A novel four-way combining catalysts for simultaneous removal of exhaust pollutants from diesel engine

A novel four-way combining catalysts containing double layers was applied to simultaneously remove four kinds of exhaust pollutants (NOx, CO, HC and PM) emitted from diesel engine. The four-way catalysts were characterized using scanning electron microscope (SEM) and Ultraviolet visible diffuse reflectance spectroscopy (UV-Vis DRS). Their catalytic performances were evaluated by temperature-programmed reaction technology. The double layer catalysts could effectively remove the four main pollutants. The highest catalytic activity was given by the two-layered catalysts of La0.6K0.4CoO3/Al2O3 and W/HZSM-5. Under the simulated exhaust gases conditions, the peak temperature of the soot combustion was 421°C, the maximal conversion of NO to N2 was 74%, the temperature of the HC total conversion was 357°C, and the maximum conversion ratio of CO was 99%.