Preparation process of a catalyst for preparing dimethyl carbonate by urea alcoholysis

Abstract

The present invention discloses a preparation process of a catalyst for preparing dimethyl carbonate by urea alcoholysis, comprising the following steps: (1) immersing zeolite powder in an acid solution to form a modified zeolite powder; (2) uniformly mixing the modified zeolite powder, glass powder, ferroferric oxide powder and a binder, and granulating the resulting precursor in a protective atmosphere at a temperature not lower than the melting temperature range of the glass powder, thereby obtaining a modified porous carrier; and (3) immersing the modified porous carrier in Cu 2+ The modified porous support is separated from a saturated solution of a source, allowed to stand, and then dried. A NaBH4 solution is then added dropwise. After completion, a solid product is magnetically separated and calcined in a protective atmosphere. After completion, the resulting solid product is treated in hydrofluoric acid to obtain a catalyst. The above process of the present invention can effectively improve the binding force of the catalytically active components on the support, reduce their loss, and extend the service life of the catalyst.

Description

Technical Field

[0001] The invention relates to the technical field of dimethyl carbonate preparation, in particular to a preparation process of a catalyst for preparing dimethyl carbonate by a urea alcoholysis method. Background Art

[0002] Dimethyl carbonate (DMCO) contains multiple organic functional groups in its molecular structure, including carbonyl (-CO-), methyl (CH3-), methoxy (CH3O-), and carbonylmethoxy (CH3O-CO-). Consequently, it possesses diverse reactivity and is an important organic synthesis intermediate, widely used in organic synthesis reactions such as carbonylation, methylation, methoxylation, and carbonylmethylation. Four main DMC synthesis technologies exist: phosgene, transesterification, methanol carbonylation oxidation, and urea alcoholysis. The phosgene method has been replaced by the transesterification method due to drawbacks such as toxic byproducts, environmental pollution, and poor safety. Currently, transesterification accounts for over 70% of DMC production capacity, making it the primary production method. Urea alcoholysis has become a popular process in recent years. It uses urea and methanol as raw materials and produces DMC over a catalyst. The generated ammonia can be recycled, resulting in low pollution and excellent economic benefits, making it the greenest process for producing DMC. However, the catalyst for preparing dimethyl carbonate by urea alcoholysis is prone to loss during use, especially the active catalytic components loaded on the carrier, which are easily lost during use, resulting in a significant decrease in the catalytic efficiency of the catalyst, an increase in the frequency of catalyst replacement, and an increase in production costs. Summary of the Invention

[0003] To address the above-mentioned issues, the present invention provides a process for preparing a catalyst for preparing dimethyl carbonate by the urea alcoholysis method, which effectively improves the binding force of the catalytically active components on the support, reduces their loss, and increases the service life of the catalyst. To achieve the above-mentioned objectives, the present invention discloses the following scheme.

[0004] A process for preparing a catalyst for preparing dimethyl carbonate by urea alcoholysis comprises the following steps:

[0005] (1) Immerse the zeolite powder in acid solution for acid leaching. After the leaching is completed, separate the zeolite powder and wash it to neutrality to obtain modified zeolite powder for later use.

[0006] (2) The modified zeolite powder, glass powder, ferrosoferric oxide powder and binder are uniformly mixed and granulated, and the obtained precursor is calcined in a protective atmosphere, and the calcination temperature is not lower than the melting temperature range of the glass powder, thereby obtaining a modified porous carrier.

[0007] (3) Immersing the modified porous support into Cu 2+The modified porous support was separated after standing and dried, and then NaBH4 solution was added dropwise to carry out Cu 2+ After the reduction reaction is completed, the solid product is separated by magnetic separation, and then the solid product is placed in a protective atmosphere for re-calcination. After completion, the obtained solid product is placed in hydrofluoric acid for etching to obtain the catalyst.

[0008] Furthermore, in step (1), the ratio of the zeolite powder to the acid solution is 1 g: 20-30 ml, and the mass fraction of the acid solution is 25-35%.

[0009] Furthermore, in step (1), the acid solution includes any one of hydrochloric acid, sulfuric acid, etc.

[0010] Furthermore, in step (1), the acid leaching treatment is carried out for 1 to 2 hours, which helps to remove soluble impurities in the zeolite powder and improve its purity.

[0011] Furthermore, in step (2), the ratio of the modified zeolite powder, glass powder, ferrosoferric oxide powder, and binder is 90-100 parts by weight: 20-27 parts by weight: 18-23 parts by weight: 10-15 parts by weight. Optionally, the binder includes any one of starch, cyclodextrin, and water glass.

