Reactor Trap To Remove Hydrocarbons from Engine Exhaust during Cold Start

The concept and the performance of a device to remove hydrocarbons from engine exhaust during cold start were described. The device consisted of a hydrocarbon adsorbent and a metal oxide that could react with the hydrocarbon by oxidation to form carbon oxide and water. The metal oxide could then be regenerated later in the drive cycle by reaction with oxygen. Using a mixed oxide containing Cr, Co, Fe, and Al; ZSM-5 zeolite as the adsorbent; and propene, propane, or toluene as the hydrocarbon, the efficiency of hydrocarbon removal was measured in the laboratory during the 2 min when the unit was heated from room temperature at a rate of 150 °C/min. The efficiency was found to be suppressed by the presence of water vapor, but not affected by the presence of CO and CO₂. With a mixture of 10% H₂O, 2% CO, 0.6% O₂,2000 ppm hydrocarbon, and the balance helium, the efficiencies were 92, 78, and 57 % for toluene, propene, and propane, respectively. A conceptual device to remove the hydrocarbon efficiently was described.