Method for continuously preparing dimethyl carbonate by utilizing low-carbon carbon source

Abstract

The invention belongs to the field of fine chemical engineering, and relates to a method for continuously preparing dimethyl carbonate by using a low-carbon carbon source, which is carried out by adopting a micro-channel reaction device. The method comprises the following steps: adjusting a micro-channel reaction device, pumping slurry prepared from methanol and a catalyst into a reaction system, adjusting the flow of a low-carbon carbon source carbon dioxide according to the feeding amount, carrying out a micro-channel reaction, and carrying out reduced pressure distillation and separation on a reaction product to obtain dimethyl carbonate. The method has the advantages that 1) the low-carbon carbon source carbon dioxide generated by biomass and waste incineration is adopted, so that the green low-carbon environment-friendly requirements are better met; and 2) various types of catalysts can be adopted, the adaptability is relatively strong, the reaction conditions are mild, and a relatively good reaction effect can be achieved. Compared with a conventional reactor, the micro-channel reaction device is a great technical breakthrough, reaction conditions can be accurately controlled, the mass transfer efficiency and the heat transfer efficiency can be greatly improved due to the large heat exchange area, the intermittent operation mode of the conventional reactor can be broken through online continuous reaction, and test errors caused by intermittent operation are reduced.

Description

Technical Field

[0001] The invention belongs to the field of fine chemicals and relates to a method for continuously preparing dimethyl carbonate by utilizing a low-carbon carbon source. Background Art

[0002] Dimethyl carbonate (DMC) has the chemical formula C3H6O3, a melting point of 2~4 ℃, a boiling point of 90 ℃, and is a colorless, transparent liquid with a pungent odor. It is an important organic synthesis intermediate and solvent. Its molecular structure contains functional groups such as carbonyl, methyl, methoxy, and carbonylmethoxy. It can be widely used in organic synthesis reactions such as carbonylation, methylation, methoxylation, and carbonylmethylation. It has a variety of reaction properties and is safe, convenient, less polluting, and easy to transport. Dimethyl carbonate is a low-toxic, environmentally friendly, and widely used chemical raw material that meets the requirements of modern clean processes. As an excellent chemical intermediate, DMC can replace phosgene as a carbonylating agent and dimethyl sulfate (DMS) as a methylating agent to produce a variety of chemical products such as polycarbonate (PC), isocyanate, polyurethane, and polycarbonate diol. Its downstream covers industries such as plastics, pesticides, and medicines. In addition, DMC can also be used as a low-toxic, excellent solvent and a potential gasoline additive. Its terminals cover the fields of automobiles and energy storage, and it has a very broad application prospect.

[0003] Since the molecular structure of dimethyl carbonate contains multiple functional groups such as CH3-, CH3O-, CH3OCO-, -CO-, etc., it has good chemical reactivity. Therefore, on the one hand, dimethyl carbonate is expected to completely replace phosgene, dimethyl sulfate, methyl chloride, methyl chloroformate and other highly toxic or carcinogenic substances in many fields to undergo carbonylation, methylation, methylation, transesterification and other reactions to generate a variety of important chemical products. On the other hand, dimethyl carbonate can be used as a raw material to develop and prepare a variety of high value-added fine specialty chemicals, which are widely used in the fields of medicine, pesticides, synthetic materials, dyes, lubricant additives, food flavoring agents, electronic chemicals, etc. In addition, its non-reactive uses, such as solvents, solvents, gasoline additives, etc., are also being or will soon be put into practical use, and its development will play a positive role in promoting my country's coal chemical industry, methanol chemical industry and carbon one chemical industry.

[0004] In recent years, carbon dioxide and CH3OH direct synthesis method has received extensive attention. Carbon dioxide is industrial emissions, is a gas that causes greenhouse effect, and is also a potential carbon source. The direct synthesis of DMC by carbon dioxide and CH3OH is of great significance in synthetic chemistry, carbon resource utilization and environmental protection. However, the reaction is limited by thermodynamics, and the yield of DMC and the conversion rate of methanol are both low, and carbon dioxide is the stable state of carbon, and how to activate is also the key to the smooth progress of the reaction. Therefore, finding suitable catalysts and carriers, promoting the activation of carbon dioxide, and improving the yield of DMC are the key technologies for producing synthetic DMC, and are also the focus of research.

