(98g) Ceria Enhancement of Sinter-Resistant Platinum-Based Catalysts for Emission Control Applications
AIChE Annual Meeting
Monday, November 14, 2022 - 2:36pm to 2:54pm
Platinum group metals (PGM) are widely used for exhaust emission abatement. Sintering that occurs during the oxidative, high temperature conditions of emission control decreases noble metal utilization efficiency. As a result, catalytic converters rely on excessive catalysts loadings, which account for 51% of the global demand for PGM. Efficient use of scarce noble metals requires sinter-resistant catalysts. We recently developed a nanocasting method for encapsulating PGM nanoparticles (NPs) inside porous Al2O3 using a templating procedure with a polymer framework. The resulting catalyst, termed Pt@Al2O3, demonstrated stability against sintering at 800°C under 3% O2 and 5% H2O, evidenced by its sustained propene combustion activity and the preservation of Pt particle size (4 nm). Encouraged by the propene combustion activity, we further simulate realistic exhaust stream conditions by targeting relevant oxidation reactions of Pt@Al2O3 with carbon monoxide (CO) and propane. Ceria (CeO2) is known to enhance CO oxidation activity of PGM particles through oxygen donation from the support. However, ceria is prone to restructure under high temperature aging conditions and loses porosity. Here, we incorporate CeO2 into the nanocasting approach to generate Pt@CeO2/Al2O3 catalysts. Through a suite of characterization techniques, we track the morphological changes of Pt and CeO2 encapsulated in an Al2O3 framework as a function of aging. Using reaction kinetics, we study the site requirements of propane, propene, and CO combustion independently and mixed. Taken together, we can enhance the reactivity of Pt for a wider range of emission components while maintaining catalyst stability during high-temperature aging conditions.