(12) INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT) (19) World Intellectual Property Organization International Bureau (10) International Publication Number (43) International Publication Date 29 April 2010 (29.04.2010) WO 2010/045689 Al

(51) International Patent Classification: (74) Agent: FREEHILLS PATENT & TRADE MARK AT¬ BOlD 53/14 (2006.01) BOlD 53/62 (2006.01) TORNEYS; Level 43, 101 Collins Street, Melbourne, BOlD 53/74 (2006.01) BOlD 53/84 (2006.01) Victoria 3000 (AU). BOlD 53/86 (2006.01) COlB 31/20 (2006.01) (81) Designated States (unless otherwise indicated, for every (21) International Application Number: kind of national protection available): AE, AG, AL, AM, PCT/AU2009/001396 AO, AT, AU, AZ, BA, BB, BG, BH, BR, BW, BY, BZ, CA, CH, CL, CN, CO, CR, CU, CZ, DE, DK, DM, DO, (22) International Filing Date: DZ, EC, EE, EG, ES, FI, GB, GD, GE, GH, GM, GT, 23 October 2009 (23.10.2009) HN, HR, HU, ID, IL, IN, IS, JP, KE, KG, KM, KN, KP, (25) Filing Language: English KR, KZ, LA, LC, LK, LR, LS, LT, LU, LY, MA, MD, ME, MG, MK, MN, MW, MX, MY, MZ, NA, NG, NI, (26) Publication Language: English NO, NZ, OM, PE, PG, PH, PL, PT, RO, RS, RU, SC, SD, (30) Priority Data: SE, SG, SK, SL, SM, ST, SV, SY, TJ, TM, TN, TR, TT, 2008905457 23 October 2008 (23.10.2008) AU TZ, UA, UG, US, UZ, VC, VN, ZA, ZM, ZW. (71) Applicant (for all designated States except US): COM¬ (84) Designated States (unless otherwise indicated, for every MONWEALTH SCIENTIFIC AND INDUSTRIAL kind of regional protection available): ARIPO (BW, GH, RESEARCH ORGANISATION [AU/AU]; Limestone GM, KE, LS, MW, MZ, NA, SD, SL, SZ, TZ, UG, ZM, Avenue, Campbell, Australian Capital Territory 2612 ZW), Eurasian (AM, AZ, BY, KG, KZ, MD, RU, TJ, (AU). TM), European (AT, BE, BG, CH, CY, CZ, DE, DK, EE, ES, FI, FR, GB, GR, HR, HU, IE, IS, IT, LT, LU, LV, (72) Inventors; and MC, MK, MT, NL, NO, PL, PT, RO, SE, SI, SK, SM, (75) Inventors/Applicants (for US only): SU, Meihong [AU/ TR), OAPI (BF, BJ, CF, CG, CI, CM, GA, GN, GQ, GW, AU]; 15/21 Cossington Smith Cr, Lyneham, Australian ML, MR, NE, SN, TD, TG). Capital Territory 2602 (AU). HARITOS, Victoria [AU/ AU]; 153 Miller Street, O'Connor, Australian Capital Ter Published: ritory 2602 (AU). — with international search report (Art. 21(3))

(54) Title: USE OF ENZYME CATALYSTS IN CO2 PCC PROCESSES

Bicarbonate production in MEA

Time [ min ]

Figure 1. Bicarbonate production in MEA solution with and without presence of carbonic aiihyclrasc. (example 1)

(57) Abstract: A method for processing a stream enriched in CO from a gas by the action of an absorbent in the stream includes desorbing CO2 from the stream by application of heat to the stream to desorb the CO2 and regenerate the absorbent in a reaction system that includes reconstitution of carbon dioxide and an alkanolamine from carbamate and ammonium ion solution. The ener gy requirement for the aforementioned reconstitution is materially reduced by the presence of a biocatalyst. The biocatalyst may be selected for its activity in cleaving urethane bonds to effect release of CO2 and an amine. In another aspect, a gas stream is con tacted with a sorbent system to effect absorption of CO2 from the gas stream, the sorbent and absorbed CO2 are separated from the gas stream to form a Cθ 2-rich stream, and the sorbent system contains a primary or secondary alkanolamine and a catalyst selected to modify the reaction kinetics of the absorption process so as to materially increase the proportion of bicarbonate in the CO2-rich stream relative to carbamate. USE OF ENZYME CATALYSTS IN CO2 PCC PROCESSES

Field of the invention

This invention relates generally to the use of enzyme catalysts in the recovery of carbon dioxide from gas streams. The invention has particular application to CO2 recovery from flue gases generated by coal- and gas-fired power plants or from process gases in a wide variety of industrial processes including steel plants, smelters, cement kilns and calciners. The ter m "process gases" refer to gas streams fed to or from a process, and embraces, e.g. syngas feed to an industrial furnace, and blast furnace gas in a steel plant.

