NOx and hydrocarbon storage and release on Pd/LTA and Pd/SSZ-13 using industrially-relevant exhaust conditions

Journal article, 2026

Large diesel engines require emissions control strategies to meet the standards that are present across the globe. The low temperature exhaust temperature associated with these engines create uniquely challenging conditions to meet these standards, and thus significant research is being pursued into approaches that can reduce the emissions of NOx and hydrocarbon (HC) criteria pollutants. This effort investigates the ability of two zeolite-based materials that have demonstrated the ability to store NOx and HCs, Pd/LTA and Pd/SSZ-13. Research was performed in controlled conditions of a flow reactor to repeatedly probe the ability of these materials to store NOx and representative HCs under industrially relevant conditions. After the 30-min storage, the NOx/HC release and reactivity were evaluated as the materials were heated to 600 °C under oxidizing conditions. Both qualitative and quantitative differences for the two types of materials are evident. It is seen that while NO capture using Pd/SSZ-13 was ∼1.6× higher than Pd/LTA, the latter stored ∼2.6–2.7× higher decane, releasing it primarily when the bed warmed to >200 °C. In each case the NOx storage behavior decreases with repeated adsorption/desorption cycles, while the HC storage behavior is stable. Using a range of characterization techniques our research focused on identifying different adsorption sites on the materials to explain the varying behavior to help guide development of new more robust materials.