熔融结晶法提纯对苯二胺

Purification of p-Phenylenediamine by Melt Crystallization

对粗对苯二胺用熔融结晶的方法进行提纯,考察了降温结晶速率、结晶终温、发汗升温速率、发汗终温对晶体纯度和产品收率的影响,并确定了最佳工艺条件:降温结晶速率为0.05℃/min,结晶终温为124℃,发汗升温速率为0.035℃/min,发汗终温为139℃。在最佳工艺条件下,通过单级熔融结晶从质量分数为92%的粗对苯二胺中得到纯度为99.5%以上的精对苯二胺,产品收率大于70%。

The refining process of p-phenylenediamine by melt crystallization was experimentally studied.Effects of the cooling rate,final temperature in the crystallization process,heating rate and final temperature in the sweating process on the purity and yield of the product were investigated.The results show that when the cooling rate is 0.05 ℃/min,the final crystallization temperature is 124 ℃,and the heating rate of sweating is 0.035 ℃/min,the final sweating temperature is 139 ℃,99.5% p-phenylenediamine can be obtained by one time melt crystallization and the yield is higher than 70%.