Influence of the swelling agents of siliceous mesocellular foams on the performances of Ni-based methane dry reforming catalysts

Abstract

For the first time, n-octane was tested as a swelling agent for the synthesis of a mesocellular silica foam (MCF(O)) and the latter was used as a Ni support for the dry reforming of methane reaction (DRM). Using n-Octane led to a MCF(O) material with smaller cells size (14 nm) than in conventional MCF(T) prepared in the presence of 1,3,5 trimethylbenzene (21 nm). Nickel precursor addition was done either by post-synthesis impregnation on preformed silica (incipient wetness impregnation (IWI), "two-solvents" (TS)) or during the synthesis of MCF (Direct synthesis, DS). All prepared materials were characterized in their calcined and reduced forms using N2 sorption, X-Ray Diffraction (XRD), Transmission Electronic Microscopy (TEM), Temperature Programmed Reduction (TPR) and X-Ray Fluorescence (XRF). A highly dispersed Ni0 active phase, mainly located in the MCF walls, as well as strong Ni-support interaction were emphasized for Ni-MCF(O)-DS. The catalytic performances of all the samples were investigated in DRM between 200 and 770 °C, then for 4 h (stability test) at 650 °C, using a Gas Hourly Space Velocity (GHSV) of 36 L g−1 h−1 and an equimolar ratio of CH4 and CO2 reactants. The Ni-MCF(O)-TS catalyst prepared by means of the "two-solvents" impregnation exhibited the highest CH4 and CO2 conversions. Compared to Ni-MCF(T), better performances were obtained with Ni-MCF(O) solids.