Kinetics of Pt oxidation and reduction in CO2 hydrogenation reaction

CO2 hydrogenation is an important reaction to convert green H2 to chemicals. We have recently developed at Pt loaded MoOx/Mo2N catalysts that achieved a catalytic activity of 2.43 × 10‒4 mol gcat‒1 s‒1 at 350 C, which is much higher than other reported catalysts. In situ XAFS at Pt L3 edge suggests a mixed Pt metallic and PtOx species under steady state, with the Pt-Pt coordination numbers (C.N.) around 2.0 and Pt-O around 2.5. In situ Raman spectroscopy shows abundant surface oxygen vacancies (VO), suggesting a M-K mechanism that involves in the oxidation of Pt by CO2 and reduction of Pt with H2. Here we apply for the Pt L3 edge QXAFS study with modulation excitation of CO2 and H2 pulses. This study will measure the rate of Pt oxidation and reduction at different temperatures, achieving kinetic data of the half reaction. Comparing the data with full reaction will determine the rate limiting step, providing methods to further improving the rate of the reaction at low temperatures.