Application and preparation of ethylene glycol

Overview

Ethylene glycol is an important national chemical raw material and strategic material, used to manufacture polyester (can further produce polyester, PET bottles, films ), ****, glyoxal, and can be used as antifreeze, plasticizer, hydraulic fluid and solvent, etc. In 2009, China’s ethylene glycol imports exceeded 5.8 million tons. It is expected that my country’s ethylene glycol demand will reach 11.2 million tons in 2015, with a production capacity of about 5 million tons. The gap between supply and demand is still 6.2 million tons. Therefore, my country’s ethylene glycol The development and application of new production technologies have good market prospects. Internationally, ethylene oxide from petroleum cracking is mainly oxidized to obtain ethylene oxide, and ethylene oxide is hydrated to obtain ethylene glycol. In view of my country’s energy resource structure of being “rich in coal but short of oil and gas” and the long-term high price of crude oil, the new coal chemical technology of coal-to-ethylene glycol can not only ensure the country’s energy security, but also make full use of my country’s coal resources. It is the most realistic choice for the future coal chemical industry.

Ethylene glycol

application

Reaction of ethylene glycol and alkyl halide

A method for synthesizing ethylene glycol monomethyl ether using methyl iodide and ethylene glycol as raw materials. The method uses iron perchlorate as a catalyst and ethylene glycol monomethyl ether. The selectivity of methyl ether is 88%. This type of method contains hydrochloric acid as a by-product, which requires high equipment anti-corrosion and will increase equipment investment.

Reaction of ethylene glycol and monohydric alcohol

Charles Baimbridge disclosed in US2004/0044253A1 and others a method for synthesizing ethylene glycol ether by reacting ethylene glycol and monohydric alcohol. The catalyst used is perfluorocarbon sulfonate. Acid polymer, Nafion; the mass ratio of monohydric alcohol and ethylene glycol is 3-5:1, reaction temperature is 100-300°C, pressure is 6.895MPa, reaction time is 4-5 hours, ethylene glycol conversion rate is 75.7%, ethyl alcohol The total selectivity of glycol methyl ether and ethylene glycol dimethyl ether is 94.3%.

Using Oxidation of Cs/P/Si A method for synthesizing ethylene glycol methyl ether by reacting ethylene glycol and methanol using a substance as a catalyst. The reaction temperature is 300°C, the reaction pressure is 0.1-12MPa, the ethylene glycol conversion rate is 46-23%, and the ethylene glycol ether selectivity is 10-76 %, that is, the ethylene glycol conversion rate at low pressure is 46%, but the selectivity of ethylene glycol methyl ether is low, which is 10%. At a high pressure of 12MPa, the selectivity of ethylene glycol methyl ether reaches 76%, but the ethylene glycol conversion rate is only 23%. And there are many by-products, including diethylene glycol, 1,4-dioxane, acetaldehyde, 3-�� and a molecule of water, the chemical equation is as follows:

2HOCH2CH2OH→HOCH2CH2OCH2CH2OH+H2O

Excessive hydrogenation of ethylene glycol produces ethanol and water. The chemical equation is as follows:

HOCH2CH2OH+H2→CH3CH2OH+H2O

The reaction of ethylene glycol and ethanol produces1,2-butanediol (1,2-BDO ) and water, the chemical equation is as follows:

HOCH2CH2OH+CH3CH2OH→HOCH2CH(CH2CH3)OH+H2O

Ethylene glycol reacts with methanol to produce1,2-propanediol (1,2-PDO) and water. The chemical equation is as follows:

HOCH2CH2OH+CH3OH→HOCH2CH(CH3)OH+H2O

As can be seen from the reaction equation, during the preparation of ethylene glycol , there will be methyl glycolate, the intermediate product of the hydrogenation of dimethyl oxalate, and the accompanying by-products are methanol, ethanol, water, diethylene glycol, glycerol, 1,2-propanediol and 1,2 -Butanediol, etc. The presence of by-products affects the purity of ethylene glycol products. For example, 1,2-propanediol and 1,2-butanediol affect the UV transmittance of ethylene glycol products. Therefore, the by-products are separated and the high value-added products contained in them are recovered. , it is very critical to improve the purity and UV transmittance of ethylene glycol products.

