Efficient eco-friendly biochar-based catalyst design for CO2 conversion via the reverse water-gas shift reaction.

Abstract

INTRODUCTION: Eco-friendly catalysts for CO2 conversion reactions are gathering momentum within the ongoing transition to a low-carbon economy. Here, we present a new family of biochar-based Fe catalysts for high temperature reverse water-gas shift (RWGS) reaction. METHODS: Almond-shell-derived biochar was prepared by pyrolysis under an argon atmosphere at 500 °C. Fe-based catalysts with iron loadings of 20 and 40 wt% were synthesised by wet impregnation, followed by pyrolysis at 700 or 1000 °C for different holding times. RESULTS: At 750 °C, the synthesized catalysts exhibited CO2 conversions ranging from 74% to 87% and CO selectivities between 82% and 100%, with four of the five catalysts achieving conversions above 80% and approximately 100% CO selectivity. Importantly, no CH4 was detected during the RWGS reaction under the tested conditions, despite the high H2/CO2 ratio of 4:1. DISCUSSION: Our biochar based systems display an complex interplay of active phases Fe0, Fe3C and Fe3O4, with metallic iron being the dominant active component responsible for commendable catalytic performance.

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