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This study explores the performances of nickel‐based materials for the dry reforming of methane (DRM), an important process for hydrogen and syngas productions. Ni nanoparticles are issued from porous phyllosilicate phase exolution under reducing conditions (in situ or ex situ). Phyllosilicate precursors were obtained by deposition/precipitation with urea onto SBA‐15 porous silica, with metal loading up to 40 wt.%. Reaction was performed at 600–700 °C. The successful formation and stabilization of highly dispersed nanoparticles (2–6 nm) is revealed, even for highly loaded formulations (20 wt.% and 40 wt.%). In DRM‐700 (CH4/CO2=1, 20 % CH4, 480,000 mL gcat−1 h−1) the formulation at 20 wt.% metal loading (Ni_20 %) activated during reaction affords 50 % and 65 % of CH4 and CO2 conversions respectively at 700 °C. Ni_20 % is showing excellent resistance toward sintering after DRM stability test of 80 h. Characterizations made for spent catalyst show high resistance toward sintering and limited carbon formation. [ABSTRACT FROM AUTHOR]

• Chemical looping dry reforming of methane (CLDRM) is highly selective to syngas. • Ni/CeO 2 carriers are active and selective at high temperature (>650 °C). • Preparation method has limited effect on properties of Ni/CeO 2 carriers. • Co/CeO 2 shows the best selectivity at low temperature (600 °C). • Commercial CeO 2 , iron or zirconia doping show the lowest activity and/or selectivity. Chemical looping dry reforming of methane (CLDRM) consists in reacting CH 4 with an oxygen carrier (OC) to produce syngas and subsequently oxidizing the OC using CO 2. Based on previous work on Ni/CeO 2 , several ceria based OCs are explored. First, different preparation methods are compared. OCs obtained by Ni impregnation on homemade ceria or coprecipitation method show similar results while the use of a commercial ceria leads to an inactive carrier. Second, Zr doping of the carrier is shown to improve the thermal stability of the material but the increased oxygen mobility promotes the total oxidation of methane instead of syngas production. Simultaneously higher amounts of coke are produced. Then, the substitution of Ni by other active elements is explored. Iron doped OC leads to very low CLDRM activity in the temperature range explored (600–800 °C). Furthermore, selectivity is negatively affected as iron oxide can contribute as oxygen carrier together with ceria, contrary to Ni or Co. Finally, substitution of Ni with Co is studied resulting in a lower reactivity towards methane. This proves to be particularly interesting at low temperature (600–650 °C) by providing good balance between surface properties for methane activation and bulk mobility of oxygen species. [ABSTRACT FROM AUTHOR]

Chemical looping dry reforming of methane (CLDRM) is performed by exposing a Ni/CeO 2 solid to CH 4 and CO 2 in a cyclic way. The solid acts as an oxygen vector producing syngas (CO + H 2 ) during exposure to CH 4 , and is re-oxidized during exposure to CO 2 . Absence of CO 2 during syngas production allows suppressing reverse water gas shift reaction and reaching high selectivity. Exposure to CO 2 restores the oxygen capacity of the support and removes residual carbon formed at the surface, thus fully regenerating the catalyst. Solids were characterized by TPR, XRD, Raman scattering, and XPS. Results show that part of the Ni is reduced and remain in metallic state during the looping process. On the other hand, Ni 2+ species in strong interaction with Ce cations are observed even after exposure to methane. Both Ni species play important roles on reactants activation and oxygen supply by the solid. Ni loading is a crucial parameter for controlling the reduction behavior of the support and therefore for CLDRM process optimization. [ABSTRACT FROM AUTHOR]