玉米秸秆木质素脱除动力学研究

Kinetic Study of the Delignification of Corn Stover by KOH Cooking

采用KOH在不同温度下蒸煮稀酸预水解后的玉米秸秆。确定了不同蒸煮温度下木质素脱除速率常数,木质素脱除动力学方程表达为:WL=0.0137exp(-∞t)+0.8433exp(-k2t)+0.1430exp(-k3t)。利用Arrhenius方程确定木质素在大量脱除段以及残余脱除段的活化能分别达到54.46kJ/mol和27.62kJ/mol。确定在该体系中最佳蒸煮温度为100℃,蒸煮时间为100min,木质素脱除率可达到90%以上。

The corn stover which was pretreated with dilute chloride acid at 120℃ was cooked with KOH at 80, 90, 100 and 110℃, respectively. The delignification kinetic model of corn stover used three first order reactions with following form： WL=0.0137 exp（-∞t）＋0.8433 exp（-kat） ＋0.1430 exp（-k3t）. The first term was essentially infinite at the time scale of cooking. The second and third terms corresponded to the bulk and residual phases of delignification. The activation energies for dilignification in cooking reaction were 54.46 and 27.62 kJ/mol in the bulk and residual phases, respectively. The optimal cooking condition was determined as following： cooking at 100℃ for 100 min. The delignification rate could be over 90%.