Preparation Of Phyllosilicate-derived Bimetallic Core-shell Catalysts And Their Catalytic Performance On 1,4-butynediol Hydrogenation

1,4 butynediol?BYD?hydrogenation is the main method for industrial production of 1,4-butanediol?BDO?.As an important raw material in fine chemicals,BDO can be widely used in many fields via its downstream products.However,since BYD possesses various unsaturated groups,its hydrogenation process involves not only hydrogenation of C?C bond,but also other side reactions,such as the isomerization of C-O bond.Up to now,the catalysts investiagted in this reaction always include precious metals?Pd,Pt,etc.?and Raney Ni.The development of noble metal catalysts in industry is limited by their high cost and low reserve.Raney Ni catalyst also has the problem of environmental pollution and safety risks due to its high metal content.In the reported work,the supported Ni-based catalyst has the advantages of low cost and easy availability.However,due to low activity/selectivity and easy deactivation,the supported Ni-based catalyst could not achieve well BYD hydrogenation performance.Based on the aobve,we intended to propose a phyllosilicatederived Ni-based core-shell catalyst for direct liquid phase hydrogenation of BYD.The effects of metal additives and their contents,bimetallic effect and metal-support interaction on BYD hydrogenation were systematically studied.The details are as follows,1.To solve the problem of low catalytic activity and poor stability of traditional impregnation catalysts in BYD hydrogenation,a phyllosilicate-derived Ni-based core-shell catalyst was proposed.According to the comparison results,phyllosilicate-derived coreshell catalyst can significantly improve the dispersibility and shell porosity of the active metal,limit the active metal particles to the core-shell interface or the interior of the phyllosilicates matrix,thus improving the hydrogenation activity and catalytic stability.2.In order to inhibit the isomerization of intermediates and improve the yield of BDO,Cu as a metal additve was introduced to the catalyst system.With the introduction of the second metal Cu,the Ni Cu@SiO₂ catalyst produced a new highly active Ni-Cu alloy site,which has a strong bimetallic synergy effect.At the same time,due to the existence of the acidity of the residual phyllosilicate structure,the Ni Cu@SiO₂ catalyst can stabilize and activate the C=C-C-OH conformation adsorbed on the adjacent bimetal sites,so as to avoid its deep isomerization into C-C-C=O conformation?a precursor of by-product?,and further improve the selectivity of BYD direct hydrogenation product BDO.Among them,the phyllosilicate-derived 9Ni1Cu@SiO₂ catalyst showed the optimal direct hydrogenation performance of BYD in the 3 h reaction,and obtained a high BDO yield of 90.5%.3.The influence of metal-support state on the hydrogenation performance of BYD was further studied for 9Ni1Cu@SiO₂ catalyst.The multifunctional active sites in phyllosilicate structure were selectively regulated by adjusting the reduction temperature of 9Ni1Cu@SiO₂.Our results show that the metal-support existence state,the bimetallic effect of Ni-Cu and the metal-support/acid interaction are main factors to influence the hydrogenation activity and BDO selectivity.Among them,,the catalyst reduction at 250 ? has mainly Cu0 species which showed less BYD activation ability.After reduction at 750 ?,the phyllosilicate structure was destroyed,thus the catalyst had a bad metal-support interaction,and the catalytic activity was decreased.In comparition,the 9Ni1Cu@SiO₂ catalyst reduced at 500 ? has the best catalytic activity due to its high active Ni site,Ni-Cu bimetal synergistic effect,strong metal-support interaction and suitable metal acid site.