[0012] Furthermore, in step (2), the calcination temperature is 600-700° C., the calcination time is 40-60 min, and the melting temperature of the glass powder is not higher than 590° C. Optionally, the protective atmosphere includes any one of nitrogen, argon, etc.

[0013] Furthermore, in step (3), the modified porous support and Cu 2+ The ratio of the saturated solution of the source is 1g:15~40ml.

[0014] Furthermore, in step (3), the Cu 2+ The saturated solution of the source includes any one of a saturated aqueous solution of copper chloride, a saturated aqueous solution of copper sulfate, a saturated aqueous solution of copper nitrate, a saturated aqueous solution of copper acetate, and the like.

[0015] Furthermore, in step (3), the standing time is 30 to 50 minutes, so that the modified porous carrier can absorb the Cu 2+ .

[0016] Furthermore, in step (3), the ratio of the dried modified porous support to the NaBH4 solution is 1 g: 15-20 ml. Optionally, the mass fraction of the NaBH4 solution is 8-12%. Optionally, the drying temperature is 80-100°C, and the drying time is 30-45 minutes.

[0017] Furthermore, in step (3), the calcination temperature is 20-30°C higher than the melting temperature of the glass powder, and the calcination time is 20-35 minutes. Optionally, the protective atmosphere includes any one of nitrogen, argon, etc.

[0018] Furthermore, in step (3), the ratio of the solid product to hydrofluoric acid is 1 g: 20-40 ml. Optionally, the mass fraction of the hydrofluoric acid is 5-12%, and the etching treatment time is 15-20 min.

[0019] Compared with the prior art, the present invention has achieved the following beneficial technical effects: the present invention first performs acid leaching on the zeolite powder, which helps to eliminate soluble impurities in the zeolite, on the one hand, helps to improve the purity of the zeolite, and on the other hand, helps to expand the pore volume of the zeolite, improve the pore structure, and enhance the loading capacity of the copper element formed after the copper ions are reduced. Furthermore, the present invention uses the modified zeolite powder and glass powder, ferroferric oxide powder, and a binder to prepare a modified porous carrier, and immerses the carrier in Cu 2+ Cu is absorbed in the saturated solution of the source 2+ Then, NaBH4 solution was used to make the Cu 2+ Reduction reaction occurs to form copper simple substance loaded on the pore surface of modified porous carrier to form catalyst, and these copper simple substances can be used as catalytic active components to promote urea and methanol to generate dimethyl carbonate. However, the copper simple substance is easily lost after falling off from the carrier during use, causing the catalytic ability of the catalyst to decline, resulting in a decrease in the service life of the catalyst. For this reason, the present invention adds glass powder when preparing the modified porous carrier, which can not only be used as a binder to bond the modified zeolite powder into one to form a carrier matrix, and when calcining treatment is carried out again after loading the copper simple substance, the glass powder is melted again, and it can make the copper simple substance bonded to the carrier surface, and when the glass powder is hardened again after cooling, the copper simple substance is firmly fixed to the carrier surface, avoiding falling off and loss in the use engineering. The ferrosoferric oxide is not only convenient for separating the magnetic separation solid product after completing the reduction reaction, but also for the recycling of catalyst. Finally, the present invention also uses hydrofluoric acid for etching treatment, and the hydrofluoric acid can corrode the glass powder to a certain extent, which helps to expose part of the copper element buried in the glass melt, increase the catalytic sites, and help improve the catalytic efficiency. DETAILED DESCRIPTION

[0020] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present invention belongs.

[0021] It should be noted that the terms used herein are intended only to describe specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular is intended to include the plural. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they specify the presence of features, steps, operations, devices, components, and / or combinations thereof. The present invention will now be further described through specific implementations. Example 1

[0022] A process for preparing a catalyst for preparing dimethyl carbonate by urea alcoholysis comprises the following steps:

[0023] (1) Zeolite powder was mixed with 30% hydrochloric acid in a ratio of 1 g: 25 ml and then acid-leached for 1.5 hours. After the mixture was acid-leached, the zeolite powder was separated and washed with clean water until neutral. The modified zeolite powder was obtained and set aside.

[0024] (2) The modified zeolite powder, glass powder (melting temperature range 550-570°C), ferrosoferric oxide powder, and wheat starch were mixed in a ratio of 96 parts by weight: 25 parts by weight: 20 parts by weight: 12 parts by weight, stirred evenly, and then wet granulated. The resulting precursor was then heated to 650°C in a nitrogen atmosphere and calcined for 50 minutes. After calcination, it was cooled to room temperature to obtain a modified porous support.

