Simultaneous shift-reactive and adsorptive process to produce hydrogen

• US 7,354,562 B2
• Filed: 10/25/2002
• Issued: 04/08/2008
• Est. Priority Date: 10/25/2002
• Status: Expired due to Fees

• Current Assignee: Air Products and Chemicals Incorporated (Linde Plc)
• Original Assignee: Air Products and Chemicals Incorporated (Linde Plc)
• Inventors: Dulley, Sarah Jane, Hufton, Jeffrey Raymond, Allam, Rodney John, Nataraj, Shankar, Xu, Jianguo, Ying, David Hon Sing
• Primary Examiner(s): Hendrickson; Stuart L.
• Assistant Examiner(s): MCCRACKEN, DANIEL
• Application Number:
  US10/280,843
• Publication Number:
  US 20040081614A1
• Time in Patent Office: 1,992 Days
• Field of Search: 423/655, 423/656, 423/437.2, 423/230, 95/96
• US Class Current: 423/437.2
• CPC Class Codes: B01D 2251/30 Alkali metal compounds
• CPC Class Codes: B01D 2251/40 Alkaline earth metal or magnesium compounds
• CPC Class Codes: B01D 2251/60 Inorganic bases or salts
• CPC Class Codes: B01D 2256/16 Hydrogen
• CPC Class Codes: B01D 2256/22 Carbon dioxide
• CPC Class Codes: B01D 2257/504 Carbon dioxide
• CPC Class Codes: B01D 2258/0208 from fuel cells
• CPC Class Codes: B01D 2259/40001 Methods relating to additional, e.g. intermediate, treatment of process gas
• CPC Class Codes: B01D 2259/402 using two beds
• CPC Class Codes: B01D 2259/4143 arranged as a mixture
• CPC Class Codes: B01D 2259/4146 Contiguous multilayered adsorbents
• CPC Class Codes: B01D 53/04 with stationary adsorbents B01D53/025 takes precedence
• CPC Class Codes: B01D 53/0462 Temperature swing adsorption
• CPC Class Codes: B01D 53/047 Pressure swing adsorption
• CPC Class Codes: B01D 53/864 Removing carbon monoxide or hydrocarbons
• CPC Class Codes: C01B 2203/0205 containing a reforming step
• CPC Class Codes: C01B 2203/0283 containing a CO-shift step, i.e. a water gas shift step
• CPC Class Codes: C01B 2203/0425 In-situ adsorption process during hydrogen production
• CPC Class Codes: C01B 2203/043 Regenerative adsorption process in two or more beds, one for adsorption, the other for regeneration
• CPC Class Codes: C01B 2203/0445 Selective methanation
• CPC Class Codes: C01B 2203/047 : the impurity being carbon monoxide
• CPC Class Codes: C01B 2203/0475 : the impurity being carbon dioxide
• CPC Class Codes: C01B 2203/1011 : Packed bed of catalytic structures, e.g. particles, packing elements
• CPC Class Codes: C01B 2203/1041 : Composition of the catalyst
• CPC Class Codes: C01B 2203/1047 : Group VIII metal catalysts
• CPC Class Codes: C01B 2203/1064 : Platinum group metal catalysts
• CPC Class Codes: C01B 2203/1076 : Copper or zinc-based catalysts
• CPC Class Codes: C01B 3/16 : using catalysts
• CPC Class Codes: C01B 3/56 : by contacting with solids; Regeneration of used solids C01B3/508 takes precedence
• CPC Class Codes: Y02C 20/40 : of CO2
• CPC Class Codes: Y02P 20/151 : Reduction of greenhouse gas [GHG] emissions, e.g. CO2

Abstract

A process for producing a high temperature CO_x-lean product gas from a high temperature CO_x-containing feed gas, includes: providing a sorption enhanced reactor containing a first adsorbent, a shift catalyst and a second adsorbent; feeding into the reactor a feed gas containing H₂, H₂O, CO and CO₂; contacting the feed gas with the first adsorbent to provide a CO₂ depleted feed gas; contacting the CO₂ depleted feed gas with the shift catalyst to form a product mixture comprising CO₂ and H₂; and contacting the product mixture with a mixture of second adsorbent and shift catalyst to produce the product gas, which contains at least 50 vol. % H₂, and less than 5 combined vol. % of CO₂ and CO. The adsorbent is a high temperature adsorbent for a Sorption Enhanced Reaction process, such as K₂CO₃ promoted hydrotalcites, modified double-layered hydroxides, spinels, modified spinels, and magnesium oxides.

Claims

1. A process for producing a CON_x-lean product gas from a CO_x-containing feed gas, said process comprising:

providing a sorption enhanced reactor containing a first bed, an intermediate bed downstream of the first bed and a second bed downstream of the intermediate bed, and wherein the first bed contains a first adsorbent, the second bed contains a mixture of a second adsorbent and a shift catalyst, and the intermediate bed contains the shift catalyst;

feeding the feed gas into the reactor at a feed gas pressure during a reaction step, wherein the feed gas comprises H₂, H₂O, CO and CO₂;

contacting the feed gas with the first adsorbent to adsorb an amount of CO₂ from the feed gas and to provide a CO₂ depleted feed gas;

contacting the CO₂ depleted feed gas with the shift catalyst to catalyze a shift reaction of CO and H₂O to form a product mixture comprising CO₂ and H₂;

contacting the product mixture with the mixture of the second adsorbent and the shift catalyst to produce the product gas, wherein the product gas comprises at least 50 vol. % H₂ and less than 5 combined vol. % CO₂ and CO;

regenerating the first adsorbent and the second adsorbent;

repressurizing the reactor with a pressurization gas; and

countercurrently purging the reactor at the feed gas pressure with a purge gas before regenerating the first adsorbent and the second adsorbent to yield an effluent stream containing unreacted CO and H₂O, and recycling the effluent stream to the feed gas.