Background of the invention

There is rapidly growing pressure for stationary sources of CO2 emissions such as power stations, to make step reductions in greenhouse gas (GHG) emissions through 1) capturing the CO2 formed from the process, and 2) storing the CO by various geological means. Most involve injecting CO2 in a supercritical or "liquefied" state into deep aquifers, coal seams and adjacent strata, or at depth in the ocean, or converting the CO2 into a solid mineral form.

In the case of power stations, as an example, there are at present three main approaches to CO2 separation from new or existing power plants: 1) post combustion capture, 2) precombustion capture, and, 3) oxygen combustion with flue gas liquefaction. In this context, the present invention is primarily applicable to post combustion capture.

In post combustion (PCC) capture, the CO2 in flue gases is preferentially separated from nitrogen and residual oxygen using a liquid solvent in an absorber. The CO2 is then removed from the solvent in a process called desorption (or regeneration, and sometimes termed "stripping"), thus allowing the solvent to be reused. The desorbed

CO2 is liquefied by compression and cooling, with appropriate drying steps to prevent hydrate formation. The main disadvantage of this process is that the CO2 partial pressure is relatively low (compared to the two alternative approaches mentioned above), which necessitates the use of CO2 selective solvents. The regeneration of these solvents releases an essentially pure CO2 stream, but this step is relatively energy intensive. Overall, this reduces the electrical power output by around 20%, due to the need to provide low temperature heat (approximately 65% of the total energy required) and work to drive the CO2 liquefaction plant and other auxiliary equipment. Both heat and work are also required for dehydration of the liquefied product CO2. The net effect is to reduce the thermal efficiency of the plant by around 9 percentage points.

Post combustion capture in this form is applicable to other stationary CO2 sources, such as steel plants, cement kilns, calciners and smelters.

Amines in general, and alkanolamines in aqueous solution in particular, are a traditional class of liquid solvent for effecting the absorbent step in post combustion capture. Well known amines in this category are monoethanolamine (HOCH 2CH2NH2, known as

MEA) and diethanolamine ((HOCH 2CH2)2NH, known as DEA), respectively examples of primary and secondary alkanolamines. With these solvents, a primary reaction with the carbon dioxide produces carbamate, which must then be hydrolysed to bicarbonate. However, with MEA and DEA, the carbamate compound is highly stable, due to the unrestricted rotation of the aliphatic carbon atom around the amino carbamate group. To overcome this disadvantage, a range of sterically hindered amines have been proposed: in this case the rotation of the alkyl group around the amino carbamate group is restricted, resulting in low stability of the carbamate compound and ready hydrolysis to bicarbonate.

Another proposal for enhancing the absorption stage of the post combustion process has been to employ biocatalysts to improve the reaction rate of the primary reactions. The usual catalyst proposed is carbonic anhydrase or its analogues. For example, international patent publication W O 2006/089423 proposes a formulation for the absorption of CO2 that comprises water, any of a wide range of CO2 absorption compounds, and a carbonic anhydrase as activator to enhance the absorption capacity of the CO2 absorption compound. This compound is said to be preferably selected from the group consisting of amines, alkanolamines, dialkylether of polyalkylene glycols and mixtures thereof. ό

Other disclosures of interest in relation to biocatalysis of absorption reactions are to be found in US patent publicatios 2004/0219090 and US 2004/0259231 , and in international patent publications WO 2004/028667 and WO 2004/056455.

It is an object of this invention to provide further enhancements of post combustion CO2 capture processes through the use of biocatalysts and in preferred implementations by enzymatic catalysis.

It is not admitted that any of the information in this specification is common general knowledge, or that the person skilled in the art could reasonably be expected to have ascertained, understood, regarded it as relevant or combined it in any way at the priority date.

Summary of the Invention

In a first aspect, the invention redirects attention from the focus of the last several years on the absorption reaction and proposes applications of biocatalysts in the desorption or stripping stage of the post combustion capture (PCC) process.

