9, characterized in that: with H₂：N₂Reducing the catalyst by using diluted hydrogen with the volume ratio of 10-20% as reducing gas; reducing gas for 20-50 h^-1The flow rate of the catalyst is 250 to 400 ℃ in a fixed bed reactor filled with the catalyst^oC. Reducing for 2-5 hours under the condition of 1-5 MPa; adjusting the space velocity of reducing gas to 1000-3000 h^-1Then, introducing ethanol at a liquid space velocity of 1-5 mL/h/mL of catalyst, and introducing the ethanol at 280-380 ℃^oC. And carrying out condensation reaction under the reaction pressure of 1-5 MPa.

Technical Field

The invention relates to a supported metal oxide catalyst and a preparation method and application thereof, belonging to the technical field of catalyst preparation and application.

Background

N-butanol is a multipurpose chemical, a raw material for producing dibutyl phthalate, butyl acrylate, butyl acetate, ethylene glycol butyl ether and surfactants, an organic synthetic intermediate and an extractant for biochemical medicines. In addition, the n-butanol can be directly used as the biofuel, and the derivative thereof can be used as the additive of diesel oil or jet fuel, so that the n-butanol is an ideal biomass fuel. Compared with bioethanol, n-butanol has superior fuel properties, such as higher energy density (-90% gasoline), lower water absorption, higher air-fuel ratio and lower heat of vaporization.

Currently, the methods commonly used for producing n-butanol include oxo synthesis, acetaldehyde condensation, and fermentation. The oxo-synthesis method is a main method for industrially producing the n-butanol, and comprises the steps of catalyzing propylene hydroformylation reaction by using a complex of cobalt or rhodium to obtain n-butyraldehyde, and then hydrogenating to obtain the n-butanol. The route excessively depends on the petrochemical industry, is greatly influenced by the fluctuation of petroleum price, has serious environmental pollution problem and low atom utilization rate, and the catalyst mostly adopts noble metal catalysts such as rhodium (Rh), ruthenium (Ru) and the like, so the production cost is higher. The acetaldehyde condensation method is that two molecules of acetaldehyde undergo aldol condensation reaction to generate butyraldehyde, the butyraldehyde is dehydrated to generate butyraldehyde, and then the n-butanol is obtained by hydrogenation. The method has serious corrosion on equipment and high production cost, and is basically eliminated by the market. The fermentation method has low production efficiency. With the continuous expansion of the application of the n-butanol, the demand is gradually increased, and methods with higher efficiency, lower production cost and newer paths are urgently needed to realize the production of the n-butanol.

The n-butanol can be obtained by self-condensation of ethanol, the raw material ethanol involved in the process can be obtained from a lower cost biomass route (bioethanol) in addition to the traditional industrial production. Therefore, the technology for producing the n-butanol by taking the ethanol as the raw material is a potential new route. The method for preparing the n-butanol by starting from the ethanol has the advantages of simple reaction process, high atom utilization rate and green production process.

The preparation of the n-butanol by the ethanol self-condensation mainly comprises catalyst systems such as homogeneous metal complex catalysts, solid acid-base catalysts, supported catalysts, metal catalysts and the like.

A ruthenium-bis (diphenylphosphino) methane complex catalyst for catalyzing ethanol to prepare n-butanol at ethanol conversion rate is reported in the literature (Angew. chem. int. Ed. 2013, 52, 9005->When the content is 20 percent, the selectivity of the n-butyl alcohol reaches 94 percent. A homogeneous catalyst of iridium complex for catalyzing ethanol to prepare n-butanol at a lower temperature (150) is reported in the literature (J. Am. chem. Soc. 2015, 137, 14264-14267)^oC) After 24 h of reaction, the conversion rate of ethanol is 37 percent, and the selectivity of n-butanol is>99 percent. The U.S. Pat. No. 4, 9902673, 2 relates to a complex catalyst of iridium and nickel or copper or zinc in the range of 100-500^oUnder the condition of C, 1-10 atm, the conversion rate of ethanol is more than or equal to 30%, and the selectivity of 1-butanol can be more than or equal to 80%. The metal complex catalyst used for the reaction of preparing the n-butanol by ethanol has the characteristics of mild reaction conditions, simple and convenient operation, good selectivity, high product yield, less pollution and the like, but has the defects of easy loss of noble metals, easy inactivation of the catalyst, poor stability of the catalyst, high preparation cost and the like.

