Remarks on studies for direct production of phenol in conventional and membrane reactors

The great interest in the oxidation reaction of benzene to phenol is linked to some disadvantages of the cumene process, such as environmental impact, production of an explosive intermediate, a multi‐step process (which involves (1) difficulty to achieve high phenol yield, in relation to the benzene used and (2) high capital investment), and a high acetone production as a co‐product which results in an over supply in the market. In this paper, we discuss various studies concerning a new approach based on a one‐step and acetone‐free method for phenol production. Particular attention is devoted to phenol production processes using various configurations of membrane reactors (MRs) and a photocatalytic membrane reactor (PMR). In particular, the biphasic MR allowed to achieving high selectivity values (97–98%). The described studies have been classified according to oxidant type such as N 2 O, O 2 , and H 2 O 2 . Each of them shows that direct oxidation of benzene to phenol is a difficult task and further efforts are needed to search and replace the three step traditional process of converting benzene into phenol with a process of direct oxidation.