Selective Catalytic Reduction of NO_<i>x</i> 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 NO_<i>x</i> 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 NO_<i>x</i> to N₂ (DeNO_<i>x</i>) 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 DeNO_<i>x</i> 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 NO_<i>x</i> with C₃H₆ over this catalyst. On the other hand, the presence of water in the feed decreased NO_<i>x</i> 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