Carbon nanotunes supported Pt and Pt-Ru catalysts for selective hydrogenation of Citral: Effect of promoters and Thermal activation of catalysts

摘要

MWCNT supported Pt, Ru, and Pt-Ru catalysts were prepared and reduced at two different temperatures, 375°C (LTR) and 675°C (HTR) for the selective hydrogenation of citral to the corresponding unsaturated alcohols (geraniol and nerol). The catalysts were characterized by BET Surface area measurement, TPD, SEM, EDAX, TEM, XRD and XPS. It was found that the XRD of Pt and Ru shows fcc and hep crystalline structure respectively, which is uniformly dispersed with an average particles size of 3.5 nm and zero valence metallic state. The removal of acidic oxygen surface group is observed when heat- treatments in a inert atmosphere at 675°C were performed. The bimetallic catalyst of Pt-Ru/MWCNT (HTR) was found to afford remarkably high conversion levels (85%) and high selectivity (95%) provided that a thermal pretreatment was performed on the catalyst. These results can be rationalized in terms of electron transfer from the support to the metal. The catalysts are environment friendly and can be recycled for more than eight times.