Matsuei Ueda

A new optimizing technique of a diesel engine aftertreatment system using HC DeNox catalyst

Abstract A new method that optimizes a control map of hydrocarbon (HC) addition to diesel exhaust gas for HC type Selective Catalytic Reduction DeNO x catalyst system has been developed. This method comprises a numerical model and a new optimization technique. The numerical model is capable of predicting performance of HC DeNO x with diesel fuel as a supplemental reductant. The control map of HC addition was optimized with the evolutionary programming based on the evolution of living things. As a result, NO x conversion with the optimized control map was found to be greater by 21% than that with the conventional control on Japanese 10–15 mode.

NOx Reduction Behavior on Catalysts With Non-Thermal Plasma in Simulated Oxidizing Exhaust Gas

NOx reduction activity in an oxidizing exhaust gas was significantly improved by discharging non-thermal plasma and catalysts (plasma assisted catalysis). We investigated effective catalyst for plasma assisted catalysis in view of hydrocarbon-selective catalytic reduction(HC-SCR). Plasma assist was effective for γ-alumina and alkali or alkaline earth metals loaded zeolite and γ-alumina showed the highest NOx conversion among these catalysts. On the other hand, Plasma assist was not effective for Cu-ZSM-5 and Pt loaded catalyst. The NOx conversion for the plasma assisted γ-alumina decreased by formation of a deposit on the catalyst below 400°C. It is shown that indium loading on γ-alumina improved the NOx reduction activity and suppressed the degradation of the NOx reduction activity at 300°C with plasma assist.

A Concept of Plasma Assisted Catalyst System Using a DeNOx Catalyst for an Automobile Diesel Engine

Through the basic research of the plasma assisted catalyst system using DeNOx catalysts and the gas analysis of the system, its conceptual use for automobile diesel engine applications has been studied. This study has shown that the length between the plasma reactor and the catalyst reactor does not affect the NOx conversion. To obtain an efficient NOx conversion, the plasma should affect both the HC as the reductant and NOx at the same time. In the case of γ-Al 2 O 3 and C 3 H 6 , the main component for NOx reduction was CH 3 CHO generated by the plasma. Under 250 deg. C, the temperature was too low for the γ-Al 2 O 3 to become effective. Therefore, the NOx conversion became low. At 400 deg. C, the NOx conversion became high. However, at 600 deg. C, the CH 3 CHO for reducing NOx was not generated, and the NOx conversion decreased. By using multi-catalysts (Na-ZSM-5, In/Al 2 O 3 and Pt/Al 2 O 3 ), an efficient NOx conversion was obtained under the transient gas temperature conditions similar to those of the automobile exhaust.