NOVEL ENZYMATIC PHASE TRANSFER SOLVENT FOR CO2/H2S CAPTURE

Abstract

The present invention relates to a novel phase transfer solvent composition for enhanced CO.sub.2 and/or H.sub.2S capture from flue gas and biogas having various gaseous compositions. Further, the present invention provides a process of preparing the phase transfer solvent composition of the present invention.

Claims

1. A phase transfer solvent composition for enhanced CO.sub.2 and/or H.sub.2S capture from flue gas and biogas having various gaseous compositions, comprising: i) a compound having minimum one primary and/or one secondary amine groups; j) a compound having minimum one tertiary amine; k) a hyperthermophilic enzyme; l) a thermoregulatory enzyme stabilizer; m) a phase splitting agent; n) a phase stabilizing micellar agent; o) a thermo-conductive fluid; and p) 200-600 ml of demineralized water/litre to make up the volume; wherein said solvent composition synergistically improves CO.sub.2/H.sub.2S loading and exhibit a phase separation behaviour with energy-efficient regeneration for CO.sub.2/H.sub.2S.

2. The phase transfer solvent composition as claimed in claim 1, wherein said compound having minimum one primary and/or one secondary amine groups are selected from group consisting of Monoethanolamine, Diethanolamine, Triethanolamine, Monomethylethanolamine, 2-(2-aminoethoxy)ethanol, Aminoethylethanolamine, Ethylenediamine (EDA), Diethylenetriamine (DETA), Triethylenetetramine (TETA). Tetraethylenepentamine (TEPA), 2-amino 2methyl-1-proponal (AMP), 2-(ethyamino)-ethanol (EAE), 2-(methylamino)-ethanol (MAE), 2-(diethylamino)-ethanol (DEAE), diethanolamine (DEA), diispropanolamine (DIPA), methylaminopropylamine (MAPA), 3-aminopropanol (AP), 2,2-dimethyl-1,3-propanediamine (DMPDA), 3-amino-1-cyclohexylaminopropane (ACHP), diglycola mine (DGA), 1-amino-2-propanol (MIPA), Isobutyl amine, 2-amino-2-methyl-ipropanol, 2-(2-aminoethylamino)ethanol, 2-amino-2-hydroxymethyl-i,3-propanediol, N-methyldiethanolamine, dimethylmonoethanolamine, diethylmonoethanolamine, triisopropanolamine and triethanolamine), trimethylamine, triethylamine, tripropylamine, tributylamine, dimethylethylamine, dimethylpropylamine, dimethylbutylamine, diethylmethylamine, diethylpropylamine, diethylbutylamine, N,N-diisopropylmethylamine, N-ethyldiisopropylamine, N,N-dimethylethylamine, N,N-diethylbutylamine, 1,2-dimethylpropylamine, N,N-diethylmethylamine, N,N-dimethylisopropylamine, 1,3-dimethylbutylamine, 3,3-dimethylbutylamine, N,N-dimethylbutylamine, N-methyl-1,3-diaminopropane, Piperazine and triethylenetetramine or a combination thereof; wherein said compound having minimum one primary and/or one secondary amine groups has a concentration range of 20-50 wt % in phase transfer solvent and depend on the feed gas CO.sub.2 concentration.

3. The phase transfer solvent composition as claimed in claim 1, wherein compounds having minimum one tertiary amine are selected from diethylethanolamine, dimethylethanolamine, diisopropanolamine, methyldiethanolamine, triethanolamine, 2-Amino-2-MethylPropan-1-ol, bis (2-dimethylaminoethyl) ether, tetramethyl-1,2-ethanediamine, tetramethyl-3-propane, N-methyl diethanolamine, Dimethylethanolamine Tetramethyl-6-hexanediamine, 1,3,5-Trimethylhexahydro-1,3,5-triazine N,N,N′,N′-Tetramethyl-2-butene-1,4-diamine, Pentamethyldipropylenetriamine, N,N-diethylethanolamine, N,N-dimethylbutylamine, 3-(methyloamino)propylamine, or a combination thereof; and wherein compound having minimum one tertiary amine has a concentration range from 20-30 wt % in phase transfer solvent and depends on the feed gas CO.sub.2 concentration.

4. The phase transfer solvent composition as claimed in claim 1, wherein said hyperthermophilic enzyme is Carbonic Anhydrase (CA) obtained from a source selected from the group consisting of Bacillus thermoleovorans IOC-S3 (MTCC 25023) and/or Pseudomonas fragi IOC S2 (MTCC 25025), and/or Bacillus stearothermophilus IOC S1 (MTCC 25030) and/or Arthrobacter sp. IOC-SC-2 (MTCC 25028); and wherein said hyperthermophilic enzyme has concentration range of 10-50 ppm of the total phase transfer solvent; and wherein said thermoregulatory enzyme stabilizer is in the concentration range of 2-4 ppm per 1000 U/mg of enzyme.

5. The phase transfer solvent composition as claimed in claim 1, wherein said phase splitting agent is selected from sulfolane, tetrahydrothiophene-1-oxide, butadiene sulfone, and a combination thereof, wherein said phase splitting agent has a concentration range from 1-5% in phase transfer solvent and depends on the tertiary amine concentration.

