Process for the manufacture of 1,2-dichloroethane

A process for manufacturing vinyl chloride, comprising:

• a) subjecting the stream of ethane to a catalytic oxydehydrogenation thus producing a gas mixture containing ethylene, unconverted ethane, water and secondary constituents;
• b) drying said gas mixture thus producing a dry gas mixture, wherein said gas mixture is optionally washed before or after said drying;
• c) after an optional additional purification step, subjecting said dry gas mixture comprising the stream of products derived from the chlorination reactor R2 separated in step e) 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) conveying said fraction A to a chlorination reactor R1 in which most of the ethylene present in said fraction A is converted into 1,2-dichloroethane, wherein the 1,2-dichloroethane so obtained is separated from the stream of products derived from the chlorination reactor R1;
• e) subjecting said fraction F1 to a desorption D1 which consists of separating said 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) subjecting said fraction F2 to a desorption D2 which consists of separating said 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 said fraction F3, of the compounds that are heavier than ethane;
• g) conveying said fraction B to an oxychlorination reactor in which most of the ethylene present in said fraction B is converted into 1,2-dichloroethane, wherein the 1,2-dichloroethane so 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;
• h) optionally, recycling to step a) 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), after having been optionally purged of gases and/or after an optional treatment in order to eliminate the chlorinated products contained therein;
• and
• i) subjecting the 1,2-dichloroethane so obtained to a pyrolysis thus producing vinyl chloride.

A process for the manufacture of polyvinyl chloride, comprising:

• a) subjecting the stream of ethane to a catalytic oxydehydrogenation thus producing a gas mixture containing ethylene, unconverted ethane, water and secondary constituents;
• b) drying said gas mixture thus producing a dry gas mixture, wherein said gas mixture is optionally washed before or after said drying;
• c) after an optional additional purification step, subjecting said dry gas mixture comprising the stream of products derived from the chlorination reactor R2 separated in step e) 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) conveying said fraction A to a chlorination reactor R1 in which most of the ethylene present in said fraction A is converted 1,2-dichloroethane, wherein the 1,2-dichloroethane so obtained is separated from the stream of products derived from the chlorination reactor R1;
• e) subjecting said fraction F1 to a desorption D1 which consists of separating said 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) subjecting said fraction F2 to a desorption D2 which consists of separating said 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 said fraction F3, of the compounds that are heavier than ethane;
• g) conveying said fraction B to an oxychlorination reactor in which most of the ethylene present in said fraction B is converted into 1,2-dichloroethane, wherein the 1,2-dichloroethane so 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) optionally, recycling to step a) 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), after having been optionally purged of gases and/or after an optional treatment in order to eliminate the chlorinated products contained therein;
• i) subjecting the 1,2-dichloroethane so obtained to a pyrolysis thus producing vinyl chloride;
• and
• j) polymerizing the vinyl chloride to produce polyvinyl chloride.