[0025] (3) The modified porous support and the saturated solution of copper chloride were mixed in a ratio of 1g:30ml and stirred evenly, and then allowed to stand for 40 minutes. After completion, the modified porous support was filtered out and dried at 90°C for 40 minutes, and then a 10% mass fraction NaBH4 solution (the ratio of the two was 1g:15ml) was added dropwise to the modified porous support for Cu 2+ The reduction reaction was carried out for 30 minutes. After completion, the solid product was magnetically separated and then calcined again at 600°C in a nitrogen atmosphere for 30 minutes. After completion, the solid product was mixed with 10% hydrofluoric acid at a ratio of 1g:30ml and allowed to stand for 15 minutes to obtain the catalyst. Example 2

[0026] A process for preparing a catalyst for preparing dimethyl carbonate by urea alcoholysis comprises the following steps:

[0027] (1) Zeolite powder was mixed with 35% hydrochloric acid in a ratio of 1 g: 20 ml and then acid-leached for 1 hour. After the mixture was acid-leached, the zeolite powder was separated and washed with clean water until neutral. The modified zeolite powder was obtained and set aside.

[0028] (2) The modified zeolite powder, glass powder (melting temperature range 580-590°C), ferrosoferric oxide powder, and water glass were mixed in a ratio of 90 parts by weight: 20 parts by weight: 18 parts by weight: 10 parts by weight, stirred evenly, and then wet granulated. The resulting precursor was then heated to 700°C in a nitrogen atmosphere and calcined for 40 minutes. After calcination, it was cooled to room temperature to obtain a modified porous support.

[0029] (3) The modified porous support and the saturated solution of copper sulfate were mixed in a ratio of 1g:15ml and stirred evenly, and then allowed to stand for 50 minutes. After completion, the modified porous support was filtered out and dried at 100°C for 30 minutes, and then 8% mass fraction NaBH4 solution (the ratio of the two was 1g:20ml) was added dropwise to the modified porous support for Cu 2+ The reduction reaction was carried out for 30 minutes. After completion, the solid product was magnetically separated and then calcined again at 620°C in a nitrogen atmosphere for 20 minutes. After completion, the solid product was mixed with 12% hydrofluoric acid at a ratio of 1g:20ml and allowed to stand for 20 minutes to obtain the catalyst. Example 3

[0030] A process for preparing a catalyst for preparing dimethyl carbonate by urea alcoholysis comprises the following steps:

[0031] (1) Zeolite powder was mixed with 25% sulfuric acid solution in a ratio of 1 g:30 ml and then acid-leached for 2 hours. After the mixture was acid-leached, the zeolite powder was separated and washed with clean water until neutral. The modified zeolite powder was obtained and set aside.

[0032] (2) The modified zeolite powder, glass powder (melting temperature range 540-560°C), ferrosoferric oxide powder, and water glass were mixed in a ratio of 100 parts by weight: 27 parts by weight: 23 parts by weight: 15 parts by weight, stirred evenly, and then wet granulated. The resulting precursor was then heated to 600°C in a nitrogen atmosphere and calcined for 60 minutes. After calcination, it was cooled to room temperature to obtain a modified porous support.

[0033] (3) The modified porous support and the saturated solution of copper acetate were mixed in a ratio of 1g:40ml and stirred evenly, and then allowed to stand for 30min. After completion, the modified porous support was filtered out and dried at 80℃ for 45min, and then a 12% mass fraction NaBH4 solution (the ratio of the two was 1g:18ml) was added dropwise to the modified porous support for Cu 2+The reduction reaction was carried out for 25 minutes. After completion, the solid product was magnetically separated and then calcined again at 580°C in a nitrogen atmosphere for 35 minutes. After completion, the solid product was mixed with 5% hydrofluoric acid at a ratio of 1g:40ml and allowed to stand for 20 minutes to obtain the catalyst. Example 4

[0034] A process for preparing a catalyst for preparing dimethyl carbonate by urea alcoholysis comprises the following steps:

[0035] (1) Zeolite powder was mixed with 30% hydrochloric acid in a ratio of 1 g: 25 ml and then acid-leached for 1.5 hours. After the mixture was acid-leached, the zeolite powder was separated and washed with clean water until neutral. The modified zeolite powder was obtained and set aside.

[0036] (2) The modified zeolite powder, glass powder (melting temperature range 550-570°C), ferrosoferric oxide powder, and wheat starch were mixed in a ratio of 96 parts by weight: 25 parts by weight: 20 parts by weight: 12 parts by weight, stirred evenly, and then wet granulated. The resulting precursor was then heated to 650°C in a nitrogen atmosphere and calcined for 50 minutes. After calcination, it was cooled to room temperature to obtain a modified porous support.

