Directional Catalytic Liquefaction Of Cellulose Into Polyols

Because of excessive exploitation and utilization of non-renewable fossil fuel,cellulose, which is of great significance for the sustainable development of chemicalindustry and human society, can be conversed into sorbitol、manntiol、ethylene glycol and1,2-propylene glycol by liquefaction in solvents. In this dissertation, cellulose wascatalysed into polyols in water over different catalysts. The main work and results in thisdissertation are as follows:(1) A high performance liquid chromatography (HPLC) method was established todetermine the concentrations of sorbitol, manntiol, glulose, ethylene glycol and1,2-propylene glycol in catalytic liquefied products of cellulose.(2) Characterization of Pd/C catalyst was investigated using thermal gravimetryanalysis (TGA), scanning electron microscope (SEM), X-ray diffraction (XRD) and N2physisorption. And the influences of reaction temperature, reaction time, initial hydrogenpressure，amount of the catalyst and solvent on the cellulose conversion were carried out.Results indicated that the conversion of cellulose and yield of sorbitol, mannitol,1,2-propylene glycol and ethylene glycol was95.85%,11.51%,8.12%,15.76%and19.08%, respectively under the optimum liquefaction conditions with reactiontemperature of245℃, reaction time of30min, initial hydrogen pressure of6Mpa, theamount of Pd/C of30wt%and the weight ratio of water/cellulose of80/1, respectively. Itwas proved that the existence of synergy in cellulose liquefaction using Lewis acid ZnCl2and Pd/C as the co-catalyst with the conversion of cellulose and polyols increased by3.57%and13.47%, respectively under the amount of ZnCl2of10%and the amount ofPd/C of30wt%, respectively. The activity of Pd/C catalyst maintained basically afterrecycling for three times.(3) After nanoscale WC catalyst was characterized, the influences of reactiontemperature, reaction time, initial hydrogen pressure, the amount of the catalyst and theamount of water on the cellulose conversion were investigated. Results indicated that theconversion of cellulose and total yield of polyols was90.52%and22.4%, respectivelyunder the optimum liquefaction conditions with reaction temperature of225℃, reactiontime of30min, initial hydrogen pressure of6Mpa, the amount of Pd/C of30wt%andthe weight ratio of water/cellulose of80/1, respectively. It was also proved that theexistence of synergy in cellulose liquefaction between Lewis acid ZnCl2and Nano WCcatalyst, where the conversion of cellulose increased to97.49%from95.31%, and totalyield of polyols increased from12.35%to13.98%, respectively. (4) Based on preparation of Ni-P/AC catalyst, Ni-P/AC catalysts with different Nimass fractions were characterized. The influence of different Ni mass fractions ofcatalyst on the catalytic activity in liquefaction of cellulose in water was carried out.Result indicated that the conversion of cellulose and total yield of polyols were90.52%and22.4%%, respectively under the liquefaction conditions with reaction temperature of225℃, reaction time of30min，initial hydrogen pressure of6Mpa, the amount of5%Ni-P/AC, and the weight ratio of water/cellulose of80/1, respectively. Comparing withPd/C catalyst and nanoscale WC catalyst, it showed that nanoscale WC catalyst had ahighest conversion of cellulose, and Ni-P/AC catalyst had a highest yield of polyols.