Approaching the 150°C Challenge with passive trapping materials and highly active oxidation catalysts
Andrew Binder, Oak Ridge National Laboratory
Here we present the analysis of HC-trapping/DOC combined system in LTC-D protocol simulated exhaust conditions. The catalysts used for this study include a Pd/ZSM-5 trapping material and a mixed-bed of core-shell SiO2@ZrO2 carrying either Pd or Pt catalyst (i.e. Pd/[SiO2@ZrO2] or Pt/[SiO2@ZrO2]). Results indicate that the addition of Pd/ZSM-5 hydrocarbon trapping material can greatly increase the effective activity of the downstream degreened DOC catalyst for both CO and THC conversion leading to 90% conversion of CO and THC over the total system at 135°C and 163°C, respectively. Even after repeated sulfation/desulfation procedures and 50 hour aging at 800°C the trap/catalyst system continues to show appreciable activity with T90 values of 175°C (CO) and 230°C (THC). This study demonstrates the both the effectiveness of hydrocarbon trapping as a way to boost overall conversion and the need for highly stable trapping materials in order to accomplish the 150°C challenge after significant aging.