Selective catalytic reduction of nitric oxide by ammonia over Cu-exchanged Cuban natural zeolites

摘要

The catalytic selective reduction of NO over Cu-exchanged natural zeolites (mordenite (MP) and clinoptilolite (HC)) from Cuba using NH_3 as reducing agent and in the presence of excess oxygen was studied.Cu(II)-exchanged zeolites are very active catalysts,with conversions of NO of approx 95%,a high selectivity to N_2 at low temperatures,and exhibiting good water tolerance.The chemical state of the Cu(II) in exchanged zeolites was characterized by H_2-TPR and XPS.Cu(II)-exchanged clinoptilolite underwent a severe deactivation in the presence of SO_2.However,Cu(II)-exchanged mordenite not only maintained its catalytic activity,but even showed a slight improvement after 20 h of reaction in the presence of 100 ppm of SO_2.