6. The phase transfer solvent composition as claimed in claim 1, wherein said thermo-conductive fluid comprises nano-fluids of SiO.sub.2, Al.sub.2O.sub.3, and TiO.sub.2, Al.sub.2O.sub.3, TiCl.sub.2/Nano-γ-Al.sub.2O.sub.3, CoFe.sub.2O.sub.4, magnetic Fe.sub.3O.sub.4, Ga.sub.2O.sub.3, functional silica, colloidal In.sub.2O.sub.3, ZnO, CoO, MnO.sub.2, Fe.sub.3O.sub.4, PbS, MFe.sub.2O.sub.4 (M=Fe, Co, Mn, Zn), Lewis acid ZrO.sub.2, silica boron sulfuric acid nanoparticles, Ni metal nanoparticles loaded on the acid-base bifunctional support (Al.sub.2O.sub.3), Co.sub.3O.sub.4 nanoparticles, oxide or metallic nano particle; and wherein said thermo-conductive fluid has a size in the range of between 10-50 nm and the concentration of the thermo-conductive fluid particle side ranges between 6-8 ppm.

7. The phase transfer solvent composition as claimed in claim 1, wherein said phase stabilizing micellar agent is selected from the group consisting of N-[2-[(2-Aminoethyl) amino]ethyl]-9-octadecenamide (AMEO), n-Benzalkonium chloride (BAC), C.sub.nH.sub.(2n+1)—COO(CH.sub.2CH.sub.2O).sub.12CH.sub.3, Polyoxythylene alkyl ether, n-Alkyltrimethyl ammonium surfactant, Potassium alkanoate, Dodecylpyridinium bromide, Octylglucoside, Sodium dodecyl sulfate, trans-Cinnamaldehyde, Sodium bis-(2-ethylhexyl)-sulfosuccinate, Cetylpyridinium chloride, Primary alcohol ethoxylate, Polyoxyethylene nonyl phenyl ether, Polyethylene glycol esters, Linoleate, dodecylamine or a combination thereof and wherein said phase stabilizing micellar agent has a concentration range from 50-70 ppm in phase transfer solvent.

8. A process of preparing the phase transfer solvent composition as claimed in claim 1, wherein said process comprises the steps of: Step-1: Preparing modified hyperthermophilic enzyme, wherein said step comprises; a) isolating hyperthermophilic enzyme from microbial strain under suitable condition; b) preparing thermoregulatory enzyme stabilizer using selective oligonucleotide metal complex, wherein selective oligonucleotide is a single stranded hexamer oligonucleotide with a minimum of two thiosine bases such as TTACTA, TTAATC, TTGATA, and TTGCTC or a combination thereof and the metal salt used for complexation is a chloride salt of Fe, Co, Cu and Ni or a combination thereof and wherein the concentration of oligonucleotides and metal salts were of 5-10 pmol/μl and 50-100 pmol/μl, respectively for the synthesis of thermoregulatory enzyme stabilize; and c) complexing thermoregulatory enzyme stabilizer prepared in step (b) with hyperthermophilic enzyme in step (a) to obtain the modified hyperthermophilic enzyme, wherein complexation of thermoregulatory enzyme stabilizer and hyperthermophilic enzyme is due to hydrogen bonding and is carried out by mixing 2 ppm of thermoregulatory enzyme stabilizer per 1000 U/mg of hyperthermophilic enzyme in presence of phosphate buffer (50 mM) of pH 6-6.5 resulting increase in the activity of hyperthermophilic enzyme; Step-2: Preparing phase transfer solvent system, wherein said Step 2 comprises: a) preparing amine solution with compounds having minimum one primary and/or one secondary amine groups by mixing said solution for 1-2 hours; b) adding compounds having at least one tertiary amine groups to the above step (a) with constant stirring; c) adding a phase splitting agent to the above step (b) and mixing till formation of a homogeneous phase; d) adding modified hyperthermophilic enzyme prepared in step-1c as defined in claims 16-23; e) adding a phase stabilizing agent to the composition in the above step (d); f) after 2 hours of constant stirring of the mixture composition obtained in the above step (e), adding a thermo-conductive fluid to the same to obtain the final phase transfer solvent composition which homogeneous at room temperature; and Step-3: Evaluating the obtained phase transfer solvent, said Step 3 comprises: a) passing of CO.sub.2/H.sub.2S gas to the phase transfer solvent at different condition; b) allowing the separation of rich and lean CO.sub.2/H.sub.2S loading phases; c) separating the CO.sub.2/H.sub.2S lean phase and recycling the lean phase into the absorber; d) withdrawing the CO.sub.2/H.sub.2S rich stream and passing the same into the stripper column for regeneration of the CO.sub.2/H.sub.2S; wherein the regeneration temperature ranges from 75° C. to 95° C.; e) After regeneration, allowing the CO.sub.2/H.sub.2S lean solvent stream to the absorber; f) measuring gas (CO.sub.2/H.sub.2S) loading in the solvent by gravimetric method and pressure drop experiment; g) determining the cyclic capacity; h) monitoring viscosity after CO.sub.2/H.sub.2S loading for a period of 200 cycles and observing no change in viscosity; i) monitoring corrosion for 0-100 days in a stainless vessel by analysis the leaching metal ion in the solvent; j) monitoring vapor pressure; wherein the pressure of CO.sub.2/H.sub.2S ranges from ambient to 10 bar and temperature ranges between 20-50° C.; and k) conducting recyclability study of phase transfer solvent.

9. The process of preparing the phase transfer solvent composition as claimed in claim 8, wherein said condition for isolation of hyperthermophilic enzyme is as follows: inducing enzyme expression by the addition of 0.5 mM ZnSO.sub.4 in a cell culture and growing the cells overnight at 55° C.; lysing the cells by the use of a Bead-Beater and removing cell debris by centrifugation; pooling fractions containing the enzyme and dialyzing the same against 0.1 M Tris/SO.sub.4 at pH 7.5; extracting the enzyme from the nutrient medium by 40% ammonium sulfate precipitation; wherein the extracted enzyme has concentration of 100-150 mg/ml with an p-NPA activity of 1800-2000 U/mg , able to be stored at −20° C. for two years without loss of activity, able to be stored at room temperature when immobilized can be stored for 1 year with 95-98% of initial activity, and has a thermal stability of 100-110° C.

