Solid base catalyst for preparing 2-propyl heptenal through valeraldehyde condensation

Abstract

The invention provides a solid base catalyst for preparing 2-propyl heptenal through valeraldehyde condensation. A carrier of the catalyst is mesoporous molecular sieve modified fluorine-doped g-nitrogen carbide, an active component is alkali metal oxide and / or alkaline earth metal oxide, and an auxiliary agent is a metalloporphyrin compound. The catalyst has the advantages of high yield and stable activity.

Description

Technical Field

[0001] The present invention belongs to the field of catalysts, and particularly relates to a solid base catalyst for the condensation of valeraldehyde to prepare 2-propylheptenal. Background Art

[0002] 2-Propylheptenal is an important chemical raw material. It can not only be hydrogenated to prepare 2-propylheptanol as a plasticizer alcohol raw material, but also be oxidized to produce 2-propylheptanoic acid, which is widely used in fields such as coatings and plastics.

[0003] Currently, the industrial production of 2-propylheptenal is mainly from a 2-propylheptanol co-production unit. Using butene and syngas as raw materials, valeraldehyde is prepared by low-pressure hydroformylation. Valeraldehyde undergoes an aldol condensation reaction under the catalysis of a 2% NaOH solution to obtain 2-propylheptenal. In the aldol condensation process, valeraldehyde first condenses to obtain a C10 hydroxyaldehyde, and then dehydrates to obtain 2-propylheptenal. The traditional process uses a 2% alkali solution as a catalyst, resulting in a large amount of wastewater. Moreover, this wastewater has problems such as high COD and high pH value, leading to prominent environmental protection issues. In addition, during the dehydration process of the C10 hydroxyaldehyde, it will continue to condense with valeraldehyde to obtain C15 heavy components, affecting the reaction selectivity. Using a solid base catalyst can effectively reduce the amount of wastewater generated and is beneficial for the dehydration reaction of the hydroxyaldehyde. However, the formation of the condensation product water will cause the rapid loss of the catalyst active center. Therefore, synthesizing an efficient solid base catalyst is the key to solving the condensation wastewater problem.

[0004] CN1105012 uses a 2% NaOH solution as a catalyst, with a catalyst-to-water ratio of 1:1. Under the conditions of a reaction temperature of 60 - 120°C and a reaction pressure of 0.1 - 1 MPa, the conversion rate of valeraldehyde condensation to prepare 2-propylheptenal can reach 95%, and the selectivity is 90%. However, the amount of wastewater is large, the pH value of the wastewater is high, and the aldehyde-containing substances are difficult to biochemically treat.

[0005] CN102093183 uses a solid base catalyst to catalyze n-butanal to prepare 2-ethylhexenal, with a conversion rate of n-butanal of 95% and a selectivity of 70%. The selectivity of this method for n-butanal is relatively low. At the same time, a large amount of solvent is required to dilute the raw materials, resulting in a low reaction efficiency.

[0006] In summary, it is necessary to find a solid catalyst with high yield and stable activity to solve the deficiencies in the prior art. Summary of the Invention

[0007] One of the objectives of the present invention is to provide a solid base catalyst for the condensation of valeraldehyde to prepare 2-propylheptenal, which has the advantages of high yield and stable activity.

[0008] To achieve the above invention objectives, the technical solutions adopted by the present invention are as follows:

[0009] A solid base catalyst for the preparation of 2-propylheptenal by the aldol condensation of valeraldehyde, wherein the carrier of the catalyst is mesoporous molecular sieve modified fluorine-doped g-carbon nitride, the active component is alkali metal oxide and / or alkaline earth metal oxide, and the promoter is metal porphyrin compound.

[0010] The mesoporous molecular sieve modified fluorine-doped g-carbon nitride composite solid base catalyst used in the present invention is simple to prepare. The carrier of this catalyst can obtain a substrate material with a spherical microstructure by modifying the mesoporous molecular sieve and adding iron porphyrin, and then coating fluorine-doped g-C3N4 can form an eggshell catalyst. This carrier has a larger specific surface area. In addition, a large number of N-containing groups can not only provide basic active centers but also effectively stabilize metal nanoparticles. The addition of the promoter not only helps the formation of the microstructure of the molecular sieve but also can change the microstructure of the alkali metal oxide to enhance its water resistance, protect the basic center, and at the same time accelerate the separation of the product water from the catalyst, improve the reaction efficiency, and solve the wastewater problem of liquid base catalysis.

[0011] In one embodiment of the present invention, the mass of the fluorine-doped g-carbon nitride accounts for 65-95 wt% of the carrier, preferably 75-85 wt%.

