GB948584A - Separation and recovery of tertiary amylenes - Google Patents

Abstract

<PICT:0948584/C3/1> Tertiary amylenes are separated from C5 hydrocarbon mixtures by absorption in 50-70% sulphuric acid, contacting the acid extract with a vaporous C3 or C4 paraffin or straight chain olefin whereby the vapours are condensed resulting in a lean acid phase and a hydrocarbon phase containing the condensed vapours and tertiary amylenes separating the hydrocarbon stream from the acid and recovering tertiary amylenes. The hydrocarbon mixture enters by line 10 and is mixed with acid from line 23 and a circulating acid-hydrocarbon mixture in line 11 which passes through constrictions 17 and 18 adjacent to the points of introducing acid and hydrocarbon. The temperature is maintained below 100 DEG F. and the average contact time at 1-15 minutes. Mixture is withdrawn through perforated baffle 19 in tank 16 and acid extract is removed through line 25. Vaporous butane, isobutane or a n-butene is introduced by line 33 at 80-135 DEG F. and is thereby condensed, thus warming the acid and the acid and condensed hydrocarbon are circulated through lines 26 and 28. If propane or propylene is used the mixture is not circulated (Fig. 2, not shown). In compartment 32 of tank 29 hydrocarbons are settled out and removed by line 35, caustic washed in tower 49 and fractionated to remove C3 or C4 hydrocarbons in fractionator 51, amylenes being recovered as bottoms and higher boiling material, e.g. polymers, separated therefrom in tower 58. Condensed C3 or C4 hydrocarbons are passed to acid cooling tower 36 to which warm acid is passed through line 34. The hydrocarbons vaporize and after cooling are recycled by line 33 and acid is simultaneously cooled and recycled by line 22.