What are the methods and processes for dehydrating ethanol to produce ethylene?
Ethylene is a very important basic raw material for petrochemical industry, and its downstream products mainly include polyethylene, polyvinyl chloride, ethylene oxide, ethylene glycol, styrene, vinyl acetate, etc.
At present, the cracking method using petroleum as raw material is mainly used to produce ethylene at home and abroad. With the dwindling petroleum resources and the rising international oil prices, ethylene production via petroleum routes will face unprecedented challenges. Many petrochemical companies around the world are actively exploring other routes, including using coal, natural gas, biomass raw materials, etc. to produce olefins to reduce ethylene's over-reliance on limited petroleum resources.
The technology of using renewable biomass raw materials to produce ethanol and then dehydrating it to produce ethylene is one of the important ways to adjust the energy structure, reduce environmental pollution, and promote the sustainable development of the national economy and society. For ethanol dehydration to produce ethylene, the current main research goals are to improve the process flow, reduce device material and energy consumption, and increase efficiency.
Among the processes for dehydrating ethanol to produce ethylene, currently the fixed bed process that has been industrially applied is mainly the fixed bed process, including the isothermal fixed bed process and the adiabatic fixed bed process. Isothermal bed process technology is more suitable for small-scale industrial devices. When the scale of the device reaches or exceeds tens of thousands of tons per year, because isothermal bed process technology is difficult to scale up, adiabatic bed process technology is usually used. US4232179 proposes an adiabatic process for ethanol dehydration reaction, that is, the ethanol dehydration reaction is carried out in an adiabatic fixed bed, and the reaction materials are heated to the temperature required for the reaction before entering the reactor. Later, US4396789 proposed a three-stage adiabatic fixed-bed reaction process for ethanol dehydration to produce ethylene, and in the early 1980s, this process was used to build a 60,000 tons/year ethylene plant. US20130178674A1 introduces a reactor and process for dehydrating ethanol to produce ethylene. The reaction process consists of multiple sections of reactors of different sizes and different catalyst filling amounts. Each section of the reactor can be independently controlled. For the adiabatic bed ethanol dehydration to ethylene process, the development of an adiabatic fixed bed reactor and reaction process with excellent performance is one of the key technologies for expanding the scale of the device.
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