Thermal decomposition of supported lithium nitrate catalysts

New catalysts for soot combustion were prepared by impregnation of different supports (SiO2, ZrO2 and ZrO2·nH2O) with a LiNO3 solution and then characterized by means of FTIR, XPS, TGA and UV–vis spectroscopy, whereby the presence of lithium nitrate in the prepared catalysts was identified and quantified. The soot combustion rate using this series of catalysts (LiNO3/support) was compared with the activity of a series of impregnated catalysts prepared using LiOH (Li2O/supports). Catalysts prepared using LiNO3 are found to be more active than those prepared using LiOH. The catalytic performance was also studied with a NO/O2 mixture in the feed, demonstrating that NO increases the combustion rate of soot, probably as a consequence of lithium oxide forming an “in situ” nitrate ion.