Modeling of monolith reactor washcoated with CuZSM5 catalyst for removing NO from diesel engine by urea

Abstract

Two sets of reaction kinetics based upon the experimental data independently obtained for NH3-SCR and urea decomposition reactions over CuZSM5 catalyst have been deduced to design the urea-SCR process for application to heavy-duty diesel engines. They were finally employed simultaneously to simulate the commercial performance of a monolith reactor for the urea-SCR process. The monolith reactor washcoated with the CuZSM5 catalyst was prepared and its SCR activity was evaluated to confirm the reaction kinetics and the reactor model developed in the present study for its commercial application. The monolith reactor model including the mass-transfer resistance directly employs the kinetic parameters obtained from the kinetic study over a packed-bed flow reactor containing 20/30 mesh powder type of CuZSM5 catalyst. The kinetic and monolith reactor models developed in the present study well predict the reactor performance of the urea-SCR process. The model is also capable of describing the effect of the reaction conditions, a critical issue for the commercial operation of the urea-SCR process to the automotive engine, including the reactor space velocity, NH3 (and/or urea)/NO feed ratio, NH3 and urea slips, and the temperature of the thermal decomposition reactor on the NO removal activity.