Chinese patent (CN 101530802A) provides a composite material prepared from nickel oxide, magnesium oxide, potassium fluoride and gamma-Al₂O₃Catalyst of composition, the catalyst being at 200^oC, under the condition that the flow rate of the ethanol is 13.5ml/h, the conversion per pass of the ethanol is 12.4 percent, and the selectivity of the n-butyl alcohol is 75.5 percent. The solid acid-base catalyst has the defects of low ethanol conversion rate and low n-butanol selectivity.

U.S. Pat. No. 3, 20180370884, 1 discloses a catalyst (Pd-Mg-hydrotalcite) for the preparation of n-butanol with ethanol conversion of 8% and n-butanol selectivity of 86% at 300 psig, 2MPa, 0.2 ml/min. Chinese patent (CN 103193593A) reports a method for preparing N-butanol by ethanol, palladium-gallium bimetal is taken as an active component, rare earth metal is taken as an auxiliary agent, hydroxyapatite or NaY type molecular sieve is taken as a carrier, and N is₂Under the atmosphere, the ethanol sample injection amount is 0.5ml/min, 2-5MPa, 350^oUnder C, the conversion rate of ethanol reaches 58.3%, and the selectivity of n-butanol is 76.2%. The conversion rate of ethanol existing on the catalyst is lowAnd low n-butanol selectivity.

Chinese patent (CN 103193593A) discloses a method for preparing n-butanol by ethanol, ethanol and water are subjected to hydrothermal reaction under the common catalysis of sodium bicarbonate and metal cobalt powder, and the reaction is carried out at 140-300-^oC, obtaining n-butyl alcohol after 1-30 days of reaction, wherein the highest selectivity of the n-butyl alcohol is 87%, but the reaction time of the method is longer.

From the reports of the documents, the n-butanol selectivity on the homogeneous complex catalyst is high, but the ethanol conversion rate is low, the homogeneous complex catalyst is a noble metal catalyst, the preparation cost is high, and meanwhile, the active components of the catalyst are easy to run off, and the catalyst stability is poor; other catalysts have the problems of low ethanol conversion rate, low n-butanol selectivity and low reaction efficiency.

Disclosure of Invention

The invention aims to provide a supported metal oxide catalyst, a preparation method and application thereof, which improve the conversion rate of ethanol and the selectivity of n-butanol.

In the invention, the process of preparing the n-butyl alcohol by ethanol condensation comprises chemical reactions of ethanol dehydrogenation to generate acetaldehyde, acetaldehyde condensation to generate the n-butyl alcohol and the like, and corresponding catalysts need dehydrogenation centers and active centers for promoting the condensation reaction. In the composite catalyst prepared by the invention, the Cu component has the main function of dehydrogenation, so that ethanol is dehydrogenated into acetaldehyde. Although Zn and Cr have dehydrogenation effect, the dehydrogenation effect of Zn and Cr is weaker than that of Cu, and the introduction of Zn and Cr can promote the dehydrogenation effect of Cu, is beneficial to the improvement of the dehydrogenation capacity of ethanol and can also play a role in dispersing Cu. Although the Cu component has good dehydrogenation effect, the Cu component is easy to sinter due to the characteristics of the Cu component, so that the catalyst is deactivated, the service life of the catalyst is shortened, and La is introduced₂O₃And ThO₂The Cu component is dispersed, the specific surface area of the catalyst is improved, the aggregation growth of Cu is inhibited, and the catalyst has better stability. The aldehyde formed is directly subjected to a condensation reaction to give a product, which needs to be carried out on the active center of the condensation reaction. ZrO (ZrO)₂By itself having an acid-base property, the condensation reaction can be catalyzed, but ZrO due to the presence of ZrO₂Is amphoteric oxide, and has weak acidity and alkalinity, so the inventionAnd further introducing an alkaline assistant to modify the catalyst so as to enhance the alkalinity of the catalyst and promote the condensation reaction.

