The effects of Bi(2)O(3) on the selective catalytic reduction of NO by propylene over Co(3)O(4) nanoplates

Bi(2)O(3)/Co(3)O(4) catalysts prepared by the impregnation method were investigated for the selective catalytic reduction of NO by C(3)H(6) (C(3)H(6)-SCR) in the presence of O(2). Their physicochemical properties were analyzed with SEM, XRD, H(2)-TPR, XPS, PL and IR measurements. It was found that the deposition of Bi(2)O(3) on Co(3)O(4) nanoplates enhanced the catalytic activity, especially at low reaction temperature. The SO(2) tolerance of Co(3)O(4) in C(3)H(6)-SCR activity was also improved with the addition of Bi(2)O(3). Among all catalysts tested, 10.0 wt% Bi(2)O(3)/Co(3)O(4) achieved a 90% NO conversion at 200 °C with the total flow rate of 200 mL min(−1) (GHSV 30 000 h(−1)). No loss in its C(3)H(6)-SCR activity was observed at different temperatures after the addition of 100 ppm of SO(2) to the reaction mixture. These enhanced catalytic behaviors may be associated with the improved oxidizing characteristics of 10.0 wt% Bi(2)O(3)/Co(3)O(2). XRD results showed that Bi(2)O(3) entered the lattice of Co(3)O(4), resulting in the formation of lattice distortion and structural defects. H(2)-TPR results showed that the reduction of Co(3)O(4) was promoted and the diffusion of oxygen was accelerated with the addition of Bi(2)O(3). XPS measurements implied that more Co(3+) formed on the 10.0% Bi(2)O(3)/Co(3)O(2) catalysts. The improved oxidizing characteristics of the catalyst with the addition of Bi(2)O(3) due to the synergistic effect of the nanostructure hybrid, thus enhanced the C(3)H(6)-SCR reaction and hindered the oxidization of SO(2). Therefore, the 10.0% Bi(2)O(3)/Co(3)O(4) catalyst exhibited the highest NO conversion and strongest SO(2) tolerance ability.