10. The process of preparing the phase transfer solvent composition as claimed in claim 8, wherein complexation of thermoregulatory enzyme stabilizer and hyperthermophilic enzyme catalyses CO.sub.2 absorption within a temperature range of 0-40° C., preferably 50-110° C.; complexation of thermoregulatory enzyme stabilizer and hyperthermophilic enzyme can be used in free flow, fixed bed, rotating bed and any other configuration; and complexation of thermoregulatory enzyme stabilizer and hyperthermophilic enzyme will be affective for phase transformation solvent, homogeneous solvent or any other form of solvent used for CO.sub.2 capture.

11. The process as claimed in claim 8, wherein said compound having minimum one primary and/or one secondary amine groups are selected from group consisting of Monoethanolamine, Diethanolamine, Triethanolamine, Monomethylethanolamine, 2-(2-aminoethoxy)ethanol, Aminoethylethanol amine, Ethylenediamine (EDA), Diethylenetriamine (DETA), Triethylenetetramine (TETA). Tetraethyl enepentamine (TEPA), 2-amino 2methyl-1-proponal (AMP), 2-(ethyamino)-ethanol (EAE), 2-(methylamino)-ethanol (MAE), 2-(diethylamino)-ethanol (DEAE), diethanolamine (DEA), diisopropanolamine (DIPA), methylaminopropylamine (MAPA), 3-aminopropanol (AP), 2,2-dimethyl-1,3-propanediamine (DMPDA), 3-amino-1-cyclohexylaminopropane (ACHP), diglycola mine (DGA), 1-amino-2-propanol (MIPA), Isobutyl amine, 2-amino-2-methyl-ipropanol, 2-(2-aminoethylamino)ethanol, 2-amino-2-hydroxymethyl-i,3-propanediol, N-methyldiethanolamine, dimethylmonoethanolamine, diethylmonoethanolamine, triisopropanolamine and triethanolamine), trimethylamine, triethylamine, tripropylamine, tributylamine, dimethylethylamine, dimethylpropylamine, dimethylbutylamine, diethylmethylamine, diethylpropylamine, diethylbutylamine, N,N-diisopropylmethylamine, N-ethyldiisopropylamine, N,N-dimethylethylamine, N,N-diethylbutylamine, 1,2-dimethylpropylamine, N,N-diethylmethylamine, N,N-dimethylisopropylamine, 1,3-dimethylbutylamine, 3,3-dimethylbutylamine, N,N-dimethylbutylamine, N-methyl-1,3-diaminopropane ,Piperazine and triethylenetetramine or a combination thereof; wherein said compound having minimum one primary and/or one secondary amine groups has a concentration range of 20-50 wt % in phase transfer solvent and depend on the feed gas CO.sub.2 concentration.

12. The process as claimed in claim 8, wherein compounds having minimum one tertiary amine are selected from diethylethanolamine, dimethylethanolamine, diisopropanolamine, methyldiethanolamine, triethanolamine, 2-Amino-2-MethylPropan-1-ol, bis (2-dimethylaminoethyl) ether, tetramethyl-1, 2-ethanediamine, tetramethyl-3-propane, N-methyl diethanolamine, Dimethylethanolamine Tetramethyl-6-hexanediamine, 1,3,5-Trimethylhexahydro-1,3,5-triazine N,N,N′,N′-Tetramethyl-2-butene-1,4-diamine, Pentamethyldipropylenetriamine, N,N-diethylethanolamine, N,N-dimethylbutylamine, 3-(methyloamino)propylamine, or a combination thereof; and wherein compound having minimum one tertiary amine has a concentration range from 20-30 wt % in phase transfer solvent and depends on the feed gas CO.sub.2 concentration.

13. The process as claimed in claim 8, wherein said hyperthermophilic enzyme is Carbonic Anhydrase (CA) obtained from a source selected from the group consisting of Bacillus thermoleovorans IOC-S3 (MTCC 25023) and/or Pseudomonas fragi IOC S2 (MTCC 25025), and/or Bacillus stearothermophilus IOC S1 (MTCC 25030) and/or Arthrobacter sp. IOC-SC-2 (MTCC 25028); and wherein said hyperthermophilic enzyme has concentration range of 10-50 ppm of the total phase transfer solvent; and wherein said thermoregulatory enzyme stabilizer is in the concentration range of 2-4 ppm per 1000 U/mg of enzyme.

14. The process as claimed in claim 8, wherein said phase splitting agent is selected from sulfolane, tetrahydrothiophene-1-oxide, butadiene sulfone, and a combination thereof, wherein said phase splitting agent has a concentration range from 1-5% in phase transfer solvent and depends on the tertiary amine concentration.

15. The process as claimed in claim 8, wherein said thermo-conductive fluid comprises nano-fluids of SiO.sub.2, Al.sub.2O.sub.3, and TiO.sub.2, Al.sub.2O.sub.3, TiCl.sub.2/Nano-γ-Al.sub.2O.sub.3, CoFe.sub.2O.sub.4, magnetic Fe.sub.3O.sub.4, Ga.sub.2O.sub.3, functional silica, colloidal In.sub.2O.sub.3, ZnO, CoO, MnO.sub.2, Fe.sub.3O.sub.4, PbS, MFe.sub.2O.sub.4 (M=Fe, Co, Mn, Zn), Lewis acid ZrO.sub.2, silica boron sulfuric acid nanoparticles, Ni metal nanoparticles loaded on the acid-base bifunctional support (Al.sub.2O.sub.3), Co.sub.3O.sub.4 nanoparticles, oxide or metallic nano particle; and wherein said thermo-conductive fluid has a size in the range of between 10-50 nm and the concentration of the thermo-conductive fluid particle side ranges between 6-8 ppm.

