Research On The Synthesis Of 5-Hydroxymethylfurfural And Methyl Levulinate Via The Catalytic Transformation Of Carbohydrates

With the gradual diminishing of petrochemical resources and the serious environmental problem caused by using petroleum resources over the past decades,researchers have already gradually paid attentions on the conversion of renewable resources to produce various chemicals and liquid fuels to replace the fossil fuels in the future.The synthesis of high value-added fine chemicals utilizing carbohydrates and its hydrolysis derivatives as raw materials become one of the most research hotspots in the current catalytic field,in which it is found that biomass derived hexoses can be transformed into 5-hydroxymethylfurfural(HMF)or levulinic esters(LEs)chemicals at suitable conditions.Moreover,both of these two target products play an important role as important platforms in chemical industry.Therefore,it is of great scientific and economic significance to convert the biomass resources into HMF and LEs.In the thesis,we first investigated the catalytic and selective dehydration of fructose to HMF.Three kinds of organic thin film catalysts containing poly(styrenesulphoic)acid(PSS),poly(styrenesulphoic)acid-graphite(PSS-C)and poly(styrenesulphoic)acid-graphite oxide(PSS-GO)were prepared by copolymerization and organic-inorganic hybrid methods.The catalysts were tested and characterized by infrared spectroscopy(FT-IR),thermal gravimetric(TG),X-ray diffraction(XRD),transmission electron microscopy(TEM),scanning electron microscopy(SEM)and physical adsorption(BET)technique,etc..Furthermore,the organic thin film catalysts were applied to the fructose dehydration,it was found that the target product of HMF has a highest yield in the medium with N-methylpyrrodinone(NMP).The reaction conditions were optimized with NMP as solvent: in the temperature of 160 °C for 4 h,with the PSS,PSS-C and PSS-GO materials as catalysts,and the product yields of HMF was 69.8 %,74.8 % and 76.5 %,respectively.Secondly,the reaction process of synthesizing methyl propionate(MLE)from glucose in methanol solution was studied.Br?nsted acid,mainly Lewis acid and mixed acid catalysts were respectively tested,and experimental results showed that individual B acid and L acid were not good to catalytic the reaction and the promotion of mixed acid catalytic is very good.Among them,when the combination of p-toluenesulfonic acid(PTSA)and Sn-beta molecular sieve as the catalytic system,the conversion of glucose in methanol was very promising and the highest yield of MLE reached 68.3%.Finally,the alcoholysis reaction of furfuryl alcohol in methanol medium was investigated in detail.Therein,the organic thin film(PSS,PSS-C and PSS-GO)were also employed as catalysts.The results show that the catalytic activities of the three materials are all square at low temperature.While when the reaction temperature is raised to 160 °C and reacted for 6 h,the catalytic effect of PSS is especially obvious and a yield of MLE 88.1 % was obtained.Meanwhile,the yield of MLE was 73.1 % and70.8 % when PSS-C and PSS-GO were used as catalysts under the same reaction conditions.Thehighest yield of MLE was around 96.4 % after optimizing the reaction conditions in the presence of PSS material.