[0005] CN115990512A discloses a catalyst and its preparation method and its application in the preparation of dimethyl carbonate from carbon dioxide and methanol. The catalyst is composed of Ce oxide, acidic molecular sieve and binder. CN115322097A discloses a method for preparing dimethyl carbonate by direct reaction of carbon dioxide and methanol, which mainly includes taking methanol as raw material, mixing 5.5~8.0% of composite catalyst, pressurizing to 5.2~5.8MPa with carbon dioxide, maintaining the vapor pressure at 6.5~7.5MPa at 165~180℃, reacting for 7~8h to prepare a crude product; purification: filtering, magnetic separation and rectification of the crude product to prepare dimethyl carbonate. The reaction processes in the above two inventions are intermittent reactions and cannot be operated continuously. Summary of the invention

[0006] The invention provides a method for continuously preparing dimethyl carbonate by utilizing a low-carbon carbon source, and the preparation process is simple and environmentally friendly.

[0007] The main technical scheme of the present invention is a method for continuously preparing dimethyl carbonate using a low-carbon carbon source, characterized in that a microchannel reaction device is used according to the following steps: The microchannel reaction device is adjusted to inject the slurry prepared by methanol and catalyst into the reaction system, and the flow rate of low-carbon carbon source carbon dioxide is adjusted according to the feed amount. After the microchannel reaction, the reaction product is subjected to reduced pressure distillation to separate dimethyl carbonate; The microchannel reaction device adopts a multi-module structure. The connection mode between modules and the number of modules can be assembled according to needs. The module material is corrosion-resistant glass.

[0008] Generally, the methanol and catalyst are fed as a mixed slurry, and the flow rate of the mixed liquid is 5-100 g / min.

[0009] The mass fraction of the catalyst is 1% to 10% based on the total mass of the mixed liquid.

[0010] The catalyst is one or a combination of a metal oxide catalyst, a supported metal catalyst, and an ionic liquid catalyst.

[0011] Preferably, the metal in the supported metal catalyst is one or a combination of Cu, Fe, Pd, Pt, and Ni.

[0012] The metal oxide catalyst is one or a combination of CeO2, ZrO2, V2O5, TiO2, In2O3, MoO3, MgO, SnO2, ZnO, Fe2O3, and Al2O3.

[0013] The ionic liquid catalyst is one or a combination of imidazole type ionic liquid, pyridine type ionic liquid, quaternary ammonium salt ionic liquid and organic base DBU type ionic liquid.

[0014] The reaction temperature is 50-200°C.

[0015] The low-carbon carbon source carbon dioxide comes from biomass and garbage incineration.

[0016] Compared with the prior art, the method of the present invention has the following advantages: 1) It uses low-carbon carbon source carbon dioxide produced by biomass and garbage incineration, which better meets the requirements of green and low-carbon environmental protection. 2) It can use a variety of catalysts with strong adaptability and mild reaction conditions, which can achieve better reaction effects. 3) The use of a microchannel reaction device is a major breakthrough in technology compared to conventional reactors. It can accurately control the reaction conditions, and the larger heat exchange area can greatly improve the mass transfer and heat transfer efficiency; 4) The online continuous reaction can break the intermittent operation mode of conventional reactors and reduce the experimental errors caused by intermittent operation. Implementation

[0017] The present invention is described in detail below with reference to the embodiments. Example 1

[0018] After adjusting the temperature of the constant temperature system to the reaction temperature of 65°C, the mass fraction of the Cu-Fe / molecular sieve catalyst was 7%, methanol and the catalyst were pumped into the microchannel reaction device, the molar ratio of methanol to carbon dioxide was 2:1, and the mixed liquid at the reaction outlet was sampled and analyzed. The methanol conversion rate was 7.3% and the dimethyl carbonate selectivity was 71.6%. Example 2

[0019] After adjusting the temperature of the constant temperature system to the reaction temperature of 65°C, the mass fraction of the Cu-Mo / SiO2 catalyst was 6%, methanol and the catalyst were pumped into the microchannel reaction device, the molar ratio of methanol to carbon dioxide was 1.8:1, and the mixed liquid at the reaction outlet was sampled and analyzed. The methanol conversion rate was 8.4% and the dimethyl carbonate selectivity was 81.2%. Example 3

[0020] After adjusting the temperature of the constant temperature system to the reaction temperature of 70°C, the mass fraction of the Cu-Ni-Zr composite metal catalyst was 4%, methanol and the catalyst were pumped into the microchannel reaction device for reaction, and the mixed liquid at the reaction outlet was sampled and analyzed. The methanol conversion rate was 13.5%, and the dimethyl carbonate selectivity was 84.5%. Example 4