In its first aspect, the invention provides a method of processing a stream enriched in

CO2 from a gas by the action of an absorbent in the stream, comprising

desorbing CO from the stream by application of heat to the stream to desorb the CO2 and regenerate the absorbent in a reaction system that includes reconstitution of carbon dioxide and an alkanolamine from carbamate and ammonium ion solution,

wherein the energy requirement for the aforementioned reconstitution is materially reduced by the present of a biocatalyst.

In certain embodiments of the invention, the aforementioned reconstitution may be represented by the following reaction sequence:

+ RNHCOO- + RNH3 = 2RNH2 + CO2 (1) where R is an alkanol group and RNH2 is the reconstituted alkanolamine and is a primary or secondary alkanolamine.

Preferably the recovered CO2 is separated and further treated, for example by being liquefied by compression and cooling.

Typically, the method of the first aspect is part of an overall cyclic post-combustion capture process that includes the earlier steps of cooling a stream of flue gases to a temperature suitable for efficient absorption of CO2, contacting the stream of flue gases with a predetermined sorbent system to effect absorption of CO2 from the stream of flue gases, separating the sorbent and absorbed CO2 from the stream of flue gases to form a CO2-rich stream, and effecting said desorbing step on the CO2-rich stream.

For the first aspect of the invention, the biocatalyst may be an enzyme. A suitable enzyme may be selected from the group consisting of the hydrolase, lyase and ligase classes, although it is thought that, due, to their activity levels, one or more selected hydrolases may be preferred.

In accordance with an advantageous implementation of the first aspect of the invention, the biocatalyst is selected for its activity in cleaving urethane bonds to effect release of

CO2 and an amine. An insight of the present invention that has given rise to this implementation is the realisation that enzymes reported to be useful for the biodegradation of polyurethane would be applicable to the desorption of CO2 from carbamate solutions because the -0-(CO)-N- functional group is common to urethane and to MEA carbamate solutions and it is the cleavage of this functional group that is catalysed by a biocatalyst in the biodegradation of polyurethane.

The thus selected biocatalyst may be a urethanase enzyme (EC 3.5.1 .75). A suitable urethanase enzyme may be prepared from inter alia, Bacillus licheniformis, Rhodococcus equi and Citrobacter freundii. Urethanase enzymes have also been extracted from Lactobacillus casei and Exophiala jeanselmei. The abbreviations "EC" and "EC numbers" herein, and accompanying notations, are references to the enzyme classification as established by the nomenclature committee of the International Union of Biochemistry and Molecular Biology (NC-IUBMD).

Also of particular interest may be the aliphatic amidohydroases and urethane amidohydrolase.

Other enzymes that may also be of interest as the biocatalyst present in a method according to the first aspect of the invention include the following:

Hydrolase class: members of the amidohydroases group with EC numbers 3 .5.1 .X, in particular 3.5.1 .3 omega-amidases, 3.5.1 .4 aliphatic amidases, 3.5.1 .5 urease, 3.5.1 .6 β-ureidopropionase, 3.5.1 .53 N-carbamoylputrescine amidohydrolase, 3.5.1 .54 urea-1- carboxylate amidohydrolase, 3.5.1 .59 N-carbamoylsarcosine amidohydrolase (and related enzymes such as N-carbamyl-amino acid amidohydrolase) and 3.5.1 .75 urethane amidohydrolase. Members of the esterase group with EC numbers 3.1.1 .X including 3.1 . 1 . 1 carboxylesterase, 3.1 .1 .3 triacylalycerol lipase and 3.1 . 1 .34 lipoprotein lipase. Also the peptide hydrolase group 3.4.X.X including 3.4.21 .X serine endopeptidases and 3.4.24.X metalloendopeptidases.

Lyase class: members of the carboxy lyases (carbon-carbon lyases) especially all decarboxylases of EC numbers 4.1 . 1 . 1 through to 4.1 .1 .86. In particular EC 4.1 . 1 .86 2,4-diaminobutanoate carboxy lyase. The decarboxylation enzymes such as those from the lyase class 4.1.1 .X can be used in combination with carbonic anhydrase to speed up turnover of this class of enzyme as has been noted (Botre, F. Mazzei F ( 1999) Bioelectrochemistry and Bioenergetics 48: 463-467). Other carbon-nitrogen lyases are also enzymes with these activities especially EC 4.2.1 .104 cyanate hydratase (cyanase) and 4.3.2.3 ureidoglycolate urea lyase.

