金属氯化物对高温液态水中葡萄糖分解反应动力学的影响

Effect of metal chlorides on glucose decomposition kinetics in high temperature liquid water

以纤维素水解产物葡萄糖为模型物质,利用小型高压反应釜测定了180℃下13种金属氯化物催化葡萄糖和中间产物5-羟甲基糠醛(5-HMF)分解反应动力学数据,并用一级反应动力学模型对葡萄糖及5-HMF分解反应动力学数据进行了拟合。结果表明,不同的金属氯化物对葡萄糖和5-HMF的分解反应具有不同的催化效果,其中FeCl3、NiCl2和ZnCl2可大大提高葡萄糖分解反应的速率,而FeCl3和CuCl2可大大提高5-HMF分解反应的速率。在碱金属、碱土金属和过渡金属氯化物中,过渡金属氯化物对葡萄糖及5-HMF分解反应的催化效果明显占优。对于第四周期金属元素,随着原子量的增加,葡萄糖分解反应速率常数呈现增加的趋势。金属氯化物对葡萄糖和5-HMF分解反应的催化活性随金属离子pKa值的减小而增强。本文得到了金属氯化物对葡萄糖和5-HMF分解反应影响的规律,为生物质资源的高效利用提供了重要的基础数据。

With a small volume pressure vessel batch reactor, glucose and 5-hydroxymethylfurfural decomposition kinetics in high temperature liquid water catalyzed with metal chlorides were determined at 180℃ .Thirteen types of metal chlorides were selected. A series of first order reactions with the consideration of parallel by-reactions were used to fit the kinetics data. The results showed that the catalytic effects of different metal chlorides on glucose and 5-hydroxymethylfurfural decomposition were totally different. Iron （Ⅲ）, nickel and zinc chlorides could greatly accelerate the decomposition rate of glucose decomposition, while the decomposition rate of 5-hydroxymethylfurfural was highly improved by adding copper chloride and iron （Ⅲ） chloride. The catalytic effect of transition metal chlorides on glucose and 5-hydroxymethylfurfural decomposition was much better than that of alkaline metal chlorides and alkaline earth metal chlorides. As to the metal elements in the fourth period, the results showed that the rate constants of glucose decomposition were increased with the increase of atomic weight except copper chloride. In addition, the lower the pKa value of different metal ions, the stronger the catalytic effects on glucose and 5-hydroxymethylfurfural decomposition. This work obtained some general rules on the effects of metal chlorides on glucose and 5-hydroxymethylfurfural decomposition to provide important basic data for efficient utilization of biomass.