The invention provides a supported metal oxide catalyst, which consists of a carrier, an active component and an alkaline assistant:

the carrier is ThO₂、La₂O₃And ZrO₂Forming a composite carrier, wherein: ZrO in a weight ratio of the corresponding oxides₂Ratio to other carriers 5: 1-10: 1;

the active components are CuO, ZnO and Cr₂O₃。

The alkaline auxiliary agent is K₂One or two of O, CaO, MgO and BaO, wherein the weight ratio of two alkaline assistants is 1.5-11: 1.

in the catalyst, the weight percentage of each component is as follows:

carrier: 65 to 88 percent of the total weight of the steel,

CuO：8%~25%，

ZnO：0.5%~9%，

Cr₂O₃：1.4%~11%，

alkaline auxiliary agent: 0.5 to 5 percent.

The invention provides a preparation method of the supported metal oxide catalyst, which comprises the following steps:

(1) ZrO was weighed separately₂、ThO₂Or La₂O₃Uniformly mixing, grinding to below 300 meshes, forming, and crushing to 20-30 meshes for later use;

(2) weighing soluble salts of Cu, Zn and Cr, dissolving the soluble salts in deionized water to prepare a solution with the total metal ion concentration of 1.2-2.5M, and mixing the solution with a carrier/CuO = 2.6-11: 1, adding a composite carrier according to a mass ratio, soaking for 3-12 h, drying by ultrasonic wave, drying for 5-15 h at 80-110 ℃, and roasting for 3-9 h at 350-600 ℃ to obtain a precursor A;

(3) weighing soluble salts of alkaline auxiliary agent components, dissolving the soluble salts in deionized water to prepare a solution with the total metal ion concentration of 0.03-1M, adding a precursor A, soaking for 3-12 h, ultrasonically evaporating to dryness, and 80-110%^oAnd C, drying for 5-15 h, and roasting for 3-9 h at the temperature of 350-600 ℃ to obtain the supported metal oxide catalyst.

Further, in the above preparation method, the soluble salt of Cu is one of copper nitrate trihydrate or copper acetate monohydrate; the soluble salt of Zn is one of zinc nitrate hexahydrate or zinc acetate; the soluble salt of Cr is one of chromium nitrate nonahydrate or chromium acetate;

further, in the soluble salt of the alkaline component,

when potassium is selected, the soluble salt of potassium is one of potassium carbonate or potassium hydroxide;

when selecting magnesium, the soluble salt of magnesium is magnesium nitrate;

when calcium is selected, the soluble salt of the calcium is calcium nitrate;

when barium is selected, the soluble salt of barium is barium nitrate.

The invention provides application of the supported metal oxide catalyst in preparation of n-butanol by ethanol condensation.

In the above application, the compound is represented by H₂：N₂Reducing the catalyst by using diluted hydrogen with the volume ratio of 10-20% as reducing gas; reducing gas for 20-50 h^-1The flow rate of the catalyst is 250 to 400 ℃ in a fixed bed reactor filled with the catalyst^oC. Reducing for 2-5 hours under the condition of 1-5 MPa; adjusting the space velocity of reducing gas to 1000-3000 h^-1Then, introducing ethanol at a liquid space velocity of 1-5 mL/h/mL (catalyst) at 280-380%^oC. And carrying out condensation reaction under the reaction pressure of 1-5 MPa.

The invention has the beneficial effects that:

(1) the invention provides a preparation method of a catalyst for preparing n-butanol by catalyzing ethanol with non-noble metal as an active component, which is simple in preparation method, low in cost and good in catalyst stability;

(2) the conversion rate of the catalyst ethanol provided by the invention is up to more than 97%, the selectivity of n-butyl alcohol in the product is up to more than 91.3%, and the catalyst has industrial application prospect.

Detailed Description

The present invention is further illustrated by, but is not limited to, the following examples.