CN103721697B - The catalyst of a kind of synthesizing acrylic ester and preparation method and application - Google Patents

Abstract

A catalyst for synthesizing propylene carbonate is a compound oxide composed of active component zinc oxide and auxiliary agent oxides, and its composition is that the mass content of Zn is 1-99%, and the mass content of auxiliary agent elements is 1-99%. %. The invention has the advantages of low cost, high selectivity, high conversion rate, mild reaction conditions, good stability and easy separation of reactants.

Description

Catalyst, preparation method and application of a kind of synthetic propylene carbonate

technical field

The invention belongs to a catalyst for synthesizing propylene carbonate, a preparation method and application.

Background technique

One of the main uses of propylene carbonate (PC) is as an efficient desulfurization and decarbonization (CO ₂ ) solvent in industrial sectors such as natural gas purification and hydrogen production. It can also be used as a strong polar solvent in petrochemical, fiber and printing and dyeing industries. It is a good solvent for extracting petroleum fractions, raw lacquers, plasticizers and other insoluble substances. At the same time, it is also the raw material for the production of dimethyl carbonate by transesterification. In addition, using propylene carbonate as the electrolyte in the battery can withstand light, heat and chemical changes under harsh conditions, and can replace phenolic resin as a wood adhesive. It is mixed with isocyanate in a certain proportion, and wood chips can be bonded into high-strength wood boards, which can be used as building materials.

The main routes for the synthesis of propylene carbonate are: phosgene method, halogenated alcohol method, transesterification method, direct oxidation of olefins and carbon dioxide, CO ₂ cycloaddition method and urea method, etc. Among the above-mentioned several methods, the phosgene method has been gradually eliminated due to environmental protection reasons. In other methods, because the raw materials that can only be obtained by traditional petroleum routes are used, their prices are easily affected by fluctuations in petroleum prices, and the reaction conditions are relatively harsh. At present, industrial production of PC mainly uses propylene oxide and CO ₂ as raw materials, pyridine as a catalyst, and PC is produced at 240 ° C and 14 MPa. The reaction is carried out under high temperature and high pressure conditions. Antiknock agent. Myrl et al. further improved the reaction conditions and catalysts, using ammonium halides as catalysts, and synthesized PC under the conditions of 100-225°C and 2.17MPa. This method simplifies the process, the catalyst can be reused, and the yield of PC can reach up to 89%. Subsequently, researchers from various countries have conducted a lot of research on the cycloaddition reaction catalyst system of epoxy compounds and carbon dioxide. However, these catalysts have low catalytic activity or selectivity, low stability or require co-solvent, high pressure or high temperature conditions. At present, the industrial production is mainly based on the homogeneous catalytic system. It is still a great challenge to use an efficient and environmentally friendly catalytic system, and to fix carbon dioxide under mild conditions to synthesize cyclic carbonates. At the same time, the homogeneous catalytic system The separation and recycling of waste remains a major issue. In the 1990s, Texaco Corporation of the United States proposed the process of synthesizing cyclic carbonates by reacting urea with dihydric alcohols. The dihydric alcohols used are mainly aliphatic α-dihydric alcohols. The main advantages of this route are: the raw materials are cheap and easy to obtain, the reaction conditions are relatively mild, the by-product ammonia can be recycled to the production unit of urea synthesis, and the raw materials and products are easy to separate; the whole process does not use (or generate) toxic, corrosive, Flammable and explosive substances, it is a real "green" synthetic route. It can be seen that the synthesis method can realize "zero emission", meets the requirements of green chemical industry, and has a good development prospect. In 1993, on the basis of Su et al., Doya et al. of Mitsubishi Corporation of Japan proposed to use urea and 6-carbon or less vicinal diols to react to generate alkylene carbonate, and improved the synthesis reaction of olefin carbonate. Under these conditions, the yield of olefinic carbonate has been significantly increased with zinc, magnesium, lead, calcium and its compounds as catalysts, and the highest yield has reached 97.2%. Li Qibiao et al. used oxide catalysts such as ZnO, the catalyst dosage was 2%, and reacted at 170°C for 2 hours. As a result, ZnO had the highest activity and the PC yield reached 98.9%. Zhao Xinqiang and others studied the synthesis of propylene carbonate by the reaction of zinc acetate catalyzed urea and 1,2 propanediol, and the highest yield was 93.7%. Zinc acetate was loaded on activated carbon, the optimal load was 15%, and the highest yield of propylene carbonate was 78%. When examining the repeatability, it was found that there was a loss of active components.

