Cu-Mn hydroxyapatite materials for toluene total oxidation

International audienceThe oxidation of 800 ppmv toluene in air has been investigated over CuMnOx ((Cu+Mn) loading: 10 wt%) dispersed on hydroxyapatite (Hap: Ca5(PO4)3(OH)) with different molar Cu/Mn compositions (2; 1; 0.5) to be compared with the corresponding supported single transition metal oxide catalysts. The solids have been prepared by wet aqueous co-impregnation method followed by a calcination at 400 °C for 4 h and physicochemically characterized by different techniques. The catalytic performances of the supported Cu−Mn oxide catalysts revealed the existence of a synergetic effect in terms of activity and selectivity towards CO2 through the formation of Cu−Mn mixed oxides. The strongest synergetic effect is observed for a Cu/Mn molar ratio of 2 as confirmed by the standardized conversion rate values determined at 190 °C (r190) which followed the decreasing sequence (/10−2 h−1): Cu2MnHap (2.57)>CuMnHap (2.04)>CuMn2Hap (1.59)>MnHap (1.13)>CuHap (0.13). The highest activity of Cu2MnHap can be explained by a better reducibility of the active phase in line with a high density of Cu-O−Mn interactions at the outermost layers as shown by ToF-SIMS results