The second major use of cobalt catalysts is in the mixed cobalt acetate/manganese sodium bromide homogeneous catalyst for production of terephthalic acid (TPA) and di-methylterephthalate(DMT).
Cobalt catalysts are used to synthesise terepthalic acid (TPA) and di-methylterephthalate (DMT) which are predominantly used as precursors in the creation of polyester (PET). 60% of PET is used in polyester fibres, used for textiles, and another 31% in polyester resin, used to make recyclable plastic bottles.
Although the cobalt can be introduced to the systems as metal, oxide, hydroxide or as an inorganic salt, the active catalyst species is a carbonyl in a semi-regenerative cycle system.
Hydroformylation, also known as the OXO reaction, produces aldehydes from alkenes using a cobalt or rhodium based catalyst. Within the reaction, a formyl group and a hydrogen atom are added across the double bond of alkenes.
Of the resulting aldehyde, most are further processed into other important chemicals including plasticising agents. Hydroformylation is also used in other industrial processes such as the production of long carbon chain alcohols used in detergents.