Microporous carbon molecular sieve as a novel catalyst for the hydroxylation of phenol

A series of microporous carbon-based catalysts were prepared by acidification and/or oxidization treatment of a commercially available carbon molecular sieve (CMS). The resultant samples were characterized by Boehm titration, X-photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), point of zero charge (pHPZC) test, N2 adsorption, and inductively coupled plasma atomic emission spectrometry (ICP-AES), and employed as catalysts for phenol hydroxylation with H2O2. It is found that the acidic functional groups of CMSs play an important role for the catalytic performance. The effects of solvents, reaction temperature, ratio of phenol/catalyst, ratio of phenol/H2O2 and reaction time were investigated. Over the sample with the strongest surface acidity among the studied CMSs, the phenol conversion, the selectivity to dihydroxybenzene, and the effective utilization of H2O2 reach 29.6%, 85.1% and 80%, respectively under optimal reaction condition. The catalyst is stable in the recycling test. Furthermore, due to its easy physical separation, environmental benignity and low cost, the microporous CMSs is promising for industrial application.

Microporous carbon molecular sieve (CMS) treated by acidification and oxidization was found to be an efficient catalyst for the hydroxylation of phenol in aqueous medium using H2O2 as oxidant, and a phenol conversion of 29.6% with 85% selectivity to dihydroxybenzene was obtained when phenol/H2O2 (mol/mol) = 3.Figure optionsDownload as PowerPoint slideResearch highlights
► Carbon molecular sieve is catalytically active for the hydroxylation of phenol.
► Stronger acidic groups on CMS contribute crucially to the catalytic activity.
► The catalyst is found rather stable.