Highly efficient Pd-doped aluminate spinel catalysts with different divalent cations for the selective catalytic reduction of NO with H2 at low temperature

Publication date: 15 January 2017
Source:Chemical Engineering Journal, Volume 308
Author(s): Chaochao Xu, Wei Sun, Limei Cao, Tingting Li, Xuanxuan Cai, Ji Yang
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 H2 (H2-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% O2 at a low temperature range of 100–350°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-AlPd>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°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 100ppm SO2 in the feed resulted in almost a 23% NO reduction at 250°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 150ppm, and the NO conversion recovered rapidly to approximately 82% after removing the SO2 from the feed stream.

Graphical abstract

http://ift.tt/2dEGDt8