Spectrokinetic Investigation of Reverse Water-Gas-Shift Reaction Intermediates over a Pt/CeO2 Catalyst

Abstract

The reactivity of the surface species present over a 2%Pt/CeO2 catalyst during the reverse water-gas-shift (RWGS) reaction was investigated by a detailed operando spectrokinetic analysis. A single reactor common for the kinetic and the spectroscopic measurements was used. The reactor employed was a modified high-temperature diffuse reflectance FT-IR (DRIFT) cell from SpectraTech. The reactivity of the surface species was monitored by DRIFT spectroscopy (DRIFTS) and mass spectrometry (MS) using steady-state isotopic transient kinetic analysis (SSITKA) techniques, i.e., switching between 1% CO2 + 4% H2 reaction mixtures containing either 13CO2 or 12CO2. The combination of these techniques allowed time-resolved simultaneous monitoring of the variation of the coverage of 12C and 13C-containing surface intermediates and the concentration of the gas-phase products 12CO(g) and 13CO(g) due to the isotope exchange. These results clearly indicated that surface formates observed by DRIFTS were not the main reaction ...