Optimizing reverse water gas shift catalysis: Minimizing metal loading and enhancing performance with Pt/ZrO2 catalysts through Rh incorporation

• Published in: Molecular catalysis 2025-01, Vol.570, p.114661, Article 114661
• Main Authors: García-Orozco, Renée S., Linares-Arroyo, Rodrigo, Zepeda, Trino A., Solís-García, Alfredo
• Format: Article
• Language: English
• Subjects: Bimetallic catalysts; In-situ FTIR; Platinum; Reaction mechanism; Rhodium; RWGS reaction; Supported catalysts; ZrO2
• ISSN: 2468-8231; 2468-8231
• DOI: 10.1016/j.mcat.2024.114661

•Pt/ZrO2 and Rh-Pt/ZrO2 demonstrated activity in catalyzing CO2 reduction at 200–300 °C in a continuous packed bed flow reactor at atmospheric pressure.•Bimetallic catalysts with Rh-Pt showed superior performance in RWGS despite lower metal content (approximately one-third-less).•Enhanced CO production in bimetallic samples can attributed to Rh increasing the extent of reduction of supported Pt, thereby facilitating the hydrogenation of bicarbonate species into formate species. Which lead to the formation of Pt0-CO, and later CO.•Rh incorporation enabled an alternative CO generation pathway through Pt0-carbonyls formed via CO2 dissociation on the Pt0 surface. In this study, the optimization of catalysts for the reverse water gas shift reaction by minimizing metal loading and enhancing the performance of supported Pt catalysts through Rh incorporation was done. The catalysts were synthesized by the wet impregnation method, in which the metal noble load in bimetallic samples decreased by approximately one-third compared to the reference platinum catalyst, with varying Rh-Pt ratios. In all materials, m-ZrO2, obtained by the hydrothermal method, was used as support. In the catalytic tests in a continuous packed-bed flow reactor at atmospheric pressure, all samples were active to catalyze CO2 reduction between 200 and 300 °C. Bimetallic samples, particularly those with an Rh-Pt atomic ratio of 20–80, exhibited superior performance in the RWGS reaction despite their lower metal content. Based on the results of H2-TPR, FTIR in situ, and XPS, we propose that the enhanced CO production in bimetallic samples compared to Pt/ZrO2 catalysts can be attributed to Rh increasing the reduction extent of supported Pt. This enhancement facilitates the hydrogenation of bicarbonate species into formate species, which subsequently evolve into Pt0-CO and ultimately into CO. Additionally, Rh incorporation enables an alternative pathway for CO generation, where Pt0-carbonyls, known for their CO-producing capability, are formed via CO2 dissociation on the Pt0 surface. However, higher Rh concentrations favor the CO2 methanation rather than the RWGS reaction. [Display omitted]