Catalytic Oxidation of Vinyl Chloride over SrCO3-Co3O4 Catalysts: Effect of the Sr:Co Molar Ratio

Abstract

Co3O4 catalysts modified with SrCO3 with various Sr:Co molar ratios were synthesized by a co-precipitation method and their catalytic behavior was examined for the gas-phase oxidation of vinyl chloride. The physicalchemical properties of the samples were thoroughly characterized by means of ICP-AES, BET measurements, XRD, H2-TPR, XPS and SEM-EDX. The obtained results revealed that the incorporation of strontium carbonate introduced changes in the textural and structural properties as well as modifications in the surface chemical composition of the catalysts. The performance of the samples was found to be controlled by the concentration of active species on the surface (Co2+/Co3+ and Oads/Olatt ratios) and the reducibility of the samples. As for the stability of the catalysts, clear evidences of deactivation (more severe when increasing the SrCO3 content) were noticed, probably caused by the decomposition of the SrCO3 phase and the formation of SrCl2 accompanied by a loss of textural properties and active surface oxygen species.