Pd/CuO Bifunctional Catalytic Membrane for Direct Synthesis of Phenol from Benzene

Synthesis of phenol, an important intermediate of the organic chemical　product, is presently carried out in a multistep process, where a large amount of energy is consumed for the separation and purification. Therefore inexpensive and environmentally benign one-step synthesis process is very much expected. As a new synthetic route of benzene to phenol, our group has examined a Pd membrane reactor being able to realize the direct hydroxylation. In this system, the active oxygen species are formed by the reaction between the dissociated hydrogen permeated through Pd membrane and the adsorbed oxygen, participating to the direct conversion of benzene to phenol. Aim of this study is to improve the reaction efficiency much more by introducing another idea.

Pd film is formed on a porous α-Al₂O₃ tube. The hydroxylation is considered to occur near the palladium film on the alumina support side. So, if an effective hydroxylation catalyst is loaded on the α-Al₂O₃ support tube, it will be expected to increase the reaction efficiency. In this study, a co-catalytic effect by adding copper oxide, which is reported to be useful, is examined.