Tuning supported catalyst reactivity with dendrimer-templated Pt-Cu nanoparticles

Area of Science:

• Materials Science
• Chemical Engineering
• Catalysis

Background:

• Heterogeneous catalysis is crucial for industrial chemical processes.
• Controlling nanoparticle composition is key to tuning catalytic activity.
• Dendrimer-encapsulated nanoparticles (DENs) offer a route to well-defined supported catalysts.

Purpose of the Study:

• To investigate the impact of copper (Cu) incorporation into platinum (Pt) nanoparticles on catalytic performance.
• To understand the role of particle composition in supported bimetallic catalysts.
• To correlate catalytic behavior with material properties using spectroscopy.

Main Methods:

• Synthesis of bimetallic Pt-Cu DENs with varying Pt/Cu ratios.
• Deposition of DENs onto alumina supports followed by thermal removal of the dendrimer template.
• Evaluation of supported catalysts using toluene hydrogenation and CO oxidation reactions.
• Characterization using infrared spectroscopy of adsorbed CO.

Main Results:

• Copper incorporation had opposing effects on the two catalytic reactions.
• Cu mildly promoted CO oxidation, with the effect being independent of Cu content.
• Cu strongly poisoned toluene hydrogenation, with activity inversely proportional to Cu content.
• Infrared spectroscopy revealed minimal electronic effects (electron donation from Cu to Pt).

Conclusions:

• The observed catalytic behaviors are primarily attributed to structural differences induced by Cu incorporation, not electronic effects.
• Supported Pt-Cu catalysts derived from DENs exhibit tunable properties for different reactions.
• Understanding composition-structure-activity relationships is vital for designing efficient heterogeneous catalysts.