Highly Active Pt/BN Catalysts for Propane Combustion: The Roles of Support and Reactant-Induced Evolution of Active Sites

摘要

The Pt catalysts supported on hexagonal BN (Pt/BN) are highly active and stable for propane combustion, with the highest specific reaction rate of 92.3 mu mol g(pT)(-1) s(-1) and turnover frequency of 0.037 s(-1) obtained on a 0.2Pt/BN catalyst at 220 degrees C. The Pt oxide in the catalyst could be partially reduced to the metallic state by propane during the reaction, which is beneficial for the improvement of activity, indicating that metallic Pt might be the active sites. The highly dispersed Pt particles stabilized at the grain boundary of BN could be more easily reduced in the reaction than those on the surface and thus are more active. Moreover, kinetic investigation reveals that the apparent activation energy of the Pt species at the grain boundary (111.6 +/- 8.0 kJ mol(-1)) is much lower than that on the surface (172.4 +/- 16.5 kJ mol(-1)), suggesting different reaction pathways on these catalysts and the possible participation of the grain boundary of the BN support in the reaction.