Propylene Oxide

General information

Propylene oxide is one of the main products of Shell Chemicals in Jurong Island. Shell Chemicals has built two Styrene Monomer/Propylene Oxide (SM/PO) plants and two polyols plants due to increases production of propylene oxide.

Propylene oxide (C3H6O) is a colourless liquid with an ether-like odour. It is a highly toxic flammable chemical compound. Below are the molecular formulae of propylene oxide in two forms.

Fig. 1 Fig. 2

Production of propylene oxide

There are three different routes to produce propylene oxide commercially. Industrial production of propylene oxide is mainly from co-oxidation of propylene with other chemicals. Below are the chemical reactions of the three routes.

Propylene + Chlorine + Lime(chlorine absorber) -> Propylene oxide + Calcium Chloride

Propylene + isobutene -> Propylene oxide + t-butyl alcohol

Propylene + ethyl benzene -> Propylene oxide + styrene

While other processes exist, the Shell Chemicals has derived a strong competitive advantage by using and continually developing their proprietary SM/PO technology, which is the third route. In this process propylene (C3) and ethyl benzene (EB) are simultaneously converted into propylene oxide (PO) and styrene monomer (SM), respectively.

The PO/SM and PO/TBA routes are responsible for the majority of current global production as seen in the figure below. However, they require relatively large capital investments and present difficulties in balancing the markets for propylene oxide and the co-products, leading to considerable volatility in the economic performance of the operations over time. Existing hydroperoxidation plants continue to be operated and incrementally improved; however, new installations may be limited in the future. Although significant propylene oxide capacity is based on the CHPO route, this route suffers from environmental liabilities and large capital investment requirements.

Applications of propylene oxide

Propylene oxide is a colorless liquid with an ether-like odour. It is a highly reactive chemical which reacts readily with compounds containing active hydrogen atoms (such as alcohols, amines, and acids). Therefore, propylene oxide is used as an intermediate for the production of numerous commercial materials containing poly-alcohols, propylene glycol, butanediol and polyalkylene glycol.


These materials have a large variety of applications. Poly-alcohols are used in urethane applications such as rigid foam, flexible foam, coatings, adhesives and sealants & Elastomer systems. Poly-alcohols can also be used in non-urethane applications such as textile surfactants and oil demulsifiers. Besides, propylene glycol produced from propylene oxide is used as aeroplane deicers, fiberglass-reinforced unsaturated polyester resins and hydraulic fluids. Butanediol are used in engineering plastics and fibres and polyalkylene glycol fuel additives and synthetic lubricants.