Process for making phenol or phenol derivatives

Abstract

A process for hydroxylating an aromatic compound comprises the steps of: (a) contacting an aromatic compound with a catalyst having an average concentration of .alpha.-sites of at least about 1.multidot.10.sup.16 per gram of catalyst, the catalyst having .alpha.-oxygen loaded thereon, whereby an hydroxylated derivative of the aromatic compound is produced; and (b) regenerating the catalyst when the concentration of .alpha.-sites falls below a predetermined value. The predetermined value will depend on the process design, but can suitably be about 1.multidot.10.sup.16 per gram of catalyst or higher. Another embodiment of the process comprises: (a) contacting an aromatic compound with a catalyst having an average concentration of .alpha.-sites of at least about 1.multidot.10.sup.16 per gram of catalyst, the catalyst having .alpha.-oxygen loaded thereon, whereby an hydroxylated derivative of the aromatic compound is produced; and (b) reloading the catalyst with .alpha.-oxygen by contacting the catalyst with a free oxidant activator. The progress of the reloading of the catalyst can be determined by: (a) passing an input gas stream over the catalyst, the input gas stream comprising an inert gas; (b) collecting an output gas stream that has passed over the catalyst; (c) introducing a plurality of nitrous oxide impulses into the input gas stream, each impulse being separated by a period in which the input gas stream contains no nitrous oxide; (d) measuring the concentrations of nitrous oxide and nitrogen gas in the output gas stream after an impulse of nitrous oxide is introduced; and (e) comparing the concentrations of nitrogen gas and nitrous oxide in the output gas stream.