Study of NOx Reduction efficiency in NSR and NSR-SCR Combined Systems 2019-28-0087
The present study was carried out to analyze the catalytic action of K2O-Al2O3 in NOx storage and Reduction (NSR) monolith catalyst in addition to Fe2O3-TiO2 in Selective Catalytic Reduction (SCR) monolith catalyst to determine their NOx reduction capabilities with respect to engine exhaust gas temperature. To accomplish this task monolith ceramic bricks were coated with K2O-Al2O3 (NSR) and Fe2O3-TiO2 (SCR) catalyst and were placed in different configurations inside the catalytic chamber. Several trials were attempted to get the optimal operating temperature that has a maximum NOx removal efficiency when successively connecting single NSR catalyst and the combined NSR–SCR double bed arrangement. Finest operation of the single NSR monolith was attained at 320 ºC, which showed NOx removal rate of 74% while, the double NSR–SCR configuration permitted the SCR catalyst storing ammonia to respond with NOx leaving the NSR in gaining higher NOx removal rates. The SCR reaction between ammonia which leaves from NSR, later adsorbed by SCR and the NO that is not reacted in NSR which enters SCR resulted in a total NOx removal efficiency of 93% when operated with double NSR–SCR system. The study also revealed that the given system is not applicable for engines having exhaust temperature range less than 250 ºC as they are unable to provide the sufficient activation energy.