Oxygen-containing functional groups of activated carbon fibers as efficient oxygen transfer channels for H2S catalytic oxidation at room temperature

Abstract

Activated carbon fibers (ACFs) with different activation degrees were developed by KOH activation method. And then, series of Na2CO3 loaded ACF catalysts were prepared and tested for H2S catalytic oxidation at room temperature. Among them, Na/ACF-8 presented the highest saturation sulfur capacity (1.22 gH2S/g). Importantly, it was found that COOH, COC/COH and COOCO were the main active oxygen species, and acted as oxygen transfer channels during the reaction. The reaction process mainly involved the dissociation of H2S, the reaction of HS− with C-O bond containing groups to form C-S bonds and sulfur-containing products. Moreover, the oxygen-containing functional groups were just responsible for water generation and the superoxide radical (O2•−) was responsible for SS bond oxidation. The O2•− was activated by ring carbon defects for Na/ACF-6 and Na/ACF-8 catalysts. And the ring carbon defects and ultramicropores were jointly responsible for the activation of O2•− for Na/ACF-2 and Na/ACF-4 catalysts.