阅读说明：本技术 可循环钴锰复合催化剂、制备方法及在制备苯乙酮中应用 (Recyclable cobalt-manganese composite catalyst, preparation method and application in preparation of acetophenone ) 是由 陈祥迎 范磊 李平 汪清 张忠洁 童庆军 于 2021-08-02 设计创作，主要内容包括：本发明公开了可循环钴锰复合催化剂、制备方法及在制备苯乙酮中应用,该催化剂制备的方法步骤如下：S1：将钴盐和锰盐溶解于乙醇形成溶液A；S2：将草酸钠溶解于去离子水形成溶液B；S3：室温下,将S2中的溶液B在搅拌状态下加入溶液A中并进行反应,反应结束后经过滤、洗涤、干燥后得Co-(x)Mn-((1-x))C-(2)O-(4)·2H-(2)O复合材料；S4：将S3中的复合材料在管式反应炉中煅烧后得无水Co-(x)Mn-((1-x))C-(2)O-(4)复合催化剂。本发明的催化剂在制备苯乙酮中具有催化效率高、可循环使用等优点。(The invention discloses a recyclable cobalt-manganese composite catalyst, a preparation method and application thereof in acetophenone preparation, wherein the preparation method of the catalyst comprises the following steps: s1: dissolving cobalt salt and manganese salt in ethanol to form a solution A; s2: dissolving sodium oxalate in deionized water to form a solution B; s3: adding the solution B in the S2 into the solution A under the stirring state at room temperature for reaction, and filtering, washing and drying after the reaction to obtain Co x Mn (1‑x) C 2 O 4 ·2H 2 An O composite material; s4: calcining the composite material in the S3 in a tubular reaction furnace to obtain anhydrous Co x Mn (1‑x) C 2 O 4 And (3) compounding a catalyst. The catalyst has the advantages of high catalytic efficiency, recycling and the like in the preparation of the acetophenone.)

1. The preparation method of the recyclable cobalt-manganese composite catalyst is characterized by comprising the following steps:

s1: dissolving cobalt salt and manganese salt in ethanol to form a solution A;

s2: dissolving sodium oxalate in deionized water to form a solution B;

s3: adding the solution B in the S2 into the solution A under the stirring state at room temperature for reaction, and filtering, washing and drying after the reaction to obtain Co_xMn_(1-x)C₂O₄·2H₂An O composite material;

s4: calcining the composite material in the S3 in a tubular reaction furnace to obtain anhydrous Co_xMn_(1-x)C₂O₄And (3) compounding a catalyst.

2. The method for preparing the recyclable cobalt-manganese composite catalyst as claimed in claim 1, wherein the cobalt salt is cobalt acetate tetrahydrate, and the manganese salt is manganese acetate tetrahydrate; the molar ratio of the cobalt salt to the manganese salt is 1: 0.3-3.

3. The method for preparing the recyclable cobalt manganese composite catalyst as claimed in claim 1, wherein the molar concentration of the solution B is 1-3 mol/L.

4. The method for preparing the recyclable cobalt manganese composite catalyst as claimed in claim 1, wherein the reaction time in S3 is 25-35 min.

5. The method for preparing the recyclable cobalt-manganese composite catalyst as claimed in claim 1, wherein the calcination condition in S4 is to perform the pyrolysis reaction in two stages under a nitrogen atmosphere, and the temperature rise rate is 4-6 ℃/min. In the first stage, the reaction temperature is 125-; in the second stage, the reaction temperature is 245-255 ℃, and the heat preservation time is 1.8-2.2 h. After the reaction is finished, the temperature is reduced for 1.5 to 2.5 hours to room temperature to obtain the anhydrous Co_xMn_(1-x)C₂O₄And (3) compounding a catalyst.

6. A recyclable cobalt manganese composite catalyst prepared according to the method of claim 1.

7. The use of the recyclable cobalt manganese composite catalyst as claimed in claim 1 in the preparation of acetophenone by the oxidation of ethylbenzene.

