Three-dimensional mesoporous manganese oxides and cobalt oxides: High-efficiency catalysts for the removal of toluene and carbon monoxide

Abstract Three-dimensional (3D) mesoporous tetragonal MnO 2 (MnO 2 -SBA16 and MnO 2 -KIT6) and cubic Co 3 O 4 (Co 3 O 4 -SBA16 and Co 3 O 4 -KIT6) with high surface areas (102–184 m 2 /g) were, respectively prepared using the nanocasting strategy with SBA-16 and KIT-6 as templates. The KIT-6- and SBA-16-derived samples displayed 3D ordered and wormhole-like mesoporous structures, respectively. The oxygen adspecies concentration and low-temperature reducibility decreased in the orders of MnO 2 -KIT6 > MnO 2 -SBA16 > MnO 2 -bulk and of Co 3 O 4 -KIT6 > Co 3 O 4 -SBA16 > Co 3 O 4 -bulk, in agreement with their catalytic performance sequences. The porous MnO 2 catalysts ( T 90%  = 217–220 °C) outperformed the porous Co 3 O 4 catalysts ( T 90%  = 233–240 °C) for toluene oxidation, but the latter ( T 90%  = 129–132 °C) were superior to the former ( T 90%  = 158–178 °C) in catalytic activity for CO oxidation. It is concluded that the high surface area and oxygen adspecies concentrations, good low-temperature reducibility, and high-quality 3D ordered mesoporous architecture accounted for the excellent catalytic performance of MnO 2 -KIT6 and Co 3 O 4 -KIT6.