Coal-based ethylene glycol products have been accepted, but they face an awkward situation

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Coal-based ethylene glycol products have been accepted, but face an awkward situation. Author/Source: Date: 2016-08-08 Clicks: 4 China is the world’s largest market for ethylene glycol, with a huge market capacity. However, domestic ethylene glycol production is still far from meeting the needs of the domestic market, so imports are required on a long-term basis. In recent years, the production of ethylene glycol from syngas in China has developed rapidly, and the product is gradually being accepted by downstream markets, allowing it to fill part of the domestic market gap. It is expected that the scale of ethylene glycol production from syngas in China will continue to expand in the coming years, and this method will play an important role in China’s ethylene glycol market. How to further reduce the overall cost of producing ethylene glycol from syngas, and how to establish industry standards for such production, have become the main challenges facing the sector at present. There is an imbalance in the supply and demand across global markets, with strong demand for ethylene glycol in China. Globally, as an important chemical product, ethylene glycol is primarily used in the production of polyesters (including polyester fibers, bottle caps, and films), as a antifreeze, and in the manufacture of unsaturated polyester resins. Among them, the production of polyester is the main application area for ethylene glycol. According to statistics, the global consumption of ethylene glycol used in polyester production each year accounts for over 85% of the total global consumption of ethylene glycol. The global ethylene glycol market is generally characterized by an oversupply, but there is an imbalance between production and consumption regions. The Middle East, Northeast Asia, and North America are the main regions that supply ethylene glycol worldwide, with their combined supply accounting for around 84% of the global total. Northeast Asia is the largest region in the world for ethylene glycol consumption, accounting for about 60% of global consumption. Among them, China, as the world’s largest consumer of ethylene glycol, consumed 12.75 million tons of it in 2015, accounting for about half of the global total consumption. By the end of 2015, China’s total capacity for producing ethylene glycol was 7.45 million tons, while the production volume that year was only 4 million tons. Imports amounted to 8.75 million tons, resulting in a large gap in the market; the self-sufficiency rate remained around 30% for a long time. Therefore, China relies on imports for ethylene glycol. According to the calculations presented by Yaha Consulting at the 7th Symposium on the Technical and Economic Aspects of Coal-based Ethylene Glycol Production, China’s consumption of ethylene glycol is expected to reach around 17 million tons by 2020. By that time, the domestic production capacity for ethylene glycol will also double. However, domestic production will still not be sufficient to meet market demand, which remains strong. There are two main production routes, with the syngas route gradually gaining recognition. Currently, the primary production methods for ethylene glycol worldwide are the ethylene-epoxyethane route and the syngas-oxalate route. The ethylene-ethylene oxide route produces ethylene glycol through the oxidation of ethylene and the hydration of ethylene oxide, and it is the production process for ethylene glycol widely adopted by major manufacturers around the world. The syngas oxalate route uses carbon monoxide and hydrogen as the main raw materials, and the process for producing ethylene glycol through carbonyl synthesis of oxalates and hydrogenation of oxalates is shown in the figure. This technology has currently been put into industrial use in China. Simplified flow diagram of the syngas-based ethylene glycol production process. The process for producing ethylene glycol using syngas was first proposed in 1966 by D.M. Fenton of United Oil Company in the United States. In the 1880s, the Fujian Institute of Physics and Chemistry under the Chinese Academy of Sciences and Tianjin University were the first in China to carry out research and development on related technologies. After more than two decades of development, the world’s first industrial plant for producing ethylene glycol via the syngas process came online in 2009. In the following years, as the coal chemical industry developed in a more refined manner downstream, ethylene glycol production plants using the syngas process were established one after another, leading to a rapid increase in production capacity. By the end of 2015, the syngas-based ethylene glycol production facilities had an output capacity of 1.87 million tons, accounting for about one-quarter of China’s total ethylene glycol production capacity. Thanks to development in recent years, the process for producing ethylene glycol from syngas has become quite mature. The key catalysts have been tested in industrial facilities, and the process flow as well as energy consumption have been optimized and integrated. Ethylene glycol produced via this syngas method has also been successfully used in the production of polyesters. The production of ethylene glycol using the syngas method is gradually gaining recognition in the industry. The sources of raw materials are diverse, offering broad prospects for commercial application. China’s abundant coal reserves provide a solid material foundation for the adoption of the syngas-based ethylene glycol production technology; at the same time, large amounts of inexpensive industrial waste gases (such as those from calcium carbide furnaces, yellow phosphorus