2. The process of claim 1, wherein the first adsorbent and the second adsorbent are independently at least one member selected from the group consisting of:

(a) K₂ CO₃ promoted hydrotalcites;

(b) modified double layered hydroxides represented by Formula I;

(Mg_(1-x)Al_X(OH)₂)(CO₃)_x/2yH₂OzM¹₂CO₃tm (I)

where 0.09≦

x≦

0.40, 0 ≦

y≦

3.5, 0≦

z≦

3.5, and M¹ is Na or K;

(c) spinels and modified spinels represented by Formula II;

Mg(A₁₂)₀₄yK₂CO₃tm (II)

where 0≦

y≦

3.5; and

(d) magnesium oxide-containing adsorbents represented by Formula Ill;

{(M₂CO₃)_m(2MHCO₃)_{(1 -im)}}_n(MgCO₃)_p(MgO)_(1-p)xH₂O tm (Ill)

where M is an alkali metal, 0≦

m ≦

1, 0≦

n ≦

1.3, 0≦

p <

1, and x represents an extent of hydration of the adsorbent, with the proviso that when n equals 0 the MgO is made by dehydration and CO₂ removal of {MgCO_3}y {Mg(OH)₂}_(1-y)xH₂, O in which 0.1 ≦

y ≦

0.9, and x indicates an extent of hydration.

3. The process of claim 1, wherein the feed gas is a syngas effluent from a high temperature shift reactor, and a raw syngas to the high temperature shift reactor is obtained from a steam methane reformer, partial oxidation reactor, air-blown autothermal reformer or oxygen-blown autothermal reformer upstream of the reactor.

4. The process of claim 1, wherein the feed gas is fed into the reactor at a flow rate of 5-50 gmole/hr/cm² and a reactor temperature during the process is maintained between 175°

C. and 550°

C.

5. The process of claim 1, wherein the purge gas comprises at least one of steam and a steam/H₂ mixture.

6. The process of claim 1, wherein the process is conducted in a series of cycles in more than one said reactor, and a first reactor is being regenerated while a second reactor is being operated in parallel to produce the product gas.

7. A process for producing a CO_x-lean product gas from a CO_x-containing feed gas, said process comprising:

providing a sorption enhanced reactor containing a first bed, an intermediate bed downstream of the first bed and a second bed downstream of the intermediate bed, and wherein the first bed contains a first adsorbent, the second bed contains a mixture of a second adsorbent and a shift catalyst, and the intermediate bed contains the shift catalyst;

feeding the feed gas into the reactor at a feed gas pressure during a reaction step wherein the feed gas comprises H₂, H₂O, CO and CO₂;

contacting the feed gas with the first adsorbent to adsorb an amount of CO₂ from the feed gas and to provide a CO₂ depleted feed gas;

contacting the CO₂ depleted feed gas with the shift catalyst to catalyze a shift reaction of

CO and H₂ O to form a Product mixture comprising CO₂ and H₂;

contacting the Product mixture with the mixture of the second adsorbent and the shift catalyst to Produce the product gas, wherein the product gas comprises at least 50 vol.

% H₂ and less than 5 combined vol. % CO₂ and CO;

regenerating the first adsorbent and the second adsorbent;

repressurizing the reactor with a pressurization gas; and

cocurrently rinsing the reactor at the feed gas pressure with a CO₂ product before regenerating the first adsorbent and the second adsorbent and recovering a CO₂-rich byproduct stream during the regenerating step.

8. The process of claim 7, wherein the first adsorbent and the second adsorbent are independently at least one member selected from the group consisting of:

(a) K₂CO₃ promoted hydrotalcites;

(b) modified double layered hydroxides represented by Formula I;

(Mg_(1-X)Al_x(OH)₂)(CO₃)_x/2yH₂OzM¹₂ CO₃tm (I)

where 0.09≦

x ≦

0.40, 0 ≦

y ≦

3.5, 0 ≦

z ≦

3.5, and M^l is Na or K;

(c) spinels and modified spinels represented by Formula II;

Mg(Al₂)O₄yK₂ CO₃tm (II)

where 0 ≦

y ≦

3.5; and

(d) magnesium oxide-containing adsorbents represented by Formula Ill;

{(M₂CO₃)_m(2MHCO₃)_(1-m)}n(MgCO₃)_p(MgO)_(1-p)xH₂O tm (Ill)

where M is an alkali metal, 0≦

m ≦

1, 0≦

n ≦

1.3, 0≦

p <

1, and x represents an extent of hydration of the adsorbent, with the proviso that when n equals 0 the MgO is made by dehydration and CO₂ removal of {MgCO₃)_y{Mg(OH)₂}_(1-y)xH₂ O, in which 0.1≦

y≦

0.9, and x indicates an extent of hydration.

9. The process of claim 7, wherein the feed gas is a syngas effluent from a high temperature shift reactor, and a raw syngas to the high temperature shift reactor is obtained from a steam methane reformer, partial oxidation reactor, air-blown autothermal reformer or oxygen-blown autothermal reformer upstream of the reactor.

10. The process of claim 7, wherein the feed gas is fed into the reactor at a flow rate of 5-50 gmole/hr/cm² and a reactor temperature during the process is maintained between 1750°

C. and 550°

C.

11. The process of claim 7, wherein the process is conducted in a series of cycles in more than one said reactor, and a first reactor is being regenerated while a second reactor is being operated in parallel to produce the product gas.