Porous biochar confined Ru nanocatalysts: Dual defense mechanism enables ultrahigh SO2 tolerance for methane dry reforming

Abstract

Methane dry reforming (DRM) can convert greenhouse gases into valuable syngas, while sulfur dioxide (SO 2 ) in feed gas easily poisons Ru-based catalysts. Herein, 1Ru/C, 1Ru/MgO and 1Ru/TiO 2 catalysts were synthesized and evaluated for DRM in the presence of SO 2 . Characterizations revealed that porous biochar with large specific surface area enabled high dispersion of Ru NPs and strong metal-support interaction, endowing 1Ru/C with excellent anti-sintering ability. The weakly acidic surface of biochar suppressed SO 2 adsorption. In-situ SO 2 -TPSR/CH 4 -TPSR/FTIR, XPS, SO 2 -TPD and Raman results verified that the weakly acidic property of biochar suppressed the adsorption and enrichment of acidic SO 2 , and the porous confinement structure prevented the direct contact between SO 2 and active Ru sites. Meanwhile, the reactive oxygen species derived from CO 2 activation and CH x species generated from CH 4 dissociation synergistically decomposed sulfur-containing intermediates, realizing the dynamic regeneration of Ru active sitess. Consequently, 1Ru/C exhibited superior catalytic activity and long-term stability with a low deactivation rate of 0.3%/h over 50 h. In contrast, alkaline MgO and TiO 2 facilitated SO 2 adsorption and formed stable sulfides, leading to severe catalyst deactivation. This work clarifies the structure-performance relationship and provides guidance for developing sulfur-resistant DRM catalysts.