As a basic organic chemical raw material and a leading product of the petrochemical industry, ethylene is honored as the “mother of petrochemicals.†With the rapid development of ethylene derivatives industry such as chemicals, energy, and materials, the contradiction between ethylene production and demand has become increasingly prominent. This provides a rare opportunity for bio-ethylene to produce ethylene from bulk biomass. During the 2007 China Biomass Energy Development Strategy Seminar, Dr. Hu Yanyan, National Institute of Biochemical Engineering Technology, Nanjing University of Technology, said in an interview that the development of bio-ethylene has become inevitable, as an important direction and breakthrough of the oil substitution strategy, bio-ethylene will Give the traditional ethylene and its derivative industry a driving force for sustainable development.
According to reports, bio-ethylene is based on bulk biomass as raw material, and ethanol is obtained through microbial fermentation, and then dehydration to ethylene under the action of a catalyst. In the 1960s, countries such as Brazil, India, China, Pakistan, and Peru successively established industrial devices for the dehydration of ethanol into ethylene. Although the process of producing ethylene from the thermal cracking of petroleum hydrocarbons has almost become the source of all ethylene, the research on the dehydration of ethanol into ethylene has not been abandoned. In 2004, China's largest 17,000 t/y bio-ethylene plant was successfully put into operation at the Anhui Fengyuan Group. Sinopec's Sichuan Vinylon Plant also has an industrialized plant that produces 9,000 tons of bio-ethylene annually.
Compared with ethylene on the petroleum route, bio-ethylene has high purity, low cost for separation and purification, low investment, short construction period, and fast return, and is not limited by the distribution of resources. Therefore, in the era of acute shortage of petroleum resources, bio-ethylene will surely serve as a sustainable green chemical route that competes with the petroleum ethylene route. Hu Yanyan told reporters that at present, the development of bio-ethylene is technically feasible and economically competitive. However, it is still necessary to solve some key technical problems of large-scale production, mainly low-cost ethanol production technology, ethanol dehydration and ethylene production. Catalytic technology, coupled process integration technology, etc., to further reduce production costs.
Low-cost ethanol production technology Currently about 80% of ethanol uses starch-based food as raw material, and about 20% of ethanol uses lignocellulose as raw material. The price of grain starchy raw materials is relatively high, which raises the production cost of ethanol. Therefore, the selection of a low-cost raw material route is the key to reducing the cost of ethanol production and improving market competitiveness. The use of straw-like lignocellulosic raw materials for the production of ethanol is an internationally recognized technical problem, but it is also one of the most promising technologies. China urgently needs to establish a high-quality pilot base for ethanol production with lignocellulose as its raw material, and focuses on raw material pretreatment, biodegradation, utilization of fermentable sugar, and comprehensive utilization of straw-like lignocellulose.
Ethanol dehydration to ethylene catalytic technology According to reports, alumina-based catalysts are relatively mature catalysts for industrial applications, but the reaction conditions are demanding, the reaction temperature is high, and the concentration of ethanol raw materials is high, resulting in high overall energy consumption. Therefore, the development of long-lived catalysts that can convert lower concentrations of ethanol with high selectivity and high conversion to ethylene at lower temperatures has become the key to the production of ethylene from ethanol intermediates. Although the activity of heteropolyacid catalysts is high, the problems of lifetime and thermal stability cannot be solved, which limits its industrial application. The hydrothermal stability and life of zeolite molecular sieve catalysts need to be further improved, and the tolerance to fermented ethanol impurities is also worth further investigation.
Process Coupling Integrated Process At present, China's existing ethanol dehydration and ethylene plant is built on the fuel ethanol production line. The process route is obsolete and the energy consumption is too high. In order to increase the market competitiveness of bio-ethylene, it is necessary to fully consider the characteristics of bio-ethylene, and organically combine the two processes of fermentation of ethanol from biomass production and dehydration of ethanol to ethylene. A systematic consideration should be given to the production process of ethylene from biomass routes, and the best balance between energy consumption, catalytic efficiency, and catalyst service life should be sought. Through the integrated design of the entire process, the thermal energy in each process is comprehensively utilized to reduce energy consumption.
It is reported that China attaches great importance to the bio-refinery technology of bio-ethylene, and the Ministry of Science and Technology has initiated the project of "biological refining of bio-based chemicals" in the national "863" plan. Many universities, research institutes and key enterprises in China have carried out joint research to solve the key technical problems in the industrialization of bio-ethylene.
