The Role of Carbon Support for Propane Dehydrogenation Over Platinum Catalysts

Carbon-supported Pt catalysts were prepared by depositing the metal from a suspension of Pt nanoparticles on a range of different carbon supports. The catalysts were characterized using a range of techniques. The results show that transmission electron microscopy (TEM) and CO stripping by cyclic voltammetry give consistent values for platinum dispersion for platinum catalysts supported by carbon nanofibers and carbon nanotubes (CNTs). There were some discrepancies between the techniques for Pt/graphite and Pt/carbon black, possibly due to issues with mass transfer limitations, the particle size distributions, and TEM resolution. The hydrogenation of ethene, a facile reaction, was also used as a characterization tool to verify the catalyst dispersion (and available metal surface area). The results from the hydrogenation of ethene were consistent with the results from TEM and cyclic voltammetry. In catalytic dehydrogenation of propane the Pt/carbon black showed higher conversion and turnover frequency than the catalysts prepared using carbon nanofibers, CNTs, and graphite as support. The propane dehydrogenation reaction over Pt/carbon black also showed less deactivation in experiments without hydrogen in the feed. The difference in activity and stability can be due to metal support interactions, causing changes in the electronic properties of platinum or a possible phase restructuring of the metal surface due to a strong interaction with the supports.