8. The application of the recyclable cobalt-manganese composite catalyst in the preparation of acetophenone by ethylbenzene oxidation according to claim 7 is characterized by comprising the following steps: mixing ethylbenzene with anhydrous Co_xMn_(1-x)C₂O₄Adding the composite catalyst into a reactor for reaction, filtering the mixture at normal temperature and normal pressure after the reaction is finished, carrying out alkali washing and liquid separation on the filtrate, and distilling the upper layer of liquid to obtain the acetophenone.

9. The use of the recyclable cobalt manganese composite catalyst as claimed in claim 8 in the preparation of acetophenone by ethylbenzene oxidation, characterized in that the anhydrous Co is_xMn_(1-x)C₂O₄The dosage of the composite catalyst is 2.2 to 2.6 percent of the molar weight of the ethylbenzene.

10. The use of the recyclable cobalt manganese composite catalyst in the preparation of acetophenone by oxidation of ethylbenzene according to claim 8, wherein the reaction conditions are as follows: the stirring speed is 220-280rpm, air is used as an oxygen source, the gas flow rate is 80-120mL/min, the reaction temperature is 115-125 ℃, and the reaction time is 22-26 h.

Technical Field

The invention relates to the technical field of acetophenone preparation, in particular to a recyclable cobalt-manganese composite catalyst, a preparation method and application in acetophenone preparation.

Background

Industrially, the production process of acetophenone is mainly an air catalytic oxidation method, and ethylbenzene and air directly react to prepare acetophenone under the catalysis of cobalt acetate. However, this process usually uses acetic acid as a solvent to form a homogeneous catalytic system with cobalt acetate, and the use of acetic acid is disadvantageous to the production plant. In addition, the traditional cobalt acetate catalyst is easy to oxidize in the reaction process, and the catalyst is difficult to recycle; and in actual production, part of the catalyst is scaled on the kettle wall, which can cause the catalytic efficiency of the reaction system to be low.

Disclosure of Invention

Based on the technical problems in the background art, the invention provides a recyclable cobalt-manganese composite catalyst, a preparation method and application in preparation of acetophenone.

The invention provides a preparation method of a recyclable cobalt-manganese composite catalyst, which comprises the following steps:

s1: dissolving cobalt salt and manganese salt in ethanol to form a solution A;

s2: dissolving sodium oxalate in deionized water to form a solution B;

s3: adding the solution B in the S2 into the solution A under the stirring state at room temperature for reaction, and filtering, washing and drying after the reaction to obtain Co_xMn_(1-x)C₂O₄·2H₂An O composite material;

s4: calcining the composite material in the S3 in a tubular reaction furnace to obtain anhydrous Co_xMn_(1-x)C₂O₄CompoundingA catalyst.

Preferably, the cobalt salt is cobalt acetate tetrahydrate, and the manganese salt is manganese acetate tetrahydrate; the molar ratio of the cobalt salt to the manganese salt is 1: 0.3-3.

Preferably, the molar concentration of the solution B is 1-3 mol/L.

Preferably, the reaction time in S3 is 25-35 min.

Preferably, the calcination condition in S4 is to perform pyrolysis reaction in two stages under nitrogen atmosphere, and the heating rate is 4-6 ℃/min. In the first stage, the reaction temperature is 125-; in the second stage, the reaction temperature is 245-255 ℃, and the heat preservation time is 1.8-2.2 h. After the reaction is finished, the temperature is reduced for 1.5 to 2.5 hours to room temperature to obtain the anhydrous Co_xMn_(1-x)C₂O₄And (3) compounding a catalyst.

The recyclable cobalt-manganese composite catalyst prepared by the method is provided by the invention.

The invention provides an application of the recyclable cobalt-manganese composite catalyst in preparation of acetophenone by ethylbenzene oxidation.

Preferably, the method steps are as follows: mixing ethylbenzene with anhydrous Co_xMn_(1-x)C₂O₄Adding the composite catalyst into a reactor for reaction, filtering the mixture at normal temperature and normal pressure after the reaction is finished, carrying out alkali washing and liquid separation on the filtrate, and distilling the upper layer of liquid to obtain the acetophenone.

Preferably, the anhydrous Co_xMn_(1-x)C₂O₄The dosage of the composite catalyst is 2.2 to 2.6 percent of the molar weight of the ethylbenzene.