[0012] In one embodiment of the present invention, the active component is one or more of calcium oxide, magnesium oxide, cesium oxide, and rubidium oxide, preferably calcium oxide and cesium oxide; preferably, the mass ratio of calcium oxide to cesium oxide is 1-10:1, preferably 2-5:1.

[0013] In one embodiment of the present invention, the active component accounts for 1-50 wt% of the catalyst, preferably 5-15 wt%.

[0014] In one embodiment of the present invention, the promoter is one or more of iron porphyrin, nickel porphyrin, and vanadium porphyrin.

[0015] In one embodiment of the present invention, the addition amount of the promoter accounts for 0.1-1 wt% of the molecular sieve, preferably 0.1-0.5 wt%.

[0016] Another object of the present invention is to provide a method for preparing the above catalyst.

[0017] A method for preparing the above catalyst, the method comprising the following steps:

[0018] S1: Synthesize spherical mesoporous molecular sieve under the action of a template agent;

[0019] S2: Add a promoter and in-situ load the active component;

[0020] S3: Coating fluorine-doped g-carbon nitride on the outside of the molecular sieve to obtain a composite solid base catalyst.

[0021] In one embodiment of the present invention, in S1, the templating agent and tetraethyl orthosilicate react at 10 - 50 °C for 2 - 8 h.

[0022] In one embodiment of the present invention, in S2, a soluble active metal salt is added, preferably one or more of calcium chloride, calcium nitrate, calcium gluconate, cesium chloride, cesium sulfate, and cesium nitrate, more preferably one or more of calcium chloride, calcium nitrate, and calcium gluconate, and further preferably calcium chloride and / or cesium chloride.

[0023] In one embodiment of the present invention, in S2, crystallization is carried out after loading the active component; preferably, the crystallization temperature is 70 - 150 °C, preferably 80 - 100 °C, and the crystallization time is 1 - 48 h, preferably 12 - 24 h.

[0024] In one embodiment of the present invention, in S3, a nitrogen-containing precursor and a fluorine-containing precursor are dissolved as a coating agent; preferably, the nitrogen-containing precursor is one or more of urea, melamine, and N,N-dimethylformamide, preferably urea; preferably, the fluorine-containing precursor is one or more of tetrafluoroethylene, ammonium bifluoride, and calcium fluoride, preferably calcium fluoride; preferably, the molar ratio of the fluorine element to the nitrogen element in the precursor is 1:20 - 50, preferably 1:40 - 50.

[0025] In one embodiment of the present invention, in S3, after adding the coating agent, drying is carried out at 40 - 60 °C for 1 - 2 h.

[0026] In one embodiment of the present invention, after drying in S3, calcination is carried out at 400 - 500 °C in a nitrogen atmosphere for 4 - 8 h.

[0027] Another object of the present invention is to provide a use of a solid base catalyst.

[0028] A use of a solid base catalyst, wherein the catalyst is the above catalyst or the catalyst prepared by the above method, and the catalyst is used for catalyzing the aldol condensation of valeraldehyde to prepare 2-propylheptenal.

[0029] Another object of the present invention is to provide a method for preparing 2-propylheptenal.

[0030] A method for preparing 2-propylheptenal, wherein the preparation method uses the above catalyst or the catalyst prepared by the above method, and n-valeraldehyde undergoes aldol condensation at a temperature of 70 - 110 °C, a pressure of 0.2 - 1 MPa, and a space velocity of 0.5 - 2 h -1 in a fixed-bed reactor to produce 2-propylheptenal.

[0031] In the present invention, unless otherwise specified, the pressure is gauge pressure.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0033] The process of the present invention is simple, the catalyst has high reaction activity, the conversion rate of valeraldehyde can reach 99%, the selectivity of enal can reach 98%, and the catalyst can be reused. The promoter can enhance the hydrophobicity of the catalyst, avoid the loss of basic centers caused by the condensation to generate water, and at the same time accelerate the separation of the product water from the catalyst, improving the reaction efficiency. Specific Embodiments

[0034] The present invention will be further described below in conjunction with specific embodiments. These embodiments are only used to illustrate the present invention, but the implementation manners of the invention are not limited thereto.

[0035] Source of raw materials: The condensation raw material valeraldehyde is the valeraldehyde obtained by the hydroformylation reaction of butene. After removing the catalyst, it directly undergoes the condensation reaction. The content of n-valeraldehyde in the valeraldehyde raw material used is 99.19 wt%, n-valeric acid is 0.2 wt%, valeraldehyde polymers are 0.61 wt%, and other raw materials are all commercially available.

