Hydroxylation of benzene to phenol using hydrogen peroxide in a bubble reactor

Abstract

This research investigated the synthesis of phenol by hydroxylation of benzene using hydrogen peroxide over titanium silicalite-1 catalyst, that was pretreated with nitric acid, in a bubble reactor. In the reactor, benzene was fed in gas phase, hydrogen peroxide was liquid phase, and catalyst, which was immersed in hydrogen peroxide, was solid. The effect of key parameters such as rate of pulse feeding of benzene, reaction time and amount of catalyst were studied experimentally to demonstrate the cause-effect relationships in a bubble reactor. The comparison showed that at a fix amount of benzene to the fed, injecting a small amount of benzene in each pulse at high frequency yielded higher benzene conversion than injecting a large amount of benzene in each pulse at low frequency. In addition, the experiment at a fixed frequency of injection showed that injecting a smaller amount of benzene in each injection a larger amount of benzene in each injection. Moreover, the expandable experiment at a varied frequency of injection by fixing the amount of benzene feeding founded that the excess frequency of benzene feeding does not cause the increased benzene conversion. Hence, the frequency of benzene feeding had to suitable for the ability of phenol production in order to convert the high activity of benzene conversion. The study of reaction time showed that, in the initial section of increasing time, the produced phenol increased continuously. However, after initial section, the increasing of reaction time does time does not play a role on the produced phenol and the trend of the phenol is stable. The higher amount of catalyst in the hydroxylation of benzene to phenol enhanced the best benzene conversion.