Polyphenylene ether(s)] prodn. - by continuous two=stage oxidative coupling of phenol(s) in a reactor with full back-mixing followed by a reactor with partial back-mixing

摘要

A process is claimed for producing polyphenylene ethers (I) by continuous 2-stage catalytic reaction of oxygen with aromatic mono-hydroxy cpd(s). (II). Stage (1) is carried out in a reactor with largely complete back-mixing, and stage (2) in a reactor with partial back-mixing. Also claimed in an appts. for the process, with 2 reactor (systems) as above. Pref. stage 1 is carried out in a ga/liq. reactor (jet reactor) with a jacket tube which is blanked off at the top and in which one or more downwardly directed liq. jets are mounted at the highest point and fed from a liq. pump circuit, so that a gas phase is entrained with and then completely dispersed in the liq.; before starting the liq. circulation, the static reactor is filled with only enough liq. to leave a gas space at the top of the reactor corresp. to the subsequent hold-up under operating conditions, this gas space is filled with inert gas at pressure pl, and the gaseous reactants are only introduced into the reactor when the action of the liq. jets has produced a dispersion of inert gas such that a coherent gas phase no longer exists. The reactor system in stage 1 consists of a jet reactor, a circulating pump and a heat exchanger. Stage 2 is carried out in a continuous flow-tube reactor. USE/ADVANTAGE - The process enables the prodn. of (I) with higher space-time yields (w.r.t. prior-art processes for PPE with comparable mol. wt.), shorter residence times, smaller amts. of off-gas and reduced by-prod. formation