Methane partial oxidation over porous nickel monoliths: The effects of NiO-MgO loading on microstructural parameters and hot-spot temperature

Abstract

Developments of highly efficient catalysts for hydrocarbon fuel conversion have a critical importance for the solid oxide fuel cell (SOFC) technology and hydrogen production. In this work, a series of catalytic monoliths made of porous Ni ribbons with various NiO-MgO loadings were prepared via impregnation with the metal acetates and calcination. The catalysts were tested for the partial oxidation of methane under adiabatic conditions without inlet flow preheating at air excess factors, O2/(2·CH4), varying in the range 0.3–0.4. When NiO-MgO loading increases, the inlet hot spot temperature was found to exhibit minima reflecting changes of the CH4 reforming rate-determining factors in the catalyst frontal layer. A model describing this unusual phenomenon in terms of the volumetric activity and gas permeability of the porous catalysts, was proposed. The model was validated using experimental results of the catalytic tests, high-resolution transmission electron microscopy and mercury porosimetry.