Detailed Action
This is a Non-Final Office action based on application 16/960,221 filed on July 6, 2020. The application is a 371 of PCT/US2019/012534 with priority to US provisional application 62/614,308 filed January 5, 2018.
Claims 1-2 and 4-25 are pending and have been fully considered.
Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Continued Examination Under 37 CFR 1.114
A request for continued examination under 37 CFR 1.114, including the fee set forth in 37 CFR 1.17(e), was filed in this application after final rejection. Since this application is eligible for continued examination under 37 CFR 1.114, and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114. Applicant's submission filed on 15 April 2026 has been entered.
Status of the Rejection
The §103 rejections presented in the Office Action of 15 October 2025 are maintained. The previous rejections are re-stated in pg 3-22 of this action.
New grounds of rejection are presented in this action responsive to the addition of claim 25. The new grounds of rejection begin on page 22 of this action.
Previously Applied Grounds of RejectionClaim Rejections - 35 USC § 103
The text of those sections of Title 35, U.S. Code not included in this action can be found in a prior Office action.
Claims 1-2, 4-10, and 12-24 are rejected under 35 U.S.C. 103 as being obvious over Stern et al (US 2013/0058857 A1) in view of Wedege et al (Scientific Reports, volume 6, article 39101, pg 1-13 and associated Electronic Supplementary Information pg 1-52 (2016)).
Regarding claim 1, Stern teaches a device for capturing CO2 comprising a liquid flow path (abstract, para [0008]-[0009]; figure 3, 6, and 12) comprising:
a) a first region (figure 6, column 202; para [0052]) comprising a first inlet and a first outlet (figure 6, column 202 comprises inlet 200 and outlet 201) and an aqueous solution or suspension comprising an organic proton-coupled redox active species (Stern discloses various “complexation agents” (redox active species) in para [0036]-[0039], [0044]-[0045], [0052], [0054], [0074]-[0076], some of which are proton-coupled; in the example of para [0037] and [0074]-[0076], the redox species is a quinone, and para [0037], [0075] illustrates how the redox reaction is proton-coupled; para [0054], the species is provided as an aqueous solution), wherein the first region is configured to receive a gas comprising CO2 via the first inlet, allow the gas to contact the aqueous solution or suspension, and to release the gas depleted of CO2 via the first outlet (per figure 6 and para [0052], a gas mixture comprising CO2 and other gases is introduced via inlet 200, contacts the solution of active species in column 202, CO2 is absorbed into solution, and feed gas depleted of CO2 is released at outlet 201);
b) a second region fluidically connected to the first region and comprising at least one electrode (figure 6, anode chamber 204 is a second region, fluidically connected to first region 202 via conduit 208, and comprising anode 206; para [0052]);
c) a third region fluidically connected to the second region and comprising a second outlet, wherein the third region is configured to release CO2 outgassing from the aqueous solution or suspension via the second outlet (per figure 6 and para [0052], flash tank 218 is a third region, connected via conduit 216 to the second region (anode chamber 204), and comprises outlet 210 configured to release CO2 outgassing from the aqueous solution); and
d) a fourth region fluidically connected to the first and third regions and comprising at least one electrode (per figure 6 and para [0052], cathode chamber 212 is a fourth region, fluidically connected to the third region (flash tank 218) via conduit 218, and to the first region (absorption column 202) via conduit 220, and cathode chamber 212 comprises cathode 214),
wherein oxidation of the organic proton-coupled redox active species releases one or more protons to decrease the pH of the aqueous solution or suspension and reduction of the proton-coupled redox active species takes up one or more protons to increase the pH of the aqueous solution or suspension (para [0024], [0036], [0045]; as e.g. in the specific example of para [0075], anodic oxidation of a quinone species dissociates two protons into solution, and cathodic reduction takes up two protons from solution; figure 10, showing that the anode pH is decreased by such reaction, and the cathode pH increased).
As the limitation "wherein CO2 is stored in the aqueous solution or suspension as dissolved inorganic carbon", this phrase further limits the material worked upon by the device, but fails to further limit the device itself. A claim is only limited by positively recited elements, and "inclusion of the material or article worked upon by a structure being claimed does not impart patentability to the claims" (In re Otto, 312 F.2d 937, 136 USPQ 458, 459 (CCPA 1963)); see MPEP 2115). Since the phrase in question further limits the composition of the CO2-loaded capture solution (material worked upon) but fails to limit the device (by a structure being claimed), this limitation of the claim does not have patentable weight.
Stern teaches that, in general, the reduction of the proton-coupled redox active species may be employed to increase the pH to a pH of up to 13 (para [0040]). However, in the embodiment of Stern where the proton-coupled redox active species is an organic species (benzoquinone, in para [0074]-[0076]), Stern teaches that the proton-coupled redox active species decomposes at high pH values and is unable to increase the pH to pH values greater than 12 (Stern at para [0075]). Stern therefore does not teach an apparatus in which reduction of an organic proton-coupled redox active species is capable of increasing the pH of the aqueous solution or suspension to a pH of greater than 12 in the first region. Note that, since “apparatus claims cover what a device is, not what a device does" (Hewlett-Packard Co. v. Bausch & Lomb Inc., 909 F.2d 1464, 1469, 15 USPQ2d 1525, 1528 (Fed. Cir. 1990), emphasis in original), the prior art applied against claim 1 would not need to actually disclose increasing the pH to greater than 12 in order to anticipate the claim; it would suffice for the prior art to disclose an apparatus that is capable of being operated to increase the pH to greater than 12 (MPEP 2114). However, since Stern’s only disclosed organic proton-coupled redox active species is unable to increase the pH to greater than 12, Stern’s device does not anticipate this functional feature of the claimed device.
