K–V–Ca catalysts supported on porous alumina ceramic substrate for soot combustion: Preparation and characterization

The KCl, KNO3, CaCl2, Ca(NO3)2, V–Ca and K–V–Ca catalysts supported on alumina ceramic substrates have been prepared. X-ray diffraction and thermogravimetry/differential scanning calorimetry were used to characterize the catalysts, and their catalytic activities were evaluated by a soot oxidation reaction using the temperature-programmed reaction system. The catalytic activity of KNO3 is higher than KCl, and the catalytic activity of Ca(NO3)2 is as much as that of CaCl2. The catalyst containing a higher KNO3 content exhibits CO2 adsorption, whereas higher CaCl2 and Ca(NO3)2 content can restrain the adsorption of CO2. The K–V–Ca catalyst with a molar ratio of 6:1:1 had the lowest soot onset combustion temperature. The melting and oxidation–reduction of KNO3, oxygen content of catalyst surface, and formation of some eutectic phase may be the key factors in improving catalytic activity of catalysts.