Method for using high capacity unsupported regenerable CO.sub.2 sorbent

• US 5,427,751 A
• Filed: 06/28/1993
• Issued: 06/27/1995
• Est. Priority Date: 03/07/1990
• Status: Expired due to Fees

• Current Assignee: United Technologies Corporation (Rtx Corporation)
• Original Assignee: United Technologies Corporation (Rtx Corporation)
• Inventors: Aylward, John R., Birbara, Philip J., Nalette, Timothy A.
• Primary Examiner(s): Straub, Gary P.
• Assistant Examiner(s): DiMauro, Peter T.
• Application Number:
  US08/083,392
• Time in Patent Office: 729 Days
• Field of Search: 423/220, 423/230, 423/232, 423/438, 423/419.1, 23/313 R, 23/313 AS, 128/205.28, 95/139
• US Class Current: 423/230
• CPC Class Codes: B01D 53/62 Carbon oxides
• CPC Class Codes: B01J 20/0233 Compounds of Cu, Ag, Au
• CPC Class Codes: B01J 20/0277 Carbonates of compounds other than those provided for in B01J20/043
• CPC Class Codes: B01J 20/043 Carbonates or bicarbonates, e.g. limestone, dolomite, aragonite
• CPC Class Codes: B01J 20/046 containing halogens, e.g. halides
• CPC Class Codes: B01J 20/10 comprising silica or silicate
• CPC Class Codes: B01J 20/28014 characterised by their form
• CPC Class Codes: B01J 20/2803 Sorbents comprising a binder, e.g. for forming aggregated, agglomerated or granulated products
• CPC Class Codes: B01J 20/3007 Moulding, shaping or extruding
• CPC Class Codes: B01J 20/3204 Inorganic carriers, supports or substrates
• CPC Class Codes: B01J 20/3236 containing metal, other than zeolites, e.g. oxides, hydroxides, sulphides or salts
• CPC Class Codes: B01J 20/3289 Coatings involving more than one layer of same or different nature
• 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: B01J 2220/42 Materials comprising a mixture of inorganic materials materials coated or impregnated on a carrier B01J20/32
• CPC Class Codes: B01J 2220/56 Use in the form of a bed
• CPC Class Codes: Y02C 20/40 of CO2

Abstract

A technique for preparing an unsupported, high capacity CO₂ sorbent. The sorbent is comprised of silver carbonate, alkali metal silicate and alkaline earth metal salt binders for structural integrity, and alkali metal carbonate for CO₂ sorption promotion. The sorbent disclosed in this invention has a high silver oxide density, consumes minimum volume, exhibits high CO₂ absorption rates, and resists dusting and degradation for at least 50 absorption/desorption cycles.

Claims

1. A method for utilizing a regenerable metal oxide CO₂ sorbent, comprising the steps of:

(a) loading a sorbent in a reactor to form a sorbent bed, wherein the sorbent loaded in the reactor is produced by a process comprising the steps of;

(1) pelletizing silver carbonate, wherein pellets of silver carbonate are formed,

(2) preparing an aqueous solution of alkali metal silicate and alkali metal carbonate,

(3) contacting the silver carbonate pellets with the alkali metal silicate/alkali metal carbonate aqueous solution, thereby forming silicate coated, alkali metal impregnated silver carbonate pellets,

(4) drying the silicate coated, alkali metal carbonate impregnated silver carbonate pellets,

(5) preparing an aqueous solution of alkaline earth metal salt,

(6) contacting the silicate coated, alkali metal carbonate impregnated silver carbonate pellets with the alkaline earth metal salt aqueous solution, thereby forming an alkaline earth metal salt coating on the silicate coated, alkali metal carbonate impregnated silver carbonate pellets,

(7) drying the alkaline earth metal salt/silicate coated, alkali metal carbonate impregnated silver carbonate pellets, and

(8) heating the pellets from step 7 to a temperature sufficient to convert the silver carbonate to silver oxide to form a silver oxide containing sorbent bed;

(b) passing a gaseous stream containing CO₂ and water over the silver oxide containing sorbent bed, under conditions sufficient to sorb CO₂.

2. The method of claim 1 wherein the sorbent bed is heated to between about 160°

C. to about 220°

C. in step 8.

3. The method of claim 1 wherein the alkali metal silicate is selected from the group consisting of sodium silicate, potassium silicate, and mixtures thereof.

4. The method of claim 1 wherein the alkali metal carbonate is selected from the group consisting of cesium carbonate, potassium carbonate, sodium carbonate, and mixtures thereof.

5. The method of claim 1 wherein the alkaline earth metal salt is selected from the group consisting of calcium chloride, magnesium chloride, barium chloride, calcium nitrate, magnesium nitrate, barium nitrate and mixtures thereof.