Ni-containing Ce-promoted hydrotalcite derived materials as catalysts for methane reforming with carbon dioxide at low temperature – On the effect of basicity

Abstract

NiMgAl mixed oxides promoted with cerium species were synthesized from their corresponding hydrotalcite precursors and subsequently characterized by elemental analysis, XRD, H2-TPR, CO2-TPD and N2 sorption techniques. The catalytic activity of the prepared catalysts was tested in the reaction of CO2 methane reforming and compared to the performance of two reference catalysts: 10Ni/Al2O3 and 10Ni/CZ (ceria-zirconia). The hydrotalcite derived materials showed a significant catalytic activity at 550°C towards the dry reforming reaction. However, the simultaneous occurrence of undesired side reactions was as well observed, mainly CH4 decomposition and RWGS reaction. In this sense, the addition of cerium by ion-exchange with [Ce(EDTA)]− complexes resulted in higher activity and selectivity, due to an increase in the reducibility of nickel species and to the introduction of new intermediate and strong basic sites (acid-base pairs and low coordinated oxygen species). The reference catalysts showed considerable loss of catalytic activity during 5h experiments, lower CO2 conversion (10Ni/CZ) and high excess of CO in the products of the reaction (10Ni/Al2O3), pointing to a generally better performance of the hydrotalcite derived catalysts.