Propylene Glycol

Process designs, investments and production cost estimates are presented for the production of propylene glycol by two processes:

• Hydration of propylene oxide to glycol; in addition to monoglycol, smaller amounts of di- and triglycols are produced as by-products.
• Catalytic oxidation of propylene in the presence of acetic acid to form glycol acetates; these are subsequently hydrolyzed to glycol

The first process is the sole source of propylene glycol at present. The second process requires a much higher investment but shows a lower product value (production cost plus 25% return before taxes).