A study of the catalytic and chemical properties of palladium and palladium-silver monolayer protected clusters.
Date on Master's Thesis/Doctoral Dissertation
Zamborini, Francis Patrick
Committee Co-Chair (if applicable)
This thesis describes a study of the ligand chemistry of Pd Monolayer-Protected Clusters (MPCs) synthesized in the presence of octylamine. MPCs consists of a metal core surrounded by various organic stabilizers. Pd MPCs coated with alkanethiols, alkylamine, dendrimers, surfactants, and polymers have recently been explored for catalysis applications.Pd MPCs coated with alkylamines are more catalytically active than alkanethiols for hydrogentation/isomerization of allyl alcohol, but at shorter chain lengths are unstable in H2. We explored Pd MPCs synthesized in the presence of octylamines and discovered that the ligands attach to Pd as octanenitrile. This amine to nitrile conversion is catalyzed by the Pd and occurs during reduction of PdCl4 2- with sodium borohydride. When nitrile-stabilized Pd MPCs are exposed to H2 or exposed to alkanethiols during a ligand place-exchange reaction, the nitriles desorb from the Pd surface and partially convert to amide and carboxylic acid groups. When the nitrilecoated Pd MPCs are heated ortreated with H2 or place-exchange with alkanethiols without O2, the nitrile ligands desorb from the surface asnitriles.The catalytic properties of dodecanethiol-coated PdAg alloy MPCs prepared by co-reduction of Pd(II) and Ag(I) salts showed an ~70% reduction in catalytic activity towards hydrogenation/isomerization of allyl alcohol with just 10% Ag incorporated into the alloy. We expected that PdAg alloys prepared by synthesizing dodecanethiol-coated Ag MPCs first followed by galvanic exchange with Pd(II) would produce more catalytically active MPCs with the Pd on the surface, however, difficulty in the isolation of PdAg MPCs prepared this way led to inconclusive results.
Hutcherson, Luther Benjamin, "A study of the catalytic and chemical properties of palladium and palladium-silver monolayer protected clusters." (2015). Electronic Theses and Dissertations. Paper 2151.