초록 ▼

The present invention relates to a method of producing hydrogen of very high purity from a feed predominantly containing said hydrogen and a minor part of impurities mainly consisting of carbon dioxide, carbon monoxide, methane and heavier hydrocarbons. The purification method by hydrogen adsorption

The present invention relates to a method of producing hydrogen of very high purity from a feed predominantly containing said hydrogen and a minor part of impurities mainly consisting of carbon dioxide, carbon monoxide, methane and heavier hydrocarbons. The purification method by hydrogen adsorption using a desorption stage at a lower pressure than the pressure of the feed, such as a PSA method for example, allows to produce the desorption stream and notably to recover the carbon dioxide under pressure and high-purity hydrogen, with a high yield. These performances are obtained by combining the successive stages of the method according to the invention with the use of a new family of adsorbent whose dynamic capacity at a high desorption pressure is greater than that of conventional adsorbents.

대표청구항 ▼

1. A method of producing hydrogen of very high purity from a feed predominantly containing said hydrogen and a minor part of impurities comprising mainly carbon dioxide, carbon monoxide, methane and heavier hydrocarbons, said feed being introduced into at least one adsorption column made up of a plu

1. A method of producing hydrogen of very high purity from a feed predominantly containing said hydrogen and a minor part of impurities comprising mainly carbon dioxide, carbon monoxide, methane and heavier hydrocarbons, said feed being introduced into at least one adsorption column made up of a plurality of beds, said method comprising at least the following stages: a) a stage of partial or complete, cocurrent or counter-current pressurization of said feed until the pressure of the adsorption stage (Pads) is reached, by an additional pure hydrogen or feed stream,b) a stage of adsorption at high pressure Pads of the impurities of the feed pressurized in stage a), carried out on an adsorbent solid contained in one or more beds,c) a stage of cocurrent or counter-current depressurization of the stream from stage b) until the desorption pressure Pdes above 0.4 MPa is reached,d) a cocurrent or counter-current desorption stage at high pressure Pdes, said pressure Pdes being lower than the adsorption stage pressure, wherein at least one adsorbent making up a bed or part of a bed has a carbon dioxide dynamic capacity of at least 2 mole/g between an adsorption pressure (Pads) of 5 MPa and a CO2 desorption pressure (Pdes) of 0.4 MPa, the dynamic capacity being defined as the difference between the amount of CO2 adsorbed under the adsorption stage conditions and the amount that remains adsorbed after desorption. 2. A method as claimed in claim 1, wherein the adsorption column comprising at least four adsorbent beds. 3. A method as claimed in claim 1, wherein at least one adsorbent has a carbon dioxide dynamic capacity of at least 4 mmole/g between an adsorption pressure (Pads) of 5 MPa and a desorption pressure (Pdes) of 0.4 MPa. 4. A method as claimed in claim 1, wherein at least one adsorbent has a carbon dioxide dynamic capacity of at least 2 mmole/g and between an adsorption pressure (Pads) of 3 MPa and a desorption pressure (Pdes) of 0.4 MPa. 5. A method as claimed in claim 1, wherein at least one adsorbent has a carbon dioxide dynamic capacity of at least 2 mmole/g and between an adsorption pressure (Pads) of 3 MPa and a desorption pressure (Pdes) of 0.5 MPa. 6. A method as claimed in claim 1, wherein the adsorption pressure (Pads) ranges between 1.5 and 5 MPa and the desorption pressure (Pdes) ranges between 0.4 and 2 MPa. 7. A method as claimed in claim 6, wherein adsorption pressure (Pads) ranges between 2 and 4 MPa and desorption pressure (Pdes) ranges between 0.4 and 0.6 MPa. 8. A method as claimed in claim 1, wherein said adsorbent solid has a pore size ranging between 5 and 50 Å, and a pore volume ranging between 0.5 and 5 ml/g. 9. A method as claimed in claim 8, wherein said adsorbent solid has a pore size ranging between 7 and 25 Å, and a pore volume ranging between 0.8 and 3 ml/g. 10. A method as claimed in claim 8, wherein the adsorbent solid is selected from the group of Metal-Organic Frameworks (MOFs), mesoporous silicas, and activated charcoals having a specific surface area above 2000 m2/g. 11. A method as claimed in claim 8, wherein the adsorbent solid is selected from among the breathing MOFs, which are flexible structures whose pores open and whose size is above 5 Å at adsorption pressure (Pads). 12. A method as claimed in claim 8, wherein the adsorbent solid is selected from among IRMOF-1, IRMOF-3, IRMOF-6, IRMOF-11, MOF-177, Cu3(tatb)2, MIL-100, MIL-101 and MIL-53. 13. A method as claimed in claim 1, operating at a temperature range between 10° C. and 250° C. 14. A method as claimed in claim 1 operated according to the PSA implementation, wherein, the impurities other than CO2 having an affinity towards the adsorbent close to that of CO2, pressurization stage a) is carried out several times and stage c) comprises at least two stages defined by: c1) one or more cocurrent partial depressurization stages,c2) one or more counter-current depressurization stages. 