Chemical Engineering Journal, Vol.308, 980-987, 2017
Highly efficient Pd-doped aluminate spinel catalysts with different divalent cations for the selective catalytic reduction of NO with H-2 at low temperature
The performance of pure and Pd-doped aluminate spinel catalysts (i.e., MAl2O4 and MAl1.95Pd0.05O4, where M = Cu, Co, Zn) for the selective catalytic reduction of NO by H-2 (H-2-SCR) were investigated in this paper. The catalytic performance over MAl2O4 is poor but can be improved significantly by incorporating Pd into the lattice, resulting in NO conversion over Co-AlPd, Zn-AlPd and Cu-AlPd catalysts of approximately 95%, 90.5% and 84%, respectively, in the presence of 2% O-2 at a low temperature range of 100-350 degrees C. Both the pure and Pd-doped aluminate spinel catalysts showed the same sequences with respect to activity: Co-Al > Zn-Al > Cu-Al and Co-AIPd > Zn-AlPd > Cu-AlPd, indicating that the selection of divalent metal M is of essential importance in designing spinel catalysts and in modifying their SCR performance. Co-AlPd catalyst showed stable activity in the presence of 3% and 5% H2O at 250 degrees C, whereas the SCR reaction was promoted and a slight positive influence of the NO conversion was observed with a further increase of the H2O concentration to 5%. The presence of 100 ppm SO2 in the feed resulted in almost a 23% NO reduction at 250 degrees C for the Co-AlPd catalyst, whereas only a 1.2% decrease of NO conversion was observed with further increase in the SO2 concentration to 150 ppm, and the NO conversion recovered rapidly to approximately 82% after removing the SO2 from the feed stream. (C) 2016 Elsevier B.V. All rights reserved.