TECHNIQUES FOR CO2 CAPTURE USING SULFURIHYDROGENIBIUM SP. CARBONIC ANHYDRASE

1 . A method for capturing CO 2 from a CO 2 -containing gas, the method comprising:

contacting the CO 2 -containing gas with an aqueous absorption solution to dissolve the CO 2 into the aqueous absorption solution, the aqueous absorption solution comprising a carbonate compound as an absorption compound;

providing a recombinant Sulfurihydrogenibium sp. carbonic anhydrase (SspCA) having improved thermostability in the presence of carbonate ions as compared to in the absence of carbonate ions, to catalyze the hydration reaction of the dissolved CO 2 into bicarbonate and hydrogen ions; and

providing operating conditions such that the SspCA displays said improved thermostability.

2 . The method of claim 1 , wherein said operating conditions comprise exposing the SspCA to temperatures between 70° C. and 95° C. at some point during said method.

3 . The method of claim 1 , wherein said contacting is performed at a temperature between 10° C. and 90° C.; and/or the pH of the absorption solution is between 8 and 11.

4 . The method of claim 1 , wherein the concentration of the absorption compound in the absorption solution is between 0.1M and 5M.

5 . The method of claim 1 , wherein the absorption compound comprises sodium carbonate, potassium carbonate, or another carbonate salt.

6 . The method of claim 1 , wherein at least a portion of the SspCA provided is dissolved in the absorption solution at a concentration of 0.1 to 50 g/L.

7 . The method of claim 1 , wherein at least a portion of the SspCA provided is immobilized, entrapped, or otherwise attached, to particles comprised in the absorption solution, to packing material, or to other fixed structures in contact with the absorption solution.

8 . The method of claim 1 , wherein the SspCA is from Sulfurihydrogenibium sp. Y03A0P1 or Sulfurihydrogenibium azorense.

9 . The method of claim 1 , wherein the SspCA comprises one or more differences as compared to a wild-type carbonic anhydrase therefrom at residue positions corresponding to positions 18, 20, 38, 52, 57, 82, 100, 130, 150, and 181 of SEQ ID NO: 8.

10 . The method of claim 9 , wherein said one more amino acid differences, with respect to the amino acid residue positioning of SEQ ID NO: 8, comprise:

(a) 18A, 18C, 18F, 18L, 18R, 18S, 18T, or 18W;

(b) 20A, 20G, 20L, 20N, 20R, 20S, 20T, or 20W;

(c) 38A, 38D, 38G, 38L, 38N, 38P, 38R, 38S, or 38W;

(d) 52C, 52E, 52G, 52P, or 52T;

(e) 57A, 57G, 57L, 57N, 57P, 57R, 57S, or 57V;

(f) 82C or 82E;

(g) 100A, 100E, 100N, 100S, 100V, or 100Y;

(h) 130A, 130C, or 130L;

(i) 150A, 150I, 150N, or 150S;

(j) 181Q, 181L, 181M, or 181R; or

(k) any combination of (a) to (j).

11 . The method of claim 10 , wherein said one more amino acid differences, with respect to the amino acid residue positioning of SEQ ID NO: 8, further comprise 14D, 65S, 88E, 114I, 116D, 122I, 126L, 148A, 155I, 205C, or any combination thereof.

12 . The method of claim 9 , wherein said one more amino acid differences, with respect to the amino acid residue positioning of SEQ ID NO: 8, comprise two or more amino acid differences which are: 18T and 20A; 18R and 20A; 2K, 181M, and 197I; 14D and 18R; 52C, 122I, 150N, and 226S; 65S and 150I; 57R and 130C; 82C and 88E; 82C and 148A; 126L and 130L; 82C and 100V; 38C, 82C, and 100V; 38G, 82C, and 100V; 38R, 82C, and 100V; 38S, 82C, and 100V; 38W, 82C, and 100V; 38S, 57A, 82C, and 100V; 38S, 57G, 82C, and 100V; 38S, 57L, 82C, and 100V; 38S, 57S, 82C, and 100V; 38S, 57V, 82C, and 100V; 18F, 20G, 38S, 57L, 82C, and 100V; 18R, 20G, 38S, 57L, 82C, and 100V; 18W, 20G, 38S, 57L, 82C, and 100V; 18R, 20W, 38S, 57L, 82C, and 100V; 18R, 20A, 38S, 57L, 82C, and 100V; 18R, 20R, 38S, 57L, 82C, and 100V; 18C, 20S, 38S, 57L, 82C, and 100V; 18C, 20V, 38S, 57L, 82C, and 100V; 18A, 20T, 38S, 57L, 82C, and 100V; or 18F, 20R, 38S, 57L, 82C, and 100V.

