Selective Reduction in CO2 to CO via the RWGS Reaction over ZnO-ZrO2-Ga2O3-Supported Catalysts Modified with Keggin-Type Heteropolyacid Precursors

Mo/ZZG and W/ZZG nanomaterials for the catalytic reduction in CO2 were successfully prepared from preformed ZnO-ZrO2-Ga2O3 (ZZG) and HPMo and HPMo heteropolyacids via simple incipient wetness impregnation. To establish the relationship between structural properties and catalytic performance, the prepared catalysts were deeply characterized using XRD, Raman spectroscopy, SEM coupled with EDX, BET, XPS, and H2-TPR techniques. The catalytic performance of the materials was evaluated in the RWGS reaction under atmospheric pressure, using a feed composition of CO2/H2/N2 = 1/3/1 across a temperature range of 250–600 °C. All materials were active in the reverse water gas shift reaction (RWGS) under these conditions, with the Mo/ZZG catalyst exhibiting the best performance, demonstrating excellent catalytic activity at low temperature with the lowest activation energy and the highest CO2 to CO conversion efficiency.