Direct hydroxylation of benzene to phenol in a novel microstructured membrane reactor with distributed dosing of hydrogen and oxygen

The direct conversion of benzene to phenol in the gas phase in a palladium membrane reactor has been investigated with deviating results by various researchers in recent years. Experiments carried out in Japan showed high phenol yields up to 23% [1]. However, researchers in The Netherlands found very low phenol yields (<1%) with carbon dioxide and water being the main products [2]. Our work on this reaction is devoted to the study of a new reactor design with separate membranes for distributed dosage of hydrogen and oxygen, respectively, into microstructured reaction channels. The production of phenol by direct hydroxylation of benzene was achieved in this reactor. The highest phenol selectivity so far obtained on a palladium-coated PdCu foil at 423 K was 9.6% with carbon dioxide being the dominant product.