MOF-derived Cu@C Catalyst For The Liquid-phase Hydrogenation Of Esters

Fatty alcohol,an important kind of chemical product,is the raw materials for the synthesis of plasticizers and surfactants.Recently,the demands for fatty alcohols has increased year by year with the increasing requirements for plasticizers and surfactants in the whole world.Synthetic fatty alcohols are generally produced from petroleum resources.Based on the relatively scarce petroleum resources in the world,it's meaningful to develop natural fatty alcohol synthesis process with renewable energy materials.The new-type synthesis process can not only effectively alleviate the current large-scale demand and over-reliance on petroleum resources,but also meet the development trend of world's energy transformation.The process for producing natural fatty alcohols by hydrogenation of natural fatty esters has the advantages of wide source of raw materials,high product purity,and environmental protection.In this work,MOF-derived Cu@C catalysts and CuZn_x@C catalysts were prepared and applied in liquid-phase hydrogenation of esters.This work compared the catalytic activity and physicochemical properties between Cu@C-N₂?Cu@C-H₂ and Cu/AC catalysts.It was found that Cu@C-H₂ catalyst exhibited higher catalytic activity compared with Cu/AC-H₂ due to its relatively small nanoparticle size of Cu and higher copper dispersion.Moreover,Cu@C-H₂ also presented a higher conversion of butyl butyrate than Cu@C-N₂,as a result of the appropriate ratio of Cu⁺/Cu⁰,which can activate both ester and H₂ molecular.A series of CuZn_x@C catalysts with different ZnO loading were prepared and their catalytic performance and physicochemical properties was investigated.Appropriate amount of zinc oxide?Zn/Cu=0.3?dopant can effectively decrease the particle size of Cu⁰ and increase the Cu⁰ surface area.Meanwhile,the content of Cu⁺in CuZn_x@C is obviously lower than that of Cu@C.The interaction between copper and carbon might be inhibited by the doping of ZnO,leading to a decrease of the Cu⁺species originated from the reduction of Cu-O-C species.However,as the amount of ZnO increases,the content of Cu⁺produced from the Cu-O-Zn interaction gradually increases due to the formation of the more Cu-O-Zn species.The catalytic performance of CuZn_x@C catalysts for the hydrogenation of butyl butyrate was significantly improved and showed a volcanic trend with the increased amount of ZnO doping.CuZn_0.3@C catalyst exhibited the best catalytic performance due to its largest Cu⁰ and Cu⁺surface area.It was also found that Cu⁺surface area exhibited positive and linear correlation with the TOF⁰_Cu,indicating that Cu⁺surface area is a key factor for the liquid-phase hydrogenation of esters.Besides,Cu@C and CuZn_x@C catalysts showed good stability in liquid-phase ester hydrogenation and was suitable for a variety of fatty esters hydrogenation systems.This research provided an important guidance for the rational design and preparation of catalysts in the liquid-phase hydrogenation of esters.