Preferably, the reaction conditions are: the stirring speed is 220-280rpm, air is used as an oxygen source, the gas flow rate is 80-120mL/min, the reaction temperature is 115-125 ℃, and the reaction time is 22-26 h.

The mechanism of action of the presence of water in the catalyst:

the beneficial technical effects are as follows:

(1) in the invention, the coprecipitation-pyrolysis method is used for preparing anhydrous Co_xMn_(1-x)C₂O₄The composite catalyst has adjustable components, and the porosity of the material can be effectively increased after the catalyst is pyrolyzed and dewatered. And the catalyst can not form hydrogen bonds with peroxy radicals and the like in the reaction process, so that the forward reaction is facilitated, and the catalyst has better catalytic efficiency.

(2) Different from the traditional soluble cobalt acetate catalytic system, the anhydrous Co in the invention_xMn_(1-x)C₂O₄The composite catalyst is not easy to be oxidized in the process of ethylbenzene catalytic oxidation reaction, so that the catalyst can be recycled, and Co_xMn_(1-x)C₂O₄The retention rate of the acetophenone yield after the composite catalyst is circulated for 5 times is more than 91 percent.

(3) Anhydrous Co used in the present invention_xMn_(1-x)C₂O₄The composite catalytic system is powder particles with strong fluidity, is uniformly dispersed in the reaction system under stirring to fully contact with a substrate, and is not easy to generate agglomeration in the catalytic oxidation reaction process of the ethylbenzene.

Drawings

FIG. 1 shows the proposed Co_0.5Mn_0.5C₂O₄·2H₂TG plot of O composite material under nitrogen atmosphere;

FIG. 2 shows the proposed Co_xMn_(1-x)C₂O₄XRD pattern of the composite catalyst;

FIG. 3 is Co_0.5Mn_0.5C₂O₄·2H₂A nitrogen adsorption and desorption isotherm (a) and a pore size distribution map (b) of O;

FIG. 4 shows Co_0.5Mn_0.5C₂O₄The nitrogen adsorption and desorption isotherm (a) and the pore size distribution map (b);

in FIG. 5, a-c are gas chromatograms of examples 1-3, respectively.

Detailed Description

The method for detecting the ethylbenzene conversion rate and the acetophenone selectivity adopts gas chromatography quantitative analysis (Agilent 6890N gas chromatograph). The chromatographic analysis conditions were: the temperature of the gasification chamber is 280 ℃; FID detection, detector temperature 260 ℃; the column temperature was programmed to 80 ℃ initially and increased to 130 ℃ at a rate of 25 ℃/min. And (5) detecting results, quantitatively analyzing the characteristic peaks of the ethylbenzene and the acetophenone, and calculating to obtain the ethylbenzene conversion rate and the acetophenone selectivity. Cobalt acetate tetrahydrate, manganese acetate tetrahydrate, ethanol and the like in the invention are all commercially available.

Example 1

The invention provides a preparation method of a recyclable cobalt-manganese composite catalyst, which comprises the following steps:

s1: dissolving cobalt acetate tetrahydrate and manganese acetate tetrahydrate in ethanol according to the ratio of 3:1 to form a solution A, wherein the concentration of cobalt salt is 1.5mol/L, and the concentration of manganese salt is 0.5 mol/L;

s2: dissolving sodium oxalate in deionized water to form a solution B, wherein the concentration of a sodium oxalate aqueous solution is 2 mol/L;

s3: adding the solution B in S2 into the solution A under stirring at room temperature, continuously stirring for 30min to allow the reaction solution to contact sufficiently, filtering, washing, and drying in a constant temperature forced air drying oven at 90 deg.C to obtain Co_0.75Mn_0.25C₂O₄·2H₂An O composite material;

s4: and (3) carrying out two-stage pyrolysis reaction on the composite material in the S3 in a tubular reaction furnace under the nitrogen atmosphere, wherein the heating rate is 4 ℃/min. In the first stage, the reaction temperature is 125 ℃, and the heat preservation time is 1.8 h; in the second stage, the reaction temperature is 245 ℃, the heat preservation time is 1.8h, and anhydrous Co is obtained after calcination_0.75Mn_0.25C₂O₄And (3) compounding a catalyst.

