(750e) Support-Induced Control of Surface Composition in Bimetallic Catalytic Particles

Supported bimetallic nanoparticles have been identified as an important class of materials with demonstrated tunable reactivity for a variety of industrial catalytic properties. The design of bimetallic surface structures with controlled geometries and compositions via density functional theory calculations has proven successful for catalyst optimization. However, the actual structure and composition of exposed catalytic surfaces on synthesized structures under reaction conditions is a complex function of interactions between the two metals, the metals and reactive environments, and the metals and support. While reaction environment induced reconstruction of bimetallic particles has been thoroughly explored, relatively little is known about how specific metal-support interactions can be used to tune and control exposed surface structures. In this talk I will describe recent work where we have identified how metal-support interactions can be used to control the surface composition of bimetallic Cu-Ni nanostructures, and how this segregation influences reactivity, selectivity, and stability of the catalysts under harsh biomass-derived compound hydrogenolysis conditions. We found that for irreducible oxide (e.g. Al₂O₃) supported Cu-Ni bimetallic particles, both Cu and Ni domains are exposed at the reactive surface, where for reducible oxide (e.g. TiO₂) supported bimetallic particles, Cu is enriched at the surface while Ni seggregated to the metal-oxide interface. As a result of the seggregation observed for Cu-Ni/TiO₂ catalysts, excellent reactivity, selectivity, and stability were observed in catalytic furfural and hydroxymethylfurfural hydrogenolysis. We propose a mechanism where we envision the support acting cooperatively with the bimetallic structure to control the exposure of desired catalytic surfaces.