Synthesis of supported bimetallic nanoparticles with controlled size and composition distributions for active site elucidation

• Controlled synthesis of bimetallic nanoparticles with narrow size and composition distributions.
• Demonstration of controlled synthesis for RhMo, PtMo, and RhRe bimetallic systems.
• Bimetallic catalysts characterized using FTIR, chemisorption, STEM/EDS, XAS, and TPR.
• Bimetallic catalysts studied using selective CO hydrogenolysis as a probe reaction.
• Elucidation of the nature of active sites for selective hydrogenolysis.

Elucidation of active sites in supported bimetallic catalysts is complicated by the high level of dispersity in the nanoparticle size and composition that is inherent in conventional methods of catalyst preparation. We present a synthesis strategy that leads to highly dispersed, bimetallic nanoparticles with uniform particle size and composition by means of controlled surface reactions. We demonstrate the synthesis of three systems, RhMo, PtMo, and RhRe, consisting of a highly reducible metal with an oxophilic promoter. These catalysts are characterized by FTIR, CO chemisorption, STEM/EDS, TPR, and XAS analysis. The catalytic properties of these bimetallic nanoparticles were probed for the selective CO hydrogenolysis of (hydroxymethyl)tetrahydropyran to produce 1,6 hexanediol. Based on the characterization results and reactivity trends, the active sites in the hydrogenolysis reaction are identified to be small ensembles of the more noble metal (Rh, Pt) adjacent to highly reduced moieties of the more oxophilic metal (Mo, Re).

Figure optionsDownload high-quality image (60 K)Download as PowerPoint slide