The method for applying the recyclable cobalt-manganese composite catalyst in the preparation of acetophenone by ethylbenzene oxidation comprises the following steps: 100mL of ethylbenzene and 2.2% of anhydrous Co based on the molar amount of ethylbenzene were added_0.75Mn_0.25C₂O₄Adding the composite catalyst into a reactor for reaction, wherein the reaction conditions are as follows: stirring speed of 220rpm, taking air as an oxygen source, keeping gas flow rate of 80mL/min, reaction temperature of 115 ℃ and reaction time of 22h,and after the reaction is finished, filtering the mixture at normal temperature and normal pressure, performing alkali washing and liquid separation on the filtrate, distilling the upper layer of liquid, collecting ethylbenzene fraction at about 140 ℃, and collecting acetophenone fraction at about 202 ℃. The product is analyzed and detected by gas chromatography, and the result shows that the conversion rate of ethylbenzene is 50.6%, the selectivity of acetophenone is 86.9%, and the yield retention rate of acetophenone is 94.30% after 5 times of circulation.

Example 2

The invention provides a preparation method of a recyclable cobalt-manganese composite catalyst, which comprises the following steps:

s1: dissolving cobalt acetate tetrahydrate and manganese acetate tetrahydrate in ethanol according to the ratio of 1:1 to form a solution A, wherein the concentration of cobalt salt is 1.0mol/L, and the concentration of manganese salt is 1.0 mol/L;

s2: dissolving sodium oxalate in deionized water to form a solution B, wherein the concentration of a sodium oxalate aqueous solution is 2 mol/L;

s3: adding the solution B in S2 into the solution A under stirring at room temperature, continuously stirring for 30min to allow the reaction solution to contact sufficiently, filtering, washing, and drying in a constant temperature forced air drying oven at 90 deg.C to obtain Co_0.5Mn_0.5C₂O₄·2H₂An O composite material;

s4: and (3) carrying out two-stage pyrolysis reaction on the composite material in the S3 in a tubular reaction furnace under the nitrogen atmosphere, wherein the heating rate is 5 ℃/min. In the first stage, the reaction temperature is 130 ℃, and the heat preservation time is 2 hours; in the second stage, the reaction temperature is 250 ℃, the heat preservation time is 2 hours, and anhydrous Co is obtained after calcination_0.5Mn_0.5C₂O₄And (3) compounding a catalyst.

The method for applying the recyclable cobalt-manganese composite catalyst in the preparation of acetophenone by ethylbenzene oxidation comprises the following steps: 100mL of ethylbenzene and 2.4% of anhydrous Co based on the molar amount of ethylbenzene were added_0.5Mn_0.5C₂O₄Adding the composite catalyst into a reactor for reaction, wherein the reaction conditions are as follows: stirring at 250rpm, using air as oxygen source, keeping the gas flow rate at 100mL/min, reaction temperature at 120 deg.C, reaction time at 24h, filtering the mixture at normal temperature and pressure after the reaction,and (3) carrying out alkali washing and liquid separation on the filtrate, distilling the upper layer liquid, collecting ethylbenzene fraction at about 140 ℃, and collecting acetophenone fraction at about 202 ℃. The product is analyzed and detected by gas chromatography, and the result shows that the conversion rate of ethylbenzene is 47.60%, the selectivity of acetophenone is 88.40%, and the yield retention rate of acetophenone is 93.70% after 5 times of circulation.

Example 3

The invention provides a preparation method of a recyclable cobalt-manganese composite catalyst, which comprises the following steps:

s1: dissolving cobalt acetate tetrahydrate and manganese acetate tetrahydrate in ethanol according to the ratio of 1:3 to form a solution A, wherein the concentration of cobalt salt is 0.5mol/L, and the concentration of manganese salt is 1.5 mol/L;

s2: dissolving sodium oxalate in deionized water to form a solution B, wherein the concentration of a sodium oxalate aqueous solution is 2 mol/L;

s3: adding the solution B in S2 into the solution A under stirring at room temperature, continuously stirring for 30min to allow the reaction solution to contact sufficiently, filtering, washing, and drying in a constant temperature forced air drying oven at 90 deg.C to obtain Co_0.25Mn_0.75C₂O₄·2H₂An O composite material;

s4: and (3) carrying out two-stage pyrolysis reaction on the composite material in the S3 in a tubular reaction furnace under the nitrogen atmosphere, wherein the heating rate is 6 ℃/min. In the first stage, the reaction temperature is 135 ℃, and the heat preservation time is 2.2 hours; in the second stage, the reaction temperature is 255 ℃, the heat preservation time is 2.2h, and anhydrous Co is obtained after calcination_0.25Mn_0.275C₂O₄And (3) compounding a catalyst.

