Shell chemicals companies are leading manufacturers and suppliers of the group of petrochemicals known as ‘aromatics’ which includes benzene, toluene and xylene. These colourless liquids with a characteristic smell are important chemical precursors or ‘building blocks’ which can be converted into many of the intermediates and polymers needed to produce an extensive range of everyday products.
Aromatics provide some of the basic building blocks of the modern petrochemical industry. Clothing, packaging, paints, adhesives, computers, compact discs, snow boards and tennis racquets are among the many products that rely on aromatics.
Benzene is extracted from two primary sources: pyrolysis gasoline (pygas), which is a co-product of ethylene manufacture; or reformate, a refinery stream resulting from the catalytic reforming process used in gasoline production. Benzene can also be derived from toluene.
Benzene is widely used across many industrial sectors, where it is combined and processed with other basic chemicals (such as ethylene or propylene) to produce countless consumer goods: clothing, packaging, paints, adhesives, plywood, computer casings, compact discs, dyes, agrochemicals, pharmaceuticals and many more.
The largest derivative outlet for benzene is ethylbenzene, an intermediate used in the production of styrene, which is further converted into materials such as polystyrene.
Benzene is also widely used to produce cumene, which in turn leads to phenol, a component in phenolic resins and adhesives; cyclohexane, a precursor of caprolactam and adipic acid, both used in nylon; and aniline, a material needed to produce methylene diphenyl diisocyanate (MDI) which is used in urethanes and other specialty applications.
Toluene is extracted from gasoline manufacturing streams and so is produced in very large quantities to one of three grades of purity: TDI, nitration, and commercial.
TDI grade toluene is used to make isocyanates, which are combined with polyols in the manufacture of polyurethanes. In turn, polyurethanes are used in a wide variety of consumer goods, such as foams for furniture and bedding, coatings for floors and furniture, artificial sports tracks, ski suits and waterproof leisure wear.
Nitration grade toluene is used as a solvent and also in the production of phenol, particularly in Europe.
Both nitration and commercial grades are used as feed in the hydrodealkylation process, which turns the toluene into benzene, and in the disproportionation process, which converts toluene it into both benzene and xylene.
Toluene has low volatility, which also makes it a good octane-enhancer for gasoline blending.
Xylenes - para-xylene, ortho-xylene and meta-xylene - are extracted or distilled from gasoline refining. They can also be produced from toluene using the disproportionation process. Xylene is mainly supplied as a mixed stream, although various processes are used to separate the individual isomers for specific end-uses.
Para-xylene is primarily used as a feedstock for terephthalic acid, a key component in polyethylene terephthalate (PET) resins. Ortho-xylene is used in plasticisers, medicines, and dyes.
Mixed xylenes can be used as solvents and in the printing, rubber, and leather industries. They are also a desirable gasoline component, but are blended less often than toluene because there is greater demand and higher value in their chemical applications.
Our key strengths in aromatics
- Global manufacturing and supply capabilities
- Access to key feedstocks within the Shell Group
- Large, efficient and integrated production
- High purity products
- On-going, concerted programme to minimise risks associated with benzene transport
- Active commitment to understanding the health and environmental effects of aromatic chemicals
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