Method for increasing propylene oxide output of an integrated process for making propylene oxide and propylene glycol

Abstract

An integrated process for making propylene oxide and propylene glycol involves reacting propene with an oxidant to provide propylene oxide, reacting a fraction of the propylene oxide with water to provide an aqueous glycol solution containing monopropylene glycol and dipropylene glycol, and separating monopropylene glycol and dipropylene glycol from the glycol solution by a multi-step distillation. The propylene oxide output can be increased without increasing capacity of the unit for reacting propene to propylene oxide, by reacting propene and hydrogen peroxide in the presence of a catalyst mixture, containing a phase transfer catalyst and a heteropolytungstate, in a liquid reaction mixture which contains an aqueous phase with a maximum apparent pH of 6 and an organic phase. The reaction mixture is separated into an organic phase, which is recycled to the reaction, and an aqueous phase containing monopropylene glycol and dipropylene glycol, which is passed to replace the glycol solution.

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