Wedege is directed to studying the chemical stability and redox potentials of various quinones, naphthoquinones, and anthraquinones in aqueous solution, with a view toward the application of these molecules as organic proton-coupled redox active species in flow battery applications (pg 1 abstract). Wedege, like Stern, teaches that the applicability of benzoquinones in aqueous alkaline electrolyte is hindered by the molecules’ poor chemical stability under high-pH conditions (pg 6 para 6-7; pg 7-8; pg 9 figure 7; per pg 6 para 7, instability is indicated by irreversibility in cyclic voltammograms see Supplementary Information pg 12-13 and 36-44). By contrast, Wedege teaches that some anthraquinones are effective for use in highly alkaline electrolyte because they are base-stable (Supplementary Information pg 6-7, 9-11, 16-21, 26-35, showing that each of the anthraquinones Wedege tested showed reversible or quasireversible oxidation and reduction when tested at a pH of 13) and they undergo proton-coupled redox reactions at pH values greater than 12 (as shown in pg 5 figure 5, “AQDH(1,8)” (1,8-dihydroxy-9,10-anthraquinone) absorbs/releases 2 proton upon its redox reactions at acidic pH of 4 or less, and 1 proton at pH values from 4 to 13, while “AQDH(2,6)” (2,6-dihydroxy-9,10-anthraquinone) undergoes 2-proton reduction/oxidation reactions over the entire pH range from 0 to 13; per pg 6 para 4, “For instance, in the Pourbaix diagram of AQDS(2,7), E0’ follows the expected −59 mv/pH unit from pH 0 to pH 7 (pKa1). Then the first (hydro)quinone group deprotonates, and the slope changes to 30 mV/pH unit until pH 10 (pKa2) and E0’ becomes pH-independent. AQDH(1,8) shows a different dependence, where pKa1 is somewhere around pH 4 and pKa2 above pH 13. AQDH(2,6) shows an even more different behaviour as E0’ follows − 59 mV/pH unit dependence straight to pH 13, which implies that both pKa values are higher than 13”). Wedege teaches that properties of anthraquinones, including their low redox potential, high solubility, good chemical stability, and low cost, make them suitable choices for redox flow battery anolyte materials (pg 11 para 2).
It would have been obvious to a person having ordinary skill in the art before the effective filing date of the claimed invention to modify Stern by substituting an anthraquinone in place of 1,4-benzoquinone as the organic proton-coupled redox active species, because Stern teaches that the proton-coupled pH adjustment could in principle achieve pH as high as 13 (para [0040]), but the base-catalyzed decomposition of 1,4-benzophenone prevents the system from achieving pH greater than 12 when 1,4-benzophenone is chosen as the organic proton-coupled redox active species (para [0075]), and, because Wedege teaches that anthraquinones are inexpensive (pg 11 para 2), anthraquinones have improved base stability compared to benzoquinone (pg 11 para 2; Supplementary Information pg 6-13) and anthraquinones are capable of proton-coupled redox reactions for pH ranges of at least from 0 to 13 (pg 5 figure 5 and pg 6 para 4). The simple substitution of one known element for another (i.e., an anthraquinone in place of a benzoquinone as the proton-coupled redox active material) is likely to be obvious when predictable results are achieved (i.e., improved chemical stability, and operability for proton-coupled redox reactions over a broad pH range) [MPEP § 2143(B)]. Furthermore, the selection of a known material, which is based upon its suitability for the intended use, is within the ambit of one of ordinary skill in the art [MPEP § 2144.07].
Regarding claim 2, modified Stern renders the device of claim 1 obvious, and Stern further teaches an ion-conducting barrier disposed between the second and fourth regions (figure 6, membrane 213 separates the second and fourth regions; para [0052]; para [0074], “separated by a Nafion 117 membrane”).
Regarding claim 4, modified Stern renders the device of claim 1 obvious, and Stern further teaches the pH in the third region is less than 8 (per figure 10, the pH of the anode chamber outlet (the liquid fed from the outlet of second region (figure 6 anode chamber 204) into the third region (figure 6 flash tank 218)) is about 3; para [0040], [0078]-[0079]).
Regarding claim 5, modified Stern renders the device of claim 1 obvious. Stern demonstrates raising the pH in the first region to over 11 (figures 7, 10), and contemplates that system may be configured to raise the pH in the first region to as high as 13 (para [0040]). Stern does not teach the system is configured to achieve a pH in the first region of greater than 13 (per figure 10, the pH of the cathode chamber outlet (the liquid fed from the outlet of the fourth region (figure 6 cathode chamber 212) into the fourth region (figure 6, column 202)) is about 11; para [0040], [0078]-[0079]).
Wedege teaches that at least some of the anthraquinone redox active species are effective as proton-coupled redox active species for pH values of up to and exceeding 13 (figure 3, when the solution pH is lower than one or both of pKa1 and pKa2 of the redox-active molecule, then oxidation/reduction is proton-coupled, i.e. capable of absorbing or releasing H+ to affect the pH; per pg 5 figure 5, “AQDH(1,8)” (1,8-dihydroxy-9,10-anthraquinone) absorbs/releases 2 proton upon its redox reactions at acidic pH of 4 or less, and 1 proton at pH values from 4 to 13, while “AQDH(2,6)” (2,6-dihydroxy-9,10-anthraquinone) undergoes 2-proton reduction/oxidation reactions over the entire pH range from 0 to 13; per pg 6 para 4, “AQDH(1,8) shows ...pKa1 is somewhere around pH 4 and pKa2 above pH 13. AQDH(2,6) shows an even more different behaviour as E0’ follows − 59 mV/pH unit dependence straight to pH 13, which implies that both pKa values are higher than 13”).
It follows that, when the system of Stern is modified in view of Wedege to use an anthraquinone as the proton-coupled redox active species, the modified system is configured to raise the pH in the first region to a pH of over 13, as required by claim 5.
Regarding claim 6, modified Stern renders the device of claim 1 obvious, and Stern further teaches the proton-coupled redox active species is present in the aqueous solution or suspension at a concentration of between 0.5 M and 2 M (para [0042], “concentration of the complexation agent in the solution may be ... between about 0.5 M and about 2 M”) which is within the claimed range of “at least 0.5 M”.
Regarding claim 7, Stern in view of Wedege renders the device of claim 1 obvious, wherein the proton-coupled redox active species incorporated from Wedege into Stern is an anthraquinone (as discussed above with respect to claim 1).
Regarding claim 8, modified Stern renders the device of claim 1 obvious, and Stern further teaches the device comprises an electrochemical cell (para [0082], “an electrochemical flow cell (e.g., see FIGS. 12a and 12b)”; para [0023], [0034], [0036], [0052], [0074]; figures 3, 6, and 12 each illustrate an electrochemical cell).
Regarding claim 9, modified Stern renders the device of claim 1 obvious, and Stern further teaches the device compromises a plurality of electrochemical cells (para [0082], “an electrochemical flow cell (e.g., see FIGS. 12a and 12b) ... Several cells may be stacked electrically in series”).
