Ce–Mn Oxide Nanocomposites for Catalytic Removal of H2S

Abstract

The development of efficient and stable nanocatalysts is crucial for the catalytic removal of H2S through selective oxidation to sulfur. Inspired by the different catalytic activity and selectivity of CeO2 and MnO2 for the reaction, cerium–manganese (Ce–Mn) nanocomposite oxides with tunable phase structure and unique surface properties were constructed to optimize the catalytic performance. By regulating the molar ratio of Ce and Mn components, a novel catalyst structure comprising Ce–Mn solid solution and amorphous CeO2 is synthesized from Ce–Mn oxide with nCe/nMn ratio of 0.5 (50Ce–Mn). Compared with the unmodified MnO2, the tailored 50Ce–Mn possesses a high specific surface area, which facilitates the access of reactants to active sites and the desorption of formed sulfur. More importantly, strong Ce–Mn interaction and abundant surface-active oxygen species are generated, contributing to the regeneration of Mn4+/Ce4+ active sites, facilitating the formation of sulfur, and inhibiting the accumulation of sulfates during the reaction. Consequently, 50Ce–Mn presents a superior catalytic activity (T100 of 150 °C), stability, and sulfur selectivity even under relatively high weight hourly space velocity conditions (23,000 mL·g–1·h–1). This study provides an example of how catalytic performance can be boosted through phase structure regulation on nanocomposites.