Hydrotalcite-like compounds derived cuznal oxide catalysts for aerobic oxidative removal of gasoline-range organosulfur compounds

A series of CuZnAl oxide-composite catalysts have been prepared via decomposition of CuZnAl hydrotalcitelike compounds (HTLcs: Cu 37%, Zn 15%, Al 48% mol) at various temperatures and examined for use with aerobic oxidative desulfurization (AODS) of gasoline-range organosulfur compounds in iso-octane. It shows that catalytically relevant properties of HTLcs-derived CuZnAl catalysts and their performance for AODS reaction can be significantly controlled by HTLcs decomposition temperatures. At 600 ̊C, CuZnAl HTLcs can be decomposed completely to form highly dispersed CuO with large specific surface area while forming a small amount of CuAl2O4 spinel phase, and meanwhile, improved CuO-ZnO interaction and promoted catalyst reducibility/reoxidizability can be obtained. By taking the above beneficial properties, this HTLcsderived CuZnAl catalyst is quite active and selective for aerobically oxidizing organosulfur compounds to SO2 at 300 ̊C and atmospheric pressure. Thiophene is not so reactive as mercaptan, organic sulfide, benzothiophene, and dibenzothiophene. Adsorptive oxidation of thiophene previously observed on Pt/CeO2 catalyst is likewise detectable on this HTLcs-derived CuZnAl catalyst by means of in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), but it hardly happens to paraffinic, olefinic, and aromatic hydrocarbon molecules.