Study On The Mechanism Of Selective Hydrogenation Of Cu-based Catalysts In Furfural

With the rapid development of modern society,the reserves of non-renewable energy fossil energy are getting less and less,and the environmental problems are increasing.People are paying more and more attention to renewable energy biomass and its biomass derivatives.Furfural is an important platform compound derived from hemicellulose in lignocellulosic biomass.China's annual output of aldehydes reaches10,000 tons,80%of which is exported as cheap raw materials,which provides the possibility of deep processing of furfural into more valuable chemicals.2-methylfuran?MF?is an important chemical raw material for the production of furan-based compounds,pentanediol,etc.It is also an excellent chemical intermediate for the production of pesticides?chrysanthemum ethyl ester?,perfumes,antimalarials?chloroquine?.Therefore,the development of MF products to replace fossil fuels or as a fuel additive will help to alleviate the current energy crisis,with a good background and research significance.Cyclopentanol?CPL?and Cyclopentanone?CPO?are important chemical raw materials that have been widely used in the synthesis of fungicides,perfume chemicals and solvents and raw materials for pharmaceuticals.Direct conversion of the biomass derivative furfural?FFA?to CPL or CPO under mild conditions will have important implications for obtaining higher FFA conversion,CPL or CPO selectivity.For the first time,the CuZnAl catalyst was systematically studied for liquid phase hydrogen transfer catalyzed FA hydrogenation to prepare MF.A series of CuZnAl catalysts and CuZn catalysts,CuAl catalysts and ZnAl catalysts were prepared by co-precipitation.The effects of different catalysts,different calcination temperatures,different CuZn molar ratios,different solvents,different pressures,different reaction temperatures and different reaction times on the preparation of MF by FA catalytic hydrogen transfer were investigated.It was found that the yield of2-methylfuran was 72%using Cu_2.5Zn-Al-600?Cu/Zn=2.5,calcination temperature of600 ^oC?in an isopropanol solvent under atmospheric nitrogen atmosphere.The ratio and cycle stability of 7.5 mmol MF/?gCat.h?are shown to be comparable to the reported catalytic properties of the noble metal.In order to further explore the relationship between catalyst structure and performance,the catalysts were characterized by XRD,XPS,H₂-TPR and TEM.It was found that the cleavage of C-O bond in furfural is indispensable for the formation of 2-methylfuran,which can be regulated and promoted by the Cu crystal phase and CuAl₂O₄ crystal phase on the catalyst surface.The Cu mass after reduction of CuZnAl catalyst has a positive correlation with the formation of 2-methylfuran.Secondly,the co-precipitation method was used to prepare different zinc and Al-based Cu-based catalysts?Cu accounted for 37 mol%?for the rearrangement of furfural in aqueous hydrogenation.The results showed that the optimal reaction conditions were 150^oC,4 MPa,and 4 h.The results of XRD,H₂-TPR,NH₃-TPD,H₂-TPD,XPS,CuLMM,and TEM,our research shows that Zn and Al are not only related to the particle size of Cu and the structure of the catalyst,but also change the valence distribution of Cu and the acidity of the catalyst.