Preparation method of olefin hydroformylation heterogeneous catalyst

Abstract

The invention provides a preparation method of a novel heterogeneous hydroformylation reaction catalyst. According to the method, by optimizing the preparation process of the catalyst, the stability, activity and selectivity of the catalyst are remarkably improved, and the problem of insufficient performance of the catalyst in the prior art is solved. The catalyst with a stable structure is obtained by accurately controlling the preparation process conditions, and the catalytic activity of the catalyst is greatly improved through the synergistic effect of the catalyst components. The catalyst disclosed by the invention is simple in preparation method and high in process adaptability, and can be efficiently applied to various industrial reactors.

Description

Technical Field

[0001] The invention relates to a method for preparing a heterogeneous catalyst for olefin hydroformylation. Background Art

[0002] Hydroformylation is an important chemical reaction with an annual global production of more than 20 million tons. It generates high-value-added aldehyde compounds by reacting unsaturated olefins with synthesis gas. Aldehydes not only have high economic value in themselves, but can also be further chemically transformed into fine chemicals such as alcohols, amines, carboxylic acids and esters, which are widely used in fragrances, medicine and other fields. As a reaction with an atomic utilization rate of 100%, hydroformylation meets the requirements of green chemistry. At the same time, by converting cheap olefins into high-value compounds, it also meets the needs of industrial upgrading.

[0003] The hydroformylation catalysts widely used in industry are mainly homogeneous catalysts, which are usually composed of rhodium (Rh) and organic phosphine ligands. Although such catalysts have high activity and selectivity, they have significant disadvantages in practical applications, including difficulty in separating the catalyst from the reaction products, high energy consumption, loss of precious metals, and discharge of phosphorus-containing wastewater. In addition, the price of precious metal rhodium has continued to rise in recent years, making it an urgent problem for the industry to reduce the amount of rhodium and develop efficient heterogeneous catalysts.

[0004] In addition, long-chain unsaturated olefins, as a bulk chemical raw material, are usually derived from petroleum cracking products or Fischer-Tropsch synthesis processes. Although they are cheap, their economic added value is low. However, their economic value can be significantly improved by converting them into long-chain aldehydes through hydroformylation reactions and further hydrogenating them to form long-chain monohydric alcohols. Long-chain monohydric alcohols are widely used in the fields of plasticizers, surfactants, and stabilizers, and their downstream products have huge market demand. Therefore, the development of efficient, environmentally friendly, and low-cost hydroformylation catalysts has important industrial value and application prospects. Summary of the invention

[0005] The purpose of the present invention is to provide a novel method for preparing a heterogeneous hydroformylation catalyst to solve the problems of difficult product separation, poor catalyst reaction performance, and low conversion rate of internal olefins by the catalyst in the existing hydroformylation technology. The catalyst synthesized by the method has the advantages of easy separation, high internal olefin reaction activity, and high catalyst stability. In order to solve the above problems, the technical solution adopted by the present invention is as follows:

[0006] The preparation method of a heterogeneous catalyst comprises the following steps: (1) dissolving a metal cobalt precursor, a precipitant and a silica sol in a solvent respectively to obtain solutions A, B and C, and mixing the three solutions under stirring to obtain a reaction liquid; (2) spray drying the reaction liquid to obtain a solid powder, and drying and calcining the solid powder in sequence, wherein the drying temperature is 60 to 200° C., the calcining temperature is 300 to 600° C., and the calcining atmosphere is an oxygen-containing atmosphere with an oxygen concentration of 10 to 30%; (3) dissolving a metal rhodium precursor and an auxiliary metal in a solvent, and mixing the mixture with the calcined solid obtained in (2) by stirring, and further drying; (4) reducing the solid obtained in (3) at a reduction temperature of 200 to 500° C., and the reducing atmosphere contains hydrogen and carbon monoxide to obtain a catalyst.

[0007] In the above scheme, the precursor of the metallic cobalt is any one of cobalt nitrate, cobalt chloride, cobalt sulfate, and cobalt carbonyl, or a combination thereof; and the precipitant is any one of hydroxide, carbonate, and bicarbonate, or a combination thereof.

[0008] In the above scheme, the mixing method is to drop one or two of the A, B and C solutions into the other solutions, the mixing reaction temperature is 10-70°C, preferably 40-60°C, and the pH value in the mixing reaction is 7-10, preferably 8-9.

[0009] In the above scheme, the metal rhodium precursor is any one of rhodium trichloride, rhodium nitrate, triphenylphosphine carbonyl rhodium hydride, dicarbonyl acetylacetonate rhodium, acetylacetonate carbonyl rhodium hydride or a combination thereof, and the molar ratio of the metal rhodium precursor to the metal cobalt precursor is 0.0005 to 0.01; the auxiliary metal is one or a combination of alkali metals and alkaline earth metals, and the molar ratio of the auxiliary metal to the metal cobalt precursor is 0.01 to 0.2.

