Decoding the Promotional Effect of Iron in Bimetallic Pt–Fe-nanoparticles on the Low Temperature Reverse Water–Gas Shift Reaction
Colin Hansen, Wei Zhou, Enzo Brack, Yuhao Wang, Chunliang Wang, James Paterson, Jamie Southouse, Christophe Copéret
Abstract
The reverse water–gas shift (RWGS) reaction is a key technology of the chemical industry, central to the emerging circular carbon economy. Pt-based catalysts have previously been shown to effectively promote RWGS, especially when modified by promoter elements. However, their active states are still poorly understood. Here, we show that the intimate incorporation of an iron promoter into metal-oxide-supported Pt-based nanoparticles can increase their activity and selectivity for the low temperature reverse water–gas shift (LT-RWGS) substantially and drastically outperform unpromoted Pt-based materials. Specifically, the study explores the promotional effect of iron in Pt–Fe bimetallic systems supported on silica (Pt x Fe y @SiO 2 ) prepared by surface organometallic chemistry (SOMC). The most active catalyst (Pt 1 Fe 1 @SiO 2 ) shows high selectivity (>99% CO) toward CO at a formation rate of 0.192 mol CO h –1 g cat –1, which is significantly higher than that of monometallic Pt@SiO 2 (96% sel. and 0.022 mol CO h –1 g cat –1 ). In-situ diffuse reflectance FT-IR spectroscopy (DRIFTS) and X-ray absorption spectroscopy (XAS) indicate a dynamic process at the catalyst surface under the reaction conditions, revealing distinct reaction pathways for the monometallic Pt@SiO 2 and bimetallic Pt x Fe y @SiO 2 systems.