Supported Inverse MnO x /Pt Catalysts Facilitate Reverse Water Gas Shift Reaction.

Catalytic conversion of CO₂ to CO via the reverse water gas shift (RWGS) reaction has been identified as a promising approach for CO₂ utilization and mitigation of CO₂ emissions. Bare Pt shows low activity for the RWGS reaction due to its low oxophilicity, with few research works having concentrated on the inverse metal oxide/Pt catalyst for the RWGS reaction. In this work, MnO_x was deposited on the Pt surface over a SiO₂ support to prepare the MnO_x/Pt inverse catalyst via a co-impregnation method. Addition of 0.5 wt% Mn to 1 wt% Pt/SiO₂ improved the intrinsic reaction rate and turnover frequency at 400 °C by two and twelve times, respectively. Characterizations indicate that MnO_x partially encapsulates the surface of the Pt particles and the coverage increases with increasing Mn content, which resembles the concept of strong metal–support interaction (SMSI). Although the surface accessible Pt sites are reduced, new MnO_x/Pt interfacial perimeter sites are created, which provide both hydrogenation and C-O activation functionalities synergistically due to the close proximity between Pt and MnO_x at the interface, and therefore improve the activity. Moreover, the stability is also significantly improved due to the coverage of Pt by MnO_x. This work demonstrates a simple method to tune the oxide/metal interfacial sites of inverse Pt-based catalyst for the RWGS reaction. [ABSTRACT FROM AUTHOR]