Improved Three-Way Catalyst with Ignition Layer for Reducing Cold Emissions

Exhaust gas regulations, such as Tier4, Euro7, and China7, are being strengthened. In addition to the regulated values during specified driving patterns, emissions must be minimized under various usage scenarios. Since vehicle catalysts have been using higher amounts of precious metals to satisfy these requirements, there is increasing demand to decrease the usage of these metals from the perspective of environmental protection. The exhaust gas emission is divided into cold emission and hot emission. Recently, improvements of cold emission have become a focus. This research focused on improving catalyst warm-up activity by positioning the palladium (Pd) layer above the rhodium (Rh) layer. At the same time, to resolve the decrease in gas utilization in the Rh layer, connectivity was enhanced, and the influence of sulfur components was suppressed through the optimization of the Pd support. As a result, the usage of precious metals has successfully lowered.