| 摘要 |
<p>A two-stage catalyst (100) comprises an oxidative stage (102) and a reductive second stage (104). The first stage (102) is intended to convert NO to NO2 in the presence of O2. The second stage (104) serves to convert NO2 to environmentally benign gases that include N2, CO2, and H2O. By preconverting NO to NO2 in the first stage (102), the efficiency of the second stage (104) for NOX reduction is enhanced. For example, an internal combustion engine exhaust is connected by a pipe (106) to a first chamber (108). A first oxidizing catalyst (110) converts NO to NO2 in the presence of O2 and includes platinum/alumina, e.g., Pt/Al2O3 catalyst. A flow of hydrocarbons (CxHy) is input from a pipe (112) into a second chamber (114). For example, propene can be used as a source of hydrocarbons. The NO2 from the first catalyst (110) mixes with the hydrocarbons in the second chamber (114). The mixture proceeds to a second reduction catalyst (116) that converts NO2 to N2, CO2, and H2O, and includes a gamma-alumina. The hydrocarbons and NOX are simultaneously reduced while passing through the second catalyst (116).</p> |
