Industrial NOx control via H2-SCR on a novel supported-Pt nanocatalyst

We describe here the performance of a novel MgO-CeO2-supported Pt nanocatalyst (similar to 1.5 nm mean Pt particle size) towards the selective conversion of NO (X-No > 90%) into N-2 (S-N2 > 80%) using H-2 (H-2-SCR) in the low-temperature range of 120-180 degrees C for a wide range of O-2, H-2 and CO2 feed concentrations. This catalytic system showed remarkable performance under industrial process conditions of NOx control [1-5]. Using a feed composition containing 150 ppm NO, 2 vol% O-2 and H-2 in the 0.2-0.8 vol% range (GHSV = 33,000 h(-1)), the NO conversion, X-NO (%) and N-2-selectivity, S-N2, (%) were found to increase with increasing H-2 feed concentration in the 120-180 degrees C range, where NO conversions in the 97-100% range and N-2-selectivities in the 83-93% range were obtained. By increasing the O-2 feed concentration from zero to 5 vol%, both the X-NO (%) and the S-N2 (%) were found to decrease by an extent which was dependent of reaction temperature. The effect of CO2 in the feed stream (0-12 vol%) was found to be slightly negative for the NO conversion, while an opposite behavior was found for the S-N2 (%), likely due to competitive adsorption of CO2 and NO on the same non-selective NOx adsorption sites. In situ DRIFTS studies have shown that the oxygen feed concentration largely influenced the surface concentration of inactive NOx and only slightly that of active NOx intermediates of H-2-SCR but not their chemical structure. (C) 2011 Elsevier BM. All rights reserved.