13 . The method of claim 1 , wherein the aqueous absorption solution further comprises a further absorption compound which is a primary amine, a secondary amine, a tertiary amine, a primary alkanolamine, a secondary alkanolamine, a tertiary alkanolamine, a primary amino acid, a secondary amino acid, a tertiary amino acid, dialkylether of polyalkylene glycols, dialkylether or dimethylether of polyethylene glycol, amino acid or a derivative thereof, monoethanolamine (MEA), 2-amino-2-methyl-1-propanol (AMP), 2-(2-aminoethylamino)ethanol (AEE), 2-amino-2-hydroxymethyl-1,3-propanediol (Tris or AHPD), N-methyldiethanolamine (MDEA), dimethylmonoethanolamine (DMMEA), diethylmonoethanolamine (DEMEA), triisopropanolamine (TIPA), triethanolamine (TEA), DEA, DIPA, MMEA, TIA, TBEE, HEP, AHPD, hindered diamine (HDA), bis-(tertiarybutylaminoethoxy)-ethane (BTEE), ethoxyethoxyethanol-tertiarybutylamine (EEETB), bis-(tertiarybutylaminoethyl)ether, 1,2-bis-(tertiarybutylaminoethoxy)ethane and/or bis-(2-isopropylaminopropyl)ether, piperazine, a piperazine derivative, a piperazine or derivative thereof substituted by at least one of alkanol group, or any combination thereof.

14 . A method for CO 2 capture, the method comprising:

in an absorption stage:

contacting a CO 2 -containing gas with an aqueous absorption solution to dissolve the CO 2 into the aqueous absorption solution, the absorption solution comprising a carbonate compound as an absorption compound;

providing a recombinant Sulfurihydrogenibium sp. carbonic anhydrase (SspCA) having improved thermostability in the presence of carbonate ions as compared to in the absence of carbonate ions, in the absorption solution to catalyze the hydration reaction of the dissolved CO 2 into bicarbonate and hydrogen ions, thereby producing an ion-rich solution comprising at least some of the SspCA and a CO 2 -depleted gas; and

in a desorption stage:

providing conditions for treating the ion-rich solution comprising at least some of the SspCA, so as to desorb CO 2 gas from the ion-rich solution, thereby producing a regenerated absorption solution and a CO 2 gas stream.

15 . The method of claim 14 , wherein the absorption is operated at temperatures between 20° C. and 80° C.; and the desorption is operated at temperatures between 70° C. and 110° C.

16 . The method of claim 14 , wherein:

(a) the absorption solution has a pH of between 8 and 11;

(b) the concentration of the absorption compound in the absorption solution is between 0.1 M and 5 M;

(c) the absorption compound comprises sodium carbonate, potassium carbonate, or another carbonate salt;

(d) at least a portion of the SspCA provided is dissolved in the absorption solution at a concentration of 0.1 to 50 g/L;

(e) at least a portion of the SspCA provided is immobilized, entrapped, or otherwise attached, to particles comprised in the absorption solution, to packing material, or to other fixed structures in contact with the absorption solution;

