Effects of acid treatments of carbon on N 2O and NO reduction by carbon-supported copper catalysts

Abstract

The influences of HCl, HNO 3 and HF treatments of carbon on N 2O and NO reduction with 20 wt% Cu-loaded activated carbon were studied. The order of activity in both N 2O and NO is as follows: Cu20/AC–HNO 3>Cu20/AC>Cu20/AC–HF>Cu20/AC–HCl. The same sequence was also observed for the amount of CO 2 evolved during TPD experiments of supports and for the catalyst dispersion. On the other hand, N 2O exhibited a higher reaction rate than NO and a higher sensitivity to acid treatments, and the presence of gas-phase O 2 had opposite effects in N 2O and NO reduction. The key role of carbon surface chemistry is examined to rationalize these findings and the relevant mechanistic and practical implications are discussed. The effects of oxygen surface groups on the pore structure of supports and catalysts are also analyzed.