Propylene glycols product overview

What is propylene glycol?

CAS number: MPG: 57-55-6
DPG (CAS 25265-71-8) is a mixture of the isomers 1,1'-oxidi-2-propanol, 2-(2'-hydroxypropoxy)-1-propanol and 2,2'-oxidi-1-propanol
Chemical formula: C3H8O2 (MPG), C6H14O3 (DPG)

Propylene glycol (PG) is the overall name for monopropylene glycol (MPG), dipropylene glycol (DPG) and tripropylene glycol (TPG). Shell chemicals companies are only involved in the manufacture of MPG and DPG. Some heavy glycol (1% of capacity) is produced which could be processed further to DPG and TPG but is instead sold as heavy propylene glycol.   

Propylene glycol is a derivative of propylene oxide (PO) and is produced in a two-step process. The first step is the reaction of PO with water into a mixture of MPG and DPG and the second step is the distillation and purification of the mixture into its two separate components. 

MPG is the largest volume propylene glycol. It is a colourless, viscous, odourless liquid. It is highly hygroscopic and miscible in all ratios with water, alcohols, esters, ketones and amines. It has limited miscibility with halogenated hydrocarbons and is not miscible with aliphatic hydrocarbons. 

DPG is a colourless, hygroscopic liquid. It is miscible with water in any ratio and highly soluble in most organic solvents. 

How is propylene glycol used?

MPG's most important end use is in the production of unsaturated polyester resins which, in turn, are used to make everyday items such as bath tubs, small boats and water/chemical tanks and pipes. Other end use application areas are paints and coatings; aeroplane de-icers/anti-icers; antifreeze and industrial coolants; detergents; hydraulic fluids; and cosmetics. 

Shell chemicals companies also supply United States Pharmacopia (USP) grade monopropylene glycol. 

The end uses of DPG include unsaturated polyester resins, plasticisers, alkyd resins, cosmetics and urethane polyols. 

What are our key strengths in the propylene glycol sector?

• Well-established presence across the globe through a strong supply network.
• Strong, integrated position in Asia Pacific.
• Strong product stewardship commitment.