The method for applying the recyclable cobalt-manganese composite catalyst in the preparation of acetophenone by ethylbenzene oxidation comprises the following steps: 100mL of ethylbenzene and 2.6% of anhydrous Co based on the molar amount of ethylbenzene were added_0.25Mn_0.75C₂O₄Adding the composite catalyst into a reactor for reaction, wherein the reaction conditions are as follows: stirring at 280rpm, taking air as oxygen source, keeping gas flow rate at 120mL/min, reaction temperature at 125 deg.C, and reaction time at 26h, filtering the mixture at normal temperature and pressure after reaction, performing alkaline washing and liquid separation on the filtrate, taking the filtrateDistilling the layer liquid, collecting ethylbenzene fraction at about 140 deg.C, and collecting acetophenone fraction at about 202 deg.C. The product is analyzed and detected by gas chromatography, the result shows that the conversion rate of ethylbenzene is 40.10%, the selectivity of acetophenone is 85.60%, and the yield retention rate of acetophenone is 91.90% after 5 times of circulation.

Comparative example 1

In S1 of this embodiment, only cobalt acetate tetrahydrate having a concentration of 2.0mol/L in ethanol solution was added under the same conditions as in example 2 to obtain CoC₂O₄The conversion rate of ethylbenzene is 22.60% and the selectivity of acetophenone is 80.30%.

Comparative example 2

MnC prepared in S1 in the same manner as in example 2 except that only manganese acetate tetrahydrate having a concentration of 2.0mol/L in ethanol solution was added₂O₄The conversion rate of ethylbenzene is 16.58% and the selectivity of acetophenone is 69.67%.

FIG. 1 shows Co_0.5Mn_0.5C₂O₄·2H₂The thermal decomposition curve of O in nitrogen atmosphere shows that the composite material has three weight loss processes in thermal decomposition in nitrogen, the weight loss temperature ranges from 44.61 ℃ to 128.64 ℃, from 130.41 ℃ to 193.54 ℃ and from 308.70 ℃ to 439.41 ℃, and the weight loss rates are respectively 6.41%, 11.43% and 45.32%. The first two weight loss processes correspond to the composite material Co_0.5Mn_0.5C₂O₄·2H₂And O loses crystal water, the weight loss in the last period of process is severe, and the composite material is pyrolyzed into corresponding oxide correspondingly.

FIG. 2 shows Co prepared at different Co-Mn ratios_xMn_(1-x)C₂O₄·2H₂O composite material, calcining at 250 ℃ in nitrogen atmosphere to obtain different samples of Co_xMn_(1-x)C₂O₄XRD pattern of (a). It can be seen from the figure that the three samples all have stronger diffraction peaks at 2 theta of 15.10 degrees, 15.80 degrees, 25.04 degrees, 32.27 degrees and the like, and are basically consistent with the standard PDF- #14-0713 of manganese oxalate; the sample has stronger diffraction peaks at the positions of 24.53 degrees, 36.25 degrees, 53.66 degrees and the like of 2 theta, and is basically consistent with the standard PDF- #37-0719 of the cobalt oxalate.

FIG. 3 is Co_0.5Mn_0.5C₂O₄·2H₂Adsorption and desorption isotherms (a) and pore size distribution (b) of O.

FIG. 4 shows Co_0.5Mn_0.5C₂O₄The adsorption and desorption isotherms (a) and the pore size distribution map (b).

FIG. 5 is a gas chromatogram of examples 1 to 3, in which the peak appearance order of each substance in the chromatogram is ethylbenzene, acetophenone and phenethyl alcohol, and the separation degree of each peak is good.

The present invention is not limited to the above preferred embodiments, and any modifications, equivalent substitutions, improvements, etc. within the spirit and principle of the present invention should be included in the protection scope of the present invention.