Ligase class: members of the EC 6.3.X.X class are involved in C-N bond formation but act reversibly. Of particular note is EC 6.3.4.6 urea carboxylase that catalyses the reversible carboxylation of urea.

In a second aspect, the invention is directed to a process for recovering carbon dioxide from a gas stream, comprising: t >

contacting the gas stream with a sorbent system to effect absorption of CO2 from

the gas stream, and separating the sorbent and absorbed CO2 from the gas

stream to form a CO2-rich stream;

wherein the sorbent system contains a primary or secondary alkanolamine and a 5 catalyst, preferably a biocatalyst, selected to modify the reaction kinetics of the absorption process so as to materially increase the proportion of bicarbonate in

the CO2-rich stream relative to carbamate.

By increasing the proportion of bicarbonate relative to carbamate, the energy cost of a

downstream desorption step, in which the CO is separated from the CO2-rich stream 0 and the absorbent is regenerated, can be materially and advantageously reduced.

Preferably, the method in its second aspect includes the further step of desorbing CO2

from the CO2-rich absorbent stream by application of heat to the absorbent stream to

desorb the CO and regenerate the sorbent system. The separated CO2 is preferably further treated, for example by being liquefied by compression and cooling.

5 Where the sorbent system contains a primary or secondary alkanolamine, the conventional principal reaction, i.e. in the absence of the selected biocatalyst of the invention, brings carbon dioxide into a solution as a carbamate according to the following reaction:

+ 2 RNH2 + CO2 RNHCOO- + RNH3 (2)

>0 where R is an alkanol group. Enzymatic catalysis is thought to favour the following reaction system:

RNH2 + CO2 + H2O . RNH3 + HCO3- (3)

By appropriate selection of the biocatalyst, the strong carbamate reaction can be relatively diminished in favour of the direct hydrolysis bicarbonate reaction.

!5 A carbonic anhydrase is a suitable biocatalyst for the practice of the second aspect of the invention. As used herein, except where the context requires otherwise the term "comprise" and variations of the term, such as "comprising", "comprises" and "comprised", are not intended to exclude other additives, components, integers or steps.

Example 1

Preparation and activity of a suitable urethanase

For urethanase production, a single clony of Bacillus licheniformis (ATCC#: 14580) was grown in 50 ml nutrient broth overnight at 370C with shaking at 200 rpm. The whole culture was then inoculated into fresh 500 ml nutrient broth and incubated at 370C with shaking at 160 rpm for another 12 hours. The cells were collected by centrifugation at 5000 x g for 15 min at 40C. The cells were resuspended in 20 mM Tris-CI buffer (pH 7.5) and disrupted with the French pressure cell press. The cell-free extract was collected by centrifugation at 6000 x g for 20 min at 40C. The cell free extract (W1) was fractionated by precipitation with 0-20 (F1), 20-40 (F2), 40-60 (F3), 60-80 (F4) and 80- 100 % (F5) saturated ammonium sulphate. Each fraction was dialyzed against 20 mM Tris-CI buffer, pH 7.5 to get rid of ammonium sulphate before test the enzyme activity by ammonia ion selective electrode.

Urethanase activity was first assessed by ammonia ion selective microelectrode (Ml- 740 Dip-type NH3 electrode, Microelectrodes, Inc., Bedford, NH, USA) based on the amount of ammonia releasing from respective substrates of urethane, acetamide and butyl carbamate. In a typical experiment, 50 µl_ of cell-free extract was added to 250 µl_ of 100 mM urethane and acetamide, 4 mM butyl carbamate solutions. The reaction solutions were prepared in a 96 well plate and the reactions were carried out at 250C in 20 mM Tris-CI buffer, pH 7.5. Measurements were taken after the reading from the electrode had stabilized. The results showed that the cell free extract and the F4 fraction (60-80% ammonium sulphate precipitation) had good urethanase activity with acetamide and butyl carbamate (table 1).

The F4 fractions that showed good initial urethanase activity were further purified by an ion exchange chromatography and eluted with a linear gradient of sodium chloride (0- 0.5M). Urethanase activity of each fraction was assessed by ammonia ion selective microelectrode based on the amount of ammonia released from the substrates, mentioned in the previous step. The fractions exhibiting urethanase activity were pooled and concentrated by ultrafiltration.

