Industrial NO x control via H 2-SCR on a novel supported-Pt nanocatalyst

Abstract

We describe here the performance of a novel MgO–CeO 2-supported Pt nanocatalyst (∼1.5 nm mean Pt particle size) towards the selective conversion of NO ( X NO > 90%) into N 2 ( S N 2 > 80 % ) using H 2 (H 2-SCR) in the low-temperature range of 120–180 °C for a wide range of O 2, H 2 and CO 2 feed concentrations. This catalytic system showed remarkable performance under industrial process conditions of NO x 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 N 2 (%) were found to increase with increasing H 2 feed concentration in the 120–180 °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 N 2 (%) were found to decrease by an extent which was dependent of reaction temperature. The effect of CO 2 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 N 2 (%), likely due to competitive adsorption of CO 2 and NO on the same non-selective NO x adsorption sites. In situ DRIFTS studies have shown that the oxygen feed concentration largely influenced the surface concentration of inactive NO x and only slightly that of active NO x intermediates of H 2-SCR but not their chemical structure.