[0037] (3) The modified porous support and the saturated solution of copper chloride were mixed in a ratio of 1g:30ml and stirred evenly, and then allowed to stand for 40 minutes. After completion, the modified porous support was filtered out and dried at 90°C for 40 minutes, and then a 10% mass fraction NaBH4 solution (the ratio of the two was 1g:15ml) was added dropwise to the modified porous support for Cu 2+ The reduction reaction was carried out for 30 minutes. After completion, the solid product was separated by magnetic separation, mixed with 10% hydrofluoric acid at a ratio of 1g:30ml and allowed to stand for 15 minutes to obtain the catalyst. Example 5

[0038] A process for preparing a catalyst for preparing dimethyl carbonate by urea alcoholysis comprises the following steps:

[0039] (1) Zeolite powder was mixed with 25% sulfuric acid solution in a ratio of 1 g:30 ml and then acid-leached for 2 hours. After the mixture was acid-leached, the zeolite powder was separated and washed with clean water until neutral. The modified zeolite powder was obtained and set aside.

[0040] (2) The modified zeolite powder, glass powder (melting temperature range 540-560°C), ferrosoferric oxide powder, and water glass were mixed in a ratio of 100 parts by weight: 27 parts by weight: 23 parts by weight: 15 parts by weight, stirred evenly, and then wet granulated. The resulting precursor was then heated to 600°C in a nitrogen atmosphere and calcined for 60 minutes. After calcination, it was cooled to room temperature to obtain a modified porous support.

[0041] (3) The modified porous support and the saturated solution of copper acetate were mixed in a ratio of 1g:40ml and stirred evenly, and then allowed to stand for 30min. After completion, the modified porous support was filtered out and dried at 80℃ for 45min, and then a 12% mass fraction NaBH4 solution (the ratio of the two was 1g:18ml) was added dropwise to the modified porous support for Cu 2+ The reduction reaction was carried out for 25 minutes. After completion, the solid product was separated by magnetic separation, and then the solid product was placed in a nitrogen atmosphere and calcined again at 580°C for 35 minutes. After completion, it was cooled to room temperature to obtain the catalyst. Example 6

[0042] A process for preparing a catalyst for preparing dimethyl carbonate by urea alcoholysis comprises the following steps:

[0043] (1) Zeolite powder was mixed with 35% hydrochloric acid in a ratio of 1 g: 20 ml and then acid-leached for 1 hour. After the mixture was acid-leached, the zeolite powder was separated and washed with clean water until neutral. The modified zeolite powder was obtained and set aside.

[0044] (2) The modified zeolite powder, glass powder (melting temperature range 580-590°C), ferrosoferric oxide powder, and water glass were mixed in a ratio of 90 parts by weight: 20 parts by weight: 18 parts by weight: 10 parts by weight, stirred evenly, and then wet granulated. The resulting precursor was then heated to 700°C in a nitrogen atmosphere and calcined for 40 minutes. After calcination, it was cooled to room temperature to obtain a modified porous support.

[0045] (3) The modified porous support and a saturated solution of copper sulfate were mixed at a ratio of 1 g:15 ml, stirred evenly, and then allowed to stand for 50 minutes. After completion, the modified porous support was filtered out and dried at 100°C for 30 minutes. The solid product was then magnetically separated and calcined again at 620°C in a nitrogen atmosphere for 20 minutes. After completion, the solid product was mixed with 12% hydrofluoric acid at a ratio of 1 g:20 ml and allowed to stand for 20 minutes to obtain a catalyst.

[0046] The catalyst prepared in the above-mentioned Examples 1 to 6 is used in a process for preparing dimethyl carbonate using urea and methanol as raw materials, and the yield of dimethyl carbonate is calculated to measure the catalytic ability of the catalyst. The higher the yield of dimethyl carbonate, the stronger the catalytic ability of the catalyst. The calculation results are shown in the following table, wherein the calculation results of Examples 1 to 4 are all test results after reusing the catalyst three times. It can be seen that the catalysts of Examples 1 to 3 still have good catalytic ability after being reused many times, while the catalytic ability of the catalyst of Example 4 decreases significantly after being reused, which is mainly due to the active catalytic component falling off from the carrier. Example 5 is not etched, resulting in a decrease in the catalytic ability of the catalyst. Example 6 lacks an effective catalytic component in the catalyst, resulting in a significant decrease in the catalytic ability of the catalyst.

