Highly selective catalytic reduction of NO via SO(2)/H(2)O-tolerant spinel catalysts at low temperature

Selective catalytic reduction of NO(X) by hydrogen (H(2)-SCR) in the presence of oxygen has been investigated over the NiCo(2)O(4) and Pd-doped NiCo(2)O(4) catalysts under varying conditions. The catalysts were prepared by a sol-gel method in the presence of oxygen within 50–350 °C and were characterized using XRD, BET, EDS, XPS, Raman, H(2)-TPR, and NH(3)-TPD analysis. The results demonstrated that the doped Pd could improve the catalyst reducibility and change the surface acidity and redox properties, resulting in a higher catalytic performance. The performance of NiCo(1.95)Pd(0.05)O(4) was consistently better than that of NiCo(2)O(4) within the 150–350 °C range at a gas hourly space velocity (GHSV) of 4800 mL g(−1) h(−1), with a feed stream containing 1070 ppm NO, 10,700 ppm H(2), 2 % O(2), and N(2) as balance gas. The effects of GHSV, NO/H(2) ratios, and O(2) feed concentration on the NO conversion over the NiCo(2)O(4) and NiCo(1.95)Pd(0.05)O(4) catalysts were also investigated. The two samples similarly showed that an increase in GHSV from 4800 to 9600 mL h(−1) g(−1), the NO/H(2) ratio from 1:10 to 1:1, and the O(2) content from 0 to 6 % would result in a decrease in NO conversion. In addition, 2 %, 5 %, and 8 % H(2)O into the feed gas had a slightly negative influence on SCR activity over the two catalysts. The effect of SO(2) on the SCR activity indicated that the NiCo(1.95)Pd(0.05)O(4) possesses better SO(2) tolerance than NiCo(2)O(4) catalyst does. [Figure: see text]