低聚合度多聚甲醛制备工艺的优化

Optimization of preparation of paraformaldehyde with low polymerization degree

考察了制备低聚合度多聚甲醛(PF)的适宜助剂、加入质量分数和效果,并研究了反应时间、反应温度和热空气线速度对制备的PF中醛质量分数和醛收率的影响规律。采用二次回归正交组合设计实验方法,建立了甲醛质量分数、甲醛收率与反应温度、反应时间和热空气线速度之间的经验数学模型,模型计算值与实验值较吻合,平均相对偏差均小于3.44%。结果表明:影响PF中甲醛质量分数的因素主次顺序为热空气线速度>温度>聚合时间;影响甲醛收率的因素主次顺序为温度>聚合时间>热空气线速度。确定了制备PF质量分数为95%同时甲醛收率达到60%—70%的适宜工艺条件。

The preparation, amount of promoters used in synthesis of paraformaldehyde （PF） with low polymerization degree were studied. The effects of the technological parameters such as reaction time, the temperature and the air linear velocity on the mass fraction of PF and yield of formaldehyde were investigated. A mathematical model of the relation between mass fraction of formaldehyde, yield of formaldehyde and the technological parameters was established by means of the quadratic regression combination design process. The estimated value is well fitted with the observed value, and the average relative deviations are all less than 3.44%. The results show that the contribution of three factors to formaldehyde mass fraction of PF is air linear velocity, reaction temperature and reaction time in turn, and the contribution of three factors to yield of formaldehyde of PF is reaction temperature, reaction time and air linear velocity in turn. With these optimal conditions, the mass fraction and yield of formaldehyde of PF are 95% and 60%-70%, respectively.