苯酚羟基化合成苯二酚反应产物分离与物料平衡的研究

Product Separation and Material Balance for Synthesis of Diphenol by Hydroxylation of Phenol

对苯酚羟基化合成苯二酚产物分离与物料平衡过程进行了研究,结果表明,采用常压脱水和减压精馏工艺,可以实现苯酚羟基化产物的分离,但常压脱水和减压精馏过程均有酚焦油生成。为得出确切的酚焦油含量,在密闭系统常压条件下,有催化剂存在时,用水、醋酸、苯酚、邻苯二酚和对苯二酚模拟羟基化反应液,进行脱水分离,并计算苯二酚损失量,即可得酚焦油生成量。经95℃反应2 h,邻苯二酚减少22.8％,对苯二酚减少4.7％。在塔顶温度114℃,塔压2.4 kPa操作条件下,将精馏得到的苯酚和邻苯二酚倒入塔底残液中再次蒸馏,邻苯二酚损失12.6％,与塔底液增加量相当。以水和苯酚为物料平衡研究对象,根据精馏结果,完成了苯酚羟基化合成苯二酚工艺过程的物料平衡研究,并与气相色谱分析结果进行了比较,分析了气相色谱分析结果与物料平衡计算结果存在的差距,其原因在于气相谱分析结果难以对酚焦油进行精确定量,且长时间脱水和蒸馏过程也会产生酚焦油。

The product separation and material balance for synthesis of diphenol by hydroxylation of phenol were studied. The result showed that the products produced in hydroxylation of phenol could be separated by both dehydration under normal pressure and distillation under vacuum in which there existed phenolic tars. In atmospheric water- tight system, catechol decreased by 22.8%, and hydroquinone decreased by 4.7% after 2 hour reaction at 95 ℃ in the presence of catalysts using water, acetic acid, phenol, catechol and hydroquinone as model liquid . Catechol decreased by 12.6% if the dehydrated products were redistilled at 114 ℃ of temperature at the top of tower under 2.4 kPa. The analytic result using gas chromatograph was compared with the result from studying material balance. The differences between the two results resulted from the formation of new phenolic tars in dehydration and distillation of hydroxylated products.