Effects of adding basic oxides of La and/or Ce to SiO2-supported Co catalysts for ethanol steam reforming

Abstract

In this study, cobalt catalysts supported on La₂O₃–CeO₂–SiO₂ were synthesized by the method of impregnation of the support with aqueous solution of the active phase precursor. These materials were tested in ethanol steam reforming (ESR). The catalysts were characterized by in situ X-ray diffraction (XRD), temperature-programmed reduction (H₂-TPR), temperature-programmed hydrogen desorption (H₂-TPD), temperature-programmed oxidation (O₂-TPO), adsorption–desorption of nitrogen (BET) and energy-dispersive X-ray spectroscopy (EDS). After reaction, the spent materials were characterized by XRD, SEM and elemental analysis. The in situ XRD analysis showed the formation of the solid solution Ce_xLa_1−xO_2−δ and identified cobalt oxide in the spinel structure (Co₃O₄) and metallic cobalt (Co⁰). The H₂-TPR analysis showed the reduction of cobalt oxide, and it was observed that the peaks of cobalt oxide shifted to lower temperatures as the content of lanthanum increased. The H₂-TPD analysis showed that metal surface area and metal dispersion decreased as the percentage of lanthanum oxide in the supports increased. The O₂-TPO analysis showed that La_2%Ce_48%Si_50% consumed the most oxygen. The SEM analysis identified filamentous carbon after reaction. The catalysts were active for H₂ and CO₂ production. The best catalytic performance was shown by Co_10%La_2%Ce_48%Si_50%, which gave the highest H₂ yield.