Paraxylene (PX) is the largest volume isomer of the mixed xylenes. Around 98 percent of PX demand comes from the polyester chain via the one of its intermediatespurified terephthalic acid (PTA) or dimethyl terephthalate (DMT). The breakdown for polyester demand is 65 percent from fibre, 27 percent from polyethylene terephthalate(PET) bottle resin and the remainder from film and other plastic end uses. Polyester demand is expected to grow at six percent a year over the next few years with the PET resin bottle market seeing the fastest growth. A small amount of PX is used as a solvent and in the production of di-paraxylene and herbicides.
Paraxylene is a flammable liquid and a fire hazard. When heated to decomposition, paraxylene emits acrid smoke and fumes. Vapours may travel to a source of ignition and flash back.
Orthoxylene (OX) is the second largest of the three commercial isomers of xylene. Almost all OX produced is consumed in the manufacture of phthalic anhydride, which is converted to plasticisers, alkyd and polyester resins. Small quantities are used in solvent applications and to make bactericides, soybean herbicides and lube oil additives. It is also used to make phthalonitrile, which is converted to copper phthalocyanine, a pigment.
Orthoxylene is a flammable liquid and a fire hazard. When heated to decomposition, orthoxylene emits acrid smoke and fumes. Vapours may travel to a source of ignition and flash back.
To find out more Para Ortho Xylene Methodology February 2012