Hydrotalcite-like compounds (HTLcs) CoMAlCO~3, where M stands for Cr, Mn,Ni,Cu,or Fe, were synthesized by coprecipitation. After calcination at 450^oC, they became mixed oxides with spinel-like structure. The mixed oxides were characterized by XRD, BET, chemical analysis and the adsorption of NO. The catalytic decomposition of NO and its reduction by CO were studied over these mixed oxides. The study showed that the catalytic activity for removal of NO~x was very high. The reaction mechanism is proposed and the effects of d-electrons of the transition metals on catalytic activity are elucidated.

Key words: HYDROTALCITE, SPINEL, COBALT OXIDE, ALUMINIUM OXIDE, CHROMIUM OXIDE, MANGANESE OXIDE, NICKEL OXIDE, COPPER OXIDE, X-RAY DIFFRACTION ANALYSIS, NITROGEN MONOXIDE