[0047]

[0048] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A process for preparing a catalyst for preparing dimethyl carbonate by urea alcoholysis, characterized in that: The steps include: (1) Immerse the zeolite powder in an acid solution for acid leaching. After the leaching is completed, separate the zeolite powder and wash it to neutrality to obtain the modified zeolite powder for later use; (2) The modified zeolite powder, glass powder, ferroferric oxide powder and binder are uniformly mixed and granulated, and the obtained precursor is calcined in a protective atmosphere, and the calcination temperature is not lower than the melting temperature range of the glass powder, thereby obtaining a modified porous carrier; (3) Immersing the modified porous support into Cu 2+ The modified porous support was separated after standing and dried, and then NaBH4 solution was added dropwise to carry out Cu 2+ After completion, the solid product is magnetically separated and then the solid product is placed in a protective atmosphere for calcination again. After completion, the solid product is placed in hydrofluoric acid for etching to obtain a catalyst.

2. The process for preparing a catalyst for preparing dimethyl carbonate by urea alcoholysis according to claim 1, wherein: In step (1), the ratio of the zeolite powder to the acid solution is 1 g: 20-30 ml; and the mass fraction of the acid solution is 25-35%.

3. The process for preparing a catalyst for preparing dimethyl carbonate by urea alcoholysis according to claim 1, wherein: In step (1), the acid solution is selected from any one of hydrochloric acid and sulfuric acid.

4. The process for preparing a catalyst for preparing dimethyl carbonate by urea alcoholysis according to claim 1, wherein: In step (1), the acid leaching treatment time is 1 to 2 hours.

5. The process for preparing a catalyst for preparing dimethyl carbonate by urea alcoholysis according to claim 1, wherein: In step (2), the ratio of the modified zeolite powder, glass powder, ferrosoferric oxide powder and binder is 90-100 parts by weight: 20-27 parts by weight: 18-23 parts by weight: 10-15 parts by weight.

6. The process for preparing a catalyst for preparing dimethyl carbonate by urea alcoholysis according to claim 1, wherein: In step (2), the binder is selected from any one of starch, cyclodextrin, and water glass.

7. The process for preparing a catalyst for preparing dimethyl carbonate by urea alcoholysis according to claim 1, wherein: In step (2), the calcination temperature is 600-700°C, the calcination time is 40-60 minutes, and the melting temperature of the glass powder is not higher than 590°C.

8. The process for preparing a catalyst for preparing dimethyl carbonate by urea alcoholysis according to claim 1, wherein: In step (2), the protective atmosphere is selected from any one of nitrogen and argon.

9. The process for preparing a catalyst for preparing dimethyl carbonate by urea alcoholysis according to claim 1, wherein: In step (3), the modified porous support and Cu 2+ The ratio of the saturated solution of the source is 1g:15~40ml.

10. The process for preparing a catalyst for preparing dimethyl carbonate by urea alcoholysis according to claim 1, wherein: In step (3), the Cu 2+ The saturated solution of the source is selected from any one of a saturated aqueous solution of copper chloride, a saturated aqueous solution of copper sulfate, a saturated aqueous solution of copper nitrate, and a saturated aqueous solution of copper acetate.

11. The process for preparing a catalyst for preparing dimethyl carbonate by urea alcoholysis according to claim 1, wherein: In step (3), the standing time is 30 to 50 minutes.

12. The process for preparing a catalyst for preparing dimethyl carbonate by urea alcoholysis according to claim 1, wherein: In step (3), the ratio of the dried modified porous carrier to the NaBH4 solution is 1 g: 15-20 ml.

13. The process for preparing a catalyst for preparing dimethyl carbonate by urea alcoholysis according to claim 1, wherein: In step (3), the mass fraction of the NaBH4 solution is 8-12%.

14. The process for preparing a catalyst for preparing dimethyl carbonate by urea alcoholysis according to claim 1, wherein: In step (3), the drying temperature is 80-100°C and the drying time is 30-45 minutes.

15. The process for preparing a catalyst for preparing dimethyl carbonate by urea alcoholysis according to claim 1, wherein: In step (3), the calcination temperature is 20-30°C higher than the melting temperature of the glass powder, and the calcination time is 20-35 minutes.

16. The process for preparing a catalyst for preparing dimethyl carbonate by urea alcoholysis according to claim 1, wherein: In step (3), the protective atmosphere is selected from any one of nitrogen and argon.

17. A process for preparing a catalyst for preparing dimethyl carbonate by urea alcoholysis according to any one of claims 1 to 16, characterized in that: In step (3), the ratio of the solid product to hydrofluoric acid is 1 g: 20-40 ml.

18. The process for preparing a catalyst for preparing dimethyl carbonate by urea alcoholysis according to any one of claims 1 to 16, characterized in that: The mass fraction of the hydrofluoric acid is 5-12%, and the etching time is 15-20 minutes.

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