16. The process of preparing the phase transfer solvent composition as claimed in claim 8, wherein the CO.sub.2 concentration ranges from 0.02% to 99%, preferably 0.02% to 90% in the source gas and the H.sub.2S concentration ranges from 0.001% to 5%; CO.sub.2/H.sub.2S phases differ in density, the rich phase is heavier than the CO.sub.2/H.sub.2S lean phase, allowing the phases to be separated by density, gravity or centrifugation apparatus; wherein the separation of phases happens in 1-10 s for both CO.sub.2 and H.sub.2S gas feed.

17. The process of preparing the phase transfer solvent composition as claimed in claim 9, wherein the CO.sub.2 and H.sub.2S rich phase is routed to different stripper column to selectively separate high pure H.sub.2S and CO.sub.2.

18. The process of preparing the phase transfer solvent composition as claimed in claim 8, wherein CO.sub.2 sources are carbon dioxide-containing flue gas, process gas or gas from bio-methanation.

19. The process of preparing the phase transfer solvent composition as claimed in claim 8, wherein, the resulting gas is passed through the solvent medium through in any suitable device forming the fine dispersion of gas which result in an increase in contact area, said gas is sparged in micro-bubble or nano-bubble size.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0038] These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings wherein:

[0039] FIG. 1 illustrates Schematic representation of phase separation of solvent upon gas absorption.

[0040] FIG. 2 illustrates CO.sub.2 loading in CO.sub.2 lean and CO.sub.2 rich phase with and without biocatalyst.

[0041] FIG. 3 illustrates flowchart of complete process for CO.sub.2/H.sub.2S capture using phase transfer solvent.

DETAILED DESCRIPTION

[0042] For the purpose of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the figures and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated system, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skilled in the art to which this invention belongs. The system, methods, and examples provided herein are illustrative only and not intended to be limiting.

[0043] The terminology and structure employed herein is for describing, teaching and illuminating some embodiments and their specific features and elements and does not limit, restrict or reduce the spirit and scope of the invention.

[0044] The invention discloses a novel phase transfer solvent composition for enhanced CO.sub.2 and/or H.sub.2S capture from flue gas and biogas having various gaseous compositions. More specifically, the disclosure relates to improved enzymatic and solvent systems, which upon CO.sub.2/H.sub.2S capture forms selective phases with higher CO.sub.2/H.sub.2S loading efficiency and low regeneration energy over the existing solvent systems. The disclosure further provides a phase transfer solvent composed of a primary amine/secondary amine, a tertiary amine, a hyperthermophilic enzyme, thermoregulatory enzyme stabilizer, phase splitting agent, phase stabilizing agent and thermo-conductive fluid, where the combination synergistically improves CO.sub.2/H.sub.2S loading and exhibit a phase separation behaviour with energy-efficient regeneration for CO.sub.2/H.sub.2S.

[0045] In an aspect of the present invention, inventors provide a phase transfer solvent composition for enhanced CO.sub.2 and/or H.sub.2S capture from flue gas and biogas having various gaseous compositions, comprising: [0046] a) a compound having minimum one primary and/or one secondary amine groups; [0047] b) a compound having minimum one tertiary amine; [0048] c) a hyperthermophilic enzyme; [0049] d) a thermoregulatory enzyme stabilizer; [0050] e) a phase splitting agent; [0051] f) a phase stabilizing micellar agent; [0052] g) a thermo-conductive fluid; and [0053] h) 200-600 ml of demineralized water per litre to make up the volume; wherein said solvent composition synergistically improves CO.sub.2/H.sub.2S loading and exhibit a phase separation behaviour with energy-efficient regeneration for CO.sub.2/H.sub.2S.

[0054] In an embodiment, said compound having minimum one primary and/or one secondary amine groups are selected from group consisting of Monoethanolamine, Diethanolamine, Triethanolamine, Monomethylethanolamine, 2-(2-aminoethoxy)ethanol, Aminoethylethanolamine, Ethylenediamine (EDA), Diethylenetriamine (DETA), Triethylenetetramine (TETA). Tetraethylenepentamine (TEPA), 2-amino 2methyl-1-proponal (AMP), 2-(ethyamino)-ethanol (EAE), 2-(methylamino)-ethanol (MAE), 2-(diethylamino)-ethanol (DEAE), diethanolamine (DEA), diisopropanolamine (DIPA), methylaminopropylamine (MAPA), 3-aminopropanol (AP), 2,2-dimethyl-1,3-propanediamine (DMPDA), 3-amino-1-cyclohexylaminopropane (ACHP), diglycola mine (DGA), 1-amino-2-propanol (MIPA), Isobutyl amine, 2-amino-2-methyl-ipropanol, 2-(2-aminoethylamino)ethanol, 2-amino-2-hydroxymethyl-i,3-propanediol, N-methyldiethanolamine, dimethylmonoethanolamine, diethylmonoethanolamine, triisopropanolamine and triethanolamine), trimethylamine, triethylamine, tripropylamine, tributylamine, dimethylethylamine, dimethylpropylamine, dimethylbutylamine, diethylmethylamine, diethylpropylamine, diethylbutylamine, N,N-diisopropylmethylamine, N-ethyldiisopropylamine, N,N-dimethyl ethyl amine, N,N-diethylbutylamine, 1,2-dimethylpropylamine, N,N-diethylmethylamine, N,N-dimethylisopropylamine, 1,3-dimethylbutylamine, 3,3-dimethylbutylamine, N,N-dimethylbutylamine, N-methyl-1,3-diaminopropane, Piperazine and triethylenetetramine or a combination thereof.

[0055] In another embodiment, said compound having minimum one primary and/or one secondary amine groups has a concentration range of 20-50 wt % in phase transfer solvent and depend on the feed gas CO.sub.2 concentration.

