Is the Liquid-Phase H2O2-Based Ethylene Oxide Process More Economical and Greener Than the Gas-Phase O2-Based Silver-Catalyzed Process?

An ethylene epoxidation process concept that employs methyltrioxorhenium (MTO) as catalyst and H2O2 as oxidant and selectively produces EO (with no CO2 as byproduct) has been demonstrated recently by researchers at the University of Kansas Center for Environmentally Beneficial Catalysis (CEBC). On the basis of a plant-scale simulation of the CEBC process using Aspen HYSYS, preliminary economic and environmental assessments of the process are performed, both of which are benchmarked against the conventional silver-catalyzed ethylene epoxidation process. The capital costs for both processes lie within prediction uncertainty. The EO production cost for the conventional process is estimated to be 58 ¢/lb EO. The CEBC process has the potential to be competitive with the conventional process if the MTO catalyst remains active, selective and stable for at least one year at a leaching rate of approximately 0.11 lb MTO/h (or 0.7 ppm Re in the reactor effluent). While CO2 emissions as byproduct are eliminated in th...