22 May 2000 00:00  [Source: ICB]

Modest growth is expected for alpha-methylstyrene (isopropenylbenzene) as producers add incremental amounts of output to their production


Alpha-methylstyrene (AMS) is a colourless liquid used as a co-monomer in a range of polymerisation processes to improve impact and heat resistance. In many applications of this kind it competes with styrene, over which it has some stability and handling advantages. It can be copolymerised with monomers such as benzene, acrylates and styrene. The primary use of AMS is in acrylonitrile-butadiene-styrene (ABS) resins, which account for around a third of demand. In ABS resins it prevents heat distortion. AMS has applications in a diverse range of products including perfumes, antioxidants, drying oils and lubricating oils. Other uses include the production of low molecular weight polymers, which form viscous liquids used in adhesives and coatings, waxes and plasticisers.


The world market for AMS is around 220 000 tonne/year, and is worth $120m, according to producers. Of this figure, the European market makes up 61 000 tonne/year valued at E38.5m ($35m) and the US market takes 75 000 tonne/year, worth $40m. Average market growth is 1-3%/year. Growth for applications in ABS, acrylic resins, waxes and adhesives is closely tied to GNP. Demand is also driven by bisphenol and polycarbonate applications, which are growing at around 6-8%/year.

AMS supply is tied to cumene and phenol production. Because it can be recycled within this process, the amount of AMS produced can be varied. This means that supply is generally well balanced with demand. AMS capacity is only added when phenol capacity expands, and when AMS can be recycled in phenol manufacturing.



AMS prices are driven by benzene price trends. List prices are in the region of $0.50/lb, fob. North European prices have been affected by availability of Russian imports. recently sold two lots of AMS totalling 600 tonne valued at approx $325 000 during an online auction.


AMS is recovered as a by-product of the phenol production process of cumene oxidation. This can then be purified by continuous distillation under reduced pressure to lower the amount of phenol, cumene and butyl benzene impurities.

Because of the cost of this purification in limited markets, many phenol producers do not separate AMS but simply recycle it by hydrogenating it back to cumene. Companies such as UOP and Kellogg license the process. Another route used in the FSU involved dehydrogenation of cumene to AMS.

Health and safety

AMS irritates the skin, eyes and throat. If burned it can release toxic gases and vapours such as carbon monoxide.

It is incompatible with strong oxidising agents, copper, mercury or alkaline pesticides.


Producer Location Capacity
North America
Sunoco Frankford, Pennsylvania 32
Aristech Haverhill, Ohio 22
JLM Chemicals Blue Island, Illinois 2
Georgia Gulf Pasadena, Texas
Plaquemine, Louisiana 14
Texaco El Dorado, Kansas 1
Others 7
Rhodia Rousillon, France 7*
Phenolchemie Gladbeck, Germany 45
EniChem Mantova, Italy 8
Porto Torres, Sardinia 15
Ertisa Huelva, Spain 12

Source: companies

* Due to close mid-2000
Capacities vary depending on phenol output, the proportion of AMS recycled and the profitability of purification for merchant markets.

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