Further purification was achieved by running size exclusion chromatography. The concentrated enzyme solution from the preceding ion exchange purification was directly applied to a sepharose column and eluted with 20 mM Tris buffer, pH 7.5. The enzyme activity was tested by microelectrode based on the amount of ammonia released from the substrates, mentioned earlier. The active fractions were pooled and concentrated by ultrafiltration.

SDS-PAGE was then run to test the purification of urethanase. Hydroxyapatite chromatography and isoelectric chromatofocusing can be applied if further purification is required.

Table 1. Enzyme activity of cell free extract (W1), 0-20 (F1), 20-40 (F2), 40-60 (F3), 60- 80 (F4) and 80-1 00% (F5) fractions against three substrates

+++: high activity ++: middle activity +: some activity -: no activity Example 2

Bicarbonate production in MEA solution with and without a biocatalvst

50 mL of freshly prepared 0.5 M monoethanolamine (MEA) solution in D2O was poured into a 125 mL Dreschel bottle and 80 µl_ of the solution was taken as a zero time

1 sample (control). 100 mL rnin of 2% CO2 in 98% N2 was bubbled into the stirred solution through the sintered glass outlet via a silicon tube in the bottle head. A subsample of the solution (80 µL) was taken every 5 minutes and the IR absorbance was immediately measured between 1300 to 1700 cm 1 . The bicarbonate peak at 1630 cm 1 was used as it was free of background noise. The area under the peak at 1630 cm 1 was calculated for each sample to provide the concentration of bicarbonate over a period of 60 minutes. The experiment was repeated under the same conditions in the presence of 10 mg of carbonic anhydrase (CA II). The results are shown in Figure 1.

The concentration of bicarbonate produced in the MEA solution without enzyme was less than 2mM and then did not increase during the 60 minutes period of bubbling. In the solution with CA II, initial production of bicarbonate was low due to formation of MEA carbamate, which is the faster reaction. The kinetics of CO2 absorption were obtained from measurements of the CO2 concentration in the exit-gas stream from the Dreschel bottle shown in Figure 2. After the initial period of MEA-carbamate formation, the concentration of bicarbonate increased linearly, reaching 14.9 mM at the end of the 60 minutes (Figure 1).

The reduced concentration of CO2 in the exit-gas stream in the presence of CA Il as shown in Figure 2 indicates that more CO2 is absorbed in the MEA solution in the presence of the enzyme compared to that without enzyme. The increased absorption of

CO2 results in higher concentration of bicarbonate produced in the MEA solution in the presence of CA Il compared to that without enzyme. It is therefore concluded that the presence of enzyme has altered the final ratio between produced carbamate and bicarbonate. Higher production of bicarbonate in MEA solution is favorable for industrial application due to lower energy demand for bicarbonate regeneration, resulting in lower regeneration costs. CLAIMS

1. A method of processing a stream enriched in CO2 from a gas by the action of an absorbent in the stream, comprising:

desorbing CO from the stream by application of heat to the stream to desorb the

CO2 and regenerate the absorbent in a reaction system that includes reconstitution of carbon dioxide and an alkanolamine from carbamate and ammonium ion solution,

wherein the energy requirement for the aforementioned reconstitution is materially reduced by the presence of a biocatalyst.

2 . The method according to claim 1, wherein the reconstitution is represented by the following reaction sequence:

+ RNHCOO- + RNH3 2RNH2 + CO2

where R is an alkanol group and RNH2 is the reconstituted alkanolamine and is a primary or secondary alkanolamine.

3 . The method according to claim 1 or 2 , wherein the recovered CO2 is separated and further treated, by being liquefied by compression and cooling.

4 . The method according to any of claims 1, 2 or 3, wherein the method is part of an overall cyclic post-combustion capture process that includes the earlier steps of cooling a stream of flue gases to a temperature suitable for efficient absorption of CO2, contacting the stream of flue gases with a predetermined sorbent system to effect absorption of CO2 from the stream of flue gases, separating the sorbent and absorbed

CO2 from the stream of flue gases to form a CO2-rich stream, and effecting said desorbing step on the CO2-rich stream.

5. The method according to any one of claims 1 to 4 , wherein the biocatalyst is an enzyme. 6. The method according to claim 5 , wherein the enzyme is selected from the group consisting of the hydrolase, lyase and ligase classes.

