关键词: Direct propylene epoxidation with H₂/O₂, Propylene oxide, Safe operation, Explosion limits estimation, Process optimization

Abstract: Direct propylene epoxidation with H₂ and O₂, an attractive process to produce propylene oxide (PO), has a potential explosion danger due to the coexistence of flammable gases (i.e., C₃H₆ and H₂) and oxidizer (i.e., O₂). The unknown explosion limits of the multi-component feed gas mixture make it difficult to optimize the reaction process under safe operation conditions. In this work, a distribution method is proposed and verified to be effective by comparing estimated and experimental explosion limits of more than 200 kinds of flammable gas mixture. Then, it is employed to estimate the explosion limits of the feed gas mixture, some results of which are also validated by the classic Le Chatelier's Rule and flammable resistance method. Based on the estimated explosion limits, process optimization is carried out using commercially high and inherently safe reactant concentrations to enhance reaction performance. The promising results are directly obtained through the interface called gOPT in gPROMS only by using a simple, easy-constructed and mature packed-bed reactor, such as the PO yield of 13.3%, PO selectivity of 85.1% and outlet PO fraction of 1.8%. These results can be rationalized by indepth analyses and discussion about the effects of the decision variables on the operation safety and reaction performance. The insights revealed here could shed new light on the process development of the PO production based on the estimation of the explosion limits of the multi-component feed gas mixture containing flammable gases, inert gas and O₂, followed by process optimization.

Key words: Direct propylene epoxidation with H₂/O₂, Propylene oxide, Safe operation, Explosion limits estimation, Process optimization