Selective Synthesis Of Bio-based Aromatics From Biomass-derived

Energy is extremely significant for human beings.Since the 21st century,with the development of the economy,industry depends more and more on fossil energy,which is non-renewable resource that can result in the problems of greenhouse effect and other environmental pollutions.Biomass is the sole renewable organic carbon carrier in nature.lignocellulose is the major form of the inedible biomass resource,therefore,transformation of lignocelluose to renewable chemicals is a promising method to replace the fossil resources for chemicals production.p-Xylene（PX）,toluene and 2,6-dimethylnaphtalene（2,6-DMN）are basis chemicals that play indispensable roles in modern industry.Developing sustainable method for the synthesis of these chemicals from biomass platform compounds is highly desirable.In this dissertation,p-xylene,2,6-DMN and their derivatives are synthesized by using readily available biomass-derived compounds.（1）Selective production of bio-based para-xylene over Fe O_x-Pd/Al₂O₃catalyst;[Bmim]Zn₂Cl₅ionic liquid was used as the catalyst for Diels-Alder rection of isoprene and acrolein to synthesize4-methyl-3-cyclohexene formaldehyde（4-MCHCA）,a precursor with a six-membered ring framework structure.A Fe O_xmodification strategy was then developed to suppress decarbonylation reaction on Pd/Al₂O₃catalyst,leading to a drastically shift in selectivity towards p-xylene（PX）with the yield up to 81.1%via a cascade dehydroaromatization-hydrodeoxygenation（DHA-HDO）pathway.Characterization and control experiments revealed that electron density of Pd sites decreased in Fe O_xmodified Pd/Al₂O₃catalyst compared to sole Pd/Al₂O₃,thus tuning the preferential adsorption mode of the substrate fromη²-（C,O）,the key transition state of decarbonylation reaction,toη¹-（O）mode that favors hydrodeoxygenation process.（2）Selective production of 2,6-dimethylnaphthalene from isoprene and para-Toluquinone:Bi-cyclic precursor was first produced from ionic liquid-catalyzed[Bmim]Zn₂Cl₅Diels-Alder reaction of isoprene and p-Toluquinone.Using dioxane as solvent,different kinds of synthesis methods Cu-based catalysts（ammonia evaporation（Cu/Si O₂-AE）,coprecipitation（Cu/Si O₂-CP）,impregnation（Cu/Si O₂-IM））,the activity of the noble metal catalysts（Pd/Al₂O₃,Pd/ZSM-5,Pd/HBeta,Pd/Si O₂,Pt/Al₂O₃,Ru/Al₂O₃,Rd/Al₂O₃）and tungsten carbide（W₂C/AC）for the synthesis of 2,6-DMN were compared under the same reaction conditions.The results showed that under the optimized conditions(300°C,H₂flow rate:20 m L.min^-1,WHSV:0.1h^-1),2,6-DMN with a yield of 94.8%was obtained over Cu/Si O₂-AE catalyst and 94.9%over the Cu/Si O₂-CP.Studies showned that Cu/Si O₂-AE have high activity and stability due to the large number of active species Cu⁺and Cu⁰strong interactions with carrier SiO₂.