阅读说明：本技术 一种氧化乙苯制苯乙酮用催化剂及其制备方法 (Catalyst for preparing acetophenone by oxidizing ethylbenzene and preparation method thereof ) 是由 刘江永 孟茹 菅盘铭 于 2020-05-29 设计创作，主要内容包括：本发明公开了一种氧化乙苯制苯乙酮用催化剂及其制备方法。该催化剂为CeO<Sub>2</Sub>-Co<Sub>3</Sub>O<Sub>4</Sub>复合金属氧化物,CeO<Sub>2</Sub>在复合金属氧化物中的质量含量为0.5～25 wt%。该催化剂以碳酸钴微球为载体,通过浸渍法负载硝酸铈,之后在空气中以一定温度焙烧后得到。该催化剂可在以氧气为氧化剂,且不使用任何溶剂和添加剂的条件下,将乙苯氧化为苯乙酮,且该催化反应体系具有对环境友好,催化剂制备过程简单且成本低,具有催化活性高,选择性好和循环使用性能好等特点。(The invention discloses a catalyst for preparing acetophenone by oxidizing ethylbenzene and a preparation method thereof. The catalyst is CeO 2 ‑Co 3 O 4 Composite metal oxide, CeO 2 The mass content in the composite metal oxide is 0.5-25 wt%. The catalyst is obtained by taking cobalt carbonate microspheres as a carrier, loading cerium nitrate by an impregnation method, and then roasting at a certain temperature in air. The catalyst can oxidize the acetophenone into the acetophenone under the conditions of taking oxygen as an oxidant and not using any solvent or additive, and the catalytic reaction system has the characteristics of environmental friendliness, simple catalyst preparation process, low cost, high catalytic activity, good selectivity, good recycling performance and the like.)

1. A catalyst for preparing acetophenone by oxidizing ethylbenzene is characterized in that the catalyst is CeO₂-Co₃O₄Composite metal oxide, CeO₂The mass content in the composite metal oxide is 0.5-25 wt%.

2. The method of preparing the catalyst of claim 1, comprising the steps of:

(1) mixing CoCO₃Dispersing in a mixed solution of water and ethanol, adding polyvinylpyrrolidone, and stirring uniformly;

(2) adding Ce (NO)₃)₂·6H₂Adding O into the solution, and continuously stirring at 50 ℃ until the solution is evaporated to dryness;

(3) and drying the obtained solid powder at 80 ℃ for 12 hours, and then roasting the dried solid powder in air at 400-700 ℃ for 2-4 hours to obtain the catalyst.

3. The method according to claim 2, wherein the volume ratio of water to ethanol in the mixed solution of water and ethanol is 1: 1.

4. The method of claim 2, wherein the CoCO is₃The mass ratio of the polyvinyl pyrrolidone to the polyvinyl pyrrolidone is 1: 1.

5. The method of claim 2, wherein Ce (NO)₃)₂·6H₂O and CoCO₃The mass ratio of (A) to (B) is 1: 100-1: 2.

6. The method of claim 2, wherein the firing temperature is 600 ℃ and the firing time is 3 hours.

7. Use of the catalyst of claim 1 in the selective oxidation of ethylbenzene to acetophenone.

8. The application of claim 7, wherein the catalyst and the ethylbenzene are added into a high-pressure reaction kettle, and the reaction is carried out under the conditions of no solvent and no additive, oxygen is used as an oxidant, and the target product acetophenone is prepared after the reaction is carried out for a period of time at a certain temperature and under a certain pressure.

9. The use according to claim 8, wherein the catalyst is used in an amount of 0.1 to 0.6wt% of the ethylbenzene.

10. The use according to claim 8, wherein the reaction temperature is 110 to 140 ℃; the reaction pressure is 0.4-1.0 MPa; the reaction time is 2-8 h.

Technical Field

The invention relates to a catalyst for preparing acetophenone by oxidizing ethylbenzene under the conditions of no solvent and no additive and a preparation method thereof, belonging to the technical field of acetophenone synthesis.

Background

Acetophenone is an important organic synthesis intermediate, widely used for synthesizing perfumes, medicines, pesticides and dyes, and is also a good solvent for cellulose ether, cellulose ester and resin and a plasticizer for plastics. Traditionally, acetophenone has been synthesized by the oxidation of an acyl halide or anhydride with a lewis acid or an alkyl aromatic hydrocarbon with a stoichiometric amount of an inorganic oxidant such as permanganate or dichromate. At present, the method for industrially producing the acetophenone is to oxidize the acetophenone into the acetophenone in the acetic acid by using the cobalt acetate as a homogeneous catalyst in the presence of oxygen, however, the methods are generally limited by the defects of complex reaction path, difficult catalyst separation, high economic cost, large generation of toxic and corrosive wastes and the like, and thus the development is limited.

