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

► Step-wise bifunctional mechanism of CH4 dry reforming was proved. ► CH4 and CO2 are independently activated on metal and oxide sites. ► CH bond breaking is rate-limiting stage. ► Strongly bound oxygen species of support selectively oxidize CH4 into syngas. ► Fast oxygen transfer from support to me...

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Bibliographic Details
Published in:Thermochimica acta 2013, Vol.567, p.27-34
Main Authors: Sadykov, Vladislav, Rogov, Vladimir, Ermakova, Eugenia, Arendarsky, Dmitry, Mezentseva, Natalia, Alikina, Galina, Sazonova, Natalia, Bobin, Aleksei, Pavlova, Svetlana, Schuurman, Yves, Mirodatos, Claude
Format: Article
Language:English
Subjects:
adsorption
Bonding strength and reactivity of oxygen species
calorimeters
Carbon dioxide
Catalysis
catalysts
CH4 dry reforming
Chemical Sciences
dissociation
Drying
Environment and Society
Environmental Sciences
Fluorite
heat
Heat of adsorption
Metal clusters
methane
nanoparticles
Nickel
oxidation
Oxides
oxygen
Perovskite and fluorite oxide supports
Perovskites
Pulse microcalorimetry
pulses
Redox mechanism
Reforming
synthesis gas
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Summary:► Step-wise bifunctional mechanism of CH4 dry reforming was proved. ► CH4 and CO2 are independently activated on metal and oxide sites. ► CH bond breaking is rate-limiting stage. ► Strongly bound oxygen species of support selectively oxidize CH4 into syngas. ► Fast oxygen transfer from support to metal sites provides conjugation of stages. 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 650kJmol−1 O2 for fluorites and ∼500kJmol−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.
ISSN:0040-6031
1872-762X
DOI:10.1016/j.tca.2013.01.034