氯化钾催化纤维素热裂解动力学研究

STUDY OF POTASSIUM CHLORIDE CATALYSIS MECHANISM ON CELLULOSE PYROLYSIS KINETICS

在差示热重分析仪上对生物质中最常见的金属元素钾的氯盐对纤维素热裂解动力学的催化效果进行了 研究。试验发现氯化钾的存在影响到热失重初始阶段活性纤维素的生成过程,导致了热重曲线向低温侧移动, 并且提高了焦炭的产率。结合Broido-Shafizadeh模型,对纤维素热解过程的催化作用机理进行探讨,发现纯纤维 素主失重阶段呈现出连续反应模式,分别对应于活性纤维素和挥发分的生成过程,并随反应温度的提高两者依 次成为整体失重过程的控制因素。钾盐的参与由于强烈催化了活性纤维素的生成反应,将控制反应转移到消耗 过程的一对竞争反应中,分别对应于焦炭和挥发份的生成。对比纯纤维素的失重动力学参数,氯化钾对活性纤 维素消耗过程中挥发份的生成反应和炭化反应均有强烈的催化效果。

The catalysis effect of potassium chloride （KCl） on pyrolysis kinetics was studied on a thermo-gravimetric balance. Experimental result showed that KCl would advance the formation of active cellulose by moving TG curve towards lower temperature, which took place in the initial stage of cellulose pyrolysis. At the same time, a higher yield of char product was obtained under KCl catalysis. On the basis of the Broido-Shafizadeh model, The catalysis mechanism of KCl on cellulose pyrolysis were investigated in detail. The main mass loss of pure cellulose appeared to be controlled by a consecutive reaction mode, corresponding the formation and consumption of active cellulose. However, with the addition of KCl to cellulose, the formation of active cellulose was catalyzed violently. The global reaction was transferred to a competitive reaction mode, corresponding to formation of char and volatile. Compared with that of pure cellulose.