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US 7,803,965 B2Granted
Method for recovery of ethylene in a recirculating gas process for the production of vinyl acetate
AssigneeWacker Chemie AG
InventorsWillibald Dafinger, Peter Holl, Wilhelm Kaiser, Jürgen Guba
Life of this patent
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Abstract
The efficiency of vinyl acetate production is increased by scrubbing of off gas followed by CO2 absorption. A portion of the off gas containing substantial quantities of ethylene is recycled to the process, whereas another portion is employed in another ethylene consuming reaction. Despite not removing non-reactive gases, selectivity and yield based on ethylene are both increased.
Claims10
A process for ethylene recovery in a recirculating gas process for preparing vinyl acetate, comprising:
- a) reacting ethylene, acetic acid and oxygen in a heterogeneously catalyzed reaction at a pressure of from 1 to 50 bar and a temperature of from 50° C. to 200° C. in a reactor,
- b) separating a product gas stream comprising ethylene, vinyl acetate, acetic acid, water, carbon dioxide and non-reactive gases, and
- c) recycling only a portion of ethylene back into the reactor, wherein
- d) the product gas stream is fed from the reactor at system pressure directly to a recycle gas scrubber charged with acetic acid, and vinyl acetate is removed to form a vinyl acetate-free recycle gas, and
- e) the vinyl acetate-free recycle gas is subsequently fed to a CO2 absorption to remove carbon dioxide to form an ethylenic gas stream, and then
- f) a portion of the ethylenic gas stream is recycled into the reactor without further non-reactive gases being separated;
- and 1% to 25% by volume of the ethylenic gas stream is discharged without further non-reactive gases being separated, and is reused in one or more processes which consume ethylene, other than processes for preparing vinyl acetate.
4 more elements
A process for ethylene recovery in a recirculating gas process for preparing vinyl acetate, comprising:
- a) reacting ethylene, acetic acid and oxygen in a heterogeneously catalyzed reaction in a reactor at a pressure of from 1 to 50 bar and a temperature of from 50° C. to 200° C.,
- b) separating a product gas stream comprising ethylene, vinyl acetate, acetic acid, water, carbon dioxide and non-reactive gases, and
- c) recycling only a portion of ethylene back into the recirculating gas process, wherein
- d) the product gas stream is fed at system pressure to a recycle gas scrubber charged with acetic acid, and vinyl acetate is removed from the recycle gas, and
- e) the vinyl acetate-free recycle gas is subsequently fed to a CO2 absorption to remove carbon dioxide, and then
- f) a portion of the ethylenic recycle gas stream is recycled into the reaction system, without further non-reactive gases being separated;
- and 1% to 25% by volume of the ethylenic gas stream is discharged without further non-reactive gases being separated, and is reused in one or more processes which consume ethylene, other than processes for preparing vinyl acetate,
- wherein the product gas stream separated from the reactor in step b) comprises:
- from 60 to 65% by volume of ethylene,
- from 12 to 18% by volume of CO2,
- from 5 to 8% by volume of ethane,
- from 4 to 9% by volume of oxygen,
- from 4 to 6% by volume of nitrogen,
- from 1 to 2% by volume of argon, and
- from 0.5 to 1% by volume of methane.
12 more elements
A process for ethylene recovery in a recirculating gas process for preparing vinyl acetate, comprising:
- a) reacting ethylene, acetic acid and oxygen in a reactor in a heterogeneously catalyzed reaction at a pressure of from 1 to 50 bar and a temperature of from 50° C. to 200° C.,
- b) separating a product gas stream comprising ethylene, vinyl acetate, acetic acid, water, carbon dioxide and non-reactive gases, and
- c) recycling only a portion of ethylene back into the recirculating gas process, wherein
- d) the product gas stream is fed at system pressure to a recycle gas scrubber charged with acetic acid, and vinyl acetate is removed from the recycle gas, and
- e) the vinyl acetate-free recycle gas is subsequently fed to a CO2 absorption to remove carbon dioxide, and then
- f) a portion of the ethylenic recycle gas stream is recycled into the reaction system, without further non-reactive gases being separated;
- and 1% to 25% by volume of the ethylenic gas stream is discharged without further non-reactive gases being separated, and is reused in one or more processes which consume ethylene, other than processes for preparing vinyl acetate,
- wherein the ethylene recycle stream, following treatment to remove carbon dioxide in step e), comprises:
- from 80 to 83% by volume of ethylene,
- from 1 to 4% by volume of CO2,
- from 2 to 4% by volume of ethane,
- from 3 to 5% by volume of oxygen,
- from 3 to 4% by volume of nitrogen,
- from 0.5 to 1% by volume of argon, and
- from 0.2 to 0.4% by volume of methane.
12 more elements
Dependencies are inferred from the claim text.