Regarding claim 10, Stern teaches a method of capturing CO2 (abstract, para [0008]-[0009], [0022]), the method comprising the steps of:
a) providing an aqueous solution or suspension comprising a proton-coupled redox active species and having a first pH (Stern discloses providing various “complexation agents” (redox active species) in para [0036]-[0039], [0044]-[0045], [0052], [0054], [0074]-[0076], some of which are proton-coupled; in the example of para [0037] and [0074]-[0076], the redox species is a quinone, and para [0037], [0075] illustrates how the redox reaction is proton-coupled; per para [0054], the species is provided as an aqueous solution having a first pH);
b) allowing a gas comprising CO2 to contact the aqueous solution or suspension under conditions for the CO2 to dissolve into the aqueous solution or suspension (para [0052], “feed gas comprising CO2 and other gaseous materials (e.g., N2) is provided by inlet 200 and is flowed through column 202 ... absorption occurs”; [0045], [0080]-[0082]) in the form of dissolved inorganic carbon (per para [0050] and [0080]-[0082], an exemplary absorption media includes an amine solution, particularly ethylenediamine, such that the CO2 complexes with the amine to form a dissolved amine-CO2 complex; Weiland studies the reaction equilibria for the complexation of CO2 with ethylenediamine and teaches that the ethylenediamine-CO2 complexes exist in equilibrium with dissolved inorganic carbon (see Weiland pg 768, figure 1 and left column para 2-6); therefore, in the embodiment of Stern that uses ethylenediamine to promote the absorption of CO2, at least a portion of the dissolved CO2 will be in the form of dissolved inorganic carbon; also note that Stern para [0045] teaches that the absorption solution may alternatively be a base solution that absorbs CO2 in the form of bicarbonate);
c) converting the pH of the aqueous solution or suspension to a second pH by oxidizing the organic proton-coupled redox active species (para [0052], “The resulting RNHCOO (e.g., in solution) species is provided to anode container 204 containing anode 206 ... application of an electrical potential to anode 206”; para [0072], [0075], [0078], the anode reaction is an oxidation reaction that releases H+ into solution; per para [0040] and figures 7, 9a, 10, the pH is changed by the anodic oxidation);
d) allowing the dissolved CO2 to outgas from the aqueous solution or suspension (para [0052], “causing CO2 to be released ... optionally via flash tank 218 (e.g., to allow release and collection of CO2 gas)”; figure 6, flash tank 218 comprises outlet 210 configured to release CO2 outgassing from the aqueous solution); and
e) converting the pH of the aqueous solution or suspension to a third pH by reducing the organic proton-coupled redox active species (para [0052], solution is provided to cathode chamber wherein the redox active species is reduced at the cathode; per para [0040] and figures 7, 9a, 10, the pH is changed by the cathodic reduction).
Stern disclose both inorganic and organic proton-coupled redox active species (para [0044]), and Stern teaches that the first pH may be as high as 13 (para [0040]). However, in the sole experimental example where the proton-coupled redox active species is an organic species (benzoquinone, in para [0074]-[0076]), Stern teaches that the proton-coupled redox active species decomposes at high pH values and is unable to attain a first pH value of greater than 12 (Stern at para [0075]). Stern therefore does not anticipate a method in which the proton-coupled redox active species is organic and also the first pH is greater than 12.
Wedege is directed to studying the chemical stability and redox potentials of various quinones, naphthoquinones, and anthraquinones in aqueous solution, with a view toward the application of these molecules as organic proton-coupled redox active species in flow battery applications (pg 1 abstract). Wedege, like Stern, teaches that the applicability of benzoquinones in aqueous alkaline electrolyte is hindered by the molecules’ poor chemical stability under high-pH conditions (pg 6 para 6-7; pg 7-8; pg 9 figure 7; per pg 6 para 7, instability is indicated by irreversibility in cyclic voltammograms see Supplementary Information pg 12-13 and 36-44). By contrast, Wedege teaches that some anthraquinones are effective for use in highly alkaline electrolyte because they are base-stable (Supplementary Information pg 6-7, 9-11, 16-21, 26-35, showing that each of the anthraquinones Wedege tested showed reversible or quasireversible oxidation and reduction when tested at a pH of 13) and they undergo proton-coupled redox reactions at pH values greater than 12 (as shown in pg 5 figure 5, “AQDH(1,8)” (1,8-dihydroxy-9,10-anthraquinone) absorbs/releases 2 proton upon its redox reactions at acidic pH of 4 or less, and 1 proton at pH values from 4 to 13, while “AQDH(2,6)” (2,6-dihydroxy-9,10-anthraquinone) undergoes 2-proton reduction/oxidation reactions over the entire pH range from 0 to 13; per pg 6 para 4, “For instance, in the Pourbaix diagram of AQDS(2,7), E0’ follows the expected −59 mv/pH unit from pH 0 to pH 7 (pKa1). Then the first (hydro)quinone group deprotonates, and the slope changes to 30 mV/pH unit until pH 10 (pKa2) and E0’ becomes pH-independent. AQDH(1,8) shows a different dependence, where pKa1 is somewhere around pH 4 and pKa2 above pH 13. AQDH(2,6) shows an even more different behaviour as E0’ follows − 59 mV/pH unit dependence straight to pH 13, which implies that both pKa values are higher than 13”). Wedege teaches that properties of anthraquinones, including their low redox potential, high solubility, good chemical stability, and low cost, make them suitable choices for redox flow battery anolyte materials (pg 11 para 2).
It would have been obvious to a person having ordinary skill in the art before the effective filing date of the claimed invention to modify Stern by substituting an anthraquinone in place of 1,4-benzoquinone as the organic proton-coupled redox active species, because Stern teaches that the proton-coupled pH adjustment could in principle achieve pH as high as 13 (para [0040]), but the base-catalyzed decomposition of 1,4-benzophenone prevents the system from achieving pH greater than 12 when 1,4-benzophenone is chosen as the organic proton-coupled redox active species (para [0075]), and, because Wedege teaches that anthraquinones are inexpensive (pg 11 para 2), anthraquinones have improved base stability compared to benzoquinone (pg 11 para 2; Supplementary Information pg 6-13) and anthraquinones are capable of proton-coupled redox reactions for pH ranges of at least from 0 to 13 (pg 5 figure 5 and pg 6 para 4). The simple substitution of one known element for another (i.e., an anthraquinone in place of a benzoquinone as the proton-coupled redox active material) is likely to be obvious when predictable results are achieved (i.e., improved chemical stability, and operability for proton-coupled redox reactions over a broad pH range) [MPEP § 2143(B)]. Furthermore, the selection of a known material, which is based upon its suitability for the intended use, is within the ambit of one of ordinary skill in the art [MPEP § 2144.07].