[0056] In yet another embodiment, compounds having minimum one tertiary amine includes but not limited to diethylethanolamine, dimethylethanolamine, diisopropanolamine, methyldiethanolamine, triethanolamine, 2-Amino-2-MethylPropan-1-ol, bis (2-dimethylaminoethyl) ether, tetramethyl-1, 2-ethanediamine, tetramethyl-3-propane, N-methyl diethanolamine, Dimethylethanolamine Tetramethyl-6-hexanediamine , 1,3,5-Trimethylhexahydro-1,3,5-triazine N,N,N′,N′-Tetramethyl-2-butene-1,4-diamine, Pentamethyldipropylenetriamine, N,N-diethylethanolamine, N,N-dimethylbutylamine, 3-(methyloamino)propylamine, or a combination thereof.

[0057] In a further embodiment, compound having minimum one tertiary amine has a concentration range from 20-30 wt % in phase transfer solvent and depends on the feed gas CO.sub.2 concentration.

[0058] In an embodiment, said hyperthermophilic enzyme is Carbonic Anhydrase (CA) obtained from a source selected from the group consisting of Bacillus thermoleovorans IOC-S3 (MTCC 25023) and/or Pseudomonas fragi IOC S2 (MTCC 25025), and/or Bacillus stearothermophilus IOC S1 (MTCC 25030) and/or Arthrobacter sp. IOC-SC-2 (MTCC 25028).

[0059] In another embodiment, said hyperthermophilic enzyme has concentration range of 10-50 ppm of the total phase transfer solvent.

[0060] In yet another embodiment, said thermoregulatory enzyme stabilizer is in the concentration range of 2-4 ppm per 1000 U/mg of enzyme.

[0061] In a further embodiment, said phase splitting agent is selected from sulfolane, tetrahydrothiophene-1-oxide, butadiene sulfone, and a combination thereof.

[0062] In an embodiment, said phase splitting agent has a concentration range from 1-5% in phase transfer solvent and depends on the tertiary amine concentration.

[0063] In another embodiment, said phase stabilizing micellar agent is selected from the group consisting of N-[2-[(2-Aminoethyl) amino]ethyl]-9-octadecenamide (AMEO), n-Benzalkonium chloride (BAC), C.sub.nH.sub.(2n+1)—COO(CH.sub.2CH.sub.2O).sub.12CH.sub.3, Polyoxythylene alkyl ether, n-Alkyltrimethyl ammonium surfactant, Potassium alkanoate, Dodecylpyridinium bromide, Octylglucoside, Sodium dodecyl sulfate, trans-Cinnamaldehyde, Sodium bis-(2-ethylhexyl)-sulfosuccinate, Cetylpyridinium chloride, Primary alcohol ethoxylate, Polyoxyethylene nonyl phenyl ether, Polyethylene glycol esters, Linoleate, dodecylamine or a combination thereof.

[0064] In yet another embodiment, said phase stabilizing micellar agent has a concentration range from 50-70 ppm in phase transfer solvent.

[0065] In a further embodiment, said thermo-conductive fluid comprises nano-fluids of SiO.sub.2, Al.sub.2O.sub.3, and TiO.sub.2, Al.sub.2O.sub.3, TiCl.sub.2/Nano-γ-Al.sub.2O.sub.3, CoFe.sub.2O.sub.4, magnetic Fe.sub.3O.sub.4, Ga.sub.2O.sub.3, functional silica, colloidal In.sub.2O.sub.3, ZnO, CoO, MnO.sub.2, Fe.sub.3O.sub.4, PbS, MFe.sub.2O.sub.4 (M=Fe, Co, Mn, Zn), Lewis acid ZrO.sub.2, silica boron sulfuric acid nanoparticles, Ni metal nanoparticles loaded on the acid-base bifunctional support (Al.sub.2O.sub.3), Co.sub.3O.sub.4 nanoparticles, oxide or metallic nano particle.

[0066] In an embodiment, said thermo-conductive fluid has a size in the range of between 10-50 nm and the concentration of the thermo-conductive fluid particle side ranges between 6-8 ppm.

[0067] In a second aspect of the present invention, the inventors provide a process of preparing the phase transfer solvent composition as claimed in claim 1, wherein said process comprises the steps of : [0068] Step-1: Preparing modified hyperthermophilic enzyme; [0069] Step-2: Preparing phase transfer solvent system; and [0070] Step-3: Evaluating the obtained phase transfer solvent.

[0071] In an embodiment, said Step 1 comprises: [0072] a) isolating hyperthermophilic enzyme from microbial strain under suitable condition; [0073] b) preparing thermoregulatory enzyme stabilizer using selective oligonucleotide metal complex; and [0074] c) complexing thermoregulatory enzyme stabilizer prepared in step (b) with hyperthermophilic enzyme in step (a) to obtain the modified hyperthermophilic enzyme.

[0075] In another embodiment, said condition for isolation of hyperthermophilic enzyme is as follows: [0076] inducing enzyme expression by the addition of 0.5 mM ZnSO.sub.4 in a cell culture and growing the cells overnight at 55° C.; [0077] lysing the cells by the use of a Bead-Beater and removing cell debris by centrifugation; [0078] pooling fractions containing the enzyme and dialyzing the same against 0.1 M Tris/SO.sub.4 at pH 7.5; [0079] extracting the enzyme from the nutrient medium by 40% ammonium sulfate precipitation;

[0080] wherein the extracted enzyme has concentration of 100-150 mg/ml with an p-NPA activity of 1800-2000 U/mg, able to be stored at −20° C. for two years without loss of activity, able to be stored at room temperature when immobilized can be stored for 1 year with 95-98% of initial activity and has a thermal stability of 100-110° C.