(f) the aqueous absorption solution further comprises a further absorption compound which is a primary amine, a secondary amine, a tertiary amine, a primary alkanolamine, a secondary alkanolamine, a tertiary alkanolamine, a primary amino acid, a secondary amino acid, a tertiary amino acid, dialkylether of polyalkylene glycols, dialkylether or dimethylether of polyethylene glycol, amino acid or a derivative thereof, monoethanolamine (MEA), 2-amino-2-methyl-1-propanol (AMP), 2-(2-aminoethylamino)ethanol (AEE), 2-amino-2-hydroxymethyl-1,3-propanediol (Tris or AHPD), N-methyldiethanolamine (MDEA), dimethylmonoethanolamine (DMMEA), diethylmonoethanolamine (DEMEA), triisopropanolamine (TIPA), triethanolamine (TEA), DEA, DIPA, MMEA, TIA, TBEE, HEP, AHPD, hindered diamine (HDA), bis-(tertiarybutylaminoethoxy)-ethane (BTEE), ethoxyethoxyethanol-tertiarybutylamine (EEETB), bis-(tertiarybutylaminoethyl)ether, 1,2-bis-(tertiarybutylaminoethoxy)ethane and/or bis-(2-isopropylaminopropyl)ether, piperazine, a piperazine derivative, a piperazine or derivative thereof substituted by at least one of alkanol group, or any combination thereof; or

(g) any combination of (a) to (f).

17 . The method of claim 14 , wherein the SspCA is from Sulfurihydrogenibium sp. Y03A0P1 or Sulfurihydrogenibium azorense ; and/or the SspCA comprises one or more differences as compared to a wild-type carbonic anhydrase therefrom at residue positions corresponding to positions 18, 20, 38, 52, 57, 82, 100, 130, 150, and 181 of SEQ ID NO: 8.

18 . The method of claim 17 , wherein said one more amino acid differences, with respect to the amino acid residue positioning of SEQ ID NO: 8, comprise:

(a) 18A, 18C, 18F, 18L, 18R, 18S, 18T, or 18W;

(b) 20A, 20G, 20L, 20N, 20R, 20S, 20T, or 20W;

(c) 38A, 38D, 38G, 38L, 38N, 38P, 38R, 38S, or 38W;

(d) 52C, 52E, 52G, 52P, or 52T;

(e) 57A, 57G, 57L, 57N, 57P, 57R, 57S, or 57V;

(f) 82C or 82E;

(g) 100A, 100E, 100N, 100S, 100V, or 100Y;

(h) 130A, 130C, or 130L;

(i) 150A, 150I, 150N, or 150S;

(j) 181Q, 181L, 181M, or 181R; or

(k) any combination of (a) to (j).

19 . The method of claim 18 , wherein said one more amino acid differences, with respect to the amino acid residue positioning of SEQ ID NO: 8, further comprise 14D, 65S, 88E, 114I, 116D, 122I, 126L, 148A, 155I, 205C, or any combination thereof.

20 . The method of claim 17 , wherein said one more amino acid differences, with respect to the amino acid residue positioning of SEQ ID NO: 8, comprise two or more amino acid differences which are: 18T and 20A; 18R and 20A; 2K, 181M, and 197I; 14D and 18R; 52C, 122I, 150N, and 226S; 65S and 150I; 57R and 130C; 82C and 88E; 82C and 148A; 126L and 130L; 82C and 100V; 38C, 82C, and 100V; 38G, 82C, and 100V; 38R, 82C, and 100V; 38S, 82C, and 100V; 38W, 82C, and 100V; 38S, 57A, 82C, and 100V; 38S, 57G, 82C, and 100V; 38S, 57L, 82C, and 100V; 38S, 57S, 82C, and 100V; 38S, 57V, 82C, and 100V; 18F, 20G, 38S, 57L, 82C, and 100V; 18R, 20G, 38S, 57L, 82C, and 100V; 18W, 20G, 38S, 57L, 82C, and 100V; 18R, 20W, 38S, 57L, 82C, and 100V; 18R, 20A, 38S, 57L, 82C, and 100V; 18R, 20R, 38S, 57L, 82C, and 100V; 18C, 20S, 38S, 57L, 82C, and 100V; 18C, 20V, 38S, 57L, 82C, and 100V; 18A, 20T, 38S, 57L, 82C, and 100V; or 18F, 20R, 38S, 57L, 82C, and 100V.