production, and coke ovens) further enrich the available raw material sources for this process. Thanks to the huge domestic market for ethylene glycol, the availability of inexpensive raw materials, and the high returns on investment associated with ethylene glycol production via the syngas method, a large number of projects for producing ethylene glycol from syngas have been planned and constructed in China in recent years. The syngas-based ethylene glycol production technology can be applied not only to the production of ethylene glycol from coal but also to the commercial utilization of industrial waste gases. In 2015, the project undertaken by Huisheng Engineering on a EPC basis for Guizhou Xinxin Chemical (Group) Co., Ltd., aimed at producing 70,000 tons per year of oxalic acid and 10,000 tons per year of ethylene glycol from phosphorus yellow waste gas, utilized the integrated technology for producing ethylene glycol from syngas – a technology for which Huisheng Engineering, Xinxin Group, and Tianjin University jointly hold full intellectual property rights. This technology uses carbon monoxide and hydrogen obtained after purifying and separating phosphorus yellow waste gas as raw materials to manufacture high-value chemical products such as ethylene glycol. Tianjin University’s integrated technology for producing ethylene glycol from syngas involves the gas-phase synthesis of oxalate esters using CO, followed by the hydrogenation of those oxalate esters to produce ethylene glycol. Since 2011, Huisheng Engineering has been collaborating with Tianjin University on the engineering development of ethylene glycol production from syngas. Tianjin University was responsible for preparing the basic process package for the industrial facility, while Huisheng Engineering took care of the preliminary design and detailed design, working together to optimize, adapt, and carry out the engineering design for the process of producing ethylene glycol from syngas. The transformed and optimized integrated technology package for producing ethylene glycol from syngas enables an annual production capacity of 300,000 tons per unit, while reducing the investment required for the main ethylene glycol production facilities by 10%. At the same time, the application of the patented technology for efficient heat pump distillation helps to further reduce the overall energy consumption of the plant, while ensuring a high rate of high-quality ethylene glycol products. The impact of low oil prices brings both opportunities and challenges. While domestic plants for producing ethylene glycol from syngas are being actively planned and constructed, international crude oil prices have plummeted sharply from levels above $100 per barrel, dropping below $30 per barrel at one point before settling around $50 per barrel at present. The prices of domestic energy, chemical raw materials, and bulk chemicals have dropped significantly; the market price of ethylene glycol has fallen from around 7,500 yuan per ton in the first half of 2014 to about 5,000 yuan per ton at present. However, thanks to the huge domestic market, ethylene glycol retains a strong ability to withstand drops in oil prices compared to other bulk chemicals. Coupled with the advantage of low costs for raw materials and energy, there is still room for profit in investing in the construction of syngas-based ethylene glycol production facilities in the current environment. Globally, since ethylene in the Middle East is mostly produced by cracking petroleum associated gas, its overall production cost has a significant advantage over the technological approach used domestically, where ethylene is obtained by cracking naphtha. However, the widespread use of syngas in the production of ethylene glycol will, to some extent, reduce China’s reliance on imported ethylene glycol, and it also plays a positive role in ensuring **energy security. In the current context, how to further reduce the overall cost of producing ethylene glycol from syngas, and how to enable the use of ethylene glycol produced from syngas in polyester manufacturing, are the main concerns within the industry. Increasing the scale of a single ethylene glycol production unit and reducing material and energy consumption are effective ways to lower investment costs. The key to this lies in improving the performance of key catalysts and optimizing process integration. For example, the carbonylation and hydrogenation catalysts developed by Tianjin University through years of research enable reactions to take place at higher concentrations of methyl nitrite (MN) and dimethyl oxalate (DMO). This not only results in higher reaction activity but also reduces the flow rate of the recycle gas; under the same conditions, the processing capacity of a single reactor can be increased by 10%–15%, thereby effectively reducing the investment cost of the entire production unit and cutting operating expenses. Meanwhile, the integration and optimization of the ethylene glycol production process carried out by Huisheng Engineering in collaboration with Tianjin University have improved energy efficiency while ensuring the long-term stable operation of the plant, thereby **significantly reducing the operational costs associated with ethylene glycol production. Although syngas-based ethylene glycol is already used to some extent in polyester production, there are currently no standards established for ethylene glycol produced via this method. Moreover, the existing standards for ethylene-based ethylene glycol do not fully reflect the quality of ethylene glycol products. Research into how the trace impurities present in syngas-produced ethylene glycol affect the quality of polyester products is also limited, and such research is becoming a focus of attention for various parties.