Ethane oxidative dehydrogenation with co-production of vinyl acetate
The invention relates to an integrated process for the production of ethylene and vinyl acetate (VAM), comprising contacting in a first reaction zone a gas stream comprising ethane and optionally ethylene with an oxygen-containing gas stream in the presence of a oxydehydrogenation catalyst under oxidative dehydrogenation conditions to produce a first product stream comprising ethane, ethylene, acetic acid and water, and optionally other compounds, separating said first product stream in a vapor permeation unit into a second stream comprising water and a third stream comprising ethane, ethylene, acetic acid, and optionally other gaseous compounds, contacting in a second reaction zone all or at least a portion of said third stream with a stream comprising concentrated acetic acid and with an oxygen-containing gas stream in the presence of a VAM catalyst, to produce a fourth product stream comprising vinyl acetate, acetic acid, ethane, ethylene, water, carbon dioxide, and optionally other compounds, separating said fourth product stream in a vinyl acetate separation zone into a fifth stream comprising vinylacetate, acetic acid, water and optionally other condensable compounds, and a sixth stream comprising ethylene, ethane, carbon dioxide and optionally other gaseous compounds, and recovering vinyl acetate from said fifth stream. The invention further relates to a reaction system for carrying out the process.
1. An integrated process for the production of ethylene and vinyl acetate (VAM), comprising
contacting in a first reaction zone a gas stream comprising ethane and optionally ethylene with an oxygen-containing gas stream in the presence of a oxydehydrogenation catalyst under oxidative dehydrogenation conditions to produce a first product stream comprising ethane, ethylene, acetic acid and water, and optionally other compounds,
separating said first product stream in a vapor permeation unit into a second stream comprising water and a third stream comprising ethane, ethylene, acetic acid, and optionally other gaseous compounds,
contacting in a second reaction zone all or at least a portion of said third stream with a stream comprising concentrated acetic acid and with an oxygen-containing gas stream in the presence of a VAM catalyst, to produce a fourth product stream comprising vinyl acetate, acetic acid, ethane, ethylene, water, carbon dioxide, and optionally other compounds,
separating said fourth product stream in a vinyl acetate separation zone into a fifth stream comprising vinylacetate, acetic acid, water and optionally other condensable compounds, and a sixth stream comprising ethylene, ethane, carbon dioxide and optionally other gaseous compounds, and
recovering vinyl acetate from said fifth stream.
2. The process according to claim 1 , wherein the vinyl acetate separation zone comprises a condenser.
3. The process according to claim 1 , wherein the vinyl acetate separation zone is a washing zone, wherein the fourth product stream is contacted with water or a liquid absorbent to produce a fifth stream comprising vinylacetate, acetic acid, water and/or absorbent and optionally other condensable compounds, and a sixth stream comprising ethylene, ethane, carbon dioxide, and optionally other gaseous compounds.
4. The process according to claim 3 , wherein said fifth stream is fed to a purification zone to produce a seventh stream comprising concentrated acetic acid, an eighth stream comprising concentrated vinyl acetate, and one or more streams comprising water and/or absorbent, and optionally other compounds.
5. The process according to claim 4 , wherein all or at least a portion of the seventh stream comprising concentrated acetic acid is used as the feed stream comprising concentrated acetic acid supplied to the second reaction zone.
6. The process according to claim 3 , wherein the sixth stream comprising ethylene, ethane, carbon dioxide, and optionally other gaseous compounds is fed to a carbon dioxide removal zone to remove carbon dioxide and optionally light condensable compounds, to produce an ninth stream enriched in ethane and ethylene.
7. The process according to claim 6 , wherein all or at least a portion of said ninth stream enriched in ethane and ethylene is recycled to the first reaction zone.
8. The process according to claim 6 , wherein said ninth stream enriched in ethane and ethylene is separated in a ethane/ethylene separation unit to produce a tenth stream enriched in ethane and an eleventh stream enriched in ethylene.
9. The process according to claim 8 , wherein all or at least a portion of the tenth stream enriched in ethane is recirculated to the first reaction zone and/or wherein all or at least a portion of the eleventh stream enriched in ethylene is recirculated to the second reaction zone.
10. A reaction system for the oxidative dehydrogenation of ethane and co-production of vinyl acetate, comprising
a first reaction zone, having
an inlet for receiving an ethane-containing feed stream,
an inlet for receiving an oxygen-containing feed stream, and
an outlet for discharging an effluent from the first reaction zone,
a vapor permeation unit, having
an inlet for receiving an effluent from the first reaction zone,
an outlet for discharging a water-depleted effluent stream from the vapor permeation unit, and
an outlet for discharging water from the vinyl acetate separation zone,
a second reaction zone, having
an inlet for receiving the water-depleted effluent stream from the vapor permeation unit,
an inlet for receiving an oxygen-containing feed stream,
an inlet for receiving a concentrated acetic acid-containing feed stream, and
an outlet for discharging an effluent from the second reaction zone,
a vinyl acetate separation zone, having
an inlet for receiving an effluent from the second reaction zone,
optionally an inlet for receiving a washing liquid stream,
an outlet for discharging a vinyl acetate-enriched liquid stream from the vinyl acetate separation zone, and
an outlet for discharging a vinyl acetate-depleted gaseous stream from the vinyl acetate separation zone,
a purification zone, having
an inlet for receiving a vinyl acetate-enriched liquid stream from the vinyl acetate separation zone,
an outlet for discharging a concentrated acetic acid-containing stream from the purification zone, and,
an outlet for discharging a concentrated vinyl acetate-containing stream from the purification zone, and
one or more outlets for discharging further compounds, and
optionally, a carbon dioxide removal zone, having
an inlet for receiving a vinyl acetate-depleted gaseous stream from the vinyl acetate separation zone, and
an outlet for discharging a carbon dioxide-depleted stream from said carbon dioxide removal zone,
and,
optionally, an ethane/ethylene separation unit, having
an inlet for receiving a carbon dioxide-depleted gaseous stream from the carbon dioxide removal zone,
an outlet for discharging an ethylene-enriched stream from said ethane/ethylene separation unit, and
an outlet for discharging an ethane-enriched stream from said ethane/ethylene separation unit.
11. The system according to claim 10 , which further comprises
means for recirculating the concentrated acetic acid-containing stream from the purification zone to the second reaction zone, and/or
means for recirculating an ethylene-enriched stream from the ethane/ethylene separation unit to the second reaction zone, and/or
means for recirculating an ethane-containing stream from the ethane/ethylene separation unit to the first reaction zone.
12. The system according to claim 10 , which further comprises means for by-passing the second reaction zone and vinyl acetate separation zone, said means comprising means for directly feeding the dewatered effluent stream from the vapor permeation unit to the vinyl acetate separation zone and/or carbon dioxide removal zone.