RESEARCH IN CATALYSIS AND NOVEL CATALYTIC MATERIALS AT THE UNIVERSITY OF CALIFORNIA AT DAVIS
The Department of Chemical Engineering and Materials Science at Davis has developed a strong experimental program in catalysis and materials research emphasizing fundamental investigations motivated by technologically important problems and close interactions with industry. The research directed by Professor B. C. Gates involves materials and catalyst preparation, characterization by physical methods, and testing in low- and high-pressure reactors, as described below.
Catalysis by supported nanoclusters
Organometallic precursors are used to prepare structurally simple metal-oxide-supported metals, including metal carbonyl clusters and metal clusters. Examples include rhenium subcarbonyls on MgO, iridium clusters such as [Ir6(CO)15]2- on MgO and g-Al2O3, and Rh4, Ir4, Rh6, Ir6, and Pt15 on MgO and in zeolite NaY. The work is leading to fundamental understanding of the structure of the metal-support interface, the structures of metal clusters on supports, and the dependence of catalytic properties on cluster structure and the structure of the metal-support interface.
Catalysis by supported metal complexes
Organometallic precursors are used to prepare structurally simple metal-oxide- and zeolite-supported metals, including single-metal-atom complexes. Examples include rhodium carbonyls and rhodium ethylene complexes supported on MgO and on zeolites. The work has led to the first truly molecular catalysts on supports.
Zeolite catalysts
We are using ship-in-a-bottle syntheses as well as more conventional preparations to prepare metal complexes, metal carbonyl clusters, and metal nanoclusters in zeolite cages. The materials include structurally simple catalysts (e.g., Rh6 in NaY zeolite) and very small metal clusters such as Ir4 in zeolite L. We have been able to interconvert metal carbonyls such as Ir4(CO)12 and metal clusters such as Ir4. Our group has also investigated acidic zeolites such as USY as paraffin conversion catalysts.
Novel supported bimetallic catalysts
We are using organometallic precursors to prepare highly dispersed supported metal catalysts, including bimetallics. Examples include Mo-Pd catalysts supported on MgO or g-Al2O3, in which the oxophilic metal Mo plays the role of stabilizing the dispersion of Pd clusters by forming a layer between the Pd and the oxide support.
Experiments with powder and single-crystal samples
Understanding of the properties of supported metal catalysts requires precise characterization of the structure, including the structure of the metal-support interface. Such understanding may emerge from characterizations of metals supported on single crystals of metal oxides, and we are investigating such materials using IR, STM, and other techniques.
Theory
We are working with theorists at the University of Southern California (Haw et al.) and at the University of Alabama (Dixon et al.) to use density functional theory to characterize metal complex and metal cluster on zeolite and oxide supports.