[0021] After adjusting the temperature of the constant temperature system to the reaction temperature of 70°C, the mass fraction of CeO2 catalyst was 6%, methanol and catalyst were pumped into the microchannel reaction device, the molar ratio of methanol to carbon dioxide was 1.7:1, and the mixed liquid at the reaction outlet was sampled and analyzed. The methanol conversion rate was 8.1% and the dimethyl carbonate selectivity was 83.1%. Example 5

[0022] After adjusting the temperature of the constant temperature system to the reaction temperature of 75°C, the mass fraction of ZrO2 / molecular sieve catalyst was 5%, methanol and catalyst were pumped into the microchannel reaction device, the molar ratio of methanol to carbon dioxide was 1.4:1, and the mixed liquid at the reaction outlet was sampled and analyzed. The methanol conversion rate was 7.2% and the dimethyl carbonate selectivity was 79.3%. Example 6

[0023] After adjusting the temperature of the constant temperature system to the reaction temperature of 75°C, the mass fraction of V2O5-CeO2 / molecular sieve catalyst was 3%, methanol and catalyst were pumped into the microchannel reaction device, the carbon dioxide flow rate was adjusted according to the feed amount for reaction, and the mixed liquid at the reaction outlet was sampled and analyzed. The methanol conversion rate was 10.2% and the dimethyl carbonate selectivity was 82.6%. Example 7

[0024] After adjusting the temperature of the constant temperature system to the reaction temperature of 80°C, the mass fraction of N-butylpyridinium bromide / molecular sieve alkaline ionic liquid catalyst was 3%, methanol and catalyst were pumped into the microchannel reaction device, the molar ratio of methanol to carbon dioxide was 1.2:1, and the mixed liquid at the reaction outlet was sampled and analyzed. The methanol conversion rate was 11.6%, and the dimethyl carbonate selectivity was 71.1%. Example 8

[0025] After adjusting the temperature of the constant temperature system to the reaction temperature of 85°C, the mass fraction of the organic base ionic liquid / carbon nanotube catalyst was 5%, methanol and the catalyst were pumped into the microchannel reaction device, the molar ratio of methanol to carbon dioxide was 1:1, and the mixed liquid at the reaction outlet was sampled and analyzed. The methanol conversion rate was 12.9% and the dimethyl carbonate selectivity was 73.9%. Example 9

[0026] After adjusting the temperature of the constant temperature system to the reaction temperature of 85°C, the mass fraction of the 1-methyl-3-propanesulfonic acid imidazolium ionic liquid catalyst was 7%, methanol and the catalyst were pumped into the microchannel reaction device, the molar ratio of methanol to carbon dioxide was 1.3:1, and the mixed liquid at the reaction outlet was sampled and analyzed. The methanol conversion rate was 10.7%, and the dimethyl carbonate selectivity was 68.4%.

Claims

1. A method for continuously preparing dimethyl carbonate using a low-carbon carbon source, characterized in that The microchannel reaction device is used according to the following steps: The microchannel reaction device is adjusted to inject the slurry prepared by methanol and catalyst into the reaction system, and the flow rate of low-carbon carbon source carbon dioxide is adjusted according to the feed amount. After the microchannel reaction, the reaction product is subjected to reduced pressure distillation to separate dimethyl carbonate; The microchannel reaction device adopts a multi-module structure. The connection mode between modules and the number of modules can be assembled according to needs. The module material is corrosion-resistant glass.

2. The method according to claim 1, characterized in that The methanol and the catalyst are fed as a mixed slurry, and the flow rate of the mixed liquid is 5-100 g / min.

3. The preparation method according to claim 1 or 2, characterized in that Based on the total mass of the mixed liquid, the mass fraction of the catalyst is 1%~10%.

4. The method according to claim 1 or 2, characterized in that The catalyst is one or a combination of a metal oxide catalyst, a supported metal catalyst and an ionic liquid catalyst.

5. The method according to claim 4, characterized in that The metal in the supported metal catalyst is one or a combination of Cu, Fe, Pd, Pt and Ni.

6. The method according to claim 4, characterized in that The metal oxide catalyst is one or a combination of CeO2, ZrO2, V2O5, TiO2, In2O3, MoO3, MgO, SnO2, ZnO, Fe2O3, and Al2O3.

7. The method according to claim 4, characterized in that The ionic liquid catalyst is one or a combination of imidazole type ionic liquid, pyridine type ionic liquid, quaternary ammonium salt ionic liquid and organic base DBU type ionic liquid.

8. The method according to claim 1, characterized in that The reaction temperature is 50-200°C, and the molar ratio of methanol to carbon dioxide is 1:1-2:

1.

9. The method according to claim 1, characterized in that Low-carbon carbon sources come from biomass and waste incineration.