[0036] The information of the raw materials used is shown in the following table:

[0037]

[0038]

[0039] The information of the equipment used is shown in the following table:

[0040] Device Name Model Manufacturer Muffle Furnace SXL-1016 Shanghai Jinghong Equipment Instrument Co., Ltd. Fixed Bed Yantai Keli Chemical Equipment Co., Ltd. Gas Chromatograph 2010PLUS Shimadzu

[0041] Analysis and characterization method: Gas chromatography equipped with an FID detector and an SE-54 capillary column (25.0 m x 0.53 mm x 0.02 mm) was used for analysis. The chromatography was analyzed by programmed temperature rise. It was maintained at 120 °C for 1 min, then raised to 200 °C at a rate of 15 °C / min and maintained for 10 min. The injection port temperature was 240 °C, the split ratio was 50:1, the detector was FID, and the temperature was 240 °C.

[0042] Example 1

[0043] Weigh 4 g of the template agent F127, put it into a 500 mL beaker, and then pour in 160 mL of dilute hydrochloric acid (1 mol / L). Stir and dissolve it at 50 °C; slowly add 10.4165 g of tetraethyl orthosilicate dropwise and then continue to stir and react for 2 h.

[0044] Weigh 0.003 g of iron porphyrin, 0.6006 g of calcium chloride, and 0.3626 g of cesium chloride and add them to the solution. Continue to stir for 4 h, then crystallize at 70 °C for 1 h. After filtration, washing with deionized water, drying at 80 °C for 1 h, and calcining at 500 °C for 4 h, the GaCs / SBA-16 molecular sieve was obtained.

[0045] Dissolve 74.4519 g of urea and 3.1022 g of tetrafluoroethylene in 50 ml of methanol and dropwise add it to the above molecular sieve, then dry it at 40 °C for 2 h, and then calcine it at 400 °C for 8 h to obtain the GaCs / SBA-16 / F-g-C3N4 composite solid base catalyst A.

[0046] Example 2

[0047] Weigh 4 g of template agent F127, put it into a 500 mL beaker and then pour in 160 mL of dilute hydrochloric acid (1 mol / L), stir and dissolve it at 40 °C; gradually add 10.4165 g of tetraethyl orthosilicate dropwise and then continue to stir and react for 4 h.

[0048] Weigh 0.0225 g of nickel porphyrin, 2.7752 g of magnesium sulfate and 0.1692 g of cesium sulfate and add them to the above solution, continue to stir for 4 h, then crystallize at 90 °C for 24 h, filter, wash with deionized water, dry at 90 °C for 1 h, and calcine at 500 °C for 4 h to obtain the MgCs / SBA-16 molecular sieve.

[0049] Dissolve 15.5583 g of melamine and 0.5274 g of ammonium hydrogen fluoride in 50 ml of ethanol and dropwise add it to the above molecular sieve, then dry it at 50 °C for 1 h, and then calcine it at 500 °C for 4 h to obtain the MgCs / SBA-16 / F-g-C3N4 composite solid base catalyst B.

[0050] Example 3

[0051] Weigh 4 g of template agent F127, put it into a 500 mL beaker and then pour in 160 mL of dilute hydrochloric acid (1 mol / L), stir and dissolve it at 35 °C; gradually add 10.4165 g of tetraethyl orthosilicate dropwise and then continue to stir and react for 5 h.

[0052] Weigh 0.015 g of iron porphyrin, 4.3722 g of calcium chloride and 0.6111 g of cesium nitrate and add them to the above solution, continue to stir for 4 h, then crystallize at 120 °C for 48 h, filter, wash with deionized water, dry at 80 °C for 2 h, and calcine at 500 °C for 4 h to obtain the GaCs / SBA-16 molecular sieve.

[0053] Dissolve 36.6251 g of N,N-dimethylformamide and 0.4528 g of calcium fluoride in 50 ml of methanol and dropwise add it to the above molecular sieve, then dry it at 60 °C for 1 h, and then calcine it at 500 °C for 6 h to obtain the GaCs / SBA-16 / F-g-C3N4 composite solid base catalyst C.

[0054] Example 4

[0055] Weigh 4 g of template F127, put it into a 500 mL beaker, then pour in 160 mL of dilute hydrochloric acid (1 mol / L), and stir to dissolve at 20 °C; gradually add 10.4165 g of tetraethyl orthosilicate dropwise, and then continue stirring and reacting for 7 h.

[0056] Weigh 0.0075 g of iron porphyrin, 34.4606 g of calcium gluconate and 2.7692 g of cesium sulfate, add them to the above solution, continue stirring for 4 h, then crystallize at 150 °C for 36 h, filter, wash with deionized water, dry at 90 °C for 2 h, and calcine at 500 °C for 4 h to obtain GaCs / SBA-16 molecular sieve.