Contents of the invention

The object of the present invention is to provide a catalyst for synthesizing propylene carbonate from urea and 1,2 propanediol, which has low cost, high selectivity, high conversion rate, mild reaction conditions, good stability and easy separation of reactants, as well as its preparation method and application.

The catalyst of the invention is a composite oxide composed of zinc oxide as an active component and auxiliary oxides, and the composition is that the mass content of Zn is 1-99%, and the mass content of auxiliary elements is 1-99%.

The additive elements mentioned above are one or more of alkaline earth metals and transition metal elements.

The alkaline earth metals mentioned above are Mg, Ca, Ba, etc., and the transition metal elements are Pb, Al, Fe, Mn, Zr, etc.

Catalyst of the present invention is prepared as follows:

1. Co-precipitation method: the catalyst is composed of a soluble metal salt, and a 5-50wt% precursor aqueous solution is prepared according to the mass ratio of the catalyst composition, and a 5-50wt% precipitant aqueous solution is prepared at the same time, and slowly added dropwise at 10-80°C In the precipitant solution, the pH value of the control process is 6-13, after the precipitation is complete, it is aged for 0.5-24h, and then washed with deionized water until no residual K ⁺ or Na ⁺ is detected, and the obtained product is filtered and in the Drying at 60-150°C for 1-24h, and finally calcining at 300-900°C for 0.5-12h to obtain the catalyst.

The soluble salts of the metals are acetates, chlorides or nitrates as mentioned above.

The precipitating agent mentioned above is sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate and the like.

2. Urea precipitation method: configure 1-60 wt% urea aqueous solution, make the catalyst into a soluble metal salt, configure it into a 1-60 wt% solution according to the molar ratio of the catalyst composition, and mix it with the above-mentioned urea solution, and then mix the The temperature of the solution is raised to 30-150°C for uniform precipitation reaction, the reaction time is 0.5-72h, after the reaction, the obtained product is used for suction filtration, then dried at 60-150°C for 1-24h, and finally calcined at 300-900°C for 0.5 -12h, the catalyst was obtained.

The soluble salts of the metals are acetates, chlorides or nitrates as mentioned above.

Application of the present invention is as follows:

The reaction conditions are: the molar ratio of propylene glycol to urea is 1-10:1, the temperature is 100-250°C, the vacuum degree is 50mmHg-650mmHg, the mass ratio of catalyst to urea is 0.001-0.1, and the reaction time is 0.5h-20h.

Compared with the prior art, the present invention has the following advantages:

1) The preparation process of the catalyst is simple and easy, with good stability and good reusability;

2) The catalyst has good performance, and is easy to separate from the product, and is easy to realize industrial scale-up;

3) The reaction raw materials are cheap and easy to obtain, the product yield is high, the by-products are less, and the economy of the synthesis process is very remarkable;

4) The reaction process is simple and easy to operate.

detailed description

Example 1:

The nitrate solution of zinc and calcium was prepared at a mass ratio of 99:1 and dissolved in distilled water to form a 15 wt% mixed solution. Co-precipitate with 30wt% sodium carbonate solution at 80°C. The precipitation process needs to be fully stirred to maintain pH = 10, then aged for 0.5h, the precipitate is washed with distilled water until no sodium ions are detected, dried at 60°C for 12h and dried After calcination at 300 °C for 12 h, the composite oxide formed by ZnO and CaO with a catalyst mass ratio of 99:1 was obtained.

The reaction between urea and 1,2 propylene glycol was carried out in a three-necked flask. The reaction conditions were as follows: the molar ratio of propylene glycol to urea was 10, the degree of vacuum was 300mmHg, T=170°C, the mass ratio of catalyst to urea was 0.03, and the reaction time was 0.5h. After the reaction, the product was separated by centrifugation, and the product composition was analyzed by gas chromatography, and the yield of PC was 82%.

Example 2.