Regarding claim 12, modified Stern renders the method of claim 10 obvious, and Stern further teaches the CO2 is captured from a point source (para [0082], “may be used to capture carbon dioxide from post-combustion flue gases of a fossil-fuel boiler or furnace”).
Regarding claim 13, modified Stern renders the method of claim 10 obvious, and Stern further teaches the second pH is less than 8 (per figure 10, the pH of liquid at the anode chamber outlet (i.e. the second pH) is about 3; para [0040], [0078]-[0079]).
Regarding claim 14, modified Stern renders the method of claim 10 obvious. Stern demonstrates raising the third pH to over 11 (figures 7, 10), and contemplates that system may be configured to raise the pH in the first region to as high as 13 (para [0040]), but, in the sole experimental example where the proton-coupled redox active species is an organic species (benzoquinone, in para [0074]-[0076]), Stern teaches that the proton-coupled redox active species decomposes at high pH values and is unable to attain a first pH value of greater than 12 (Stern at para [0075]). However, Wedege teaches that at least some of the anthraquinone redox active species are effective as proton-coupled redox active species for pH values of up to and exceeding 13 (figure 3, when the solution pH is lower than one or both of pKa1 and pKa2 of the redox-active molecule, then oxidation/reduction is proton-coupled, i.e. capable of absorbing or releasing H+ to affect the pH; per pg 5 figure 5, “AQDH(1,8)” (1,8-dihydroxy-9,10-anthraquinone) absorbs/releases 2 proton upon its redox reactions at acidic pH of 4 or less, and 1 proton at pH values from 4 to 13, while “AQDH(2,6)” (2,6-dihydroxy-9,10-anthraquinone) undergoes 2-proton reduction/oxidation reactions over the entire pH range from 0 to 13; per pg 6 para 4, “AQDH(1,8) shows ...pKa1 is somewhere around pH 4 and pKa2 above pH 13. AQDH(2,6) shows an even more different behaviour as E0’ follows − 59 mV/pH unit dependence straight to pH 13, which implies that both pKa values are higher than 13”). It follows that, when the method of Stern is modified in view of Wedege to use an anthraquinone as the proton-coupled redox active species, the modified method is configured to achieve a third pH of greater than 12, as required by claim 14.
Regarding claim 15, modified Stern renders the method of claim 10 obvious, and Stern further teaches the second pH is converted to the third pH in a single step (para [0044], each of the reduction reactions of each individual “complexation agent” considered by Stern is presented as a single step reaction; para [0045], [0082] each describe modifying the pH with a single step of applying suitable reducing potential).
Regarding claim 16, modified Stern renders the method of claim 10 obvious, and Stern further teaches the second pH is converted to the third pH in two or more steps (para [0038]-[0039], “In some cases, a system/method may comprise more than one type of complexation agent (e.g., a first type of complexation agent and a second type of complexation agent different from the first type of complexation agent). Those of ordinary skill in the art will be aware that each type of complexation agent will have a suitable pH range in which it is capable of affecting the pH of a solution to which it is exposed ... In addition, each type of complexation agent may require a different range of electrical potentials to cause association and/or dissociation of an acid and/or base”; it follows that, in the embodiment where two complexation agents (redox active agents) are used, the shift from second pH to third pH entails a first step of reducing one of the agents at a first cathode potential, and a second step of reducing the other of the agents at a second cathode potential).
Regarding claim 17, modified Stern renders the method of claim 10 obvious, and Stern further teaches the method operates continuously (para [0035], “carry out semi-continuous and/or continuous reactions”).
Regarding claim 18, modified Stern renders the method of claim 10 obvious, and Stern further teaches the method operates sequentially (para [0034] discloses the method may be carried out in discrete, isolated batches, i.e. sequentially).
Regarding claim 19, Stern in view of Wedege renders the method of claim 10 obvious, wherein the proton-coupled redox active species incorporated from Wedege into Stern is an anthraquinone (as discussed above with respect to claim 10).
Regarding claim 20, modified Stern renders the method of claim 10 obvious, and Stern further teaches the oxidizing in step (b) and/or reducing in step (d) are carried out electrochemically (para [0009], [0026], [0052]).
Regarding claims 21 and 22, modified Stern renders obvious the method of claim 10 and the device of claim 1 respectively, and Stern further teaches the aqueous solution or suspension does not comprise a metal catalyst (metal catalyst is not mentioned anywhere in Stern's disclosure; in para [0074]-[0076], the embodiment of Example 2, include sodium chloride as a supporting electrolyte, and no other metal species; there is no suggestion that the sodium has any catalytic activity; in para [0080]-[0082], the embodiments of examples 4 and 5, the aqueous solution includes sodium and copper ions as components of the capture solution, but does not suggest either of the metals have any catalytic activity).
Regarding claims 23 and 24, modified Stern renders obvious the device of claim 1 and the method of claim 10 respectively. Since the absorption solution of Stern is substantially identical in its composition to the absorption solution recited in the claims, it follows that when CO2 is absorbed by Stern’s solution, it will be dissolved and stored in substantially the same form as when it is absorbed by applicant’s claimed solution, i.e. essentially as dissolved inorganic carbon. Where the claimed and prior art products are identical or substantially identical in structure or composition, or are produced by identical or substantially identical processes, a prima facie case of either anticipation or obviousness has been established. A chemical composition and its properties are inseparable. Therefore, if the prior art teaches the identical chemical structure, the properties applicant discloses and/or claims are necessarily present (see MPEP 2112.01(I-II) and case law discussed therein). Moreover, Stern explicitly teaches that the absorption solution may be a base solution that dissolves and stores CO2 in the form of bicarbonate (para [0045]), i.e. dissolved inorganic carbon.
Claim 11 is rejected under 35 U.S.C. 103 as being obvious over Stern and Wedege as applied to claim 10 above, in further view of Kohl et al (US 2,926,751 A) and Volkamer et al (US 4,553,984 A).