[0057] Dissolve 8.2367 g of melamine and 0.1959 g of tetrafluoroethylene in 50 ml of isopropanol, dropwise add it to the above molecular sieve, then dry at 40 °C for 2 h, and then calcine at 450 °C for 5 h to obtain GaCs / SBA-16 / F-g-C3N4 composite solid base catalyst D.

[0058] Example 5

[0059] Weigh 4 g of template F127, put it into a 500 mL beaker, then pour in 160 mL of dilute hydrochloric acid (1 mol / L), and stir to dissolve at 10 °C; gradually add 10.4165 g of tetraethyl orthosilicate dropwise, and then continue stirring and reacting for 8 h.

[0060] Weigh 0.03 g of vanadium porphyrin, 22.8194 g of calcium nitrate and 0.9324 g of cesium chloride, add them to the above solution, continue stirring for 4 h, then crystallize at 100 °C for 12 h, filter, wash with deionized water, dry at 100 °C for 1 h, and calcine at 500 °C for 4 h to obtain GaCs / SBA-16 molecular sieve.

[0061] Dissolve 7.2773 g of urea and 0.2304 g of ammonium hydrogen fluoride in 50 ml of methanol, dropwise add it to the above molecular sieve, then dry at 50 °C for 2 h, and then calcine at 400 °C for 7 h to obtain GaCs / SBA-16 / F-g-C3N4 composite solid base catalyst E.

[0062] Comparative Example 1

[0063] Compared with Example 5, the difference is that only the molecular sieve is used to load alkali metals and it is not modified by carbon nitride.

[0064] Weigh 4 g of template F127, put it into a 500 mL beaker, then pour in 160 mL of dilute hydrochloric acid (1 mol / L), and stir to dissolve at 10 °C; gradually add 10.4165 g of tetraethyl orthosilicate dropwise, and then continue stirring and reacting for 8 h.

[0065] Weigh 0.03 g of vanadium porphyrin, 22.8194 g of calcium nitrate, and 0.9324 g of cesium chloride, add them to the above solution, continue stirring for 4 h, then crystallize at 100 °C for 12 h. After filtration, washing with deionized water, and drying at 100 °C for 1 h, calcine at 500 °C for 4 h to obtain the comparative solid base catalyst F.

[0066] Application Example

[0067] Example 1: Preparation of 2-propylheptenal by aldol condensation of valeraldehyde catalyzed by the catalyst:

[0068] A continuous experiment was carried out in a high-pressure fixed bed, filling 100 g of catalyst A. Valeraldehyde was at a temperature of 70 °C, a pressure of 0.2 MPa, and a space velocity of 0.5 h -1 Aldol condensation to produce 2-propylheptenal was carried out in a fixed bed reactor. The reaction products were quantified by gas chromatography, and the valeraldehyde raw material used was the above-mentioned raw material.

[0069] Example 2: Preparation of 2-propylheptenal by aldol condensation of valeraldehyde catalyzed by the catalyst:

[0070] A continuous experiment was carried out in a high-pressure fixed bed, filling 100 g of catalyst B. Valeraldehyde was at a temperature of 90 °C, a pressure of 0.6 MPa, and a space velocity of 1 h -1 Aldol condensation to produce 2-propylheptenal was carried out in a fixed bed reactor. The reaction products were quantified by gas chromatography, and the valeraldehyde raw material used was the same raw material.

[0071] Example 3: Preparation of 2-propylheptenal by aldol condensation of valeraldehyde catalyzed by the catalyst:

[0072] A continuous experiment was carried out in a high-pressure fixed bed, filling 100 g of catalyst C. Valeraldehyde was at a temperature of 100 °C, a pressure of 0.8 MPa, and a space velocity of 1.5 h -1 Aldol condensation to produce 2-propylheptenal was carried out in a fixed bed reactor. The reaction products were quantified by gas chromatography, and the valeraldehyde raw material used was the same raw material.

[0073] Example 4: Preparation of 2-propylheptenal by aldol condensation of valeraldehyde catalyzed by the catalyst:

[0074] A continuous experiment was carried out in a high-pressure fixed bed, filling 100 g of catalyst D. Valeraldehyde was at a temperature of 80 °C, a pressure of 0.4 MPa, and a space velocity of 0.7 h -1 Aldol condensation to produce 2-propylheptenal was carried out in a fixed bed reactor. The reaction products were quantified by gas chromatography, and the valeraldehyde raw material used was the same raw material.

