Experimental research on dynamic response characteristics of the vanadium-based SCR catalyst on diesel engine

The SCR dynamic response characteristic, especially the effects of reaction temperature and space velocity on NOx conversion and NH3 storage-release characteristic, was investigated on vanadium-based SCR catalysts on a real engine bench. The results shows that when temperature is lower than 300C, NOx conversion efficiency increases with the increase of temperature and decreases with the increase of space velocity. Exhaust gas temperature and space velocity have little effect on NOx conversion efficiency when temperature is between 300C and 400C. Temperature and space velocity plays a negative influence on the amount of NH3 stored in SCR converter. At low temperature, the influence of space velocity on the storage of NH3 is obvious. NH3 storage and release rates increase with the increase of exhaust temperature and space velocity. NH3 can not release completely at low temperature. To avoid the fluctuations in NOx conversion efficiency and excessive NH3 leakage, matching between reductant injection control strategy and SCR calibration must effectively use the NH3 storage-release characteristics.