Preparation of high capacity unsupported regenerable CO.sub.2 sorbent

• US 5,079,209 A
• Filed: 03/07/1990
• Issued: 01/07/1992
• Est. Priority Date: 03/07/1990
• Status: Expired due to Term

• Current Assignee: United Technologies Corporation (Rtx Corporation)
• Original Assignee: United Technologies Corporation (Rtx Corporation)
• Inventors: Birbara, Philip J., Nalette, Timothy A., Aylward, John R.
• Primary Examiner(s): Dees, Carl F.
• Application Number:
  US07/490,016
• Time in Patent Office: 671 Days
• Field of Search: 502/243, 502/407, 502/411, 423/230, 423/232
• US Class Current: 502/411
• 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 preparation of regenerable metal oxide CO₂ sorbent, said method using silver carbonate, an alkali metal silicate, an alkali metal carbonate, and an alkaline earth metal salt, which comprises:

a. pelletizing silver carbonate, wherein pellets are formed;

b. preparing an aqueous solution of alkali metal silicate and alkali metal carbonate, wherein the amount of alkali metal silicate and alkali metal carbonate are determined via the desired wt% of each in the final product;

c. contacting said pellets with said alkali metal silicate/alkali metal carbonate aqueous solution, thereby forming silicate coated, alkali metal carbonate impregnated pellets;

d. drying said silicate coated, alkali metal carbonate impregnated pellets;

e. preparing an aqueous solution of alkaline earth metal salt, wherein the amount of alkaline earth metal salt utilized is determined by the desired wt% of alkaline earth metal salt in the final product;

f. contacting said silicate coated/alkali metal carbonate impregnated pellets with said alkaline earth metal salt aqueous solution, thereby forming an alkaline earth metal coating on said silicate coated, alkali metal carbonate impregnated pellets;

g. drying said alkaline earth metal/silicate coated, alkali metal carbonate impregnated pellets.

2. A method as in claim 1 wherein the pellet size ranges from about 0.30 mm to about 3.00 mm in diameter.

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

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

5. A method as in claim 1 wherein the alkaline earth metal salt is selected from the group consisting of nitrates and chlorides of calcium, magnesium, barium, and mixtures thereof.

6. A method as in claim 1 wherein contacting and drying of said pellets with said alkali metal silicate/alkali metal carbonate aqueous solution, and alkaline earth metal salt aqueous solution is preformed within a rotatory evaporator.

7. A method as in claim 1 wherein heat is applied to any of the operations to reduce sorbent preparation time.

8. A method as in claim 1 wherein the desired wt % of alkali metal silicate in the final product is between about 3.0 wt % to about 8.0 wt %.

9. A method as in claim 1 wherein the desired wt % of alkali metal carbonate in the final product is between about 8.0 wt % to about 15.0 wt %.

10. A method as in claim 1 wherein the desired wt % of alkaline earth metal salt in the final product is between about 2.0 wt % to about 5.0 wt %.

11. A regenerable metal oxide CO₂ sorbent, which comprises:

a. silver carbonate for CO₂ sorption;

b. alkali metal silicate and alkaline earth metal salt as binders;

c. alkali metal carbonate as a sorption promoter.

12. A regenerable metal oxide CO₂ sorbent as in claim 11, wherein said sorbent preparation comprises:

a. pelletizing silver carbonate, wherein pellets are formed;

b. preparing an aqueous solution of alkali metal silicate and alkali metal carbonate, wherein the amount of alkali metal silicate and alkali metal carbonate to utilize is determined via the desired wt % of alkali metal silicate and alkali metal carbonate in the final product;

c. contacting said pellets with said alkali metal silicate/alkali metal carbonate aqueous solution, thereby forming silicate coated, alkali metal carbonate impregnated pellets;

d. drying said silicate coated, alkali metal carbonate impregnated pellets;

e. preparing an aqueous solution of alkaline earth metal salt, wherein the amount of alkaline earth metal salt to utilize is determined by the desired wt % of alkaline earth metal salt in the final product;

f. contacting said silicate coated, alkali metal carbonate impregnated pellets with said alkaline earth metal salt aqueous solution, thereby forming an alkaline earth metal coating on said silicate coated, alkali metal carbonate impregnated pellets;

g. drying said alkaline earth metal/silicate coated, alkali metal carbonate impregnated pellets.

13. A regenerable metal oxide CO₂ sorbent as in claim 12 wherein the pellet size ranges from about 0.30 mm to about 3.00 mm in diameter.

14. A regenerable metal oxide CO₂ sorbent as in claim 12 wherein contacting and drying of said pellets with said alkali metal silicate/alkali metal carbonate aqueous solution, and said alkaline earth metal salt aqueous solution is preformed within a rotatory evaporator.

15. A regenerable metal oxide CO₂ sorbent as in claim 12 wherein the desired wt % of alkali metal silicate in the final product is between about 3.0 wt % to about 8.0 wt %.

16. A regenerable metal oxide CO₂ sorbent as in claim 12 wherein the desired wt % of alkali metal carbonate in the final product is between about 8.0 wt % to about 15.0 wt %.

17. A regenerable metal oxide CO₂ sorbent as in claim 12 wherein the desired wt% of alkaline earth metal salt in the final product is between about 2.0 wt % to about 5.0 wt %.

18. A regenerable metal oxide CO₂ sorbent as in claim 11 wherein the alkali metal silicate is selected from the group consisting of sodium and potassium silicate, and mixtures thereof.

19. A regenerable metal oxide CO₂ sorbent as in claim 11 wherein the alkali metal carbonate is selected from the group consisting of cesium, potassium, and sodium carbonate, and mixtures thereof.

20. A regenerable metal oxide CO₂ sorbent as in claim 11 wherein the alkaline earth metal salt is selected from the group consisting of nitrates and chlorides of calcium, magnesium, barium, and mixtures thereof.

21. A regenerable metal oxide CO₂ sorbent as in claim 11 wherein heat is applied to any of the operations to reduce sorbent preparation time.