[0081] In yet another embodiment, the thermoregulatory enzyme stabilizer is prepared using metal complexation with selective oligonucleotide.

[0082] In a further embodiment, the oligonucleotide is a single stranded hexamer oligonucleotide with a minimum of two thiosine bases such as TTACTA, TTAATC, TTGATA, and TTGCTC or a combination thereof and the metal salt used for complexation is a chloride salt of Fe, Co, Cu and Ni or a combination thereof.

[0083] In an embodiment, the concentration of oligonucleotides and metal salts were of 5-10 pmol/μl and 50-100 pmol/μl, respectively for the synthesis of thermoregulatory enzyme stabilizer.

[0084] In another embodiment, complexation of thermoregulatory enzyme stabilizer and hyperthermophilic enzyme is due to hydrogen bonding.

[0085] In yet another embodiment, complexation of thermoregulatory enzyme stabilizer and hyperthermophilic enzyme is carried out by mixing 2 ppm of thermoregulatory enzyme stabilizer per 1000 U/mg of hyperthermophilic enzyme in presence of phosphate buffer (50 mM) of pH 6-6.5.

[0086] In a further embodiment, the activity of hyperthermophilic enzyme is enhanced after complexation with thermoregulatory enzyme stabilizer.

[0087] In an embodiment, complexation of thermoregulatory enzyme stabilizer and hyperthermophilic enzyme catalyses CO.sub.2 absorption within a temperature range of 0-40° C.

[0088] In another embodiment, complexation of thermoregulatory enzyme stabilizer and hyperthermophilic enzyme catalyses CO.sub.2 desorption in the temperature range of 50-110° C.

[0089] In yet another embodiment, the complexation of thermoregulatory enzyme stabilizer and hyperthermophilic enzyme can be used in free flow, fixed bed, rotating bed and any other configuration.

[0090] In a further embodiment, the complexation of thermoregulatory enzyme stabilizer and hyperthermophilic enzyme will be affective for phase transformation solvent, homogeneous solvent or any other form of solvent used for CO.sub.2 capture.

[0091] In an embodiment, said Step 2 comprises: [0092] a) preparing amine solution with compounds having minimum one primary and/or one secondary amine groups by mixing said solution for 1-2 hours; [0093] b) adding compounds having at least one tertiary amine groups to the above step (a) with constant stirring; [0094] c) adding a phase splitting agent to the above step (b) and mixing till formation of a homogeneous phase; [0095] d) adding modified hyperthermophilic enzyme prepared in step-1c as defined in the present invention; [0096] e) adding a phase stabilizing agent to the composition in the above step (d); [0097] f) after 2 hours of constant stirring of the mixture composition obtained in the above step (e), adding a thermo-conductive fluid to the same to obtain the final phase transfer solvent composition which homogeneous at room temperature.

[0098] In another embodiment, said Step 3 comprises: [0099] a) passing of CO.sub.2/H.sub.2S gas to the phase transfer solvent at different condition; [0100] b) allowing the separation of rich and lean CO.sub.2/H.sub.2S loading phases; [0101] c) separating the CO.sub.2/H.sub.2S lean phase and recycling the lean phase into the absorber; [0102] d) withdrawing the CO.sub.2/H.sub.2S rich stream and passing the same into the stripper column for regeneration of the CO.sub.2/H.sub.2S; [0103] e) After regeneration, allowing the CO.sub.2/H.sub.2S lean solvent stream to the absorber; [0104] f) measuring gas (CO.sub.2/H.sub.2S) loading in the solvent by gravimetric method and pressure drop experiment; [0105] g) determining the cyclic capacity; [0106] h) monitoring viscosity after CO.sub.2/H.sub.2S loading for a period of 200 cycles and observing no change in viscosity; [0107] i) monitoring corrosion for 0-100 days in a stainless vessel by analysis the leaching metal ion in the solvent; [0108] j) monitoring vapor pressure; and [0109] k) conducting recyclability study of phase transfer solvent.

[0110] In yet another embodiment, the CO.sub.2 concentration ranges from 0.02% to 99% , preferably 0.02% to 90% in the source gas and the H.sub.2S concentration ranges from 0.001% to 5%.

[0111] In a further embodiment, the CO.sub.2/H.sub.2S phases differ in density, the rich phase is heavier than the CO.sub.2/H.sub.2S lean phase, allowing the phases to be separated by density, gravity or centrifugation apparatus.

[0112] In an embodiment, the separation of phases happens in 1-10 s for both CO.sub.2 and H.sub.2S gas feed.

[0113] In another embodiment, the CO.sub.2 and H.sub.2S rich phase is routed to different stripper column to selectively separate high pure H.sub.2S and CO.sub.2.

[0114] In yet another embodiment, the regeneration temperature ranges from 75° C. to 95° C.

[0115] In a further embodiment, CO.sub.2 sources are carbon dioxide-containing flue gas, process gas or gas from bio-methanation.

[0116] In an embodiment, the resulting gas is passed through the solvent medium through in any suitable device forming the fine dispersion of gas which result in an increase in contact area, said gas is sparged in micro-bubble or nano-bubble size.

[0117] In another embodiment, the pressure of CO.sub.2/H.sub.2S ranges from ambient to 10 bar and temperature ranges between 20-50° C.

[0118] The following examples and experiments are for illustrative purposes only and not intended to limit the scope of this disclosure.

