Plasma-enhanced catalytic oxidation of ethylene oxide over Fe–Mn based ternary catalysts

Abstract

In this work, Fe–Mn based ternary catalysts (Fe–Mn-X, X = Ce, Co and Cu) were evaluated in the plasma-catalytic oxidation of ethylene oxide (EO) using a cylindrical dielectric barrier discharge (DBD) reactor. The addition of transition metal dopants to the Fe–Mn catalyst significantly improved the performance of plasma-catalyzed EO oxidation compared to the reaction using plasma only and the Fe–Mn catalyst. The highest EO conversion (91.9%) and CO2 selectivity (78.9%) were obtained over the Fe–Mn–Co catalyst at a specific energy input (SEI) of 730.2 J l−1. Moreover, the presence of water vapor improved EO conversion and CO2 selectivity in the relative humidity (RH) range of 0–60%, while further increasing the RH to 80% reduced EO conversion. The interactions between Fe, Mn and dopants increased the specific surface area and pore volume of the Fe–Mn-X catalyst, while maintaining the crystalline structure of the catalysts. The presence of the dopants enhanced the reducibility of the Fe–Mn-X catalysts and produced more surface adsorbed oxygen (Oads) on the catalyst surfaces. Moreover, the interactive effects among the Fe, Mn and dopants facilitated the plasma-catalytic oxidation reactions via enhanced surface reactions. The coupling of plasma with the Fe–Mn–Co catalyst reduced the formation of organic by-products in the plasma-catalyzed oxidation of EO.