Optimal Design of Gas-Expanded Liquid Ethylene Oxide Production with Zero Carbon Dioxide Byproduct

The concept of ethylene epoxidation over methyltrioxorhenium (MTO) catalyst could save the world from global warming since the epoxidation reaction never produces carbon dioxide as byproduct. Unlike the conventional gas epoxidation reaction with oxygen, this reaction takes place in the (ethylene) gas-expanded liquid solvent phase (methanol) while the reaction oxidant is hydrogen peroxide. The reaction takes place at temperatures and pressures close to the ethylene critical point (Pc = 50.42 bar; Tc = 48.56 degrees F) (Gas Encyclopedia by Air Liquide, https://encyclopedia.airliquide.com/ethylene). In this paper, an optimized design and operation for MTO based ethylene oxide (EO) production processes has been developed, which has less manufacturing costs compared with the one from the current literature (Ind. Eng. Chem. Res. 2013, 52, 18-29). The developed EO system could produce 200,000 tons of ethylene oxide per year at a purity of 99.9%. It has two reactors for ethylene epoxidation and hydrogen peroxide decomposition, one flash drum, and three distillation columns for product and recycled material purification. The design has secured the safety of the operation by not presenting oxygen and flammable vapor mixtures in any of the process equipment. The EO manufacturing costs $0.52 per pound, and the fixed capital investment of the project is $66,240,000, which is estimated to be paid back after 7.3 years, while the net present value is $56,900,000.