Crafting a Methanation-Resistant, Reverse Water–Gas Shift-Active Nickel Catalyst with Significant Nanoparticle Dimensions Using the Molten Salt Approach

Silica-supported Ni-based catalysts, synthesized using the molten salt method (MSM) in a NaCl and KCl medium, were employed in a reverse water–gas shift (RWGS) system. These catalysts featured Ni0 particles (10–40 nm) coated with salts, which showed inhomogeneous distribution, with Na and K surface enrichments and Cl depletion. This resulted in Ni-salt interface interactions. The most promising catalyst, [email protected](10.7)/SiO2-red, achieved near-theoretical CO2 conversions at 450 °C (44%) and 500 °C (49%), producing CO exclusively within 350–500 °C. It demonstrated durability and coking resistance over a 100 h test. In situ analyses indicated that RWGS proceeded via a redox mechanism. In addition to the bicarbonate (*HCO3) and linear-bound CO (*CO) pathways, [email protected](10.7)/SiO2-red revealed a new route involving monodentate carbonate (m-*CO3) as an intermediate. Residual salts were found to suppress the deep hydrogenation of formate (*HCO2) and formyl (*CHO) to CH4. These findings underscore the potential of MSM-synthesized Ni-based catalysts for efficient reduction of CO2 to CO.