ディーゼル機関における触媒還元脱硝法の適用

概要

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The efficiency of TiO_2-V_2O_5 catalyst for selective catalytic reduction (SCR) of NO_x was investigated using a single-cylinder direct-injection diesel engine. Ammonium carbonate solution and urea solution were mixed with exhaust gas as deoxidizer instead of NH_3 gas injection. The catalyst provided a substantial reduction in NO_x emissions for a catalyst bed temperature of about 190-430℃. NO_x removal rate was about 70-95% for a space velocity of 6300-12500 h^<-1>, catalyst temperature of : 350-400℃ and NH3 molar ratio of 1-2. Reaction at temperatures above 400℃ induced combustion of NH_3 and catalyst sintering. It was recommended that the urea solution be used as deoxidizer in practical application to achieve high denitration efficiency and low leakage of NH_3. However, injection of urea solution caused an increase of Bosch smoke pollution and a reduction of SO_2 concentration due to the emission of sulfate dust produced by reaction of leakage NH_3 with SO_2 and particulate matter (PM). The PM contained a relatively large amount of Na^+, K^+ and SO_4^<-->, which contribute to deterioration of catalyst efficiency, and therefore the PM had a significant effect on the catalyst activity.
一般社団法人日本機械学会の論文
1995-02-25