Study On Acid Hydrolyzation Of Cellulose And Its Catalytic Hydrogenation To Produce Polyols

To search alternative and renewable energy and to improve the utilization of energy is currently the main task and the developing direction of industrial research. As a huge reserved energy material and renewable energy source, cellulose becomes a starting point. Cellulose had been used for long time, such as paper, artificial fibers, etc. But it has become a hot spot as an energy source just in rencent years. It's generally divided into two steps in the traditional method of producing polyols from cellulose. The first step is hydrolysis of cellulose to form glucose. And the second step is the catalytic hydrogenation of glucose to polyols. Such reaction processe is time-consuming and complicated. So to develop new catalysts and catalytic technologies to catalyze cellulose to produce polyols in a simple one step is of great importance.In this study, the hydrolysis of cellulose in the synergetic action of microwave and ultrasonication was carried out to improve the hydrolysis rate of cellulose and the selectivity of sugar. With HCl(wt%): HCOOH(wt%): H2O(wt%) = 4:78.2:17.88 as acid hydrolysis system of cellulose, the influence factors, such as reaction temperature, reaction time on the conversion of cellulose and yield of sugar, were investigated. The result show that conversion rate of cellulose is 18.3 % and the yield of reducing sugar is 14.6 % in the reaction condition of 0.5 h at 70℃, which is a significantly improvement compared to the traditional method.In this study, the catalytic hydrogenation of cellucose by Ru/CNTs was investigated. The influence factors, such as active component, support material, Ru loading, solvent usage amount, reaction time, temperature and pressure, on conversion of cellulose and yield of polyols were evaluated. The results show that the conversion rate of cellulose is 80% and the yield of polyols is 38 % with Ru/CNTs as catalyst and hydrogen as reducing agent and with 0.5h reaction time at 225℃and 6MPa. In this reaction system, CNT promotes the hydrolysis of cellulose and Ru is main active component to catalyze the soluble reducing sugar to convert to polyols. Since cellulose can not achieve 100 % conversion, it is not conveniant to recovery and reuse of the catalyst. So, it is necessary to add a second active component to improve the conversion. It was found that the second component of Ni can greatly improve the conversion rate of cellulose. With the addition of Ni into Ru to form RuNi/CNTs, the conversion of cellulose can be improved to 99 % above and the yield of polyols can improved to 55%, which indicates that the addition of a second active component is beneficial for the catalytic reaction and the yield of polyols.