甲酸/乙酸/氯化钠催化玉米芯水解条件优化

Optimization of corncob hydrolysis coupled with formic acid/acetic acid/sodium chloride system as catalyst

为解决目前糠醛行业使用无机酸做催化剂存在的严重污染及收率低等问题,提出两步法有机酸/无机盐复合体系催化玉米芯水解生产糠醛新工艺。文中以获得第1步水解玉米芯过程中较高的五碳糖收率和低的糠醛质量浓度为目的。研究了反应温度、反应时间、酸质量分数及氯化钠浓度对玉米芯中半纤维素水解的影响。通过响应曲面法,对水解条件进行了优化,建立了糖收率和糠醛质量浓度的2个二次多项式模型。由响应面分析和模型方程优化得出玉米芯水解的最佳水解条件:反应时间90 min、氯化钠浓度1.5 mol/L、温度134.7℃和酸质量分数为4.67%,此时糖收率为36%、糠醛质量浓度为1.98 g/L,为下一步五碳糖水解生产糠醛提供了较为满意的糖质量浓度和糠醛质量浓度,同时在最佳水解条件下的验证实验结果与模型预测值十分接近,说明模型是适用的。

In order to solve the problems using inorganic acid as catalyst to produce furfural has some disadvantages of serious pollution and low yield of furfural, the two-step hydrolysis technology was put forward with organic acid/ inorganic salt as catalyst. The objectives of the study were to obtain high pentose yield and low mass concentration of furfural in the first step. The effects of temperature, reaction time, acid mass fraction, and sodium chloride concentration on the hydrolysis process of corncob were studied. The response surface methodology was used to optimize the hydrolysis conditions, and the second-order model equations of the sugar yield and mass concentration of furfural were built. Using the professional software and the models, the hydrolysis conditions were optimized as follows： reaction time 90 min, sodium chloride concentration 1.5 mol/L, reaction temperature 134.7 ℃, and acid mass fraction 4. 67%. Under those conditions, sugar yield and mass concentration of furfural are 36% and 1.98 g/L respectively, which meet the need of the second step. The result conducted under the optimum conditions demonstrates that the models fit the experimental data well.