Simultaneous Removal of NOx and Soot in Diesel Exhaust by Using a Centrifugal Fluidized Bed

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Reduction of nitrogen oxides emitted from a diesel engine with soot over a Cu-ZSM-5 zeolite catalyst has been experimentally. It was found that in the presence of oxygen, the soot promoted NO_x reduction into nitrogen over the Cu-ZSM-5 zeolite catalyst. Restults show that NO_2 is formed through the reaction of NO and O_2 and is then partially reduced into N_2 by soot over the CU-ZSM-5 zeolite catalyst. Activated carbon was observed to be also as effective as soot in the removal of nitrogen oxides over this catalyst. At 693 K, the rate of the nitrogen oxide removal reaction was found to be proportional to the NO concentration. The mechanisms of this reaction are discussed based on the results obtained from the kinetic study.In addition, in order to remove NOx and soot simultaneously, the application of the centrifugal fluidized bed with ultrafine catalyst particles is proposed. The fluidization of nanoparticles has been conducted in a centrifugal fluidized bed (CenFB). In the case of 7 and 20 nm particle systems, the nanoparticles are fluidized with forming agglomerates in the range of 9.1<G<18.5. The fluidization quality of nanoparticles with high G is affected by not only the primary particle size but also agglomerates size and its structure.