US 12,391,548 B2
Process for producing carbon monoxide-containing streams
Robert Franke, Marl (DE); Peter Kreis, Dortmund (DE); and Dirk Fridag, Haltern am See (DE)
Assigned to Evonik Oxeno GmbH & Co. KG, Marl (DE)
Filed by Evonik Oxeno GmbH & Co. KG, Marl (DE)
Filed on Dec. 16, 2022, as Appl. No. 18/067,687.
Claims priority of application No. 21215852 (EP), filed on Dec. 20, 2021.
Prior Publication US 2023/0192486 A1, Jun. 22, 2023
Int. Cl. B01D 53/22 (2006.01); C01B 3/50 (2006.01); C07C 51/14 (2006.01)
CPC C01B 3/501 (2013.01) [B01D 53/226 (2013.01); C07C 51/14 (2013.01); C01B 2203/0405 (2013.01); C01B 2203/047 (2013.01); C01B 2203/06 (2013.01); C01B 2203/1258 (2013.01); C01B 2203/146 (2013.01); C01B 2203/148 (2013.01); C01B 2203/1614 (2013.01); C01B 2203/1628 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A process for separating synthesis gas into a hydrogen-rich gas stream and a carbon monoxide-rich gas stream in a membrane separation unit comprising at least three membrane separation stages, the process comprising:
a. providing synthesis gas and pretreating the synthesis gas for at least partial removal of one or more secondary component(s) present in the synthesis gas, to obtain a pretreated synthesis gas;
b. feeding a feed stream comprising the pretreated synthesis gas and a recyclate stream to a first separation stage to obtain a first retentate and a first permeate, wherein carbon monoxide is enriched in the first retentate and hydrogen is enriched in the first permeate;
c. feeding the first retentate to a second separation stage to obtain a second retentate and a second permeate, wherein the second retentate is withdrawn as a carbon monoxide-rich gas stream and consists of carbon monoxide to an extent of 85% by volume or more, and wherein the second permeate is recycled upstream of the first separation stage; and
d. feeding the first permeate to a third separation stage to obtain a third retentate and a third permeate, wherein the third permeate is withdrawn as a hydrogen-rich gas stream and consists of hydrogen to an extent of 70% by volume or more, and wherein the third retentate is recycled upstream of the first separation stage,
wherein the second permeate and the third retentate are combined to form the single recyclate stream and a pressure of the recyclate stream is increased with the aid of a compressor before the recyclate stream is combined with the pretreated synthesis gas upstream of the first separation stage to give the feed stream in b), wherein a ratio of the pretreated synthesis gas to the recyclate stream in the feed stream is in a range of 4:1 to 1:1.5, based on a respective standard volume flow rate of the pretreated synthesis gas and the recyclate stream,
wherein a ratio of hydrogen to carbon monoxide in the synthesis gas is in a range from 70:30 to 30:70, based on a respective proportion by volume of hydrogen and carbon monoxide in the synthesis gas, and
wherein the second separation stage or the third separation stage has the highest capacity of the at least three membrane separation stages, and
wherein the synthesis gas has a CO/CH4 ratio of more than 10 mol/mol.