Production of ethylene glycol

At present, there are two main production methods of ethylene glycol: petroleum route and non-petroleum route. There are three main production processes for producing ethylene glycol from petroleum ethylene, namely, hydration of ethylene oxide (EO), synthesis of ethylene glycol from ethylene oxide through intermediates, and co-production of ethylene glycol and dimethyl carbonate. There are two main production processes for non-petroleum routes, namely direct synthesis and indirect synthesis.

Petroleum route production technology

Ethylene oxide hydration method. Hydration of ethylene oxide is the main method to produce ethylene glycol in the world today. In this method, ethylene oxide is usually mixed with water, and then exchanges heat with the mixture of ethylene glycol and water leaving the hydrolysis reactor, and then enters the hydrolysis reactor for hydrolysis after preheating. Due to the large water consumption and low conversion rate of the above processes, direct catalytic hydration technology has been paid attention to in recent years, among which heterogeneous catalytic hydration method of Shell Company and homogeneous catalytic hydration method of Dow Company are representative, and MeteorEG300 catalyst of Dow Company has also been running in the demonstration device, and the ethylene glycol selectivity is over 95%.

Process for synthesizing ethylene glycol from ethylene oxide through intermediates. At present, the process of producing ethylene glycol from ethylene oxide through ethylene carbonate is relatively mature. Shell Omega process is that ethylene oxide reacts with carbon dioxide to produce ethylene carbonate, which is then hydrolyzed under the action of catalyst to produce ethylene glycol and carbon dioxide. The selectivity from EO to EG of this process is more than 99%, which is higher than that of the traditional process, and the investment, energy consumption and material consumption of the device are reduced. It has been industrialized in ethylene glycol plants such as Korea Lotte Dashan Company. Asahi Kasei Corporation of Japan produces polycarbonate (PC) and ethylene glycol by reacting ethylene oxide with carbon dioxide and then transesterification with methanol. The process has been commercialized in Taiwan Province Asahi Kasei Co., Ltd.

Co-production of dimethyl carbonate and ethylene glycol. The method of co-production of dimethyl carbonate (DMC) from ethylene glycol was developed by Texaco Chemical Company in recent years. At present, there is no industrial production device for this process in China. Non-petroleum route production technology

Direct synthesis is the simplest and most effective method. However, the reaction conditions of direct synthesis method are harsh, which requires high temperature and high pressure catalyst, and rhodium catalyst is very expensive. At the same time, a large number of by-products formate are produced, and the conversion rate and selectivity of the reaction are low, so it has not been widely popularized and applied.

Indirect synthesis method is to produce synthesis gas from coal gasification, and then synthesize dimethyl oxalate from synthesis gas, and then further react to synthesize ethylene glycol. Indirect synthesis method has long process flow, complex steps, complex equipment types and many by-products. At present, this technology is widely used in domestic buildings.

2007-20 17 Changes of Ethylene Glycol Capacity and Output in China

The global ethylene glycol market has shown a situation of overcapacity and slow demand growth, while the Middle East with resource advantages is planning and building a large number of petrochemical plants, including large ethylene glycol plants and polyester plants, and the focus of world ethylene glycol production is shifting to the eastern region, especially the Middle East. At the same time, China's domestic ethylene glycol production capacity cannot meet the market demand in the short term, and it will mainly rely on imports in recent years. Before 20 19, the domestic ethylene glycol production capacity will increase by about 400,000 tons/year, but the coal-to-ethylene glycol production capacity has great potential. According to statistics, the production capacity of coal-based ethylene glycol currently under construction and proposed is over 2 million tons/year. From 2007 to 20 17, the average annual growth rate of ethylene glycol production capacity in China was about 16.6%, and the average annual growth rate of output was about 16. 1%.

In the future, the domestic ethylene glycol industry will present a situation of diversified raw materials and fierce competition. The domestic petroleum route ethylene glycol will face the dual pressures of importing ethylene glycol from the Middle East and producing ethylene glycol from domestic coal, and the market competition will be further intensified. This kind of competition will promote the scientific and technological development and progress of the whole industry, which is conducive to the healthy development of downstream enterprises.

In 20 17, there were 9 national ethylene glycol production enterprises 19, with a total production capacity of 5.27 million tons/year and an output of about 4.605 million tons; There are 10 coal-to-ethylene glycol producers, with a total production capacity of 2.87 million tons/year and an output of about 1.54 million tons. The production area is mainly concentrated in East China with a total production capacity of 3.63 million tons/year, accounting for 44.5% of the national production capacity. The main reason is that the largest downstream polyester production of ethylene glycol is concentrated in East China, so the ethylene glycol production capacity in this area is relatively concentrated.

The vast majority of ethylene glycol production enterprises in China are large state-owned petrochemical enterprises, of which 1 1 belongs to China Petrochemical Company, with a total production capacity of 32 1 10,000 tons/year, accounting for about 39.4% of China's total ethylene glycol production capacity. There are five oil companies in China with a total production capacity of 770,000 tons/year, accounting for 7.8% of the total domestic production capacity. China CNOOC 1 has a production capacity of 350,000 tons/year, accounting for about 4.3% of the total domestic production capacity. In addition, there is a Liaoning Huajin Chemical (Group) Co., Ltd., a new production enterprise in the 20 10 ethylene glycol industry, with an existing production capacity of 200,000 tons/year, accounting for about 2.5% of the total domestic production capacity. By the end of 20 17, there were 1 1 national coal-based ethylene glycol producers, namely Xinjiang Tianye, Henan Jinyong Chemical Industry, Liaotong Jinmei, Lu Hua Hengsheng, Hubei Fertilizer, Huaihua Group, SIA Energy, Yangmei Shenzhou, Yangmei Shouyang and Yangmei Pingding.

In the next few years, the number of new ethylene glycol projects will increase significantly. In addition to the second phase project of China Shipping Shell, which was put into operation on 20 18, 400,000 tons/year of ethylene glycol will be added, and large-scale ethylene glycol plants will be built, including Hengli Petrochemical, Zhejiang Petrochemical, Sinochem Quanzhou Ethylene and Hong Sheng Petrochemical. In the last two years, more than 10 new ethylene glycol plants will be put into production, and the new production capacity will exceed 2 million tons/year.