15. A method as claimed in claim 1 operated according to the PSA implementation, wherein, the impurities other than CO2 having an affinity towards the adsorbent markedly lower than that of CO2, at least one adsorbent bed comprises two different adsorbent types, the first one having a dynamic capacity of at least 2 mmole/g between an adsorption pressure (Pads) of 5 MPa and a desorption pressure(Pdes) of 0.4 MPa, and a second adsorbent for the adsorption of impurities other than CO2. 16. A method as claimed in claim 15, wherein the two different adsorbents are distributed in at least two successive bed layers and pressurization stage a) is carried out several times, stage c) comprises two stages defined by: c1) one or more cocurrent partial depressurization stages,c2) one or more counter-current depressurization stages, and stage d) comprises two stages defined by: d) a counter-current desorption stage at the CO2 desorption pressure of between 2 and 0.4 MPa,e) a cocurrent or counter-current desorption stage at a low pressure ranging between 0.4 MPa and atmospheric pressure. 17. A method as claimed in claim 15, wherein the two different adsorbents are distributed in at least two specific beds. 18. A method as claimed in claim 17, comprising a first bed high-pressure adsorption stage b) carried out in series with a second bed, and the first bed desorption stage d) is carried out at high pressure in a counter-current flow. 19. A method as claimed in claim 17, comprising a second bed high-pressure adsorption stage b) carried out in series with the first bed, and stage c) comprises two stages defined by: c1) one or more cocurrent partial depressurization stages,c2) one or more counter-current depressurization stages, and first bed desorption stage d′) is carried out at low pressure in a counter-current flow. 20. A method as claimed in claim 1 operated according to the SMB implementation, comprising the following stages: a) a stage of contacting under adsorption conditions at a pressure Pads the feed (1) containing hydrogen and impurities with an adsorbent solid contained in a plurality of beds so as to adsorb impurities,b) a stage of displacement of the hydrogen contained in interstitial and macroporous volumes of said adsorbent solid through sweeping by a stream (3) containing either desorbent or a mixture of impurities,c) an adsorbent desorption stage comprising:one or more cocurrent or counter-current depressurization substages at a high pressure Pdes lower than pressure Pads, optionally with a desorbent allowing to obtain an extract stream (4) containing the impurities and part of the desorbent,a desorption substage at pressure Pdes during which the bed is swept by a gas stream either desorbent or hydrogen (5), allowing to obtain an extract stream (6) containing the impurities and part of the desorbent,one or more cocurrent or counter-current repressurization substages with part of the pure hydrogen stream (raffinate) or with a desorbent stream (7),d) a stage of withdrawal of a raffinate (2) containing the purified hydrogen and possibly part of the desorbent,e) in case of use of a desorbent, a stage of separation of the extract into a first stream containing the desorbent and a second stream containing the impurities,f) in case of use of a desorbent, a stage of separation of the raffinate into a first stream containing the desorbent and a second stream containing the high-purity hydrogen. 21. A method as claimed in claim 1 operated according to the SMB implementation, comprising the following stages: a) a stage of contacting under suitable adsorption conditions at a pressure Pads feed (1) containing hydrogen and impurities with an adsorbent solid contained in a plurality of beds so as to adsorb the impurities,b) an adsorbent desorption stage comprising:one or more cocurrent or counter-current depressurization substages at a high pressure Pdes lower than pressure Pads, optionally with a desorbent, and allowing to obtain an extract stream (4) containing the impurities and part of the desorbent,a desorption substage at pressure Pdes during which the bed is swept by a gas stream of desorbent or hydrogen (5), allowing to obtain an extract stream (6) containing the impurities and part of the desorbent,one or more cocurrent or counter-current repressurization substages with part of the pure hydrogen stream (raffinate) or with a desorbent stream (7),c) a stage of withdrawal of a raffinate (2) containing the purified hydrogen and optionally part of the desorbent,d) in case of use of a desorbent, a stage of separation of the extract into a first stream containing the desorbent and a second stream containing the impurities,e) in case of use of a desorbent, a stage of separation of the raffinate into a first stream containing the desorbent and a second stream containing the high-purity hydrogen. 22. A method as claimed in claim 1, coupled with membrane separation or a solvent extraction. 23. A method as claimed in claim 1, wherein a polar impurity is added to the feed to increase the dynamic capacity of the adsorbent.