The acetate solution of zinc and magnesium was prepared at a mass ratio of 1:1 and dissolved in distilled water to form a 5wt% mixed solution. Co-precipitate with 50wt% sodium carbonate solution at 60°C. The precipitation process needs to be fully stirred to maintain pH = 7, and then aged for 12 hours. The precipitate is washed with distilled water until no sodium ions are detected, dried at 150°C for 1 hour, and It was prepared by calcination at 900℃ for 0.5h, and the composite oxide formed by ZnO and MgO with catalyst mass ratio of 1:1 was obtained.

The reaction conditions of urea and 1,2 propylene glycol are as follows: the molar ratio of propylene glycol to urea is 1, the degree of vacuum is 500mmHg, T=140°C, the mass ratio of catalyst to urea is 0.01, and the reaction time is 2h. The composition of the product was analyzed by gas chromatography, and the yield of PC was 90%.

Example 3.

The nitrate solution of zinc, magnesium and iron was prepared according to the mass ratio of 1:98:1 and dissolved in distilled water to form a 50wt% mixed solution. Co-precipitate with 45wt% sodium carbonate solution at 10°C. The precipitation process needs to be fully stirred to maintain pH = 13, and then aged for 8 hours. The precipitate is washed with distilled water until no sodium ions are detected, dried at 100°C for 10 hours and passed through It is prepared by calcining at 450℃ for 6h, and the catalyst mass ratio is 1:98:1, which is a composite oxide formed by ZnO, MgO and Fe ₂ O ₃ .

The reaction conditions of urea and 1,2 propylene glycol are as follows: the molar ratio of propylene glycol to urea is 3, the degree of vacuum is 650mmHg, T=100°C, the mass ratio of catalyst to urea is 0.04, and the reaction time is 12h. The composition of the product was analyzed by gas chromatography, and the yield of PC was 84%.

Example 4.

The nitrate solution of zinc, aluminum and iron was prepared in a mass ratio of 4:2:1 and dissolved in distilled water to form a 40wt% mixed solution. Co-precipitate with 5wt% sodium carbonate solution at 60°C. The precipitation process needs to be fully stirred to maintain pH = 6, then aged for 24 hours, the precipitate was washed with distilled water until no sodium ions were detected, dried at 150°C for 14 hours and passed The catalyst was prepared by calcining at 650°C for 0.5h. Composite oxides formed by ZnO, Al ₂ O ₃ and Fe ₂ O ₃ with catalyst mass ratio of 4:2:1.

The reaction conditions of urea and 1,2 propylene glycol are as follows: the molar ratio of propylene glycol to urea is 5, the degree of vacuum is 200mmHg, T=170°C, the mass ratio of catalyst to urea is 0.02, and the reaction time is 2h. After the reaction, it was separated by centrifugation, and the composition of the product was analyzed by gas chromatography, and the yield of PC was 98%.

Example 5.

The zinc-calcium acetate solution was prepared at a mass ratio of 1:99 and dissolved in distilled water to form a 30wt% mixed solution, which was then mixed with a 60wt% urea aqueous solution. The temperature of the mixed solution was raised to 150° C. for a uniform precipitation reaction, and the reaction time was 12 h. After the reaction, the obtained product was suction filtered, then dried in an oven at 60°C for 24 hours, and finally calcined at 900°C for 12 hours to obtain a composite oxide formed of ZnO and CaO with a catalyst mass ratio of 2:1.

The reaction conditions of urea and 1,2 propylene glycol are as follows: the molar ratio of propylene glycol to urea is 4, the degree of vacuum is 50mmHg, T=200°C, the mass ratio of catalyst to urea is 0.001, and the reaction time is 6h. After the reaction, the product was separated by centrifugation, and the product composition was analyzed by gas chromatography, and the yield of PC was 85%.

Example 6.

The nitrate solution of zinc and aluminum is prepared at a mass ratio of 1:1 and dissolved in distilled water to form a 1% mixed solution, and then mixed with a 1% urea aqueous solution as a precipitating agent. The temperature of the mixed solution was raised to 120° C. for a uniform precipitation reaction, and the reaction time was 24 h. After the reaction, use the obtained product to carry out suction filtration, then dry it in an oven at 150°C for 12 hours, and finally calcinate it at 350°C for 12 hours. The composite oxide formed by ZnO and Al ₂ O ₃ with a catalyst mass ratio of 1:1 _.

