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US-12616932-B2 - Displacement purge adsorption process for separating CO2 from another gas

US12616932B2US 12616932 B2US12616932 B2US 12616932B2US-12616932-B2

Abstract

The present invention concerns a process for the separation of a gas mixture containing CO 2 and at least one inert gaseous species, comprising (a) feeding the gas mixture into an adsorption column via a first inlet located at a first side of the column, wherein the adsorption column contains a solid CO 2 sorbent loaded with H 2 O molecules and thereby desorbing H 2 O molecules and adsorbing CO 2 molecules, to obtain a sorbent loaded with CO 2 and an inert product stream; and then (b) feeding a stripping gas comprising H 2 O into the adsorption column via a second inlet located at a second side which is opposite to the first inlet, thereby stripping the sorbent and desorbing CO 2 molecules and adsorbing H 2 O molecules, to obtain a sorbent loaded with H 2 O and the CO 2 product stream, wherein the adsorption column is re-used in step (a) after being stripped in step (b). The invention also concerns an apparatus for performing the process according to the invention.

Inventors

  • Jurriaan Boon
  • Hendricus Adrianus Johannes Van Dijk
  • Paul Dean COBDEN
  • Jebin Duthie James

Assignees

  • NEDERLANDSE ORGANISATIE VOOR TOEGEPAST-NATUURWETENSCHAPPELIJK ONDERZOEK TNO

Dates

Publication Date
20260505
Application Date
20210913
Priority Date
20200911

Claims (10)

  1. 1 . A process for the separation of a gas mixture containing CO 2 and at least one inert gaseous species into a CO 2 product stream and an inert product stream, comprising: (a) feeding the gas mixture into an adsorption column via a first inlet located at a first side of the column, wherein the adsorption column contains hydrotalcite as a solid CO 2 sorbent loaded with H 2 O molecules and thereby desorbing H 2 O molecules and adsorbing CO 2 molecules, to obtain a sorbent loaded with CO 2 and the inert product stream; and then (b) feeding a stripping gas comprising H 2 O into the adsorption column via a second inlet located at a second side which is opposite to the first inlet, thereby stripping the sorbent and desorbing CO 2 molecules and adsorbing H 2 O molecules, to obtain a sorbent loaded with H 2 O and the CO 2 product stream, wherein the adsorption column is re-used in step (a) after being stripped in step (b) and wherein the process is performed at a temperature in the range of 200-500° C.
  2. 2 . The process according to claim 1 , wherein the steps (a) and (b) are performed at a pressure in the range of 1 to 50 bar, wherein the pressure during the process varies for at most 1 bar, wherein the temperature during the process varies for at most 40° C.
  3. 3 . The process according to claim 1 , wherein two or more adsorption columns operate in parallel, wherein at least one is performing step (a) and at least one is simultaneously performing step (b).
  4. 4 . The process according to claim 1 , wherein downstream of step (a) inert gaseous molecules are separated from the inert product stream.
  5. 5 . The process according to claim 1 , wherein the pressure during the process varies for at most 0.3 bar, and/or wherein the temperature during the process varies for at most 10° C.
  6. 6 . The process according to claim 1 , wherein the inert gaseous species do not adsorb to the adsorption column at the process conditions.
  7. 7 . The process according to claim 6 , wherein the inert gaseous species is selected from H 2 , N 2 , CH 4 and other hydrocarbons.
  8. 8 . The process according to claim 1 , wherein the gas mixture that is fed during step (a) is a product mixture from a water gas shift process containing at least CO 2 and H 2 .
  9. 9 . The process according to claim 1 , wherein the process is performed at a temperature in the range of 300-500° C.
  10. 10 . The process according to claim 4 , wherein downstream of step (a) inert gaseous molecules are separated from the inert product stream by condensation of H 2 O.

