Sopported Cu-based Catalysts For Selective Hydrogenation Of 5-Hydroxymethylfurfural

5-hydroxymethylfurfural?HMF?is one of very important platform chemicals,and listed as one of the ten most important platform compounds by the US Department of Energy.At the same time,it is also considered as the key material and bridge linking between biomass energy and petroleum profession.Lots of furan ring derivatives with high added value can be obtained through HMF oxidation,hydrogenation and etherification.2,5-Bis?hydroxymethyl?furan?BHMF?is a hydrogenation product from HMF,which can be used in the preparation of resins,polymers and artificial fibers,as well as the synthesis of drugs and crown ethers.Therefore,it is very necessary to develop an economical and efficient catalyst to catalyze5-hydroxymethylfurfuralhydrogenationforacquiring2,5-bis?hydroxymethyl?furan with highly selectivity.Finding suitable carriers and adding trace auxiliaries are effective ways to prepare fruitful catalysts.In this thesis,HMF hydrogenation was carried out in a fixed bed reactor with Cu as an active center.The study mainly included two aspects:the hydrogenation performance of Cu-based catalysts with different carriers and the impact of K promoter on Cu/Al₂O₃ catalyst in catalyzing the selective hydrogenation of HMF to BHMF.The main work done by the author is as follows:?1?Five kinds of carriers with different structure and surface acidity were selected in this experiment,including Al₂O₃?SiO₂-Al₂O₃?AlPO₄-11?SAPO-11?ZSM-5.A series of Cu-based catalysts with different carriers were prepared with loading the same mass fraction of metal Cu on the carriers by incipient-wetness impregnation method,and the effect of the carriers on the hydrogenation performance of 5-hydroxymethylfurfural was investigated in a fixed bed reactor.Results showed that Cu/Al₂O₃ and Cu/AlPO₄-11 showed high reactivity.The catalysts and carriers were characterized by XRD,TEM and NH₃-TPD,and it was preliminarily investigated about the effect of its structure and surface acidity on HMF selective hydrogenation to prerare BHMF.The carriers changed the distribution of Cu metal particles and affected hydrogenation activity.Furthermore,the surface acidity of the carrier promoted the occurrence of etherification,cracking,polymerization and other side reactions,resulting in the reduction of the selectivity of the main product BHMF.The dispersion of Cu metal on the Al₂O₃ carrier is more uniform and the particles are smaller.The weakest acid of Al₂O₃ carrier inhibits the occurrence of etherification in the process of HMF hydrogenation.Therefore,the hydrogenation performance of Cu/Al₂O₃ catalyst is the best with the highest conversion of HMF and the selectivity of BHMF.Taking Cu/Al₂O₃ as the best catalyst,we explored the influence of reaction temperature and mass velocity on the catalytic performance and the stability of the catalyst.In the optimal reaction conditions,2 MPa,100^oC and 0.30 h^-1,the conversion of HMF was 99.65%,the selectivity of BHMF reached 98.51%.?2?We chose K as an auxiliary agent.The K and Cu were loaded on Al₂O₃carrier by continuous incipient-wetness impregnation method,obtaining the Cu-nK/Al₂O₃ catalyst?n=0,0.5,1.5,3 wt%?.The catalysts were also used to catalyze HMF selective hydrogenation in a fixed bed reactor.Cu-1.5K/Al₂O₃ catalyst exhibited the best activity and selectivity to BHMF.XRD,XRF,N₂O dissociation adsorption,BET and NH₃-TPD were used to characterize the performance characteristics of the carriers and catalysts.It was found that a small amount of K load could promote the dispersion of Cu metal and improve the hydrogenation performance of the catalysts.At the same time,the K promoter could reduce the surface acidity of the catalyst and inhibit the etherification and other side reactions during the hydrogenation of HMF.