PROCESS FOR THE MANUFACTURE OF 1,2-DICHLOROETHANE

摘要

Process for the manufacture of 1,2-dichloroethane starting from a stream of ethane according to which: a) the stream of ethane is subjected to a catalytic oxydehydrogenation producing a gas mixture containing ethylene, unconverted ethane, water and secondary constituents; b) said gas mixture is optionally washed and dried thus producing a dry gas mixture; c) after an optional additional purification step, said dry gas mixture comprising the stream of products derived from the chlorination reactor R2 separated in step e) is subjected to an absorption A which consists of separating said gas mixture into a fraction enriched with the compounds that are lighter than ethylene containing some of the ethylene (fraction A) and into a fraction F1; d) fraction A is conveyed to a chlorination reactor R1 in which most of the ethylene present in fraction A is converted into 1,2-dichloroethane and the 1,2-dichloroethane obtained is separated from the stream of products derived from the chlorination reactor R1; e) fraction F1 is subjected to a desorption D1 which consists of separating fraction F1 into an ethylene fraction depleted of the compounds that are lighter than ethylene (fraction C) which is conveyed to a chlorination reactor R2, the stream of products derived from this reactor being added to the dry gas mixture subjected to step c) after having optionally extracted the 1,2-dichloroethane formed, and into a fraction F2; f) fraction F2 is subjected to a desorption D2 which consists of separating fraction F2 into a fraction enriched with ethylene (fraction B) and into a fraction F3, optionally containing the 1,2-dichloroethane formed in the chlorination reactor R2 then extracted, if it has not previously been extracted, which is recycled to the absorption A, optionally after an additional treatment intended to reduce the concentration, in fraction F3, of the compounds that are heavier than ethane; g) fraction B is conveyed to an oxychlorination reactor in which most of the ethylene present in fraction B is converted into 1,2-dichloroethane, the 1,2-dichloroethane obtained is separated from the stream of products derived from the oxychlorination reactor and is optionally added to the 1,2-dichloroethane formed in the chlorination reactor R1 and optionally to that formed in the chlorination reactor R2; and h) the stream of products derived from the oxychlorination reactor, from which the 1,2-dichloroethane has been extracted, optionally containing an additional stream of ethane previously introduced in one of steps b) to g), is optionally recycled to step a) after having been optionally purged of gases and/or after an optional treatment in order to eliminate the chlorinated products contained therein.