초록 ▼

A two-stage method for NOx reduction in an oxygen-rich engine exhaust comprises a plasma oxidative stage and a storage reduction stage. The first stage employs a non-thermal plasma treatment of NOx gases in an oxygen-rich exhaust and is intended to convert NO to NO2 in the presence of O2 and hydroca

A two-stage method for NOx reduction in an oxygen-rich engine exhaust comprises a plasma oxidative stage and a storage reduction stage. The first stage employs a non-thermal plasma treatment of NOx gases in an oxygen-rich exhaust and is intended to convert NO to NO2 in the presence of O2 and hydrocarbons. The second stage employs a lean NOx trap to convert such NO2 to environmentally benign gases that include N2, CO2, and H2O. By preconverting NO to NO2 in the first stage with a plasma, the efficiency of the second stage for NOx reduction is enhanced. For example, an internal combustion engine exhaust is connected by a pipe to a first chamber in which a non-thermal plasma converts NO to NO2 in the presence of O2 and hydrocarbons, such as propene. A flow of such hydrocarbons (CxHy) is input from usually a second pipe into at least a portion of the first chamber. The NO2 from the plasma treatment proceeds to a storage reduction catalyst (lean NOx trap) that converts NO2 to N2, CO2, and H2O, and includes a nitrate-forming catalytic site. The hydrocarbons and NOx are simultaneously reduced while passing through the lean-NOx trap catalyst. The method allows for enhanced NOx reduction in vehicular engine exhausts, particularly those having relatively high sulfur contents.

대표청구항 ▼

1. A method for reducing nitrogen oxides (NOx) in exhausts from high-temperature combustion, the method comprising the steps of:converting substantially all NO in an engine exhaust with a non-thermal plasma to an intermediate gas flow including NO2; converting, in the presence of hydrocarbons, subst

1. A method for reducing nitrogen oxides (NOx) in exhausts from high-temperature combustion, the method comprising the steps of:converting substantially all NO in an engine exhaust with a non-thermal plasma to an intermediate gas flow including NO2; converting, in the presence of hydrocarbons, substantially all of said intermediate gas flow including NO2 to an output gas flow comprising NO2 conversion products of N2, CO2 and H2O and substantially little NO and NO2 (NOx); and wherein, a storage reduction catalyst is used to convert said NO2 in the presence of said hydrocarbons, to N2, CO2, and H2O.