DocumentationUS4,966,658 proposed to use ethylbenzene , 3-heptanone, diisobutyl ketone, etc. are used as entrainers to separate ethylene glycol from 1,2-butanediol and 1,3-butanediol using azeotropic distillation method. Theoretical plate of the distillation tower The number is 30. Document CN103193594A uses a stream containing ethylene glycol and 1,2-butanediol to remove light components through a separation tower and then enters the middle and lower part of the azeotropic distillation tower, where the ethylene glycol forms a co-evaporator with the entrainer added at the top of the tower. The boiling matter is evaporated from the top of the tower and enters the phase separator after condensation. After phase separation, the upper entrainer-rich phase returns to the top of the tower to continue participating in the azeotrope, and the lower ethylene glycol-rich phase enters the fourth separation tower for purification to obtain ethyl alcohol. Glycol products.

Documentation CN102372601A uses resolving agent I and resolving agent Agent II plus distillation to separate ethylene glycol, propylene glycol and butylene glycol. Wu Liangquan et al. analyzed the mechanism of impurities produced during the hydrogenation of oxalate esters to ethylene glycol, and briefly described the impact of different impurities on the UV value of ethylene glycol products (Natural Gas Chemical Industry, 2011, 36(6):66-70) . CN203174007U uses a two-stage dealcoholization tower for methanol recovery and adds a dealcoholization tower to recover ethanol and a dealtylene glycol tower to collect butanediol. It can collect ethanol and butanediol with higher purity to increase revenue and reduce costs. At the same time, Part of the qualified ethylene glycol extracted from the top of the ethylene glycol refining tower is returned to the dealtylene glycol tower.

Main reference materials

[1] Bai Ying, Lu Chunshan, Ma Lei, Chen Ping, Zheng Yifan, & Li Xiaonian. (2006). Ce and mg modified γ-al2o3 supported pt catalyst catalyzes hydrogen production by aqueous reforming of ethylene glycol. Journal of Catalysis, 27(3).

[2] Zhao Guanhong, Zheng Mingyuan, Wang Aiqin, & Zhang Tao. (2010). Catalytic conversion of cellulose to ethylene glycol by tungsten phosphide. Journal of Catalysis, 31(8), 928-932.

[3] Zhou Zhangfeng, Li Shaoji, Pan Pengbin, Lin Ling, Qin Yeyan, & Yao Yuangen. . Progress in coal-to-ethylene glycol technology. Chemical Industry Progress (11), 7-13.

�� and a dealylene glycol tower is used to collect butanediol, which can collect ethanol and butanediol with higher purity to increase revenue and reduce costs. At the same time, qualified ethylene glycol will be extracted from the top of the ethylene glycol refining tower. A portion is returned to the dealtylene glycol tower.

Main reference materials

[1] Bai Ying, Lu Chunshan, Ma Lei, Chen Ping, Zheng Yifan, & Li Xiaonian. (2006). Ce and mg modified γ-al2o3 supported pt catalyst catalyzes hydrogen production by aqueous reforming of ethylene glycol. Journal of Catalysis, 27(3).

[2] Zhao Guanhong, Zheng Mingyuan, Wang Aiqin, & Zhang Tao. (2010). Catalytic conversion of cellulose to ethylene glycol by tungsten phosphide. Journal of Catalysis, 31(8), 928-932.

[3] Zhou Zhangfeng, Li Shaoji, Pan Pengbin, Lin Ling, Qin Yeyan, & Yao Yuangen. . Progress in coal-to-ethylene glycol technology. Chemical Industry Progress (11), 7-13.