EXAMPLES

[0119] Material and Methods:

[0120] The typical concentration of components used in phase transfer solvent of the present invention are given in the following table-1

TABLE-US-00001 TABLE 1 Detail concentration of different components of phase transfer solvent Concentration in phase Component transfer solvent Compounds having minimum one primary 20-50 wt % and/or one secondary amine groups. Compounds having minimum one 20-30 wt % Tertiary amine Hyperthermophilic enzyme 10-50 ppm (1800-2000 U/mg) Thermoregulatory enzyme stabilizer 2-4 ppm per 1000 U/mg of enzyme Phase splitting agent 1-5 wt % Phase stabilizing micellar agent 50-70 ppm Thermo-conductive fluid 6-8 ppm DM water To make up the volume

Example 1: CO.SUB.2 .Capture by Novel Phase Transfer Solvent

[0121] 1. Preparation of Modified Hyperthermophilic Enzyme

[0122] The hyperthermophilic enzyme was extracted from Bacillus stearothermophilus IOC S1 (MTCC 25030). Initially, the microbes were grown in media having composition (in g/l) 6.0 g of Na.sub.2HPO.sub.4, 3.0 g of KH.sub.2PO.sub.4, 1.0 g of NH.sub.4Cl, 0.5 g of NaCl, 0.014 g of CaCl.sub.2, 0.245 g of MgSO.sub.4.7H.sub.2O, 10 mg of thiamine hydrochloride and 10 g of starch, and with 1 mM IPTG at 55° C. and 6.5 pH.

[0123] Enzyme expression was induced by the addition of 0.5 mM ZnSO.sub.4 and the cells were grown overnight at 55° C. The cells were lysed by the use of a Bead-Beater and cell debris was removed by centrifugation. The pooled fractions containing the enzyme were dialyzed against 0.1 M Tris/SO.sub.4 at pH 7.5. The enzyme was extracted from the nutrient medium by ammonium sulfate precipitation method. The purity of the enzyme was monitored by SDS/PAGE by comparing it with commercially available enzyme. The concentration of extracted enzyme was found to be 145 mg/ml by UV-Vis assay with p-NPA activity of 1955 U/mg. The enzyme was stored at RT.

[0124] For the preparation of thermoregulatory enzyme stabilizer, oligonucleotid of sequence TTACTA was synthesized. Oligonucleotides (100 mM oligonucleobases) and Iron chloride (100 mM) were prepared in HEPES buffer (10 mM, 1 mM magnesium nitrate, and pH 7.2).

[0125] Oligonucleotides and Iron chloride were then mixed with equal volumes. The final concentration of both oligonucleobases and iron chloride were both 50 mM. After equilibration at 30° C. for 10 minutes, the stable Fe-oligonucleotides complex was obtained and confirmed by appearance of sharp ligand to metal charge transfer spectra at 622 nm. The complex was collected by centrifugation with an rpm 8000 for 10 min.

[0126] 2 ppm of thermoregulatory enzyme stabilizer was added to isolated hyperthermophilic enzyme (1L) having an activity of activity of 1955 U/mg. The solution was placed in the shaker overnight at 120 rpm at 60° C. resulting the modified hyperthermophilic enzyme. The characteristic of modified hyperthermophilic enzyme is given in table-2 Comparison of the activity for hyperthermophilic enzyme and modified hyperthermophilic enzyme using CO.sub.2 or p-NPA as substrate is given in Table-2.

TABLE-US-00002 TABLE 2 Activity of biocatalyst before and after modification Biocatalyst Activity Hyperthermophilic enzyme 1955 U/mg Modified hyperthermophilic enzyme 3569 U/mg Hyperthermophilic enzyme@100° C. for 720 h 1912 U/mg Modified hyperthermophilic enzyme@100° C. for 720 h 3522 U/mg

[0127] 2. Preparation of Phase Transfer Solvent System

[0128] In a 2L flask 5M diethylethanolamine and N,N-Dimethyl-1,3-diaminopropane (2M) were mixed for 2 h. To the solution 0.2M sulfolane was added drop-wise with 2 ml/min with constant stirring. To the same solution 50 ppm of modified hyperthermophilic enzyme was inserted followed by 70 ppm of phase stabilizing micellar agent (Sodium dodecyl sulfate). After 2 h of constant stirring 8 ppm of thermo-conductive fluid (Fe.sub.2O.sub.4 having average particle side 24 nm) was inserted to obtain the final phase transfer solvent system. The mixture is homogeneous at Room temperature.

[0129] 3. Evaluation of Novel Phase Transfer Solvent

[0130] A known volume and mass (500 ml) of the solvent was weighed into the reactor and a synthetic mixture of CO.sub.2 (35%) and balance N.sub.2) was inserted to the solution, with a flow of 20 ml/min, was bubbled into the solvent. After bubbling through the solution, the gas stream was cooled on-line through two condensers placed on top of each other and the condensate was directly returned to the reactor. The purified gas was collected for GC analysis. The CO.sub.2 loading was studied by gravimetric method under equilibrium condition. It was observed that upon CO.sub.2 loading, the CO.sub.2-rich phase formed in the bottom constitute 22% of the total solvent volume. The CO.sub.2 rich phase was separated after used for desorption tests in stripping column.

TABLE-US-00003 TABLE 3 Table represents % of phase separation with respect to time. Time (s) CO.sub.2 Lean phase (%) CO.sub.2 Rich phase (%) 0 No Separation No Separation 2 68 32 5 71 29 10 78 22 20 78 22 100 79 21 500 79 21

[0131] 4. CO.sub.2 Loading Capacity in Rich and Lean Amine

[0132] FIG. 2 provides the comparative CO.sub.2 loading in phase transfer solvent with and without biocatalyst. As shown in the figure, the biocatalyst significantly increase the CO.sub.2 loading in CO.sub.2 rich phase (6.31 mol/L) compared to that of rich solvent without biocatalyst (4.9 Mol/L).

