Cascade Processing of NOx by Two-Step Discharge/Catalyst Reactors

We present here a phenomenological analysis of a cascade of two-step discharge-catalyst reactors. That is, each step of the cascade consists of a discharge reactor in series with a catalyst bed. These reactors are intended for use in the reduction of tailpipe emission of NOx from diesel engines. The discharge oxidizes NO to NO₂, and partially oxidizes HC. The NO₂ then reacts on the catalyst bed with hydrocarbons and partially oxidized HCs and is reduced to N₂. The cascade may be essential because the best catalysts for this purpose that we have also convert significant fractions of the NO₂ back to NO. As we show, reprocessing the gas may not only be necessary, but may also result in energy savings and increased device reliability.