摘要
A dual-templating method was used to synthesize a series of hierarchical carbon supports containing different proportions of spherical macropores(ca.200 nm in diameter)and mesoporous channels(ca.4 nm in diameter).These and some other conventional carbon materials were subsequently impregnated with Ni and tested for the conversion of glycerol.The hierarchical catalysts exhibited a significantly higher conversion(96%)and selectivity(77%)to 1,2-propanediol,and the specificity selectivity coefficient(6.1)towards 1,2-propanediol against lactic acid was three times higher than that observed over a conventional Ni/Cmnicro catalyst(2.1).The enhanced performance of these materials,compared with the Ni nanoparticles supported on conventional carbon supports,was attributed to their high surface areas(>1110 m^2·g^-1)and large pore volumes(ca.0.4 cm^3·g^-1)permitting greater accessibility of substrate and/or intermediates to Ni active sites.Given that the concentration of accessible Ni sites in these materials is higher,a competitive benzilic-acid-rearrangement reaction to produce lactic acid was suppressed,leading to an enhanced hydrogenation selectivity to 1,2-propanediol.This study evidences the potential benefits,which can be established from utilizing hierarchical support materials in the valorization of biomass.
