棉秆水热法制备5-羟甲基糠醛的动力学研究

Dynamics of 5-Hydroxymethylfurfural Preparation From Cotton Stalk with Hydrothermal Method

为了提高生物质中纤维素的降解率和5-羟甲基糠醛(5-hydroxymethylfurfural,5-HMF)的产率,对棉杆水热法降解生成5-HMF的过程进行了研究。通过分析各因素对纤维素降解和5-HMF合成的影响,确定最佳操作工艺条件;在催化剂SO42-/ZrO2存在与不存在时,对棉秆水热法制备5-HMF的过程进行了动力学分析。研究结果表明,催化剂SO42-/ZrO2添加质量分数为20%,在230℃下反应90 min时,纤维素降解率可达94.43%,5-HMF产率可达25.3%,相同条件下较无催化剂可提高79.4%。动力学研究表明催化剂SO42-/ZrO2对纤维素降解和5-HMF合成都具有正向催化效果。加入催化剂后,纤维素降解反应活化能由106.0 kJ·mol-1降低至96.7 kJ·mol-1,5-HMF合成反应活化能由119.4 kJ·mol-1降低至84.2 kJ·mol-1。

In order to improve the degradation rate of cellulose in biomass and the yield of 5-hydroxymethylfurfural （5-HMF）, the process for the degradation of cotton stalk to the 5-HMF generation with hydrothermal method were studied. The influences of various factors on the degradation of cellulose and 5-HMF synthesis were analyzed to determine the optimum process operating conditions; the dynamics of 5-HMF preparation from cotton stalk with hydro- thermal method with or without catalyst SO42-/ZrO2 were analyzed. The results showed that when the reaction carried out at 230 ℃ for 90 min and the dosage of catalyst SO42-/ZrO2was 20%, the degradation rate of cellulose is up to 94.43% and the yield of 5-HMF is about 25.3%, which increased by 79.4% compared with no catalyst under the same conditions. The results of kinetics study showed that catalyst SO42-/ZrO2 had positive catalytic effect on cellulose degradation and 5- HMF synthesis, and with the addition of catalyst 5042-/ZRO2, the activation energy of cellulose degradation reaction decreased from 106 kJ ·mol^-1 to 96.7 kJ ·mol^-1 and the activation energy of the preparation of 5-HMF decreased from 119.4 kJ ·mol^-1 to 84.2 kJ ·mol^-1.