The reaction conditions of urea and 1,2 propylene glycol are as follows: the molar ratio of propylene glycol to urea is 3, the degree of vacuum is 600mmHg, T=250°C, the mass ratio of catalyst to urea is 0.1, and the reaction time is 20h. The composition of the product was analyzed by gas chromatography, and the yield of PC was 86%.

Example 7.

The chloride solution of zinc, magnesium and iron is prepared according to the mass ratio of 1:1:1 and dissolved in distilled water to form a 60% mixed solution, and then mixed with a 50% urea aqueous solution as a precipitating agent. The temperature of the mixed solution was raised to 30° C. for a uniform precipitation reaction, and the reaction time was 0.5 h. After the reaction, use the product obtained for suction filtration, then dry it in an oven at 60°C for 12 hours, and finally calcinate it at 550°C for 4 hours. The catalyst mass ratio is 1:1:1 formed by ZnO, MgO and Fe ₂ O ₃ composite oxides.

The reaction conditions of urea and 1,2 propylene glycol are as follows: the molar ratio of propylene glycol to urea is 2, the degree of vacuum is 600mmHg, T=180°C, the mass ratio of catalyst to urea is 0.001, and the reaction time is 6h. The composition of the product was analyzed by gas chromatography, and the yield of PC was 87%.

Example 8.

Prepare zinc-zirconium-iron chloride solution at a mass ratio of 1:98:1 and dissolve it in distilled water to form a 40% mixed solution, and then mix it with 60% urea aqueous solution as a precipitant. The temperature of the mixed solution was raised to 120° C. for a uniform precipitation reaction, and the reaction time was 72 hours. After the reaction, use the product obtained for suction filtration, then dry it in an oven at 150°C for 12 hours, and finally calcinate it at 300°C for 4 hours. The catalyst mass ratio is 2:1:2 ZnO, ZrO ₂ and Fe ₂ O ₃ composite oxides.

The reaction conditions of urea and 1,2 propylene glycol are as follows: the molar ratio of propylene glycol to urea is 2, the degree of vacuum is 500mmHg, T=250°C, the mass ratio of catalyst to urea is 0.1, and the reaction time is 0.5h. The composition of the product was analyzed by gas chromatography, and the yield of PC was 83%.

Claims (3)

1. A catalyst for synthesizing propylene carbonate is characterized in that the catalyst is a composite oxide compound composed of active component zinc oxide and auxiliary agent oxide, and its composition is that the mass content of Zn is 1-99%, and the auxiliary agent element The mass content is 1-99%, wherein the additive element is a compound of Fe and Zr; and prepared by the following method: Method 1: The catalyst is composed of a soluble salt of the metal, and a 5-50 wt% precursor aqueous solution is prepared according to the mass ratio of the catalyst composition, and a 5-50 wt% precipitant aqueous solution is prepared at the same time, and slowly added dropwise to the precipitate at 10-80°C In the solvent solution, the pH value of the control process is 6-13. After the precipitation is complete, it is aged for 0.5-24h, and then washed with deionized water until no residual K ⁺ or Na ⁺ is detected. The obtained product is filtered at 60- Drying at 150°C for 1-24h, and finally calcining at 300-900°C for 0.5-12h to obtain the catalyst; Or method two: configure 1-60 wt% urea aqueous solution, make the soluble salt of the catalyst composition metal, configure it into a 1-60 wt% solution according to the molar ratio of the catalyst composition, mix it with the above-mentioned urea solution, and then raise the temperature of the mixed solution Carry out uniform precipitation reaction at 30-150°C, the reaction time is 0.5-72h, after the reaction, use the obtained product to carry out suction filtration, then dry at 60-150°C for 1-24h, and finally calcinate at 300-900°C for 0.5-12h , get the catalyst; Described precipitation agent is sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate or potassium bicarbonate. 2. a kind of catalyst of synthetic propylene carbonate as claimed in claim 1 is characterized in that the soluble salt of described metal is acetate, chloride or nitrate. 3. the application of a kind of catalyst of synthetic propylene carbonate as claimed in claim 1 or 2, is characterized in that comprising the steps: The molar ratio of propylene glycol to urea is 1-10:1, the temperature is 100-250°C, the vacuum degree is 50mmHg-650mmHg, the mass ratio of catalyst to urea is 0.001-0.1, and the reaction time is 0.5h-20h.