Synthesis Of Cu-based Catalysts For Selective Hydrogenation Based On Self-sacrifice Template

Currently,supported noble metal catalysts（e.g.,Pd,Pt）are widely used for selective hydrogenation of unsaturated hydrocarbons.However,due to their high price and low reservation,much attention now has paid on supported non-noble metal catalysts,such as Cu.Cu-based catalysts have high potential for the substituent of noble-metallic catalysts as their high selectivity and moderate activity for selective hydrogenation reaction,however,simplifing preparation process and achieving further high catalytic stability are very difficult.In this paper,the metal components were in situ introduced into HKUST-1 template,the precursor of Cu-based catalyst,by self-assembling of Cu²⁺and organics.Then,the was self-sacrificial template method was adopted to prepare the target catalyst.Herein,the highly-dispersed Cu-based catalysts supported by hierarchically porous supporter were obtained by one-step carbonization of the precursor.The goal of this work is to investigate the structural variation of Cu-based catalysts with different carbonation conditions,and the effect of above factors on catalytic performance in selective hydrogenation of unsaturated hydrocarbons by using1.3-butadiene as a probe reactant.The main research contents and conclusions obtained are as follows:1.The HKUST-1 precursor with high crystallinity,high specific surface area of1599 m²/g and large total pore volume of 0.91 cm³/g can be obtained by the control of the hydrothermal synthesis conditions.In the process of carbonization,the oganic part of HKUST-1 acted as the self-sacrificial template,which can promote the formation of hierarchically porous supporter and the reduction of Cu²⁺.Here,the porous hierarchy of carbon supporter and the dispersion of copper nanoparticles of the Cu/C catalyst can be precisely tuned by controlling the carbonization temperature.In the selective hydrogenation of 1,3-buadiene,the catalytic activity of the Cu/C catalysts exhibited a volcanic trend with the carbonization temperature increasing.Remarkably,all catalysts of this typle are of high selectivity to butene（>98%）.Specially,the Cu/C catalyst carbonized at 600^oC for 4 h showed a rather low reaction temperature at 75^oC for 100%butadiene conversion with 100%selectivity to butenes,due to its reasonable porous hierarchy and highly-dispersed copper sites.Even the reaction as long as 120 h at 75^oC,the catalytic performance remained unchanged.2.Furthermore,by controlling the carbonization time of the HKUST-1 at 600^oC,the properties of Cu/C catalysts such as the particle size of Cu and the porous hierarchy of supporter,can also be precisely tuned.With the extension of carbonization time,the Cu particle size of the catalyst increased gradually.Besides,the porous hierarchy of the supporter was affected by the variation of Cu particle size and the decomposition of organic template.It is found that the exposed active metal sites of Cu/C catalysts become more obviously with the carbonization time increasing.In addition,due to the good diffusion of hierarchically porous supporter,the Cu/C catalysts showed excellent catalytic performance in the selective hydrogenation reaction of 1,3-butadiene.In view of the research on the carbonization conditions for HKUST-1 and the catalytic performance of the Cu/C catalysts,it can be found that the selectivity of hydrogenation reaction of 1,3-butadiene mainly depends on the particle size of Cu,while the activity and stability of the catalysts are mainly determined by the number of exposed active sites and the diffusion of the supporter.All in all,one-step carbonization with self-sacrificial template is an effective method to obtain highly-dispersed metallic catalysts with high efficiency for selective hydrogenation.