Transition Metals Cobaltites Spinel for Depollution of NOₓ Emissions using SCR Technology

ECO PHYSICS CLD 62

The catalytic performance of various transition metal (M = Cu, Mn, and Ni) cobaltites prepared by nanocasting method were investigated for the selective catalytic reduction (SCR) of NO under lean burn conditions. KIT-6 was used as a hard template in the nanocasting method for preparation of catalysts. The catalyst samples were characterized by various techniques such as XRD, low-temperature N₂ physisorption, SEM-EDS, and XPS. The catalysts were examined for the SCR of NO by NH₃ and H₂-LPG in a packed bed tubular flow reactor under the following reaction conditions: 500 ppm NO, 8 % O₂, (0.1 % NH₃) or (1000 ppm LPG, 1 % H₂) in Ar with 200 mg catalyst. The inlet and outlet gases of the reactor were analyzed by an Eco Physics CLD 62 chemiluminescence NO/NOx analyzer and online GC. NO and NO₂ measurements were done by an Eco Physics CLD 62 chemiluminescence NO/ NOx analyzer. Two separate GCs equipped with Porapak Q/ capillary columns and FID/ ECD detectors were used to analyze the hydrocarbons/ -N₂O respectively. The addition of 1 % H2 with LPG promoted NO reduction at a remarkably low temperature. It was found that the nature of the dispersed metal affects strongly the light-off temperature (52 °C) and enhances NO conversion. The oxygen-deficient MnCo₂O₄ spinel structure enhanced NO reduction (87.1 %) at a lower temperature of 250 °C as compared to Cu and Ni cobaltites using H₂-LPG-SCR. The H₂-LPG reductant showed the best de-NO_x activity and the order of catalyst activity followed the sequence: MnCo₂O₄ > CuCo₂O₄ > NiCo₂O₄.

http://onlinelibrary.wiley.com/doi/10.1002/cjce.23079/