Plasma-assisted catalytic conversion of NO over Cu-Fe catalysts supported on ZSM-5 and carbon nanotubes at low temperature

Abstract

A series of Cu-Fe catalysts with fixed metal content and variable ratios of ZSM-5 and CNTs were used to investigate NO removal in a plasma-catalyst system at low temperature. The catalysts were characterized by BET, XRD, TGA, XPS, H2-TPR and NH3-TPD. The results showed that the catalyst promoted the NO conversion rate from only plasma system, and 1Z3C catalyst exhibited the best NO conversion rate of 86.1% at 191.5 J/L. Composite support promoted the catalytic activity at low temperature, and greatly improved the Cu2+ and Fe3+ concentration on the 1Z3C catalyst, both Cu2+ and Fe3+ contributed greatly to catalytic reaction of NO conversion. Chemisorbed oxygen also acted as activated sites for NO conversion. When the input energy was 75 J/L, the NO conversion rate decreased from 70% to 41% with adding 500 ppm SO2, which decreased with increasing SO2 concentration, while generation rate of SO3 was less than 0.2% in the combination system. In the presence of SO2, copper sulfate species, ferric sulfate species and ammonium sulfates generated on the surface of catalyst, which consumed Lewis acid sites and blocked the active sites, decreasing NO conversion rate.