ECO PHYSICS AG

Transition metals cobaltites spinel for depollution of NOₓ emissions using SCR technology

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Abstract

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-NOx activity and the order of catalyst activity followed the sequence: MnCo2O4 > CuCo2O4 > NiCo2O4.

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