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A concept of catalytic reversed flow converter (RFC) is discussed for three emerging areas of emission control after automotive engines. The first potential application concerns with oxidation of methane and CO emitted from dual fueled, natural gas/diesel engines (DDF). The behavior of RFC is studied under typical transient conditions of DDF engine exhaust using mathematical modeling and experiments with converter prototype. It was shown that the RFC with a single catalyst monolith can be well suited for this application. The second potential application is aimed at NOx emission control from diesel engines. An RFC comprising a catalyst bed flanked by two beds of inert material is discussed based on a lumped kinetics of NOx reduction over a noble metal lean-NOx catalyst. Contrary to a traditional converter, the RFC retains high efficiency of NOx reduction for long time after typical excursion of NOx concentration and temperature of engine exhaust gas. Finally, an idea of RFC combining catalyst and adsorbent is suggested for emission control during cold start of automotive engines.

The paper discusses the development of catalytic converter for aftertreatment of exhaust gas from diesel engines powered with natural gas. The converter, operated with periodical reversals of the flow, ensures destruction of CO and hydrocarbons, including methane. Both computer simulation and engine testing results are presented.

Publisher Summary Interaction of the dynamic properties of a catalyst, a micro-scale physic-chemical system, and the dynamic properties of the macro-scale reactor creates an opportunity to improve the performance of catalytic processes using forced unsteady-state operation. Forced dynamic operation makes it possible to generate spatio-temporal patterns of temperature, composition and catalyst states that cannot be attained under steady-state operation. Probably, a potential for increase of efficiency of partial oxidation processes due to FUSC is tremendous. Frequently observed small effects apparently result from current research philosophy: trial-and-error experimentation with different forced periodic regimes while searching for drastic improvement. Money should be spent for elucidation of the process mechanism, developing models appropriate for numerical simulation, search for optimums using computer simulation, then testing the results in the lab or pilot unit.