Production Of Aromatics From Biomass-derived Furanics

Aromatic compounds are important chemical commodities,which are widely used in the production of pesticides,medicines,perfumes and polymer materials.In order to reduce the dependence of aromatics production on petroleum resources,preparation of aromatics from biomass-based platform compounds has gradually become a research hotspot,which is of great significance for reducing environmental pollution and protecting energy security.In this thesis,catalytic conversion of biomass-based furan compounds into renewable aromatics through Diels-Alder and dehydration reaction has been carried out.First of all,SAPO-34 zeolite was utilized to produce p-xylene from Diels-Alder and dehydration reaction between 2,5-dimethylfuran and ethylene.The selectivity of pxylene could approximately reach 75%under optimized reaction conditions.When the reaction time was prolonged from 12 h,the selectivity of p-xylene was almost unchanged,indicating that SAPO-34 zeolite might have good selectivity for the conversion of 2,5-dimethylfuran to p-xylene.Catalyst characterization revealed that SAPO-34 has a large Lewis acid ratio,which is efficient at inhibiting the formation of by-products and thus exhibited high p-xylene selectivity.However,the average pore size of SAPO-34 was small and could cause reactant diffusion problems and poor mass transfer,resulting in low reaction conversion.What is more,a two-step method for the preparation of benzoates from furfural through "oxidation-cycloaddition-dehydration" route was established.The first step was the oxidative esterification of furfural and the second step was the Diels-Alder and dehydration reaction of methyl furoate.This new reaction pathway could effectively utilize the oxygen atom on the aldehyde group of furfural and had high atomic economy.For the oxidative esterification of furfural,two different oxidation systems were studied,including persulfate oxidation system and NHPI-H2O2 system.In addition,H-Beta zeolites were used to catalyze the Diels-Alder and dehydration reactions of methyl furfurate to produce benzoates.If ethyl acetate was used as the solvent,Diels-Alder and dehydration reaction and transesterification reaction were combined,which could not only increase the conversion of furfural to more than 80%,but also lead to the coproduction of methyl benzoate and ethyl benzoate.Finally,based on the results of the oxidative esterificationn of furfural,the oxidative esterification of 5-hydroxymethylfurfural was also explored under the TBHPCuCh oxidation system.The results showed that the yield of diethyl furandicarboxylate was low.Besides,in order to extend the reaction route for preparing aromatics from 5hydroxymethylfurfural and establish a novel reaction pathway,production of dienophiles from 5-hydroxymethylfurfural and its conversion into aromatics through Diels-Alder reaction was developed.In this case,the oxidative cleavage of 5hydroxymethylfurfural under heteropolyacid-H2O2 oxidation system was carried out.The dicarboxylic acid esters produced mainly included malonate,maleate,succinate and malate,and the dominant products are malonate and succinate.