Catalytic reduction of nitrogen oxides by olefins in the presence of oxygen over copper/alumina: Influence of copper loading and formation of byproducts
- Swiss Federal Institute of Technology, Zurich (Switzerland); and others
The performance of copper/alumina in the selective catalytic reduction of NO{sub x} by olefins in excess oxygen has been studied by means of FTIR gas phase analysis. Special emphasis was devoted to the formation of harmful byproducts such as N{sub 2}O, HCN, and NH{sub 3}. The effect of copper loading, reaction temperature, nitrogen oxides (NO, NO{sub 2}), hydrocarbons (ethene, propene), and water on activity and on the formation of byproducts has been investigated. Increasing the copper loading from 0.46 to 1.65 wt% CuO resulted in a shift of the maximum activity to lower temperatures and in slightly lower nitrogen yields. NO{sub 2} was reduced more efficiently than NO with both reductants, whereas no significant difference in activity was observed when either ethene or propene was used as a reductant. Water addition suppressed catalytic activity and leveled off the influence of copper loading. Substantial amounts of N{sub 2}O, HCN, and NH{sub 3} were observed for copper-containing catalysts, with ethene showing a markedly lower tendency to form HCN and N{sub 2}O. Addition of water to the feeds eliminated HCN formation and suppressed the production of N{sub 2}O but had only a marginal effect on NH{sub 3} formation. The findings are in accordance with a mechanism in which a nitrogen-containing precursor, which can be a nitrile or an oxime species, reacts to surface isocyanate and/or cyanide species. Hydrolysis of these intermediates provides a pathway to NH{sub 3}. 60 refs., 13 figs., 4 tabs.
- OSTI ID:
- 563505
- Journal Information:
- Journal of Catalysis, Vol. 167, Issue 1; Other Information: PBD: 1 Apr 1997
- Country of Publication:
- United States
- Language:
- English
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