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New Technologies Help Reduce Costs in Coal Chemical Industry Author/Source: Sinochem New Network Date: 2019-07-01 Clicks: 17 From June 20th to 21st, 2019, the 5th China (Yulin) International Symposium on New Coal Chemical Technologies was held in Yulin, Shaanxi, where a range of new technologies in this field were showcased. According to interviews by reporters from China Chemical Industry News, three new technologies – plasma-based pyrolysis of coal to produce acetylene, production of DMMn series of new materials from methanol, and conversion of methanol into ethanol via acetic acid – will significantly reduce the manufacturing costs of coal chemical products. Plasma-based production of acetylene is superior to the calcium carbide method. Acetylene is an important chemical raw material, and it is mostly produced using the calcium carbide method, which is a traditional process that is energy-intensive, causes significant pollution, and involves high resource consumption. The direct production of acetylene from coal via plasma pyrolysis is a new technology that has emerged in recent years. Universities and research institutions in China have also carried out experimental studies in this area, but no industrial-scale operations have been implemented yet. As a key research and development project funded by the Ministry of Science and Technology, the 10-megawatt hydrogen plasma-based coal pyrolysis project for producing acetylene, undertaken in collaboration between Zhejiang University and Xinjiang Yuehetai Chemical Technology Co., Ltd., is currently under experimental phase. The company’s technical director explained that coal powder passes through a magnetic rotary arc plasma torch/reactor; 1 ton of coal powder is combined with 1,000 cubic meters of hydrogen to produce gases such as acetylene and hydrogen. Among them, hydrogen accounts for 70%–80% and acetylene for 4%–5%, with by-products such as CO, methane, and ethylene being produced; part of the hydrogen is recycled as a reaction medium, while the excess hydrogen can be sold or separated for further processing. In 2017, Yuehetai built a pilot-scale platform for producing acetylene from coal using megawatt-level hydrogen plasma pyrolysis in Kuitun, Xinjiang. Each unit is capable of processing 30,000 tons of coal per year, enabling the production of 6,000 tons of acetylene. Through continuous expansion of the experimental scale, preliminary operation results show that the acetylene yield exceeds 20% with an energy consumption of 12 kWh/kg, which is superior to advanced foreign technologies. The cost of producing one ton of acetylene is 7,000 yuan (this cost is even lower if the hydrogen produced as a by-product is reused); this is more than 20% cheaper than the current method of producing acetylene using calcium carbide. Moreover, it solves problems such as slag formation associated with the current plasma-based method for producing acetylene from coal, and there are no emissions of any type of waste during this process. DMMn: The development of new materials. Polydimethyl methoxide with a high oxygen content (DMMn) can be used as a clean and environmentally friendly component in diesel blends, as well as a solvent with excellent solvency properties. It has become a highly sought-after new product derived from methanol in the industry; however, its polymerization degree generally ranges only from 3 to 8. The benzene-free extraction green process developed by Suzhou Shuanghu Chemical Technology Co., Ltd. enables the production of a range of oxygen-containing compounds such as polymethoxydimethyl ether, polymethoxydiethyl ether, and polymethoxydibutyl ether through aldol condensation. This process not only solves technical problems related to low polymerization degrees and unstable by-product hemiacetals, but the new catalysts also significantly reduce the cost of trioxane; the cost of equipment construction is cut in half, and less than 1.3 tons of methanol are required per ton of DMMn product produced. “We can achieve a polymerization degree of over 30; such polymers become highly thermally stable polyoxymethylenes, new types of epoxy resins, COPNA resins, and new high-molecular materials for self-lubricating aviation lubricants. A pilot plant with an annual production capacity of 300 tons has already been built, with plans to move toward industrial production. Meanwhile, technical experiments on DMMn with a relative molecular mass of 100–500 have been completed. ”Sun Yucheng, deputy general manager of Shuanghu Chemical, explained that DMMn can also be used to produce many new products, such as five-membered cyclic esters obtained by the condensation of ethylene glycol with trimellitic anhydride, and six-membered cyclic esters obtained by the condensation of propylene glycol with trimellitic anhydride; these are all high-quality solvents and additives. Research by Shuanghu Chemical has shown that new types of triomethyleneglycol can be condensed with olefins to produce 1,3-dioxane and similar compounds, which are primarily used in the synthesis of highly effective and low-toxicity pesticides, vitamins, and water-reducing agents. It is an important monomer for synthesizing polyester materials through the condensation of trioxane with aromatic hydrocarbons; Skoda is used to produce film materials from modified polyesters, while the condensation of formaldehyde with ethanol yields another oxide compound, diethoxymethane. The lowest cost for producing ethanol directly from acetic acid. As another route for the further processing of methanol, the production of ethanol from coal (methanol) is also a process within the framework of new coal chemical technologies. Existing techniques include the catalytic conversion of syngas, syngas fermentation, the production of ethanol from methanol via ethyl acetate, and the production of ethanol from methanol through dimethyl ether and methyl acetate carbonylation. In the view of Tian Shuxun, a senior engineer at the Beijing Institute of Low-Carbon Clean Energy of the Energy Group, among the existing methods for producing ethanol indirectly from coal (methanol), the process of directly hydrogenating methanol to produce ethanol via acetic acid offers the highest energy conversion efficiency and the lowest costs. “The technology for producing acetic acid from methanol is mature; large-scale production and the use of domestic equipment are already feasible. Moreover, the production cost has remained below 2,000 yuan per ton for many years. On this basis, we carry out direct hydrogenation reactions to produce ethanol; this process features the shortest workflow and lowest investment among the technologies for producing ethanol indirectly, with a project investment of only 200 million to 300 million yuan for a capacity of 200,000 tons per year. ”Tian Shuxun explained that they developed and completed the industrial scale-up of solid catalysts, and carried out pilot tests on a scale of 100 tons per year in collaboration with domestic companies; the test results showed an acetic acid conversion rate of 100% and an ethanol selectivity of around 92%. Taking all energy consumption factors into account, 1 ton of ethanol requires 1.5 tons of methanol, and the cost per ton of ethanol is below 4,000 yuan. Tian Shuxun also revealed that this technology enables a co-production mode of \"acetic acid + ethanol\", with acetic acid serving both as an intermediate product and as a final product. Acetic acid can be produced when its price is high, and ethanol can be produced when the ethanol market is favorable. By flexibly adjusting the product mix, companies can increase their profit margins and enhance their resilience to market risks. Currently, they have completed the development of the 300,000 tons/year process package, ready for industrialization.