Intermetallic compounds (IMCs), used as heterogeneous catalysts, possess two key advantages, structural stability and tunable electronic properties. The use of IMCs as heterogeneous catalysts could lead not only to enhanced activity and selectivity, but also to the replacement or reduction the usage of catalysts based on precious metals. IMCs have been used as heterogeneous catalysts for chemical conversions. However, considering the availability of IMCs with different structures (~ 100,000 binaries, ternaries, and quaternaries discovered so far), their catalytic properties are largely unexplored. Moreover, the size effect of intermetallic compound nanoparticles on catalysis has been barely touched. One of the major reasons is the difficulty in synthesizing pure phase intermetallic nanoparticles (NPs) with a controlled size. Traditional wetness impregnation methods usually produce alloys with mixed phases. The recent colloidal synthesis approaches could produce pure phase intermetallic NPs, but their size distributions are broad due to the aggregation of particles at high temperature, a step required to form intermetallic phases.In this presentation, I will discuss two high-temperature stable structures based on inorganic mesoporous oxide shell to synthesize pure phase intermetallic compound nanoparticles (NPs) of tunable size. The mesoporous oxide or carbon shell could not only prevent the aggregation and overgrowth of intermetallic NPs under high temperature synthesis conditions, but also render the intermetallic NPs accessible by reactant molecules. This general inorganic capping strategy could be applied to the synthesis of monodisperse intermetallic compound NPs with a range of structures and compositions. These intermetallic compound NPs could serve as a platform for the community to study their bulk and surface structures, as well as chemisorption and catalytic properties. These structure-catalytic property correlations are necessary for the understanding of the unique surface structure of intermetallic compounds on elementary steps of chemical reactions.

Inorganic capping synthesis of pure phase intermetallic nanoparticle catalysts for hydrocarbon conversions

248th National Meeting (2014)

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