Porous acicular mullite(3Al2O3·2SiO2)is promising material for filtration of diesel engine exhaust.It appears that microstructure consisting of elongated,prism-like,mullite grains efficiently captures carbonaceous matter without causing considerable pressure drop.In order to provide an undisturbed operation of diesel engine it is necessary to continuously remove(oxidize)the captured carbonaceous particles.In this study,it was shown that the reaction of oxidation of carbon particles located in porous mullite can be catalyzed by the presence of Cu3Mo2O9.