Enhancement of plasma-catalytic oxidation of ethylene oxide (EO) over FeMn catalysts in a dielectric barrier discharge reactor.

Abstract

In this work, an integrated system combining non-thermal plasma (NTP) and FeMn catalysts was developed for ethylene oxide (EO) oxidation. The effect of Fe/Mn molar ratio on the oxidation rate of EO and energy yield of the plasma-catalytic process has been investigated as a function of specific energy density (SED). Compared with the case of using plasma alone, the combination of plasma and FeMn catalysts greatly enhanced the reaction performance by the factor of 25.2% to 97.6%. The maximum oxidation rate of 98.8% was achieved when Fe1Mn1 catalyst was placed in the dielectric barrier discharge (DBD) reactor at the SED of 656.1 J·L-1. The highest energy yield of 2.82 g·kWh-1 was obtained at the SED of 323.2 J·L-1 over the Fe1Mn1 catalyst. The interactions between Fe and Mn species resulted in larger specific surface area of the catalyst. Moreover, the reducibility of the catalysts was improved, while more surface adsorbed oxygen (Oads) was detected on the catalyst surfaces. Moreover, the redox cycles between Fe and Mn species facilitated consumption and supplementation of reactive oxygen species, which contributed to the plasma-catalytic oxidation reactions. The major reaction products of plasma-induced EO oxidation over the FeMn catalysts, including CH3COOH, CH3CHO, CH4, C2H6 and C2H4, were observed using the FT-IR analyzer and GC-MS instrument. The reaction mechanisms of EO oxidation were discussed in terms of both gas-phase reaction and catalyst surface reaction. The redox cycles between Fe and Mn species facilitated the plasma reaction and accelerated the deep oxidation of by-products.