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

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 C 3 H 6 as reactants to form PO. We show that hydrogen peroxide (H 2 O 2 ) generated in the interactions of water with plasma serves as a critical oxidizing agent that can epoxidize C 3 H 6 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 C 3 H 6 epoxidation system is limited by the rate of H 2 O 2 production, strategies to improve H 2 O 2 production were also investigated.