速生桉木硫酸盐浆氧脱木素过程中甲醇生成的动力学模型

A Kinetic Model of Methanol Formation during Oxygen Delignification of Fast-growing Eucalyptus Kraft Pulps

关键词:  甲醇  速生桉  硫酸盐浆  氧脱木素  动力学模型

Key Words:methanol  fast-growing eucalyptus pulp  oxygen delignification  kinetic model

摘要:考察了速生桉木硫酸盐浆氧脱木素过程中，温度、氧压、NaOH用量及时间对甲醇生成的影响，并据此建立了预测甲醇生成量的动力学模型。结果表明，该模型对初始卡伯值为32.8（高卡伯值）和16.9（低卡伯值）的纸浆在氧脱木素过程中甲醇的生成量均能得到很好的预测（R2分别为0.986和0.974）；高、低两种卡伯值纸浆氧脱木素过程中甲醇生成反应的活化能、NaOH浓度及氧压的反应级数分别为55.4、49.3 kJ/mol，1.02、0.362及0.472、0.299；高卡伯值纸浆可有效减少脱木素过程中的甲醇生成量（对后续氧脱木素目标卡伯值为10的生产工艺，甲醇生成量可减少12%）。对不同原料碱法浆氧脱木素过程中降低单位卡伯值的甲醇生成量进行比较，结果表明，阔叶木浆最多（29.1 mg/L）、麦草浆次之（13.8 mg/L）、针叶木浆最少（11.0 mg/L）。

Abstract:The effects of temperature, oxygen pressure, alkali charge, and time on the formation of methanol during oxygen delignification (OD) of eucalyptus kraft pulp were investigated, from which a kinetic model for predicting the methanol formation during the OD process was established. The results showed that the model can provide a good prediction for the methanol formation during OD of different kappa number pulps at different process conditions. The active energies and the reaction orders of NaOH concentration and oxygen pressure for the methanol formation reaction of high/low kappa number pulps are 55.4/49.3 kJ/mol, 1.02/0.362, 0.472/0.299, respectively. And also, at the given target kappa number (10) of the subsequent OD process, the methanol formation in the process for the high kappa number pulp can be considerably reduced (by 12%). The amounts of methanol formed per unit kappa number reduction during OD process of the pulps from different raw materials are different, which are 29.1, 11.0, and 13.8 mg/L for eucalyptus, southern pine, and wheat straw pulps, respectively.