Selective Catalytic Reduction of NOx of Ship Diesel Engine Exhaust Gas with C3H6 over Cu/Y Zeolite

Abstract

Various solid Cu-containing catalysts were prepared. Their performance in the selective catalytic reduction of NOx using propene as reducing agent from 150 to 450 °C in an O2-rich model exhaust gas in the presence of water vapor was investigated. This research aimed at the development of a catalytic NOx to N2 (DeNOx) step to be part of a ship diesel exhaust abatement system in combination with other techniques, such as nonthermal plasma. Among the catalysts tested, Cu on zeolite Y with an optimized load of 16 wt % (denoted as 16Cu/Y) displayed excellent DeNOx activity with highest selectivity toward N2 at 290 °C. The influence of other variables, such as Cu load, calcination temperature, feed composition, and GHSV on the performance of 16Cu/Y was studied, as well. The highest N2 yield of 98% was achieved using 2000 ppm of propene in the gas feed. The presence of O2 proved to be a crucial factor for promoting the selective reduction of NOx with C3H6 over this catalyst. On the other hand, the presence of water in the feed decreased NOx to N2 conversion. However, the catalyst showed excellent stability over 120 h, even at high water concentration, and also after repeated heating from ambient temperature to 450 °C, and it was reusable after downtimes without remarkable loss in activity. The nature of the Cu species was studied by XPS, XRD, and TPR experiments.