Compared with homogeneous catalysis, the heterogeneous catalysis process has the characteristic that the catalyst and the product are easy to separate and recover, and the application prospect is wider. In recent years, processes for the selective catalytic oxidation of ethylbenzene to acetophenone under heterogeneous conditions have received much attention. Among the various types of oxidizing agents such as oxygen, hydrogen peroxide and tert-butyl hydroperoxide, the more environmentally friendly, less expensive, and sustainable oxygen is the most desirable end-use oxidizing agent from an economic and practical production standpoint. However, compared with other oxidants, oxygen is difficult to activate, and various solvents (Molecular Catalysis 470 (2019)) 1-7, applied Catalysis A: General512(2016) 9-14) and/or additives (materials Chemistry and Physics 232 (2019)) 393 399; New journal of Chemistry 43 (2019)8189 + 8194) are often added into the currently reported research system to improve the performance of the ethylbenzene oxidation reaction with oxygen as the oxidant. Therefore, in the process using oxygen as oxidant, it is very challenging to achieve good ethylbenzene oxidation performance under the conditions of no solvent and no additive. Through literature research and data review, it can be found that there are few reports in this respect, and there are many problems in the reported systems, such as poor reaction effect (Molecular Catalysis 458 (2018) 1-8; Materials Chemistry and Physics 214 (2018) 239-. Therefore, the development of low-cost, high-activity, high-selectivity and high-stability catalysts remains a difficult and breakthrough point in the field.

Disclosure of Invention

In order to solve the problems, the invention aims to provide a catalyst for preparing acetophenone by oxidizing ethylbenzene under the conditions of no solvent and no additive and a preparation method thereof.

In order to achieve the purpose, the invention adopts the following technical scheme: a catalyst for preparing acetophenone by oxidizing ethylbenzene is CeO₂-Co₃O₄Composite metal oxide, CeO₂The mass content in the composite metal oxide is 0.5-25 wt%.

Prepared by the following steps:

(1) mixing CoCO₃Dispersing in mixed solution of water and ethanol, adding polyvinylpyrrolidone (PVP,K30) stirring uniformly;

(2) adding Ce (NO)₃)₂·6H₂Adding O into the solution, and continuously stirring at 50 ℃ until the solution is evaporated to dryness;

(3) drying the obtained solid powder at 80 ℃ for 12 h, and then roasting the dried solid powder in air at 400-700 ℃ for 2-4 h to obtain CeO₂-Co₃O₄A composite metal oxide catalyst.

Further, the volume ratio of water to ethanol in the mixed solution of water and ethanol is 1: 1.

Further, CoCO₃The mass ratio of the polyvinyl pyrrolidone to the polyvinyl pyrrolidone is 1: 1.

Further, Ce (NO)₃)₂·6H₂O and CoCO₃The mass ratio of (A) to (B) is 1: 100-1: 2.

Furthermore, the roasting temperature is 600 ℃, and the roasting time is 3 hours.

The invention also provides CeO₂-Co₃O₄The catalyst is applied to preparing acetophenone by selective oxidation of ethylbenzene.

The reaction process is as follows: adding proper amount of CeO₂-Co₃O₄Adding catalyst and ethylbenzene into high-pressure reactor, and reacting in the absence of solvent and additive by using oxygen as oxidant inReacting for a period of time at a certain temperature and pressure to obtain the target product acetophenone.

Preferably, the CeO₂-Co₃O₄The dosage of the catalyst is 0.1-0.6 wt% of the ethylbenzene.

Preferably, the reaction temperature is 110-140 ℃.

Preferably, the reaction pressure is 0.4-1.0 MPa.

Preferably, the reaction time is 2-8 h.

Compared with the prior art, the invention has the following beneficial effects:

(1) CeO of the invention₂-Co₃O₄The catalyst has simple preparation method and low preparation cost.

(2) The catalytic system of the invention has simple reaction conditions, does not add any solvent or additive, takes oxygen as an oxidant, is environment-friendly and has good industrial application value.

(3) CeO synthesized by the invention₂-Co₃O₄Under the better reaction condition, the conversion rate of ethylbenzene is up to 73.4%, the selectivity of acetophenone is 78.5%, and the catalytic effect is not obviously reduced after repeated use, and the stability is good; under the same reaction condition, the comprehensive catalytic performance of the catalyst is obviously superior to that of the related catalytic system reported at present.

Drawings

FIG. 1 shows CeO prepared in examples 1 to 6 of the present invention₂-Co₃O₄XRD patterns of the series of catalysts.

FIG. 2 shows 5wt% CeO prepared in example 1 of the present invention₂-Co₃O₄HRTEM image of catalyst.

Detailed Description

The present invention is described in further detail below with reference to examples, but it should not be construed that the scope of the above subject matter of the present invention is limited to the following examples, and that all the technologies realized based on the above subject matter of the present invention belong to the scope of the present invention.