Industrial nox control via h2-scr on a novel supported-pt nanocatalyst

Abstract

We describe here the performance of a novel MgO-CeO2-supported Pt nanocatalyst (∼1.5nm mean Pt particle size) towards the selective conversion of NO (XNO>90%) into N2 (SN2>80%) using H2 (H2-SCR) in the low-temperature range of 120-180°C for a wide range of O2, H2 and CO2 feed concentrations. This catalytic system showed remarkable performance under industrial process conditions of NOx control [1-5]. Using a feed composition containing 150ppm NO, 2vol% O2 and H2 in the 0.2-0.8vol% range (GHSV=33,000h-1), the NO conversion, XNO (%) and N2-selectivity, SN2 (%) were found to increase with increasing H2 feed concentration in the 120-180°C range, where NO conversions in the 97-100% range and N2-selectivities in the 83-93% range were obtained. By increasing the O2 feed concentration from zero to 5vol%, both the XNO (%) and the SN2 (%) were found to decrease by an extent which was dependent of reaction temperature. The effect of CO2 in the feed stream (0-12vol%) was found to be slightly negative for the NO conversion, while an opposite behavior was found for the SN2 (%), 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 H2-SCR but not their chemical structure.