Simplified Kinetic Model for NH 3 -SCR Over Cu-CHA Based on First-Principles Calculations

Abstract

Selective catalytic reduction with ammonia as reducing agent (NH 3-SCR) is an efficient technology to control NO x emission during oxygen excess. Catalysts based on Cu-chabazite (Cu-CHA) have shown good performance for NH 3-SCR with high activity and selectivity at low temperature and good hydrothermal stability. Here, we explore a first-principles based kinetic model to analyze in detail which reaction steps that control the selectivity for N 2 and the light-off temperature. Moreover, a simplified kinetic model is developed by fitting lumped kinetic parameters to the full model. The simplified model describes the reaction with high accuracy using only five reaction steps. The present work provides insight into the governing reaction mechanism and stimulates design of knowledge-based Cu-CHA catalysts for NH 3-SCR.