La-Sr-Ni-Co-O based perovskite-type solid solutions as catalyst precursors in the CO2 reforming of methane

Abstract

La1−xSrxNi0.4Co0.6O3 and La0.8Sr0.2Ni1−yCoyO3 solid solutions with perovskite-type structure were synthesized by the sol–gel resin method and used as catalytic precursors in the dry reforming of methane with CO2 to syngas, between 873 and 1073K at atmospheric pressure under continuous flow of reactant gases with CH4/CO2 = 1 ratio. These quaternary oxides were characterized by X-ray diffraction (XRD), BET specific surface area and temperature-programmed reduction (TPR) techniques. XRD analyses of the more intense diffraction peaks and cell parameter measurements showed formation of La-Sr-Ni-Co-O solid solutions with La0.9Sr0.1CoO3 and/or La0.9Sr0.1NiO3 as the main crystallographic phases present on the solids depending on the degree of substitution. TPR analyses showed that Sr doping decreases the temperature of reduction via formation of intermediary species producing Ni0, Co0 with particle sizes in the range of nanometers over the SrO and La2O3 phases. These metallic nano particles highly dispersed in the solid matrix are responsible for the high activity shown during the reaction and avoid carbon formation. The presence of Sr in doping quantities also promotes the secondary reactions of carbon formation and water–gas shift in a very small extension during the dry reforming reaction.