Emission control catalysts have gained increasing interest primarily due to the more rigorous requirement to reduce emissions of various hazardous pollutants, such as hydrocarbons and CO. Currently, most catalysts use Pt and Pd to remove the pollutants since these elements are known for their high efficiency in combusting hydrocarbons. However, there still are open questions regarding the catalytic behavior of Pd and Pt since the conventional catalysts preparation results in non-uniform metal morphology and site distribution. Thus, understanding how the structure and change of these materials relate with performance is crucial to optimize the use of these expensive metals and improve their performance at lower temperatures as needed by new engine requirements. In this talk, I will discuss our recent work on using well-defined Pd and Pt nanocrystals prepared by colloidal synthesis to shed light on the most active sites for hydrocarbon combustion with theory insights using DFT calculations and in-depth characterization. We systematically study the effect of composition, support, and the location of active sites following restructuring under reaction conditions. The use of well-defined nanocrystals further allow to tune the design of such catalysts to improve their stability at high temperatures. Taken all together, this data clarifies the active sites in Pd and Pt based materials for hydrocarbon combustion. These insights help in the design of improved catalytic materials where the use of noble metals can be optimized.

Developing active and stable heterogeneous catalysts using nanocrystal precursors

ACS Fall 2021

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