Plasma-Induced Selective Propylene Epoxidation Using Water as the Oxygen Source

Abstract

Propylene oxide (PO) is a critical gateway chemical used in large-scale production of plastics and many other compounds. In addition, PO is also used in many smaller-scale applications that require lower PO concentrations and volumes. These include its usage as a fumigant and disinfectant for food, a sterilizer for medical equipment, as well as in producing modified food such as starch and alginate. While PO is currently mostly produced in a large-scale propylene epoxidation chemical process, due to its toxic nature and high transport and storage costs, there is a strong incentive to develop PO production strategies that are well-suited for smaller-scale on-site applications. In this contribution, we designed a plasma–liquid interaction (PLI) catalytic process that uses only water and C3H6 as reactants to form PO. We show that hydrogen peroxide (H2O2) generated in the interactions of water with plasma serves as a critical oxidizing agent that can epoxidize C3H6 over a titanium silicate-1 (TS-1) catalyst dispersed in a water solution with a carbon-based selectivity of more than 98%. As the activity of this plasma C3H6 epoxidation system is limited by the rate of H2O2 production, strategies to improve H2O2 production were also investigated.