On-Road Demonstration of NOx Emission Control for Heavy-Duty Diesel Trucks using SINOx™ Urea SCR technology - Long-term Experience and Measurement Results 2001-01-1931

The Selective Catalytic Reduction (SCR) is one of the most efficient technologies to reduce nitrogen oxide (NOx) emissions arising from technical combustion processes [1,2]. For compliance with future emission limits for heavy-duty Diesel engines the SCR technology might play an important role [3]. In two long-term field demonstrations heavy duty (HD) trucks were equipped with SCR emission control systems (SINOx™-System) and were operated under daily working conditions.

A number of measurements of both the performance and the activity of the catalyst during the entire operation time were performed. On the engine test bench the NOx reduction at the beginning of the road test was compared to the NOx-reduction at the end of the program. The initial NOx remained unchanged within the measurement accuracy of the analyzing equipment. On-road measurements of the emissions were done using an analyzer test cell installed on the loading area of the truck. During the course of the demonstration program the catalyst activity was measured at defined test conditions in a bench scale reactor. Therefore catalyst samples were taken from the operating systems at certain mileages to monitor the activity of the catalyst as a function of operating time. Information about the deterioration of the catalysts allows for sizing the system accordingly to meet the emission requirements over the useful life. The results obtained demonstrate the capability of the SINOx™-System for NOx reduction and the long-term durability of the catalyst.

With the experience from the demonstration program the SINOx™-Filter was improved. By means of a catalyst with optimized properties the performance in NOx reduction could be improved further. On-road demonstration programs with the improved system are on the way in the US and more are planned.