Regarding claim 11, modified Stern renders the method of claim 10 obvious. Stern teaches carrying out their method of capturing CO2 using a device for capturing CO2 comprising a liquid flow path (abstract, para [0008]-[0009], [0022]), said device comprising:
a) a first region (figure 6, column 202; para [0052]) comprising a first inlet and a first outlet (figure 6, column 202 comprises inlet 200 and outlet 201) and an aqueous solution or suspension comprising a proton-coupled redox active species (Stern discloses various “complexation agents” (redox active species) in para [0036]-[0039], [0044]-[0045], [0052], [0054], [0074]-[0076], some of which are proton-coupled; in the example of para [0037] and [0074]-[0076], the redox species is a quinone, and para [0037], [0075] illustrates how the redox reaction is proton-coupled; para [0054], the species is provided as an aqueous solution), wherein the first region is configured to receive a gas comprising CO2 via the first inlet, allow the gas to contact the aqueous solution or suspension, and to release the gas depleted of CO2 via the first outlet (per figure 6 and para [0052], a gas mixture comprising CO2 and other gases is introduced via inlet 200, contacts the solution of active species in column 202, CO2 is absorbed into solution, and feed gas depleted of CO2 is released at outlet 201) ;
b) a second region fluidically connected to the first region and comprising at least one electrode (figure 6, anode chamber 204 is a second region, fluidically connected to first region 202 via conduit 208, and comprising anode 206; para [0052]);
c) a third region fluidically connected to the second region and comprising a second outlet, wherein the third region is configured to release CO2 outgassing from the aqueous solution or suspension via the second outlet (per figure 6 and para [0052], flash tank 218 is a third region, connected via conduit 216 to the second region (anode chamber 204), and comprises outlet 210 configured to release CO2 outgassing from the aqueous solution); and
d) a fourth region fluidically connected to the first and third regions and comprising at least one electrode (per figure 6 and para [0052], cathode chamber 212 is a fourth region, fluidically connected to the third region (flash tank 218) via conduit 218, and to the first region (absorption column 202) via conduit 220, and cathode chamber 212 comprises cathode 214).
Stern does not teach the third region comprises a second inlet fluidically connected to the second outlet, wherein the second inlet is connected to a carrier gas source.
Kohl teaches a method and system for removing CO2 from a mixed gas stream (col 1 ln 14-32) by contacting the gas stream in an absorption column with an absorbent solvent that dissolves CO2 (figure 1, feed gas passes into column 11 and is mixed with solvent introduced at inlet 12; col 3 ln 24-59), then passing the resulting solution to a flash desorption chamber (figure 1, flash chamber 20) to separate the CO2 from the solvent (col 3 ln 62 - col 4 ln 15). Kohl further teaches that a portion of the dissolved CO2 remains dissolved after the flash desorption, and that the amount of CO2 recovered from the solution can be further increased by contacting the solution with a stripping gas (col 4 ln 12-25; col 5 ln 21-26). The stripping takes place in a chamber that comprises a second inlet fluidically connected to its liquid outlet, wherein the second inlet is connected to a carrier gas source (figure 1, air stripping chamber 24 comprises solvent inlet 25, solvent outlet 26, carrier gas inlet 27, gas outlet 28).
Volkamer is directed to a system and method for removing CO2 from a mixed gas stream, by contacting the gas stream in an absorption column with an aqueous absorbent solution that dissolves CO2 (col 4 ln 11-23 and figure 1, gas stream 1 and absorption liquid stream 3 are contacted in absorption column 2, forming scrubbed gas stream 13 and CO2-laden liquid solution 4; col 2 ln 34-46, Volkamer's absorbent is an aqueous solution of alkanolamine), then passing the resulting solution to a desorption chamber to separate the CO2 from the solvent (col 4 ln 24 - 38 and figure 1, solution 4 is passed to flash desorption chamber 6 where it is partially desorbed to form a gas stream 7 comprising CO2 and a liquid solution 8; solution 8 is then passed to a second flash desorption chamber 10 to desorb more CO2 into gas stream 11). Kohl further teaches that some of the water in the aqueous solution is volatilized during CO2 desorption and lost, and that the lost water is compensated for by feeding makeup water into the circuit in the form of steam (col 4 ln 38-43 and figure 1, steam stream 14 is fed in at desorption stage 10 to compensate for water losses; per col 3 ln 44-68, the steam stream functions both to make up lost water and to make up lost heat).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Stern by including, at the third region, a gas stripping stage including a second gas inlet connected to a carrier gas source and fluidically connected to the second outlet, in order to increase the amount of CO2 removed from solution at the third region as taught in Kohl (col 4 ln 12-25; col 5 ln 21-26), and thereby increase the amount of CO2 that is recovered in each pass through Stern’s CO2 recovery system.
It would have been obvious to a person having ordinary skill in the art before the effective filing date of the claimed invention to further modify Stern by including a makeup stream to replace water that is lost to evaporation in the flash desorption module, based on Volkamer's teaching that water is in fact lost during the flash desorption of aqueous CO2 absorption solutions, and that the lost water can be compensated by a makeup stream (col 3 ln 44-68, col 4 ln 38-43, figure 1).
New Grounds of RejectionClaim Rejections - 35 USC § 112
The following is a quotation of the first paragraph of 35 U.S.C. 112(a):
(a) IN GENERAL.—The specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same, and shall set forth the best mode contemplated by the inventor or joint inventor of carrying out the invention.
Claim 25 is rejected under 35 U.S.C. 112(a) as failing to comply with the written description requirement. The claim contains subject matter which was not described in the specification in such a way as to reasonably convey to one skilled in the relevant art that the inventor or a joint inventor, at the time the application was filed, had possession of the claimed invention.
Specifically, claim 25 is rejected under §112(a) because the range of concentrations that it recites (“at least 1.0 M”) is broader than the range of concentrations that find support in the original disclosure. The broadest disclosure of mediator ranges anywhere in the disclosure is at instant figure 10 where applicant discloses having contemplated mediator concentrations of from 0.1 M to 10.0 M. There is no support in the disclosure for the rest of the claimed range, i.e. concentrations of from greater than 10 M to infinity. Claim 25 therefore includes subject matter that does not comply with the written description requirement of §112(a). See In re Wertheim, 541 F.2d 257, 191 USPQ 90 (CCPA 1976).
If claim 25 were amended to instead recite that the concentration is in a range of from 1.0 M to 10.0 M, then the written description requirement would be met.