[0075] Example 5: Preparation of 2-propylheptenal by aldol condensation of valeraldehyde catalyzed by the catalyst:

[0076] Continuous experiments were carried out in a high-pressure fixed bed, filling 100 g of catalyst E. Valeraldehyde was at a temperature of 110 °C, a pressure of 1 MPa, and a space velocity of 2 h -1 Aldol condensation was carried out in a fixed bed reactor to produce 2-propylheptenal. The reaction products were quantified by gas chromatography, and the same raw material of valeraldehyde was used.

[0077] Preparation of 2-propylheptenal by aldol condensation of valeraldehyde catalyzed by the catalyst of Comparative Example 1:

[0078] Continuous experiments were carried out in a high-pressure fixed bed, filling 100 g of catalyst F. Valeraldehyde was at a temperature of 110 °C, a pressure of 1 MPa, and a space velocity of 2 h -1 Aldol condensation was carried out in a fixed bed reactor to produce 2-propylheptenal. The reaction products were quantified by gas chromatography, and the same raw material of valeraldehyde was used.

[0079] The reaction results of all examples are shown in the following table:

[0080]

Claims

1. A solid base catalyst for the preparation of 2-propylheptenal by the aldol condensation of valeraldehyde, characterized in that, The carrier of the catalyst is mesoporous molecular sieve modified fluorine-doped g-carbon nitride, the active component is alkali metal oxide and / or alkaline earth metal oxide, and the promoter is metal porphyrin compound.

2. The catalyst according to claim 1, wherein The mass of the fluorine-doped g-carbon nitride accounts for 65-95 wt% of the carrier, preferably 75-85 wt%; and / or, the active component is one or more of calcium oxide, magnesium oxide, cesium oxide, rubidium oxide, preferably calcium oxide and cesium oxide; Preferably, the mass ratio of calcium oxide to cesium oxide is 1-10:1, preferably 2-5:1; and / or, the active component accounts for 1-50 wt% of the catalyst, preferably 5-15 wt%; and / or, the promoter is one or more of iron porphyrin, nickel porphyrin, vanadium porphyrin; and / or, the addition amount of the promoter accounts for 0.1-1 wt% of the molecular sieve, preferably 0.1-0.5 wt%.

3. A method for preparing the catalyst according to claim 1 or 2, characterized in that, The method comprises the following steps: S1: Synthesize spherical mesoporous molecular sieve under the action of a template agent; S2: Add a promoter and in-situ load the active component; S3: Coating fluorine-doped g-carbon nitride on the outside of the molecular sieve to obtain a composite solid base catalyst.

4. The method according to claim 3, wherein In S1, the template agent and tetraethyl orthosilicate react at 10-50 °C for 2-8 h.

5. The method according to claim 3, wherein In S2, soluble active metal salts are added, preferably one or more of calcium chloride, calcium nitrate, calcium gluconate, cesium chloride, cesium sulfate, cesium nitrate, more preferably one or more of calcium chloride, calcium nitrate, calcium gluconate, and further preferably calcium chloride and / or cesium chloride; and / or, crystallization is carried out after loading the active component in S2; Preferably, the crystallization temperature is 70-150 °C, preferably 80-100 °C, and the crystallization time is 1-48 h, preferably 12-24 h.

6. The method according to claim 3, characterized in that, In S3, the nitrogen-containing precursor and the fluorine-containing precursor are dissolved as the coating agent; Preferably, the nitrogen-containing precursor is one or more of urea, melamine, N,N-dimethylformamide, preferably urea; Preferably, the fluorine-containing precursor is one or more of tetrafluoroethylene, ammonium bifluoride, calcium fluoride, preferably calcium fluoride; Preferably, the molar ratio of F element to N element in the precursor is 1:20-50, preferably 1:40-50; and / or, after adding the coating agent in S3, it is dried at 40-60 °C for 1-2 h; and / or, after drying in S3, it is calcined at 400-500 °C in a nitrogen atmosphere for 4-8 h.

7. Use of a solid base catalyst, the catalyst is the catalyst described in claim 1 or 2, or the catalyst prepared by the method described in any one of claims 3-6, and the catalyst is used for catalyzing the aldol condensation of valeraldehyde to prepare 2-propylheptenal.

8. A method for preparing 2-propylheptenal, wherein the preparation method uses the catalyst described in claim 1 or 2, or the catalyst prepared by the method described in any one of claims 3-6, and is characterized in that, n-Valeraldehyde undergoes aldol condensation to produce 2-propylheptenal in a fixed-bed reactor at a temperature of 70-110°C, a pressure of 0.2-1 MPa, and a space velocity of 0.5-2 h -1 ​

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