Study On The Synthesis Of Oxygen-Containing Fuels And Chemicals From Biomass Furanyl Platform Molecule

As the only renewable and green organic carbon resource,biomass resources are considered to be an ideal substitute of fossil resources for production of liquid fuels and high value-added chemicals.5-hydroxymethylfurfural(5-HMF)and furfural are important furan platform molecules.The selective catalytic conversion of HMF and furfural can realize the preparation of various oxygen-containing fuels and chemicals.2,5-bis(methoxymethyl)furan(BMMF)have been proven to be used in six-cylinder heavy-duty engines for any test mixing ratio without finding significant differences in engine operation.At present,the preparation of BMMF requires the cooperation of hydrogenation catalyst and acidic catalyst,and the product selectivity were lower in reported systems.In order to solve the above problems,a bifunctional cobalt catalyst containing hydrogenation activity and etherification activity was developed for the selective reduction etherification of HMF to BMMF.Medium chain fatty carboxylic acids are widely used in the manufacture of various chemicals and intermediates,and the market prospect is very optimistic.At present,the medium-chain fatty carboxylic acids are mainly obtained from the cracking of oil crops,but the source of raw materials is limited and the products are difficult to be separated and purified.In order to solve the above problems,extension of carbon chain length is necessary through condensation of biomass substrates and their derivatives.Meanwhile,the carboxyl functional group is selectively retained and other C-O bonds are selectively cleavage by using the Pd/C+M(OTf)x co-catalytic system.The medium-chain carboxylic acids with different carbon chain lengths are achieved,which are different from the current complete hydrodeoxygenation to alkanes.2,5-furandicarboxylic acid(FDCA)is a new type of polymer monomer,which could be widely used in medicine and industry.At present,the preparation of FDCA requires the additional alkali and excess inorganic acid which resulting in more discharge of waste salt and waste water.In order to solve the above problems,a method for the conversion of HMF to FDCA under mild,alkali-free conditions is developed.In the first chapter,the composition and utilization of biomass are introduced.And the preparation methods and downstream products of the furan platform molecule furfural and HMF are briefly summarized.In the second chapter,the simple reduced Co3O4 catalyst was developed for the reduction etherification of HMF to BMMF.Meanwhile,the reaction conditions and structure-activity relationship of catalysts were investigated.It was found that HMF was completely converted by using a Co-400 catalyst at 140 ?,2 MPa H2 for 1 h,and a yield of 98.5%BMMF was obtained.XRD and XPS analysis showed that the coexistence of hydrogenation activity and etherification activity due to the presence of Co0 species and amorphous Co3O4 species in the catalyst.The reaction process was studied in detail by 1H-NMR characterization and the possible reaction mechanism was proposed.Finally,the preparation of BMMF in two steps starting from fructose was carried out and the total isolated yield reached to 66.5%.In the third chapter,the effect of reaction conditions on product distribution by using aldol condensation product(condensation of furfural and levulinic acid)as model substrate was investigated.A maximum yield of 98.2%decanoic acid was obtained at 180 ?,3 MPa H2,10 h.It was found that the product yield increased as the effective charge density of triflate increases.Acetic acid and metal triflate can significantly promote the ring opening of tetrahydrofuran and the depolymerization of oligomer intermediates according to the 1H-NMR and ESI-MS analysis.Further expanding the substrate scope,other medium-chain carboxylic acids were obtained at a yield of 72%or more,which showing good compatibility of the catalytic system.In the fourth chapter,the TEMPO catalytic system was developed to realize the conversion of HMF to FDCA under acidic conditions.The highest FDCA yield of 84%was obtained at 30 ? for 24 h.It is found that FFCA and FDCA were the main products of the reaction.The reaction mechanism study showed that nitrogen oxides was formed in the presence of oxygen,sodium nitrite and hydrochloric acid,which promoted the cycle of TEMPO.And the presence of water under acidic conditions will promote the hydration of aldehyde groups.This provides the possibility for further oxidation of DFF to FDCA.Finally,the conversion of fructose to FDCA was realized in acidic conditions.In the fifth chapter,the full paper was summarized and forecasted.In summary,this thesis mainly uses biomass furan platform molecules as research objects:1)A simple and efficient bifunctional Co catalyst was developed for highly selective reductive etherification of HMF to BMMF.The Co catalyst has the characteristics of simple preparation,strong cycle and high activity of reductive etherification reaction;2)The development of a new route for the conversion of furan-based platform molecules into a variety of different carbon chain length carboxylic acids through a two-step process of condensation and hydrodeoxygenation.The catalytic system has a highly selective carboxyl group retention feature,which providing an effective method for the conversion of biomass molecules to carboxylic acid compounds;3)The conversion of HMF to FDCA under acidic conditions is realized,and the introduction of inorganic base is avoided,which provides a new method for the preparation of FDCA.