Preparation And Investigation Of Porous Carbon-supported Precious Metal Catalysts In Chemoselective Hydrogenation Of Cinnamaldehyde

Carbon materials have been testified to be one of the best choices as the catalyst support for heterogeneous reactions in the liquid phase owing to their excellent mechanical strength and stability under hydrothermal conditions,good electronic properties,large surface area,easy recovery-refining-recycling for precious metals,relatively low cost as well as versatile existing forms.A monolithic carbon-supported Pt nanocomposite with an interconnected three-dimensionally hierarchical porous carbon framework and ultra-high dispersion of Pt nanoparticles?Pt/3DHPC?is synthesized by using an effective“liquid phase impregnation template”strategy.The obtained Pt/3DHPC possesses rich mesoporosity and a low amount of oxygen-containing functional groups,which notably improve the accessible internal surface area of macropores,number of active Pt sites,and electron transfer ability.When used as a catalyst for the selective cinnamaldehyde?CMA?hydrogenation towards cinnamyl alcohol?CMO?,Pt/3DHPC exhibits high CMA conversion?92.7%?and CMO selectivity?91.1%?,and the corresponding activity(1553.7 h^-1)greatly surpasses not only the single-sized mesoporous carbon and microporous activated carbon-supported counterparts but also the previously reported Pt catalysts dispersed on other forms of carbon.Furthermore,Pt/3DHPC can be reused at least fifteen times without pronounced decay owing to the strong interaction between Pt and carbon.The present work demonstrates the validity of multiscale control in carbon-supported Pt catalysts by overall consideration of the mass transportation,and the accessibility,quantity,and capability of active sites towards chemoselective hydrogenation of CMA,which is expected to be extended to other catalysis-related processes.In addition,we prepare reduced graphite oxide?rGO?supported iridium?Ir/rGO?catalyst with hydrazine hydrate as reducing agent.It is found that the Ir/r GO catalyst exhibits a high CMA conversion of 92%and a good CMO selectivity of 85%in chemoselective hydrogenation of cinnamaldehyde.