Reducibility of Platinum Supported on Nanostructured Carbons

Abstract

The nanostructure of graphite like carbon, i.e. carbon nanofibers (CNF), carbon nanotubes (CNT) and carbon nanoplatelets (CNP), displayed a significant influence on the reducibility of platinum deposited on these carbons. The onset temperature for reduction increased from 461 K for Pt/CNF to 466 K for Pt/CNP and 487 K for Pt/CNT. The retarded reduction for Pt/CNT was related to the higher amount of acidic oxygen surface groups on this support resulting in a strong stabilization of the cationic platinum species. A higher reduction temperature for that sample increased the amount of metallic platinum, however the platinum particle size was larger (2–11 nm) compared to that of Pt/CNF and Pt/CNP (both 1–3 nm). The orientation of the graphene sheets had a significant influence on the selectivity for cinnamaldehyde hydrogenation: Pt/CNP resulted in a higher selectivity towards cinnamyl alcohol compared to Pt/CNF.