Catalytic Conversion Of Glucose And Xylose To Chemicals

The efficient conversion of biomass to chemicals is a hot topic in recent years.Glucose and xylose are the abundant monosaccharides in nature.It is great significance for high value utilization of glucose and xylose to develop green recycling economy.However,valuable chemicals derived from glucose and xylose are few at present.The purpose of this thesis is to convert glucose and xylose into high value-added chemicals and to develop efficient and robust catalysts.?1?A series of MoO₃/?catalysts containing different Mo content were prepared by using H-?zeolite as support.The catalytic performance of the catalyst for the epimerization of glucose to mannose was studied.It revealed that MoO₃/?could selectively epimerize glucose to mannose,and the yield of mannose was 36.9%.XRD and UV-Vis DRS were used to identify the active sites of the catalyst.?2?Activated carbon was used as the support to fabricate Mo/AC catalysts with different loading.The effects of reaction conditions such as reaction temperature,reaction time and catalyst dosage on the epimerization of glucose were investigated.Under the optimum reaction conditions,the yield of mannose was 34.5%for Mo/AC,and the yield of mannose was 38.0%obtained over MoO₃.Mo/AC exhibited a better stability and was easier to recycle in comparison with MoO₃.The mechanism of glucose epimerization was revealed by isotopic labeling method.The reaction mechanism for the epimerization of glucose conforms to the classical“Bílik Reaction”,that is,carbon rearrangement reaction.?3?The activated carbon was prepared from Cunninghamia lanceolata sawdust through carbonization followed by water vapor activation method.Nitrogen-doped activated carbon was gained by treating activated carbon with ammonia at high temperature.The Pt/N-C catalyst was synthesized by loading Pt on the nitrogen-doped activated carbon.The hydrogenation activity of xylose over the catalysts was evaluated.The xylitol yields of 22.7%and 17.9%were obtained using 1wt.%Pt/C1 and 1wt.%Pt/N-C1-900 as catalyst,respectively.The activated carbon was fabricated from Cunninghamia lanceolata sawdust by using potassium hydroxide as the activating reagent.Nitrogen-doped activated carbon was obtained by treating activated carbon with ammonia as the activating reactant.The Ni/N-C catalyst was prepared by loading Ni on the nitrogen-doped activated carbon.The hydrogenation performance toward xylose of the catalyst was studied.The yield of xylitol up to 87.5%was achieved at 99.0%conversion of xylose over the 5wt.%Ni/C2-H-400 catalyst under the optimal conditions.