Low temperature complete combustion of a lean mixture of LPG emissions over cobaltite catalysts

LPG is used as a cleaner substitute for gasoline and diesel for automobiles. However, it is a source of hydrocarbon (HC) emissions, causing adverse effects on living beings and the environment. Therefore, to reduce tailpipe HC emissions, this work aims to develop cobaltite spinel catalysts for the oxidation of a lean mixture of LPG. Cobaltite spinel catalysts i.e. MCo2O4 (M = Ni, Cu, Zn) were synthesized by a coprecipitation method and characterized by FTIR, N-2 adsorption and XRD. The XRD/FTIR of the prepared cobaltite catalysts showed the formation of the corresponding MCo2O4 spinels. Among the studied catalysts, NiCo2O4 showed the highest activity with total oxidation of LPG below 200 degrees C. When CO was also added into the feed, a synergistic effect was observed for the simultaneous oxidation of LPG and CO at lower temperature. The total conversion was obtained at a temperature 10 C less than that for the oxidation of LPG alone over NiCo2O4. The order of activity of the catalysts calcined at 300 degrees C was as follows: NiCo2O4 > CuCo2O4 > ZnCo2O4. With calcination of NiCo2O4 at higher temperatures of 400 and 500 degrees C, total LPG conversion was obtained at higher temperatures of 228 degrees C and 265 degrees C respectively. However, it maintained 100% LPG conversion over a 50 h continuous run at a constant temperature of 265 degrees C. Thus, NiCo2O4 is suitable for low temperature (>300 degrees C) complete combustion of a lean mixture of LPG emissions.