Studies About The Catalyzed Deoxygenation Reactions Of Biomass-derived Compounds And Related Bifunctional Catalysts

Non-renewable fossil resources play irreplaceable roles as energy carriers and materials in today's society.However,the rapid depletion of fossil resources generated a huge amount of carbon dioxides and harmful substances(such as NOx,SOx,haze...),which resulted in a series of irreversible damages to our natural environment.Serious environmental issues had already affected people's lives.Meanwhile,since the rapid consumption of the limited fossil resources,they would not support the needs of Mankind.The development of society would also be trapped by the scarce fossil resources.Hence,during those decades,people had been looking for green and renewable resources to instead of fossil resources for future energy and materials support.Biomass,as the only renewable carbon resource in nature,had drawn researchers' attentions.Since biomass is abundant,wide distribution and clean carbon resources,it matches the all requirements for the future renewable resources.Grease and lignocellulose are two kinds of representative biomass resources,yielding as by-products with the grain production and food cooking.What's more,since those above materials were produced through the photosynthesis,their production would reduce the carbon emission in the atmosphere,and mitigate the greenhouse effect.Hence,the conversion and utilization of grease and lignocelluloses had developed quickly during the past decade.However,because of complicated components,grease and lignocelluloses need to be converted to fatty acids(esters),5-hydroxymethylfurfural and lignin-derived phenols for the followed chemical conversion.Noteworthily,all the biomass-derivates,such as fatty acid(ester),5-hydroxymethylfurfural and lignin-derived phenols,have high oxygenation content in their molecule.Hence,they were hardly converted into fuels(long-chain alkane and dimethylfuran)and high-valued chemicals(alcohols and secondary amines)in one step.Therefore,catalyzed deoxygenation was the necessary process for the utilization of those biomass-derived compounds.The development of bifunctional deoxygenation catalysts was the core issues for the catalyzed deoxygenation process of biomass-derivates.Based on above problems,we fabricated kinds of bifunctional catalysts for the deoxygenation of fatty acid methyl ester,5-hydroxymethylfurfural and lignin-derived phenols.The reaction mechanisms for three reaction systems were all investigated.In the first chapter,we first introduced the necessity of developing biomass resources for human society and the research status of biomass utilization.Subsequently,the developments of the first and second generation biodiesel were presented based on the investigations of catalyst.After that,the synthesis of biomass-derived furan compounds(5-Hydroxymethylfurfural)and its utilization through selectively catalyzed deoxygenation were both shown.Additionally,the depolymerization of lignin and the catalyzed deoxygenation of its derived phenols were also discussed in the followed part.At the end of this chapter,the development of bifunctional deoxygenation catalyst was briefly introduced.In the second chapter,we introduced the catalyzed deoxygenation of fatty acid methyl ester to long-chain alkane over Mo doped nickel phyllosilicates(Mo-Ni@PSi)catalyst.With the ammonia evaporation method,bifunctional Mo-Ni@PSi catalysts were successfully fabricated.Through the analysis of various characterizations,it was proved that the introduction of Mo element reduced the interaction between Ni2+cations and phyllosilicate support.Besides,the amounts of acid sites and hydrogenation sites were also improved over the surface of catalyst with the doping of Mo element.Based on the optimized Mo-Ni@PSi catalyst,the fatty acid methyl ester(methyl palmitate)was effectively converted to long-chain alkane under mild reaction conditions.In the mechanism study,hydrodecarbonylation process(HDC)and hydrodeoxygenation process(HDO)were both confirmed as the main reaction pathways in the catalyzed conversion.Meanwhile,the catalytic stability of Mo-Ni@PSi catalyst was investigated,and slight deactivation was detected.The oxidation of Ni nanoparticles was mainly reason for the catalytic deactivation.Fortunately,the deactivated Mo-Ni@PSi catalyst would be recovered through reduced regeneration.In the third chapter,we introduced the selectively catalyzed deoxygenation of 5-hydroxymethylfurfural to dimethylfuran over Mo doped copper phyllosilicate(Mo-Cu@PSi)catalyst.The copper phyllosilicate precursor was successfully synthesized through the ammonia evaporation method.5-hydroxymethylfurfural was converted to dimethylfuran over the bifunctional Mo-Cu@PSi catalyst under mild conditions,while furfural was transferred into furfuryl alcohol in the same reaction conditions.With the XRD and FT-IR characterizations,the formation of copper phyllosilicate was confirmed.The strong interaction between Cu2+ and phyllosilicate was confirmed with the H2-TPR and XPS measures.With doping of Mo element,the amount of acid sites over the Cu based catalyst was obviously improved which was proved in the NH3-TPD results.Highly dispersive Cu nanoparticles,abundant acid sites and the synergy of above two active species were considered as the mainly factors for the high catalytic activity.In the fourth chapter,we introduced the reductive amination of lignin-derived phenols to secondary amines over PdHx/Al2O3 catalyst.Through the NaBH4 liquid phase reduction method,Al2O3 supported PdHx alloy catalyst was synthesized successfully.With the characterizations of XRD,XPS,FT-IR measures,it was proved that the excellent catalyzed performance would be mainly due to the formed PdHx species,which was not existed in the impregnated Pd/Al2O3 catalyst.Meanwhile,the abundant acidic sites over Al2O3 support also had positive effect on the reductive amination of phenols.In the study of reaction mechanism,it was found that the phenol was first hydrogenated to cyclohexanone over PdHx surface.Then,formed cyclohexanone was coupled with primary amines over acidic sites of catalyst and yielded an intermediate imine.Finally,the intermediate imine was hydrogenated to target amine over PdHx sites.Besides,this superior catalyst also showed a wide tolerance for different substrates and good catalyzed stability.In the fifth chapter,we summarized all the paper and gave an outlook for the catalyzed deoxygenation of biomass-derivates and the development of bifunctional catalyst.