A process for producing ethylene

Abstract

The present invention provides a process for producing ethylene, the process at least comprising the steps of: (a) providing a CO-containing stream (10); (b) converting the CO-containing stream (10) provided in step (a) in an electrolyzer (2) thereby producing an ethylene-containing vapour stream (30) and an ethanol-containing liquid stream (40); (c) subjecting at least a part of the ethylene-containing vapour stream (30) obtained in step (b) to hydration thereby obtaining a first ethanol-enriched stream (90); (d) separating the first ethanol-enriched stream (90) obtained in step (c) thereby obtaining a second ethanol-enriched stream (110) and a water-enriched stream (120); and (e) subjecting the second ethanol-enriched stream (110) to dehydration thereby obtaining ethylene (140).

1 . A process for producing ethylene, the process at least comprising the steps of:
 (a) providing a CO-containing stream ( 10 );   (b) converting the CO-containing stream ( 10 ) provided in step (a) in an electrolyzer ( 2 ) thereby producing an ethylene-containing vapour stream ( 30 ) and an ethanol-containing liquid stream ( 40 );   (c) subjecting at least a part of the ethylene-containing vapour stream ( 30 ) obtained in step (b) to hydration thereby obtaining a first ethanol-enriched stream ( 90 );   (d) separating the first ethanol-enriched stream ( 90 ) obtained in step (c) thereby obtaining a second ethanol-enriched stream ( 110 ) and a water-enriched stream ( 120 ); and   (e) subjecting the second ethanol-enriched stream ( 110 ) to dehydration thereby obtaining ethylene ( 140 ).   
     
     
         2 . The process according to  claim 1 , wherein the CO-containing stream ( 10 ) provided in step (a) has been obtained from a CO 2 -containing stream. 
     
     
         3 . The process according to  claim 1 , wherein the CO-containing stream ( 10 ) provided in step (a) comprises at least 25 mol. % CO, preferably at least 50 mol. % CO. 
     
     
         4 . The process according to  claim 1 , wherein the electrolyzer ( 2 ) in step (b) has a cathode that comprises copper (Cu). 
     
     
         5 . The process according to  claim 1 , wherein the electrolyzer ( 2 ) in step (b) has an anode that comprises a metal selected from the group consisting of nickel (Ni), iron (Fe), iridium (Ir), cobalt (Co), manganese (Mn), ruthenium (Ru) or combinations thereof. 
     
     
         6 . The process according to  claim 1 , wherein the electrolyzer ( 2 ) in step (b) is operated at a temperature of from 20 to 100° C., preferably from 40 to 90° C. 
     
     
         7 . The process according to  claim 1 , wherein the ethylene-containing vapour stream ( 30 ) obtained in step (b) comprises at least 0.5 mol. % ethanol, preferably at least 1.0 mol. % ethanol. 
     
     
         8 . The process according to  claim 1 , wherein the ethanol-containing liquid stream ( 40 ) obtained in step (b) comprises at most 5.0 mol. % ethylene, preferably at most 1.0 mol. %. 
     
     
         9 . The process according to  claim 1 , wherein the ethylene-containing vapour stream ( 30 ) produced in step (b) is, before subjecting to hydration in step (c), separated thereby obtaining an ethylene-enriched gas stream ( 50 ) and a third ethanol-enriched stream ( 60 ), and wherein the ethylene-enriched gas stream ( 50 ) is subjected to the hydration in step (c). 
     
     
         10 . The process according to  claim 9 , wherein the third ethanol-enriched stream ( 60 ) and the first ethanol-enriched stream ( 90 ) formed in step (c) are combined thereby obtaining a combined ethanol stream ( 100 ), and wherein the combined ethanol stream ( 100 ) is used in the separation of step (d). 
     
     
         11 . The process according to  claim 1 , wherein the first ethanol-enriched stream ( 90 ) obtained in step (c) is temporarily stored before separating in step (d). 
     
     
         12 . The process according to  claim 1 , wherein the ethanol-containing liquid stream ( 40 ) obtained in step (b) is separated thereby obtaining a fourth ethanol-enriched stream ( 160 ) and an oxygen-enriched gas stream ( 170 ). 
     
     
         13 . The process according to  claim 12 , wherein the fourth ethanol-enriched stream ( 160 ) is separated thereby obtaining a fifth ethanol-enriched stream ( 190 ) and a propanol-enriched stream ( 180 ). 
     
     
         14 . The process according to  claim 13 , wherein the fourth ethanol-enriched stream ( 160 ) is temporarily stored before being separated to obtain the fifth ethanol-enriched stream ( 190 ). 
     
     
         15 . The process according to  claim 10 , wherein the fifth ethanol-enriched stream ( 190 ) is combined with the combined ethanol stream ( 100 ). 
     
     
         16 . The process according to  claim 13 , wherein the propanol-enriched stream ( 180 ) is separated thereby obtaining a purified propanol stream ( 200 ) and an electrolyte-enriched stream ( 210 ); wherein at least a part of the electrolyte-enriched stream ( 210 ) is separated in a further electrolyte-enriched stream ( 220 ) and an acetic acid-enriched stream ( 230 ); wherein the acetic acid-enriched stream ( 230 ) is hydrogenated thereby obtaining a further ethanol stream ( 240 ); and wherein the further ethanol stream ( 240 ) is subjected to dehydration in step (e). 
     
     
         17 . An apparatus ( 1 ) suitable for performing the process for producing ethylene according to  claim 1 , the apparatus ( 1 ) at least comprising:
 an electrolyzer ( 2 ) for converting a CO-containing stream ( 10 ), thereby producing an ethylene-containing vapour stream ( 30 ) and an ethanol-containing liquid stream ( 40 );   a hydration unit ( 4 ) for hydrating at least a part of the ethylene-containing vapour stream ( 30 ), thereby obtaining a first ethanol-enriched stream ( 90 );   an alcohol separation unit ( 5 ) for separating the first ethanol-enriched stream ( 90 ), thereby obtaining a second ethanol-enriched stream ( 110 ) and a water-enriched stream ( 120 ); and   a dehydration unit ( 6 ) for dehydrating the second ethanol-enriched stream ( 110 ) thereby obtaining ethylene ( 140 ).