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

Introduction Eco-friendly catalysts for CO 2 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 CO 2 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 CH 4 was detected during the RWGS reaction under the tested conditions, despite the high H 2 /CO 2 ratio of 4:1. Discussion Our biochar based systems display an complex interplay of active phases Fe 0 , Fe 3 C and Fe 3 O 4 , with metallic iron being the dominant active component responsible for commendable catalytic performance.