7. The method according to claim 6 , wherein the hydrolase class includes members of the amidohydroases group with EC numbers 3.5.1 .X , including 3.5.1 .3 omega- amidases, 3.5.1 .4 aliphatic amidases, 3.5.1 .5 urease, 3.5.1 .6 β-ureidopropionase, 3.5.1 .53 N-carbamoylputrescine amidohydrolase, 3.5.1 .54 urea-1-carboxylate amidohydrolase, 3.5.1 .59 N-carbamoylsarcosine amidohydrolase (and related enzymes such as N-carbamyl-amino acid amidohydrolase) and 3.5.1 .75 urethane amidohydrolase, members of the esterase group with EC numbers 3.1. 1 .X including

3.1 .1 . 1 carboxylesterase, 3.1 . 1 .3 triacylalycerol lipase and 3.1 . 1 .34 lipoprotein lipase, and members of the peptide hydrolase group 3.4.X.X including 3.4.2 1.X serine endopeptidases and 3.4.24.X metalloendopeptidases.

8. The method according to claim 6 or 7, wherein the lyase class includes members of the carboxy lyases (carbon-carbon lyases) including all decarboxylases of EC numbers 4.1 .1 . 1 through to 4.1.1 .86, EC 4.1 .1 .86 2,4-diaminobutanoate carboxy lyase, and carbon-nitrogen lyases including EC 4.2.1 .104 cyanate hydratase (cyanase) and 4.3.2.3 ureidoglycolate urea lyase.

9. The method according to any one of claims 6 to 8 , wherein the ligase class includes members of the EC 6.3.X.X class including EC 6.3.4.6 urea carboxylase.

10. The method according to any one of claims 1 to 9 wherein the biocatalyst is selected for its activity in cleaving urethane bonds to effect release of CO2 and an amine.

11. The method according to claim 10 wherein the biocatalyst is a urethanase enzyme.

12. The method according to claim 11 wherein the urethanase enzyme has been prepared from one of Bacillus licheniformis, Rhodococcus equi, Citrobacter freundii, Lactobacillus case/ and Exophiala jeanselmei. 13. The method according to any one of claims 1 to 5 wherein the biocatalyst is selected from aliphatic amidohydroases and urethane amidohydrolases.

14. The method according to claim 6 , wherein the enzyme is one of cyanate hydratase (cyanase), EC number: 4.2.1 .104 and N-carbamoylputrescine amidohydrolase, EC number: 3.5.1 .53.

15. The method according to claim 6, wherein the enzyme is one of beta- ureidopropionase, EC number: 3.5.1 .6 and N-carbamoylsarcosine amidohydrolase, EC number: 3.5.1 .59.

16. A process for recovering carbon dioxide from a gas stream, comprising:

contacting the gas stream with a sorbent system to effect absorption of CO2 from the gas stream, and separating the sorbent and absorbed CO2 from the gas stream to form a CO2-rich stream;

wherein the sorbent system contains a primary or secondary alkanolamine and a catalyst selected to modify the reaction kinetics of the absorption process so as to materially increase the proportion of bicarbonate in the CO2-rich stream relative to carbamate.

17. The process according to claim 16, wherein the catalyst is a biocatalyst.

18. The process according to claim 16 or 17, further including the step of desorbing

CO2 from the CO2-rich absorbent stream by application of heat to the absorbent stream to desorb the CO2 and regenerate the sorbent system.

19. The process according to claim 18, wherein the separated CO2 is further treated by being liquefied by compression and cooling.

20. The process according to any one of claims 16 to 19, wherein the biocatalyst is a carbonic anhydrase.

International application No INTERNATIONAL SEARCH REPORT PCT/ A U 2009/00 1396

A CLASSIFICATION OF SUBJECT MATTER lnt Cl

BOlD 53/14 (2006 0 1) BOlD 53/74 (2006.0 1) BOlD 53/86 (2006.0 1) BOlD 53/62 (2006 0 1) BOlD 53/84 (2006.0 1) COlB 31/20 (2006 0 1)

According to International Patent Classification (IPC) or to both national classification and IPC

B. F IELDS SEARCHED

Minimum documentation searched (classification system followed by classification symbols)

Documentation searched other than minimum documentation to the extent that such documents are included in the fields searched

