Sorbent for separation of carbon dioxide (CO2) from gas mixtures

• US 7,067,456 B2
• Filed: 02/06/2003
• Issued: 06/27/2006
• Est. Priority Date: 02/06/2003
• Status: Active Grant

• Current Assignee: Ohio State University
• Original Assignee: Ohio State University
• Inventors: Gupta, Himanshu, Fan, Liang-Shih
• Primary Examiner(s): Johnson, Edward M.
• Application Number:
  US10/359,763
• Publication Number:
  US 20060039853A1
• Time in Patent Office: 1,237 Days
• Field of Search: 502/400, 502/417, 502/340, 502/439
• US Class Current: 502/400
• CPC Class Codes: B01D 2251/402 of magnesium
• CPC Class Codes: B01D 2251/404 of calcium
• CPC Class Codes: B01D 53/62 Carbon oxides
• CPC Class Codes: B01J 20/041 Oxides or hydroxides
• CPC Class Codes: B01J 20/043 Carbonates or bicarbonates, e.g. limestone, dolomite, aragonite
• CPC Class Codes: B01J 20/28057 Surface area, e.g. B.E.T specific surface area
• CPC Class Codes: B01J 20/28069 Pore volume, e.g. total pore volume, mesopore volume, micropore volume
• CPC Class Codes: B01J 20/28088 Pore-size distribution
• CPC Class Codes: B01J 20/3433 of sorbents or filter aids other than those covered by B01J20/3408 - B01J20/3425
• CPC Class Codes: B01J 20/3483 by thermal treatment not covered by groups B01J20/3441 - B01J20/3475, e.g. by heating or cooling
• CPC Class Codes: C01F 11/06 of carbonates
• CPC Class Codes: C01P 2002/72 by d-values or two theta-values, e.g. as X-ray diagram
• CPC Class Codes: C01P 2006/12 Surface area
• CPC Class Codes: C01P 2006/14 Pore volume
• CPC Class Codes: C01P 2006/17 Pore diameter distribution
• CPC Class Codes: C04B 2/10 Preheating, burning calcining or cooling decarbonation during burning of cement raw materials C04B7/43; obtaining CaO or MgO otherwise than by thermal decomposition of the corresponding carbonates C01F11/02, C01F5/02
• CPC Class Codes: Y02C 20/40 of CO2
• CPC Class Codes: Y02P 20/151 Reduction of greenhouse gas [GHG] emissions, e.g. CO2
• CPC Class Codes: Y02P 40/40 Production or processing of lime, e.g. limestone regeneration of lime in pulp and sugar mills

Abstract

A reaction-based process has been developed for the selective removal of carbon dioxide (CO₂) from a multicomponent gas mixture to provide a gaseous stream depleted in CO₂ compared to the inlet CO₂ concentration in the stream. The proposed process effects the separation of CO₂ from a mixture of gases (such as flue gas/fuel gas) by its reaction with metal oxides (such as calcium oxide). The Calcium based Reaction Separation for CO₂ (CaRS-CO₂) process consists of contacting a CO₂ laden gas with calcium oxide (CaO) in a reactor such that CaO captures the CO₂ by the formation of calcium carbonate (CaCO₃). Once “spent”, CaCO₃ is regenerated by its calcination leading to the formation of fresh CaO sorbent and the evolution of a concentrated stream of CO₂. The “regenerated” CaO is then recycled for the further capture of more CO₂. This carbonation-calcination cycle forms the basis of the CaRS-CO₂ process. This process also identifies the application of a mesoporous CaCO₃ structure, developed by a process detailed elsewhere, that attains >90% conversion over multiple carbonation and calcination cycles. Lastly, thermal regeneration (calcination) under vacuum provided a better sorbent structure that maintained reproducible reactivity levels over multiple cycles.

Claims

1. A method for producing a sorbent, said method comprising the steps of:

obtaining a structurally altered high surface area calcium carbonate having a surface area of at least 25.0 m²/g, a pore volume of at least 0.05 cm³/g, and a mesoporous pore size distribution; and

calcining said structurally altered high surface area calcium carbonate so as to produce a sorbent having a surface area of less than 22 m²/g, a pore volume of at least 0.005 cm³/g, and a mesoporous pore size distribution.

2. The method according to claim 1 wherein said calcining is conducted under at least partial vacuum.

3. The method according to claim 1 wherein said calcining is conducted by steam.