Combined Steam and CO2 Reforming of CH4 on LaSrNiOx, Mixed Oxides Supported on Al2O3-Modified SiC Support

Abstract

The combined steam and CO2 reforming reaction of CH4 was investigated using LaSrNiOx mixed oxides supported on Al2O3-modified beta-SiC to elucidate the largely enhanced CO2 conversion at an optimal concentration of Al2O3 modifier. The dispersion of Al2O3 on the SiC support simultaneously altered the dispersion of LaSrNiOx crystallites increasing their strength when combined with the Al2O3-modified SiC. Although all tested catalysts showed similar activation energies, the increased Al2O3 dispersion on SiC at around 10 wt % Al2O3 modifier was well-correlated with the increased dispersion of active perovskite-like La2NiO4 crystallites which resulted in an enhanced catalytic activity. The formation of smaller NiO and La2NiO4 crystallites through an intimate contact with Al2O3 particles seems to be responsible for the suppressed aggregation of nickel crystallites during higher temperature reforming reactions. The higher amounts of CO2 adsorption on the well-dispersed basic lanthanum and strontium oxides contained in the LaSrNiOx mixed oxides are also responsible for the enhanced CO2 conversion. Observed surface properties including the crystallite size of active components, the reducibility of NiO, and the CO2 adsorption property are explained in terms of the results obtained from X-ray diffraction, X-ray photoelectron spectroscopy, temperature-programmed reduction, CO2 temperature-programmed desorption (CO2-TPD), and NH3-TPD analyses