De–NO x conversion of selective catalytic reduction system for diesel engine using dual catalyst coated ceramic monoliths

Abstract Selective Catalytic Reduction (SCR) is a well-known method for reducing Oxides of Nitrogen (NO x ) emissions from the exhaust manifold of the engine. Retrofitting SCR system to the diesel engines and, enhancing the catalyst activity along with injection controller of this system has become necessary because of stringent emission standards. In this work, dual catalyst is used to increase catalytic activity and, controlled urea injection is applied to decrease the slip of SCR system for stationary diesel engine. First, a pair of ceramic monolith substrate is selected and, coated with cerium oxide and Cu–zeolite for oxidation and SCR catalyst, respectively. XRD, BET and TGA–DSC are used to analyze the structural, and electrochemical behavior of the synthesized catalyst. The morphology and element composition of dual catalyst coated over the substrates are studied using FE-SEM and XEDS. Second, the thermocouple and rotary encoder are used to control the injector of SCR system, which injects the urea when the burned NO x leaves the engine exhaust manifold and enters the SCR. Finally, the diesel engine performance indicators and emission reduction due to the SCR system are evaluated under Non Road Steady Cycle (NRSC). From the experimental results, it is observed that the combined action of catalyst provides wide operating range between 153 and 425 °C and, controlled urea injection at 220° of exhaust valve opening with rate of 24.44 ms per cycle achieved a high De–NO x conversion efficiency of 93.4 % for SCR system, with a marginal reduction in engine Brake Thermal Efficiency (BTE) at maximum Brake Power (BP) condition. Thus, diesel engine exhaust retrofitted with SCR system proposed in this work will meet the Euro-VI emission standards.