TABLE-US-00004 TABLE 4 The time-dependent CO.sub.2 uptake with various components of phase transfer solvents measured at 30° C. and 1 atm pressure using the gravimetric method. Observation of CO.sub.2 loading phase separation Code Components (Mol/L) behaviors A Diethylethanolamine 2.3 No Phase separation B N,N-Dimethyl-1, 3- 1.1 No Phase diaminopropane separation C Dulfolane ND No Phase separation D Hyperthermophilic enzyme 0.04 No Phase separation E Thermoregulatory enzyme ND No Phase stabilizer-(Fe-TTACTA) separation F phase stabilizing micellar ND No Phase agent (Sodium dodecyl separation sulfate) G thermo-conductive fluid ND No Phase separation A + B 3.48 No Phase separation A + C 2.5 No Phase separation A + B + C 3.9 Phase separation A + B + D 4.2 No Phase separation A + B + E 3.45 No Phase separation A + B + F 3.42 No Phase separation A + B + C + D 4.9 Phase separation A + B + C + E 3.86 Phase separation A + B + C + F 1.91 Phase separation B + C + D + F 2.31 No Phase separation A + B + C + D + E + F + G 6.31 Phase separation (Novel phase transfer solvent)

TABLE-US-00005 TABLE 5 Desorption of CO.sub.2 rich phase transfer solvent at 85-95° C. Phase transfer solvent Desorption (%) Phase transfer solvent-Without bio 68% catalyst phase transfer solvent-With 71% Hyperthermophilic enzyme phase transfer solvent-With 94% Modified Hyperthermophilic enzyme

TABLE-US-00006 TABLE 6 Cyclic capacity refers to the difference between lean and rich loading of a solvent. In this study, the lean loading was defined as CO.sub.2 loading corresponding to CO.sub.2 at equilibrium partial pressure of 0.05 kPa at 85-90° C. Lean Rich Cyclic loading loading capacity (mol CO.sub.2/ (molCO.sub.2/ (mol CO.sub.2/ Solvent kg-solv) kg-solv) kg-solv) MEA 1.68 2.52 0.84 Phase transfer 0.07 6.3 6.23 solvent

Example-2: Biogas Purification by Phase Transfer Solvent

[0133] Preparation of Phase Transfer Solvent

[0134] The phase transfer solvent was prepared based on the protocol mentioned step-1,2 and 3 of the example-1.

[0135] Biogas of composition (75% Methane, 5000 ppm H.sub.2S balance CO.sub.2) was used for the study. The flow rate of solvent was kept 20 ml/min, was bubbled into the solvent. After bubbling through the solution, the gas stream was cooled on-line through two condensers placed on top of each other and the condensate was directly returned to the reactor. The purified gas was collected for GC analysis. The CO.sub.2/H.sub.2S loading was studied by gravimetric method under equilibrium condition. It was observed that upon CO.sub.2 loading, the CO.sub.2-rich phase formed in the bottom constitute 21.5% of the total solvent volume, H2S rich phase was 7% of the total volume. The CO.sub.2 and H.sub.2S rich phase were separated after used for desorption tests in stripping column.

TABLE-US-00007 TABLE 7 Table represents % of phase separation with respect to time. CO.sub.2/H.sub.2S Lean CO.sub.2 Rich phase H.sub.2S Rich phase Time (s) phase (%) (%) (%) 0 No Separation No Separation No Separation 2 62 29 9 5 65 28 7 10 71 22 7 20 71.5 22 6.5 100 72.5 21 6.5 500 72.5 21 6.5

TABLE-US-00008 TABLE 8 Effect of biocatalyst in CO.sub.2 and H.sub.2S loading CO.sub.2 CO.sub.2 H.sub.2S H.sub.2S loading in loading in loading in loading in rich phase rich phase rich phase rich phase (No (With (No (With Time biocatalyst) biocatalyst) biocatalyst) biocatalyst) 0 0 0 0 0 1 1.6 3.6 0.7 1.1 2 3.2 4.2 0.9 1.7 5 4.8 6.1 1.01 2.2 10 4.9 6.2 1.05 2.3 20 4.9 6.2 1.05 2.3 30 4.9 6.2 1.05 2.3

TABLE-US-00009 TABLE 9 Input Biogas Output methane Solvent system composition recovery Phase transfer CH.sub.4 (50 V %) CH.sub.4 (99.8 V %) solvent CO.sub.2 (49.7 V %) CO.sub.2 (0.2 V %) H.sub.2S (3000 ppm) H.sub.2S (N.D) CH.sub.4 (60 V %) CH.sub.4 (99.9 V %) CO.sub.2 (39.6 V %) CO.sub.2 (0.1 V %) H.sub.2S (4000 ppm) H.sub.2S (N.D) CH.sub.4 (70 V %) CH.sub.4 (99.9 V %) CO.sub.2 (29.9 V %) CO.sub.2 (0.1 V %) H.sub.2S (1000 ppm) H.sub.2S (N.D) CH.sub.4 (80 V %) CH.sub.4 (99.9 V %) CO.sub.2 (19.5 V %) CO.sub.2 (0.1 V %) H.sub.2S (5000 ppm) H.sub.2S (N.D)

[0136] It will thus be seen that the objects set forth above, among those made apparent from the preceding description, are efficiently attained, and since certain changes may be made in the constructions set forth without departing from the spirit and scope of the invention, it is intended that all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense. The invention has been described with reference to preferred and alternate embodiments. Modifications and alterations will become apparent to those skilled in the art upon reading and understanding the detailed discussion of the invention provided herein. This invention is intended to include all such modifications and alterations insofar as they come within the scope of the present invention. These and other modifications of the preferred embodiments as well as other embodiments of the invention will be obvious from the disclosure herein, whereby the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.

[0137] Finally, to the extent necessary to understand or complete the disclosure of the present invention, all publications, patents, and patent applications mentioned herein are expressly incorporated by reference therein to the same extent as though each were individually so incorporated.