Mechanism of CH4 dry reforming by pulse microcalorimetry: Metal nanoparticles on perovskite/fluorite supports with high oxygen mobility

The mechanism of CH4 dry reforming on Pt, Ru, Ni, Ni + Ru-supported perovskite (PrFeOx, LaPrMnCrOx) or fluorite (LnCeZrO(x)) 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) O-2 for fluorites and similar to 500 kJ mol(-1) O-2 for perovskites) and their replenishment by CO2 dissociation, respectively. These features demonstrate a step-wise red-ox (Marsvan-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. (C) 2013 Elsevier B.V. All rights reserved.