Electronic data base consulted during the international search (name o f data base and, where practicable, search terms used) EPODOC & WPl IPC & ECLA marks as above and key words. Carbon dioxide, absorb+, absorp+, desorp+, desorb+, biocatalyst, enzyme+ and similar terms

C DOCUMENTS CONSIDERED TO BE RELEVANT

Category* Citation of document, with indication, where appropriate, of the relevant passages Relevant to claim N o WO 2009/000025 A l (COMMONWEALTH SCIENTIFIC AND INDUSTRIAL RESEARCH ORGANISATION) 3 1 December 2008 P X Whole document particularly abstract and claims 1, 3-6. 16-20

WO 2006/108532 A l (SALOMON!, CESARINO ET AL) 19 October 2006 X Whole document particularly abstract; pages 2-4; page 2 1, lines 6-9; claims 1-4 1, 3, 5-6, 16-1 7, 19-20 Y Whole document particularly abstract; pages 2-4: page 21, lines 6-9; claims 1-4 4, 18

U S 2004/025923 1 A l (BHATTACHARYA) 23 December 2004 Whole document particularly abstract; all claims 16-1 7. 20

Further documents are listed in the continuation of Box C X See patent family annex

* Special categories of cited documents "A" documeni defining ihe general stale of the an which is "T" later document published after the international tiling date or prio π ry dale and nol in nol considered to be ol particular relevance conflict with the application but cited to understand the principle or theory underlying the invention "E" earlier application or patent but published on or after the "X" documeni of particular relevance the claimed ιn\enlion cannot be considered novel international filing date or cannot be considered to involve an inventive step when the document is taken alone ' L" documeni which may throw doubts on priority cla ιm(s) "Y" document of particular relevance, the claimed invention cannot be considered to or which is cited to establish the publication date of involve an inventive step when the documeni is combined with one or more other another citation or other special reason (as specified) such documents, such combination being obvious to a person skilled in the art "O" documeni referring to an oral disclosure, use, exhibition or other means "ii" documeni member of the same patent family ' P" documeni published prior to the international filing date 'but later than the priority dale claimed Date o f the actual completion of Ihe international search Date of mailing of the international search report 12 November 2009 1 8 NOV 2009 Name and mailing address o l the I S /AU Authorized officer SANTOSH GLPTA AUSTRALIAN PATENT OFFICE PO BOX 200. WODEN ACT 2606. AUSTRALIA AUSTRALIAN PATENT OFFICE E-mail address pct@ ιpaustral ιa gov au ( ISO 900 1 Quality .Certified Service) Facsimile No +6 1 2 6283 7999 Telephone No +6 1 2 6283 7947

Form PCT/ISA/2 10 (second sheet) (July 2009) INTERNATIONAL SEARCH REPORT International application No PCT/AU2009/001396 C (Continuation) DOCUMENTS CONSIDERED TO BE RELEVANT

Category* Citation of document, with indication, where appropriate, of the relevant passages Relevant to claim No

WO 2006/089423 A l (CO2 SOLUTIONS INC.) 3 1 August 2006 X Whole document particularly abstract; page 1, linesl 0-1 7; all claims 16-17, 20

WO 2004/056455 A l (CO2 SOLUTIONS INC.) 8 July 2004 Whole document particularly abstract; all claims 16-1 7, 20

WO 2007/012143 A l (COMMONWEALTH SCIENTIFIC AND INDUSTRIAL RESEARCH ORGANISATION) I February 2007 Y Abstract, Claims I and 5 4, 18

Form PCT/ISA/2 10 (continuation o t second sheet) (July 2009) INTERNATIONAL SEARCH REPORT International appl ication No. Information on patent family members PCT/AU2009/001396

This Annex lists the known "A" publication level patent family members relating to the patent documents cited in the above-mentioned international search report. The Australian Patent Office is in no way liable for these particulars which are merely given for the purpose of information.

Patent Document Cited in Patent Family Member Search Report

WO 2009000025 NONE WO ' 2006108532 EP 1984098 IT BO200502I 7 US 2004259231 US 2005214936 WO 2006089423 AU 200621 7575 CA 2599493 EP 1850947 US 2008148939 WO 2004056455 AU 2003292930 CA 2414871 CA 2509989 WO 2007012143 AU 2006274437

Due to data integration issues this family listing may not include 10 digit Australian applications filed since May 2001 .

END OF ANNEX

Form PCT/ISA/2 10 (patent family annex) (July 2009)