Ethylene oxide (EO) is exclusively made from ethylene by direct oxidation, using oxygen or air. This report establishes that using oxygen is more economical than using air. Existing EO plants are integrated with ethylene glycol (EG) production, with part or all EO processed into EG in situ. Plants can also be designed to produce essentially only marketable EO. All of these variations are evaluated.
Propylene oxide (PO) is made either by the chlorohydrin process or the hydroperoxide process. The chlorohydrin process needs lime or cell liquor for neutralization; in the latter case, the PO plant is virtually integrated with a chlorine plant. The hydroperoxide process uses isobutane or ethylbenzene to coproduce t-butyl alcohol or styrene. All of these processes, with variations in the methods of treatment of the recycle in the case of chlorohydrin process and in the amount of coproduction in the case of isobutane hydroperoxide process, are evaluated in this report.
The numerous noncommercial processes briefly evaluated include: a chlorohydrin process involving tert butyl hypochlorite; another chlorohydrin process using ally1 chloride; several hydroperoxide processes using isobutane, cumene, or cyclohexene; a glycol acetate process; and a peracid process. Given the present state of the art and trade, none of them is viable. The most economical process for making PO remains the hydroperoxide process, with coproduction of gasoline grade t-butyl alcohol; next are the hydroperoxide process with coproduction of styrene and the chlorohydrin process using lime or cell liquor.