The following is a quotation of 35 U.S.C. 112(b):
(b) CONCLUSION.—The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the inventor or a joint inventor regards as the invention.
Claim 25 is rejected under 35 U.S.C. 112(b) as being indefinite for failing to particularly point out and distinctly claim the subject matter which the inventor or a joint inventor, regards as the invention.
Claim 25 recites the limitation "[t]he method of claim 1". There is insufficient antecedent basis for this limitation in the claim, because claim 1 does not recite a method. For the purpose of treatment against the art in this action, Examiner interprets claim 25 as though it depended from method claim 10.
Claim Rejections - 35 USC § 103
The text of those sections of Title 35, U.S. Code not included in this action can be found in a prior Office action.
Claims 1-2, 4-10, and 12-24 are rejected under 35 U.S.C. 103 as being obvious over Stern et al (US 2013/0058857 A1) in view of Orita et al (Nature Communications, volume 7, article 13230, pg 1-8 (2016)).
Regarding claim 1, Stern teaches a device for capturing CO2 comprising a liquid flow path (abstract, para [0008]-[0009]; figure 3, 6, and 12) comprising:
a) a first region (figure 6, column 202; para [0052]) comprising a first inlet and a first outlet (figure 6, column 202 comprises inlet 200 and outlet 201) and an aqueous solution or suspension comprising an organic proton-coupled redox active species (Stern discloses various “complexation agents” (redox active species) in para [0036]-[0039], [0044]-[0045], [0052], [0054], [0074]-[0076], some of which are proton-coupled; in the example of para [0037] and [0074]-[0076], the redox species is a quinone, and para [0037], [0075] illustrates how the redox reaction is proton-coupled; para [0054], the species is provided as an aqueous solution), wherein the first region is configured to receive a gas comprising CO2 via the first inlet, allow the gas to contact the aqueous solution or suspension, and to release the gas depleted of CO2 via the first outlet (per figure 6 and para [0052], a gas mixture comprising CO2 and other gases is introduced via inlet 200, contacts the solution of active species in column 202, CO2 is absorbed into solution, and feed gas depleted of CO2 is released at outlet 201);
b) a second region fluidically connected to the first region and comprising at least one electrode (figure 6, anode chamber 204 is a second region, fluidically connected to first region 202 via conduit 208, and comprising anode 206; para [0052]);
c) a third region fluidically connected to the second region and comprising a second outlet, wherein the third region is configured to release CO2 outgassing from the aqueous solution or suspension via the second outlet (per figure 6 and para [0052], flash tank 218 is a third region, connected via conduit 216 to the second region (anode chamber 204), and comprises outlet 210 configured to release CO2 outgassing from the aqueous solution); and
d) a fourth region fluidically connected to the first and third regions and comprising at least one electrode (per figure 6 and para [0052], cathode chamber 212 is a fourth region, fluidically connected to the third region (flash tank 218) via conduit 218, and to the first region (absorption column 202) via conduit 220, and cathode chamber 212 comprises cathode 214),
wherein oxidation of the organic proton-coupled redox active species releases one or more protons to decrease the pH of the aqueous solution or suspension and reduction of the proton-coupled redox active species takes up one or more protons to increase the pH of the aqueous solution or suspension (para [0024], [0036], [0045]; as e.g. in the specific example of para [0075], anodic oxidation of a quinone species dissociates two protons into solution, and cathodic reduction takes up two protons from solution; figure 10, showing that the anode pH is decreased by such reaction, and the cathode pH increased).
As the limitation "wherein CO2 is stored in the aqueous solution or suspension as dissolved inorganic carbon", this phrase further limits the material worked upon by the device, but fails to further limit the device itself. A claim is only limited by positively recited elements, and "inclusion of the material or article worked upon by a structure being claimed does not impart patentability to the claims" (In re Otto, 312 F.2d 937, 136 USPQ 458, 459 (CCPA 1963)); see MPEP 2115). Since the phrase in question further limits the composition of the CO2-loaded capture solution (material worked upon) but fails to limit the device (by a structure being claimed), this limitation of the claim does not have patentable weight.
Stern teaches that, in general, the reduction of the proton-coupled redox active species may be employed to increase the pH to a pH of up to 13 (para [0040]). However, in the embodiment of Stern where the proton-coupled redox active species is an organic species (benzoquinone, in para [0074]-[0076]), Stern teaches that the proton-coupled redox active species decomposes at high pH values and is unable to increase the pH to pH values greater than 12 (Stern at para [0075]). Stern therefore does not teach an apparatus in which reduction of an organic proton-coupled redox active species is capable of increasing the pH of the aqueous solution or suspension to a pH of greater than 12 in the first region. Note that, since “apparatus claims cover what a device is, not what a device does" (Hewlett-Packard Co. v. Bausch & Lomb Inc., 909 F.2d 1464, 1469, 15 USPQ2d 1525, 1528 (Fed. Cir. 1990), emphasis in original), the prior art applied against claim 1 would not need to actually disclose increasing the pH to greater than 12 in order to anticipate the claim; it would suffice for the prior art to disclose an apparatus that is capable of being operated to increase the pH to greater than 12 (MPEP 2114). However, since Stern’s only disclosed organic proton-coupled redox active species is unable to increase the pH to greater than 12, Stern’s device does not anticipate this functional feature of the claimed device.
Orita is directed to redox flow batteries employing organic proton-coupled redox active species, and in particular to the use of riboflavin-5’-monophosphate sodium salt (abbreviated “FMN-Na”) as a redox active species (pg 1 abstract, pg 2 paragraphs 1-3, pg 2 figure 1). Orita teaches that organic redox active species are attractive redox active species because they are inexpensive and comprise earth-abundant elements (pg 2 left column para 1, pg 6 right column para 3 – pg 7 left column para 1), and FMN-Na in particularly is an attractive choice of redox active species because it has high water solubility and stable cycling performance (pg 2 right column para 3 – pg 3 left column para 1). Orita teaches that the solubility of FMN-Na is highest in strongly alkaline conditions (pg 6 left column para 2), that the maximum solubility they observed of FMN-Na was about 1.5 M in pH 14 conditions (pg 6 left column para 2), and in the interest of maximizing energy density, it is desirable to operate the redox flow battery at the highest FMN-Na concentration possible (pg 6 right column para 2). Orita characterizes the proton-coupled redox behavior of FMN-Na in electrolytes of various pH value, and teaches that the electrolyte pH at which charge transfer to and from FMN-Na is most efficient is strongly alkaline electrolyte with pH of about 13 (pg 3 left column para 2 – right column para 2; pg 4 figure 3a). Orita uses a pH 13 aqueous solution of FMN-Na as the negative electrode of a redox flow battery and shows that the FMN-Na has a high cycling stability in this highly alkaline electrolyte (pg 4 right column para 2 – pg 6 right column para 2).
