A more modern Tenneco Chemicals process called ‘Cosorb’ employs a solution of CuCl and AlC1, in toluene for the selective absorption of CO from synthesis gas. The Cu(1)-CO complex is formed at ca. 25°C and up to 20 bar. The CO is released at 100 - 1 10 “C and 1 -4 bar. Water, olefins, and acetylene affect the absorption solution and must therefore be removed before the separation. Many large-scale plants are - following the startup of a prototype in 1976 - in operation worldwide