[0010] In the above scheme, according to the catalyst preparation method according to claim 1, the molar ratio of hydrogen to carbon monoxide is 0.5-2.

[0011] On the other hand, the present invention provides a method for synthesizing aldehydes using the heterogeneous catalyst of the present invention, the specific scheme is:

[0012] In a CO / H2 mixed atmosphere, a mixture containing unsaturated olefins, the heterogeneous catalyst and a solvent is subjected to a hydroformylation reaction at 80-200°C to obtain the corresponding aldehyde, the total pressure of the H2 / CO synthesis gas is 3-7 MPa, and the H2 / CO synthesis gas ratio is 0.5-3.

[0013] In the above scheme, the reaction process involves three phases: gas, liquid and solid. The main component of the gas phase is synthesis gas, the liquid phase is mainly olefin reactants and aldehyde products, the solid phase is a solid catalyst, and the reactor is one or a combination of an intermittent stirred tank, a slurry bed, and a trickle bed reactor.

[0014] In the above scheme, the main reaction process is the hydroformylation reaction, which satisfies the following equation:

[0015]

[0016] In the above scheme, the side reactions include hydrogenation of olefins to alkanes and isomerization of double bonds of olefins. Internal olefins (such as β-olefins, γ-olefins, etc.) in the reactants, as well as internal olefins after isomerization of α-olefins, can be hydroformylated to obtain the corresponding aldehydes, and the equation is as follows:

[0017]

[0018] The present invention significantly improves the stability, activity and selectivity of the catalyst by optimizing the preparation process of the catalyst, and solves the problem of insufficient catalyst performance in the prior art. Specifically, by accurately controlling the calcination and reduction process conditions, a catalyst with a stable structure is obtained; the synergistic effect of metal rhodium, metal cobalt and auxiliary metal greatly improves the catalytic activity of the catalyst. In addition, the catalyst preparation method of the present invention is simple and has strong process adaptability. It can be efficiently applied in a variety of industrial reactors and has significant industrial value. DETAILED DESCRIPTION

[0019] The following describes in detail the implementation methods of multiple preferred implementation cases of the present invention, and further describes the above content of the present invention in detail. The following examples are only for illustration and should not be regarded as limiting the scope of the present invention.

[0020] Example 1

[0021] A metal cobalt precursor, a precipitant and a silica sol are dissolved in a solvent to obtain solutions A, B and C respectively, and the three are mixed and reacted under stirring to obtain a reaction liquid; the reaction liquid is spray-dried to obtain a solid powder, which is dried and calcined in sequence, wherein the drying temperature is 100°C, the calcination temperature is 450°C, and the calcination atmosphere is an oxygen-containing atmosphere with an oxygen concentration of 20%; a metal rhodium precursor and an auxiliary metal are dissolved in a solvent, stirred and mixed with the calcined solid, and further dried; the dried solid is reduced at a reduction temperature of 300°C, and the reducing atmosphere contains hydrogen and carbon monoxide to obtain a catalyst A.

[0022] In this embodiment, the auxiliary metal is a potassium metal salt, and the molar ratio of the auxiliary metal to the metal cobalt precursor is 0.05; the metal rhodium precursor is rhodium trichloride, and the molar ratio of the metal rhodium precursor to the metal cobalt precursor is x, and the catalyst is named Ax according to different molar ratios;

[0023] Example 2

[0024] A metal cobalt precursor, a precipitant and a silica sol are dissolved in a solvent to obtain solutions A, B and C respectively, and the three are mixed and reacted under stirring to obtain a reaction liquid; the reaction liquid is spray-dried to obtain a solid powder, which is dried and calcined in sequence, wherein the drying temperature is 100°C, the calcination temperature is 450°C, and the calcination atmosphere is an oxygen-containing atmosphere with an oxygen concentration of 20%; a metal rhodium precursor and an auxiliary metal are dissolved in a solvent, stirred and mixed with the calcined solid, and further dried; the dried solid is reduced at a reduction temperature of 300°C, and the reducing atmosphere contains hydrogen and carbon monoxide to obtain a catalyst B.

[0025] In this embodiment, the metal rhodium precursor is rhodium trichloride, the molar ratio of the metal rhodium precursor to the metal cobalt precursor is 0.001, the auxiliary metal is a metal sodium salt, and the molar ratio of the auxiliary metal to the metal cobalt precursor is y; the catalyst is named By according to different molar ratios;

[0026] Example 3

[0027] A metal cobalt precursor, a precipitant and a silica sol are respectively dissolved in a solvent to obtain solutions A, B and C, and the three are mixed and reacted under stirring to obtain a reaction liquid; the reaction liquid is spray-dried to obtain a solid powder, which is then dried and calcined in sequence, wherein the drying temperature is 100°C, the calcination temperature is 450°C, and the calcination atmosphere is an oxygen-containing atmosphere with an oxygen concentration of 20%; a metal rhodium precursor and an auxiliary metal are dissolved in a solvent, stirred and mixed with the calcined solid, and further dried; the dried solid is subjected to a reduction treatment, and the reducing atmosphere contains hydrogen and carbon monoxide to obtain a catalyst C.