It would have been obvious to a person having ordinary skill in the art before the effective filing date of the claimed invention to modify Stern by substituting the molecule “FMN-Na”, disclosed in Orita, in place of Stern’s 1,4-benzoquinone as the organic proton-coupled redox active species, because Stern teaches that the proton-coupled pH adjustment could in principle achieve pH as high as 13 (para [0040]), but the base-catalyzed decomposition of 1,4-benzophenone prevents the system from achieving pH greater than 12 when 1,4-benzophenone is chosen as the organic proton-coupled redox active species (para [0075]), and, because Orita teaches that it is desirable to use organic species as the redox species (pg 2 paragraphs 1-2), that FMN-Na is particularly suitable because it has high cycling stability and can be used at concentrations of 1.5 M (pg 2 right column para 3 – pg 3 left column para 1, pg 6 left column para 2 and right column para 2), and that FMN-Na is particularly suitable for use in aqueous solution at pH 13 (pg 3 left column para 2 – right column para 2; pg 4 figure 3a; pg 4 right column para 2 – pg 6 right column para 2). The simple substitution of one known element for another (i.e., “FMN-Na” as disclosed in Orita in place of the 1,4-benzoquinone as the proton-coupled redox active material in Stern’s device) is likely to be obvious when predictable results are achieved (i.e., high solubility limit, and good redox kinetics and chemical and cycling stability at the relevant pH range) [MPEP § 2143(B)]. The selection of a known material, which is based upon its suitability for the intended use, is within the ambit of one of ordinary skill in the art [MPEP § 2144.07].
Regarding claim 2, modified Stern renders the device of claim 1 obvious, and Stern further teaches an ion-conducting barrier disposed between the second and fourth regions (figure 6, membrane 213 separates the second and fourth regions; para [0052]; para [0074], “separated by a Nafion 117 membrane”).
Regarding claim 4, modified Stern renders the device of claim 1 obvious, and Stern further teaches the pH in the third region is less than 8 (per figure 10, the pH of the anode chamber outlet (the liquid fed from the outlet of second region (figure 6 anode chamber 204) into the third region (figure 6 flash tank 218)) is about 3; para [0040], [0078]-[0079]).
Regarding claim 5, modified Stern renders the device of claim 1 obvious. Stern demonstrates raising the pH in the first region to over 11 (figures 7, 10), and contemplates that system may be configured to raise the pH in the first region to as high as 13 (para [0040]). Stern does not teach the system is configured to achieve a pH in the first region of greater than 13 (per figure 10, the pH of the cathode chamber outlet (the liquid fed from the outlet of the fourth region (figure 6 cathode chamber 212) into the fourth region (figure 6, column 202)) is about 11; para [0040], [0078]-[0079]).
Orita teaches that the redox active species “FMN-Na”, is particularly effective as proton-coupled redox active species for alkaline pH values e.g. at pH of 13 (pg 3 left column para 2 – right column para 2; pg 4 figure 3a; pg 4 right column para 2 – pg 6 right column para 2).
It follows that, when the system of Stern is modified in view of Wedege to use an anthraquinone as the proton-coupled redox active species, the modified system is configured to raise the pH in the first region to a pH of over 13, as required by claim 5.
Regarding claim 6, modified Stern renders the device of claim 1 obvious, and Stern further teaches the proton-coupled redox active species is present in the aqueous solution or suspension at a concentration of between 0.5 M and 2 M (para [0042], “concentration of the complexation agent in the solution may be ... between about 0.5 M and about 2 M”) which is within the claimed range of “at least 0.5 M”. Orita further teaches that FMN-Na is soluble at concentrations of up to 1.5 M (pg 6 left column para 2), and it is desirable to use it at concentrations of about 1.5 M (pg 6 right column para 2).
Regarding claim 7, Stern in view of Orita renders the device of claim 1 obvious, wherein the proton-coupled redox active species incorporated from Orita into Stern is an isoalloxazine (as discussed above with respect to claim 1, it is riboflavin-5’-monophosphate sodium salt; Orita pg 2 left column para 1 – right column para 1, “The planar isoalloxazine ring forms the basic structure for riboflavin, flavin mononucleotide (FMN), and flavin adenine dinucleotide (FAD)”).
Regarding claim 8, modified Stern renders the device of claim 1 obvious, and Stern further teaches the device comprises an electrochemical cell (para [0082], “an electrochemical flow cell (e.g., see FIGS. 12a and 12b)”; para [0023], [0034], [0036], [0052], [0074]; figures 3, 6, and 12 each illustrate an electrochemical cell).
Regarding claim 9, modified Stern renders the device of claim 1 obvious, and Stern further teaches the device compromises a plurality of electrochemical cells (para [0082], “an electrochemical flow cell (e.g., see FIGS. 12a and 12b) ... Several cells may be stacked electrically in series”).