After long-term research, Hu Yanyan’s research group has already had a good foundation in the pilot test and industrialization project of fuel ethanol, and achieved results in the dehydration of bioethanol to produce ethylene-specific catalysts, as well as ethanol fermentation and ethylene industry. Chemical engineering design, process optimization and other fields have accumulated rich practical experience. Hu Yanyan said that their goal is to build an energy-saving, clean 20,000-ton/year bio-ethylene industrial demonstration plant with Chinese characteristics and using low-cost renewable resources as raw materials.
According to reports, bio-ethylene is based on bulk biomass as raw material, and ethanol is obtained through microbial fermentation, and then dehydration to ethylene under the action of a catalyst. In the 1960s, countries such as Brazil, India, China, Pakistan, and Peru successively established industrial devices for the dehydration of ethanol into ethylene. Although the process of producing ethylene from the thermal cracking of petroleum hydrocarbons has almost become the source of all ethylene, the research on the dehydration of ethanol into ethylene has not been abandoned. In 2004, China's largest 17,000 t/y bio-ethylene plant was successfully put into operation at the Anhui Fengyuan Group. Sinopec's Sichuan Vinylon Plant also has an industrialized plant that produces 9,000 tons of bio-ethylene annually.
Compared with ethylene on the petroleum route, bio-ethylene has high purity, low cost for separation and purification, low investment, short construction period, and fast return, and is not limited by the distribution of resources. Therefore, in the era of acute shortage of petroleum resources, bio-ethylene will surely serve as a sustainable green chemical route that competes with the petroleum ethylene route. Hu Yanyan told reporters that at present, the development of bio-ethylene is technically feasible and economically competitive. However, it is still necessary to solve some key technical problems of large-scale production, mainly low-cost ethanol production technology, ethanol dehydration and ethylene production. Catalytic technology, coupled process integration technology, etc., to further reduce production costs.
Low-cost ethanol production technology Currently about 80% of ethanol uses starch-based food as raw material, and about 20% of ethanol uses lignocellulose as raw material. The price of grain starchy raw materials is relatively high, which raises the production cost of ethanol. Therefore, the selection of a low-cost raw material route is the key to reducing the cost of ethanol production and improving market competitiveness. The use of straw-like lignocellulosic raw materials for the production of ethanol is an internationally recognized technical problem, but it is also one of the most promising technologies. China urgently needs to establish a high-quality pilot base for ethanol production with lignocellulose as its raw material, and focuses on raw material pretreatment, biodegradation, utilization of fermentable sugar, and comprehensive utilization of straw-like lignocellulose.
Ethanol dehydration to ethylene catalytic technology According to reports, alumina-based catalysts are relatively mature catalysts for industrial applications, but the reaction conditions are demanding, the reaction temperature is high, and the concentration of ethanol raw materials is high, resulting in high overall energy consumption. Therefore, the development of long-lived catalysts that can convert lower concentrations of ethanol with high selectivity and high conversion to ethylene at lower temperatures has become the key to the production of ethylene from ethanol intermediates. Although the activity of heteropolyacid catalysts is high, the problems of lifetime and thermal stability cannot be solved, which limits its industrial application. The hydrothermal stability and life of zeolite molecular sieve catalysts need to be further improved, and the tolerance to fermented ethanol impurities is also worth further investigation.
Process Coupling Integrated Process At present, China's existing ethanol dehydration and ethylene plant is built on the fuel ethanol production line. The process route is obsolete and the energy consumption is too high. In order to increase the market competitiveness of bio-ethylene, it is necessary to fully consider the characteristics of bio-ethylene, and organically combine the two processes of fermentation of ethanol from biomass production and dehydration of ethanol to ethylene. A systematic consideration should be given to the production process of ethylene from biomass routes, and the best balance between energy consumption, catalytic efficiency, and catalyst service life should be sought. Through the integrated design of the entire process, the thermal energy in each process is comprehensively utilized to reduce energy consumption.
It is reported that China attaches great importance to the bio-refinery technology of bio-ethylene, and the Ministry of Science and Technology has initiated the project of "biological refining of bio-based chemicals" in the national "863" plan. Many universities, research institutes and key enterprises in China have carried out joint research to solve the key technical problems in the industrialization of bio-ethylene.
After long-term research, Hu Yanyan’s research group has already had a good foundation in the pilot test and industrialization project of fuel ethanol, and achieved results in the dehydration of bioethanol to produce ethylene-specific catalysts, as well as ethanol fermentation and ethylene industry. Chemical engineering design, process optimization and other fields have accumulated rich practical experience. Hu Yanyan said that their goal is to build an energy-saving, clean 20,000-ton/year bio-ethylene industrial demonstration plant with Chinese characteristics and using low-cost renewable resources as raw materials.
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