甲缩醛催化精馏过程宏观动力学研究

以强酸型阳离子交换树脂为催化剂,甲醇、稀甲醛为原料在间歇反应釜中合成甲缩醛(二甲氧基甲烷)。实验中,各组分的测定采用校正面积归一化法与亚硫酸钠分析法相结合的方式。通过实验,考察了催化剂用量与不同温度对甲醛反应速率的影响,测定了反应平衡常数。文章采用拟均相模型对实验数据进行拟合,考察了313,318,323,328 K 4个温度下的正逆反应速率。实验结果表明:催化剂A的最佳用量为总溶液质量分数的3%;采用拟均相模型对实验线性拟合,线性关系显著,验证了假设的反应机理,并回归得到了在313—328 K下的指前因子k0、活化能Ea及宏观动力学方程,反应表现级数为二级。通过对实验与计算值的比较验证,此宏观动力学方程合理,可用于模拟计算。

Macrokinetics of methylal synthesis by catalytic distillation

Methylal was synthesized from methanol and dilute formaldehyde in a batch reactor in the presence of strong acidic cation exchange resin catalyst.The purities of methylal,methanol and formaldehyde were determined by calibration area normalization and sodium sulfite titration.The effects of catalyst quantity and reaction temperature on the reaction rate were investigated and the reaction equilibrium constant was determined.The rates of positive reaction and reverse reaction at 313,318,323,328 K were investigated by using pseudo-homogeneous model.The results show that the optimal mass fraction of catalyst A is 3% of the total solution;the curve fitted by pseudo-homogeneous model is significantly linear,and the supposed mechanism is proved;the pre-exponential factor,activation energy and macro kinetic equations are obtained at 313-328 K,and the reaction is second-order reaction.The calculation data are in good agreement with the experimental data,which shows that the macro kinetic equations are reasonable and are suitable for simulation calculation.