The main chemical use of toluene is to make benzene and xylenes using a number of technologies. In the hydrodealkylation (HDA) process, toluene and hydrogen are reacted to make benzene only. A toluene disproportionation (TDP) plant will convert toluene to benzene and xylenes while there are selective toluene disproportionation (STDP) processes that produce a paraxylene-rich stream. The transalkylation (TA) process takes toluene and C9 aromatics to produce xylenes.
Toluene is also used as a solvent but this application is expected to continue to weaken because of environmental and health regulations restricting solvent emissions. The definition of solvent end use and quality varies around the world. In most industrialised countries, solvent grade toluene is a high quality stream where purity is essential as environmental exposure levels must be quantified.
Toluene is consumed in the manufacture of toluene diisocyanate (TDI) which is used in the manufacture of polyurethane flexible foams used in upholstery, mattresses and automotive seats. Smaller uses for TDI include polyurethane elastomers and coatings.
Other minor chemical uses include the manufacture of phenol, caprolactam, nitrobenzene, benzoic acid and benzyl chloride.
In non-chemical uses, toluene is used in large quantities as an octane booster in gasoline but most of that portion is not removed from refinery streams