1979 PhD, Stanford University
1982 – 1993 Section Head, Catalysis Science, Company Exxon Research and Engineering
1988 – 1993 Consulting Professor for Chemical Engineering an der Stanford University
1993 – today Professor for Chemical Engineering, University of California (UC), Berkeley
2006 – 2015 Director of the Berkeley Catalysis Center
2009 – today Theodore Vermeulen Chair of Chemical Engineering, UC Berkeley
2004 Wilhelm Manchot Professorship of the TU Munich
Seine Forschungsgruppe befasst sich mit Design, Synthese, sowie Charakterisierung von anorganischen Feststoffen, die als Katalysatoren für spezielle chemische Reaktionen eingesetzt werden.
„Tailoring Binding Sites and their Environments”
The properties of the molecular species that act as intermediates and transition states and of the binding sites that stabilize them act in concert to determine reactivity and selectivity for catalytic reactions. The dynamics of this interplay are specifically addressed here for acid-base and oxidation catalysis on oxides. Experiment and theory are used to elucidate site requirements and mechanisms at the level of atomic structures and elementary steps on catalytically active solids of known structure. The deprotonation energy of the acid and the proton affinity of gaseous analogs of transition states combine to determine reactivity, as well as the role of acid strength, in acid catalysis, because of the ubiquitous involvement of proton transfer and cation-anion pairs at transition states. Similarly, aerobic oxidation cycles on redox-active oxides depend on the dynamics of elementary steps that cause the reduction of metal centers in oxides by H-abstraction from C-H bonds in reactants. The late transition states that mediate such steps consist of interacting di-radical pairs that contain a nearly-formed O-H bond and a nearly-cleaved C-H bond, thus making H-addition energies at lattice O-atoms in oxides and C-H bond dissociation energies in reacting substrates the respective binding site and molecular properties relevant for reactivity and selectivity.
For both types of reactions, more accurate descriptions, however, require assessments of how molecular species and sites interact and delocalize electron density in stabilizing intermediates and transition states, specifically as ion-pairs and di-radicals in acid and oxidation catalysis, respectively.
The environment that surrounds the binding site provides solvation effects that can preferentially stabilize specific reactive intermediates and transition states through weak concerted van der Waals or H-bonding interactions. Such stabilization can be conferred by inorganic hosts with voids of molecular size or by the presence of denser phases around the binding site, either as liquids or as bound adlayers of chemisorbed species.
Taken together, the properties of the binding sites and of their local environment act to confer solids with their remarkable diversity in channeling chemical reactivity towards specific products in the practice of heterogeneous catalysis.