乙基叔戊基醚的合成及反应动力学研究

Synthesis of tert-Amyl Ethyl Ether and Kinetics Research

用国产NKC-29型强酸性阳离子交换树脂为催化剂,在常压液相条件下用乙醇和叔戊醇为原料合成了乙基叔戊基醚。讨论了温度、催化剂浓度、反应物初始摩尔比等参数对反应速度以及反应选择性的影响。结果表明: 反应温度升高, 将加快反应速度,但是当温度过高将加速叔戊醇的分解,使反应的选择性降低;催化剂浓度与产物的初始生成速率成线性关系, 表明反应为动力学控制步骤;增加乙醇与叔戊醇的初始摩尔比,可有效抑制叔戊醇分解为水与异戊烯的副反应。与另一种国产S-54型树脂催化剂比较的结果显示:NKC-29的催化活性及选择性优于S-54根据实验结果并考虑水对催化剂的阻碍效应, 建立了该反应的动力学模型,并得到了相应的模型参数, 即反应速度常数和水的阻碍系数。实验结果与模型计算值吻合得较好。

Ethanol and tert-amyl alcohol were employed to synthesize tert-amyl ethyl ether in the liquid phase at atmospheric pressure. The strong acid cation exchange resin, NKC-29, was used as catalyst. The reaction mechanism was investigated. The effects of temperature, catalyst concentration and the initial molar ratio of ethanol to tert-amyl alcohol on the reaction rate and selectivity were discussed. Experimental results show that the conversion of tert-amyl alcohol increases with temperature increasing. However, the selectivity of tert-amyl ethyl ether decreases when temperature increases. The initial reaction rate is proportional to the catalyst amount and the side reaction rate of tert-amyl alcohol dehydration will become slow when the molar ratio of ethanol to tert-amyl alcohol is increased. The performance of NKC-29 was compared with another cation exchange resin S-54. It shows that both of the reaction activity and selectivity for the NKC-29 are better than for the S-54. Based on these experiment results, a kinetic model which considers the six reversible reactions and the inhibition of water was obtained. The relationships of the rate constant ki and the inhibition coefficient kw with the temperature were given, and the activation energies were calculated. The model agrees well with the experimental results.