Catalytic performance of Co-doped CuFe mixed oxides derived from layered double hydroxides for enhanced CO₂ conversion through reverse water–gas shift reaction

Background Catalysts for the reverse water–gas shift (RWGS) reaction often face challenges in achieving high selectivity and stability. Methods In this work, cobalt-doped copper–iron mixed metal oxide (CoCuFe MMO) was prepared by calcining the precursor layered double hydroxides (LDHs). The catalysts were evaluated at atmospheric pressure over 450–650 °C with an H₂/CO₂ ratio of 2 and a gas hourly space velocity (GHSV) of 20 L g⁻¹ h⁻¹. Significant findings The CoCuFe MMO exhibited superior activity, achieving a CO₂ conversion of 54 % and a CO yield of 53 % at 650 °C, compared to 31 % conversion and 26 % CO yield for the CuFe MMO under identical conditions, while maintaining nearly 100 % CO selectivity with no detectable methane formation. The Co-doped catalyst sustained approximately 52.5 % CO₂ conversion and 50 % CO yield over six hours without deactivation. CO₂ temperature-programmed desorption profiles showed a systematic shift of desorption peaks toward higher temperatures for CoCuFe MMO, indicating a redistribution toward stronger basic sites. H₂ temperature-programmed reduction analysis further demonstrated enhanced reducibility and suppression of high-temperature reduction features associated with bulk Fe oxide species. Raman spectroscopy and thermogravimetric analysis confirmed negligible overall carbon deposition, indicating good resistance to coking. The catalytic performance is therefore governed by a combination of enhanced reducibility, optimized basic site distribution, and thermodynamic limitations at high temperature.