Synthesis and characterization of mesoporous NiO2/ZrO2-CeO2 catalysts for total methane conversion

Abstract

This work reports the synthesis and characterization of mesoporous NiO/ZrO2-CeO2 composites. These materials are still being developed due to their excellent morphological and structural properties, especially for solid oxide fuel cells (SOFCs) anodes. A soft chemical route using a polymeric template was utilized to synthesize the samples. The structure after two different calcination processes at 400 °C and 540 °C was studied by X-ray diffraction and Rietveld refinement, before and after NiO loading. Nitrogen adsorption, scanning/transmission electron microscopy and small angle X-ray scattering revealed a nanocrystalline bi-phasic porous material. Temperature programmed reduction experiments showed higher Ni and Ce reduction values for samples calcined at 400 °C and 540 °C, respectively. Methane conversion values in the temperature range studied were similar for both calcination temperatures, showing 50% CH4 conversion around 550 °C and 80% around 650 °C. However, a sample calcined at 400 °C exhibited better morphological and textural properties leading to an enhancement in NiO and CeO2 reducibility that might be responsible for an improvement in oxygen surface exchange and gasification of carbon species in catalytic experiments.