[0028] In this embodiment, the metal rhodium precursor is rhodium trichloride, the molar ratio of the metal rhodium precursor to the metal cobalt precursor is 0.001, the auxiliary metal is a metal sodium salt, and the molar ratio of the auxiliary metal to the metal cobalt precursor is 0.02; the reduction temperature is T, and the catalyst is named CT according to different reduction temperatures;

[0029] In an intermittent reactor, 100 mg of any catalyst in Examples 1 to 3 was added, and then 30 mL of toluene solvent and 4 mL of α-undecene reactant were added. The reactor was then sealed, filled with N2 for gas replacement 3 times, and finally filled with 3 MPa of synthesis gas, wherein CO / H2=1:1. The reaction temperature was set to 180°C and the mechanical stirring speed was 800 rpm. The reaction performance of each catalyst is shown in Table 1:

[0030] Table 1. Performance of the synthetic catalysts in Examples 1 to 3 in the hydroformylation reaction

[0031] Example Catalyst No. Reaction time / h Conversion rate / % Alcohol / aldehyde chemical selectivity % Example 1 A-0.0005 3 40.7 91.9 Example 1 A-0.001 3 57.2 96.5 Example 1 A-0.005 3 98.6 98.9 Example 1 A-0.007 3 94.9 97.5 Example 1 A-0.01 3 90.3 97.5 Example 2 B-0.01 3 80.7 87.4 Example 2 B-0.02 3 93.2 98.0 Example 2 B-0.05 3 98.0 98.5 Example 2 B-0.1 3 78.2 88.5 Example 2 B-0.2 3 40.3 58.0 Example 3 C-200 3 73.2 98.0 Example 3 C-300 3 93.2 93.0 Example 3 C-350 3 98.2 97.5 Example 3 C-450 3 88.2 98.5 Example 3 C-500 3 70.3 98.0

Claims

1. A method for preparing a heterogeneous catalyst for olefin hydroformylation, characterized in that: The following steps are involved: (1) dissolving a metal cobalt precursor, a precipitant and a silica sol in a solvent to obtain solutions A, B and C respectively, and mixing the three solutions under stirring to obtain a reaction solution; (2) spray drying the reaction solution to obtain a solid powder, which is then dried and calcined in sequence, wherein the drying temperature is 60 to 200° C., the calcination temperature is 300 to 600° C., and the calcination atmosphere is an oxygen-containing atmosphere with an oxygen concentration of 10 to 30%; (3) dissolving the metal rhodium precursor and the auxiliary metal in a solvent, stirring and mixing with the calcined solid from (2), and further drying; (4) The solid obtained in (3) is subjected to reduction treatment at a reduction temperature of 200 to 500° C. in a reducing atmosphere containing hydrogen and carbon monoxide to obtain a catalyst.

2. The catalyst preparation method according to claim 1, wherein the precursor of the metallic cobalt is any one of cobalt nitrate, cobalt chloride, cobalt sulfate, and cobalt carbonyl, or a combination thereof; and the precipitant is any one of hydroxide, carbonate, and bicarbonate, or a combination thereof.

3. The catalyst preparation method according to claim 1, wherein the mixing method is to drop one or two of the A, B and C solutions into the other solutions, the mixing reaction temperature is 10 to 70°C, and the pH value in the mixing reaction is 7 to 10.

4. The method for preparing a catalyst according to claim 1, wherein the metal rhodium precursor is any one of rhodium trichloride, rhodium nitrate, triphenylphosphine carbonyl rhodium hydride, dicarbonyl acetylacetonate rhodium, acetylacetonate carbonyl rhodium hydride or a combination thereof, and the molar ratio of the metal rhodium precursor to the metal cobalt precursor is 0.0005 to 0.01; the auxiliary metal is one or a combination of alkali metals and alkaline earth metals, and the molar ratio of the auxiliary metal to the metal cobalt precursor is 0.01 to 0.

2. The method for preparing a catalyst according to claim 1 , wherein the molar ratio of hydrogen to carbon monoxide is 0.5 to 2.

6. A method for synthesizing aldehydes using the heterogeneous catalyst according to any one of claims 1 to 5, Features: In a CO / H2 mixed atmosphere, a mixture containing unsaturated olefins, the heterogeneous catalyst and a solvent is subjected to a hydroformylation reaction at 80-200°C to obtain the corresponding aldehyde, the total pressure of the H2 / CO synthesis gas is 3-7 MPa, and the H2 / CO synthesis gas ratio is 0.5-3.

7. The method for producing aldehyde according to any one of claims 1 to 6, characterized in that The reaction process involves three phases: gas, liquid and solid. The main component of the gas phase is synthesis gas, the liquid phase is mainly olefin reactants and aldehyde products, the solid phase is a solid catalyst, and the reactor is one or a combination of an intermittent stirred tank, a slurry bed and a trickle bed reactor.

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