Robust microwave catalytic decomposition of H2S into H2 and S at low temperature over Mo2C@CeO2 catalysts

Abstract

The new technology of direct decomposition of H₂S into high value-added H₂ and S, as an alternative to the Claus process in industry, is an ideal route that can not only deal with toxic and abundant H₂S waste gas but also recover clean energy H₂, which has significant socio-economic and ecological advantages. However, the highly effective decomposition of H₂S at low temperatures is still a great challenge, because of the stringent thermodynamic equilibrium constraints (only 20% even at high temperature of 1010 °C). Conventional microwave catalysts exhibit unsatisfactory performance at low temperatures (below 600 °C). Herein, Mo₂C@CeO₂ catalysts with a core-shell structure were successfully developed for robust microwave catalytic decomposition of H₂S at low temperatures. Two carbon precursors, para-phenylenediamine (Mo₂C-p) and meta-phenylenediamine (Mo₂C-m), were employed to tailor Mo₂C configurations. Remarkably, the H₂S conversion of Mo₂C-p@CeO₂ catalyst at a low temperature of 550 °C is as high as 92.1%, which is much higher than the H₂S equilibrium conversion under the conventional thermal conditions (2.6% at 550 °C). To our knowledge, this represents the most active catalyst for microwave catalytic decomposition of H₂S at low temperature of 550 °C. Notably, Mo₂C-p demonstrated superior intrinsic activity (84%) compared to Mo₂C-m (6.4%), with XPS analysis revealing that its enhanced performance stems from a higher concentration of Mo²⁺ active sites. This work presents a substitute approach for the efficient utilization of H₂S waste gas and opens up a novel avenue for the rational design of microwave catalysts for microwave catalytic reaction at low-temperature.