Description

FIELD OF THE INVENTION The present invention relates to field of separation of gaseous mixtures, in particular in the context of a sorption-enhanced water gas shift (SEWGS) process. BACKGROUND ART Energy-intensive sectors such as steel, refining and chemical industries are still largely dependent on fossil fuels and raw materials, so that it remains important to capture and reuse the released CO2. Unused CO2 can be stored safely, for example in depleted natural gas fields in the North Sea. In the long term, negative CO2 emissions may become the target, which can be obtained by, for example, storing the released CO2 in the use of biomass. The overall reduction in the CO2 emitted into the atmosphere is one of the major challenges in the present-day society, especially for industries where large amounts of carbon atoms remain as side-product, which are typically emitted as CO2. Sorption-enhanced water-gas shift (SEWGS) has been developed for the conversion of CO to H2 and CO2, allowing the formation of a CO2 product stream and an H2 product stream, wherein CO2 is captured and reused by means of adsorption. This process can be employed to purify the H2 gas in a syngas mixture containing CO and/or CO2, to obtain a H2 product stream and a by-product stream wherein the incoming carbon atoms are captured in a CO2 stream. The CO2 product stream may then be subjected to CO2 storage and as such eliminate CO2 emissions into the atmosphere. Removal and subsequent storage of CO2 from other gases can be accomplished in similar fashion. WO 2010/059055 (EP 2362848) discloses a water gas shift process with a reaction stage, wherein the reaction stage comprises (a) providing a gas mixture comprising CO, H2O and an acid gas component to a reactor containing an adsorbent, and (b) subjecting the gas mixture to water gas shift reaction conditions to perform the water gas shift reaction. The adsorbent used in WO 2010/059055 comprises an alkali promoted hydrotalcite material, and the acid gas component comprises H2S. WO 2013/122467 (EP 2814775) discloses that the high-pressure steam supply in a hydrogen production process can be made more efficient by a water gas shift process which comprises, in alternating sequence (i) a reaction stage wherein a feed gas comprising CO and H2O is fed into a water gas shift reactor containing a sorbent material capable of adsorbing H2O and CO2 and wherein a product gas issuing from the reactor is collected, (ii) a regeneration stage wherein CO2 is removed from the reactor, (iii) a loading stage, wherein H2O is fed into the reactor, wherein said feed gas mixture has a molar ratio of H2O to CO below 1.2, and the loading stage is performed at a lower pressure than the pressure of the reaction stage. WO 2004/076017 discloses adsorptive gas separation for high-temperature fuel cell applications, and regeneration of adsorbent materials, via (rotary) pressure-swing adsorption (PSA), displacement purge, thermal swing, or combinations thereof. WO 2004/076017 specifically also discloses a hydrogen-enrichment rotary adsorption module with displacement purge regeneration, and solid oxide fuel cell power plants including a water gas shift reactor with typical exit temperatures in the range of about 200° C. to about 400° C. WO 2004/076017 further specifically discloses that in a molten-carbonate high-temperature fuel cell (MCFC), an enrichment of anode exhaust gas in hydrogen can be done via a displacement purge adsorption process, for recycle to the anode inlet, with the benefit that the purge desorption gas stream enriched in carbon dioxide may be recycled to the cathode inlet to increase the concentration of carbon dioxide in the cathode inlet gas relative to that of air, as opposed to discharge into the atmosphere (page 17, lines 13-18). WO 2006/133576 discloses adsorptive gas bulk separation systems in which a feed gas source, typically comprising at least one fuel gas component and at least one diluent, is separated through a displacement purge adsorptive separator apparatus with an adsorbent bed, further using a purge gas source for purge regeneration of the adsorbent bed. The displacement purge adsorptive separator apparatus adsorbs at least a portion of the at least one diluent component from the feed gas stream to produce an upgraded gas. WO 2006/133576 further discloses that pretreated blast furnace gas may be passed through a conventional water gas shift module to convert at least a portion of the carbon monoxide fuel gas in the pretreated blast furnace gas stream into hydrogen fuel gas via the water gas shift reaction. The resulting blast furnace feed gas stream comprises at least a hydrogen fuel gas component and a diluent gas component, such as CO2 and/or N2, and may be supplied to displacement purge bulk separator for adsorption of at least a portion of the diluent gas component on suitable adsorbent materials in adsorbent beds in order to produce an upgraded fuel gas product for downstream use,