文摘
The mechanism of CH4 dry reforming on Pt, Ru, Ni, Ni + Ru-supported perovskite (PrFeOx, LaPrMnCrOx) or fluorite (LnCeZrOx) oxides was studied using a Setaram Sensys DSC TG calorimeter and a pulse kinetic installation. For catalysts in the steady-state, CH4 and CO2 transformation in separate pulses proceeds with the rate and products selectivity equal to that in mixed CO2 + CH4 pulses. Heat effects of separate stages correspond to CH4 oxidation into syngas by strongly bound bridging oxygen forms of support (heat of adsorption up to 650 kJ mol?1 O2 for fluorites and ¡«500 kJ mol?1 O2 for perovskites) and their replenishment by CO2 dissociation, respectively. These features demonstrate a step-wise red-ox (Mars-van-Crevelen) mechanism of CH4 dry reforming. Fast oxygen transfer from the sites of oxide support to the metal/oxide interface provides required conjugation of stages.
