Study On Liquid Phase Selective Catalytic Hydrogenation Of Furfural To Furfuryl Alcohol

Furfuryl alcohol is an important feedstock in the chemical industry.There are two ways to produce furfuryl alcohol,that is,liquid phase hydrogenation and vapor phase hydrogenation.However,the liquid phase hydrogenation has some disadvantages,such as high energy consumption,difficulties in catalysts separation and high requirements for reaction equipment.In this thesis,the catalysts with high conversion and high selectivity were obtained by screening different copper-based materials under mild reaction conditions.The composition and structure of the catalyst were deeply understood by physical adsorption,XRD,TEM,H₂-TPR,N₂O-TPR,NH₃-TPD and other characterization methods.In this paper,copper based catalysts with different supports were firstly synthesized.The results showed that the Cu/SiO₂ and Cu/Al₂O₃ catalysts is the best.Under the reaction conditions of 150 ^oC reaction temperature,5 MPa of initial hydrogen pressure,reacted for 1 hours,the furfural was completely converted.The selectivity of the main product furfuryl alcohol was up to 97.6%and 99.0%,as well as ethyl-furfuryl ether the by-products.Through the characterization of N₂O-TPR,TEM and stem,it can be seen that most of the active components of Cu/SiO₂ and Cu/Al₂O₃ catalysts are uniformly dispersed on the support,and the active components have a high degree of dispersion.According to NH₃-TPD and Pyridine adsorption IR spectra analysis,the number of L-acid on the surface of Cu/SiO₂ and Cu/Al₂O₃ catalysts is less.Then we investigated the effects of loading,reduction temperature and reaction temperature on the catalytic performance of Cu/SiO₂ and Cu/Al₂O₃ catalysts.The 30%Cu/Al₂O₃ catalyst was prepared by impregnation method.It exhibited much higher furfural conversion and furfuryl alcohol selectivity under reduction conditions of350 ^oC reduction temperature and reaction conditions of 150 ^oC during the reaction time of 1h at the H₂ pressure of 5 MPa,very less by-product ethyl furfuryl ether was observed.The structure and physicochemical properties of the catalyst were also analyzed by TEM,XRD,H₂-TPR,NH₃-TPD and N₂O-TPR.Meanwhile,the Cu/Al₂O₃-IM catalyst still presented excellent catalytic activity after repeated use for three times,with furfural conversion of 98.8%and furfuryl alcohol selectivity of 98.2%.Therefore,30%Cu/Al₂O₃ catalyst prepared by impregnation method has the best catalytic activity and thermal stability.Ethyl furfuryl ether was detected in the product obtained by the reaction of furfural liquid-phase hydrogenation to furfuryl alcohol.In order to explore the reflection path of ethyl furfuryl ether,we made product distribution maps of different reaction times.The results show that ethyl furfuryl ether is mainly produced by etherification of furfuryl alcohol and solvent ethanol.Further research indicates that the loading of copper,the reaction temperature,and the number of acid sites on the catalyst surface are the most important factors affecting the formation of by-product ethyl furfuryl ether.