Regarding claim 10, Stern teaches a method of capturing CO2 (abstract, para [0008]-[0009], [0022]), the method comprising the steps of:
a) providing an aqueous solution or suspension comprising a proton-coupled redox active species and having a first pH (Stern discloses providing various “complexation agents” (redox active species) in para [0036]-[0039], [0044]-[0045], [0052], [0054], [0074]-[0076], some of which are proton-coupled; in the example of para [0037] and [0074]-[0076], the redox species is a quinone, and para [0037], [0075] illustrates how the redox reaction is proton-coupled; per para [0054], the species is provided as an aqueous solution having a first pH);
b) allowing a gas comprising CO2 to contact the aqueous solution or suspension under conditions for the CO2 to dissolve into the aqueous solution or suspension (para [0052], “feed gas comprising CO2 and other gaseous materials (e.g., N2) is provided by inlet 200 and is flowed through column 202 ... absorption occurs”; [0045], [0080]-[0082]) in the form of dissolved inorganic carbon (per para [0050] and [0080]-[0082], an exemplary absorption media includes an amine solution, particularly ethylenediamine, such that the CO2 complexes with the amine to form a dissolved amine-CO2 complex; Weiland studies the reaction equilibria for the complexation of CO2 with ethylenediamine and teaches that the ethylenediamine-CO2 complexes exist in equilibrium with dissolved inorganic carbon (see Weiland pg 768, figure 1 and left column para 2-6); therefore, in the embodiment of Stern that uses ethylenediamine to promote the absorption of CO2, at least a portion of the dissolved CO2 will be in the form of dissolved inorganic carbon; also note that Stern para [0045] teaches that the absorption solution may alternatively be a base solution that absorbs CO2 in the form of bicarbonate);
c) converting the pH of the aqueous solution or suspension to a second pH by oxidizing the organic proton-coupled redox active species (para [0052], “The resulting RNHCOO (e.g., in solution) species is provided to anode container 204 containing anode 206 ... application of an electrical potential to anode 206”; para [0072], [0075], [0078], the anode reaction is an oxidation reaction that releases H+ into solution; per para [0040] and figures 7, 9a, 10, the pH is changed by the anodic oxidation);
d) allowing the dissolved CO2 to outgas from the aqueous solution or suspension (para [0052], “causing CO2 to be released ... optionally via flash tank 218 (e.g., to allow release and collection of CO2 gas)”; figure 6, flash tank 218 comprises outlet 210 configured to release CO2 outgassing from the aqueous solution); and
e) converting the pH of the aqueous solution or suspension to a third pH by reducing the organic proton-coupled redox active species (para [0052], solution is provided to cathode chamber wherein the redox active species is reduced at the cathode; per para [0040] and figures 7, 9a, 10, the pH is changed by the cathodic reduction).
Stern disclose both inorganic and organic proton-coupled redox active species (para [0044]), and Stern teaches that the first pH may be as high as 13 (para [0040]). However, in the sole experimental example where the proton-coupled redox active species is an organic species (benzoquinone, in para [0074]-[0076]), Stern teaches that the proton-coupled redox active species decomposes at high pH values and is unable to attain a first pH value of greater than 12 (Stern at para [0075]). Stern therefore does not anticipate a method in which the proton-coupled redox active species is organic and also the first pH is greater than 12.
Orita is directed to redox flow batteries employing organic proton-coupled redox active species, and in particular to the use of riboflavin-5’-monophosphate sodium salt (abbreviated “FMN-Na”) as a redox active species (pg 1 abstract, pg 2 paragraphs 1-3, pg 2 figure 1). Orita teaches that organic redox active species are attractive redox active species because they are inexpensive and comprise earth-abundant elements (pg 2 left column para 1, pg 6 right column para 3 – pg 7 left column para 1), and FMN-Na in particularly is an attractive choice of redox active species because it has high water solubility and stable cycling performance (pg 2 right column para 3 – pg 3 left column para 1). Orita teaches that the solubility of FMN-Na is highest in strongly alkaline conditions (pg 6 left column para 2), that the maximum solubility they observed of FMN-Na was about 1.5 M in pH 14 conditions (pg 6 left column para 2), and in the interest of maximizing energy density, it is desirable to operate the redox flow battery at the highest FMN-Na concentration possible (pg 6 right column para 2). Orita characterizes the proton-coupled redox behavior of FMN-Na in electrolytes of various pH value, and teaches that the electrolyte pH at which charge transfer to and from FMN-Na is most efficient is strongly alkaline electrolyte with pH of about 13 (pg 3 left column para 2 – right column para 2; pg 4 figure 3a). Orita uses a pH 13 aqueous solution of FMN-Na as the negative electrode of a redox flow battery and shows that the FMN-Na in this highly alkaline electrolyte has good chemical stability (pg 3 right column para 3 – pg 4 left column para 2) and electrochemical cycling stability (pg 4 right column para 2 – pg 6 right column para 2).
It would have been obvious to a person having ordinary skill in the art before the effective filing date of the claimed invention to modify Stern by substituting the molecule “FMN-Na”, disclosed in Orita, in place of Stern’s 1,4-benzoquinone as the organic proton-coupled redox active species, because Stern teaches that the proton-coupled pH adjustment could in principle achieve pH as high as 13 (para [0040]), but the base-catalyzed decomposition of 1,4-benzophenone prevents the system from achieving pH greater than 12 when 1,4-benzophenone is chosen as the organic proton-coupled redox active species (para [0075]), and, because Orita teaches that it is desirable to use organic species as the redox species (pg 2 paragraphs 1-2), that FMN-Na is particularly suitable because it has high cycling stability and can be used at concentrations of 1.5 M (pg 2 right column para 3 – pg 3 left column para 1, pg 6 left column para 2 and right column para 2), and that FMN-Na is particularly suitable for use in aqueous solution at pH 13 (pg 3 left column para 2 – right column para 2; pg 4 figure 3a; pg 4 right column para 2 – pg 6 right column para 2). The simple substitution of one known element for another (i.e., “FMN-Na” as disclosed in Orita in place of the 1,4-benzoquinone as the proton-coupled redox active material in Stern’s device) is likely to be obvious when predictable results are achieved (i.e., high solubility limit, and good redox kinetics and chemical and cycling stability at the relevant pH range) [MPEP § 2143(B)]. The selection of a known material, which is based upon its suitability for the intended use, is within the ambit of one of ordinary skill in the art [MPEP § 2144.07].
Regarding claim 12, modified Stern renders the method of claim 10 obvious, and Stern further teaches the CO2 is captured from a point source (para [0082], “may be used to capture carbon dioxide from post-combustion flue gases of a fossil-fuel boiler or furnace”).
Regarding claim 13, modified Stern renders the method of claim 10 obvious, and Stern further teaches the second pH may be less than 8 (para [0040], the second pH may be from 1 to 13; in the example of figure 10, the pH of liquid at the anode chamber outlet (i.e. the second pH) is about 3; para [0078]-[0079]).
Regarding claim 14, modified Stern renders the method of claim 10 obvious and Stern further teaches the third pH may be greater than 12 (para [0040], the pH is contemplated as going as higher as 14). Orita also teaches that FMN-Na is configured for efficient redox reactions at pH of 13 (pg 3 left column para 2 – right column para 2; pg 4 figure 3a; pg 4 right column para 2 – pg 6 right column para 2).
Regarding claim 15, modified Stern renders the method of claim 10 obvious, and Stern further teaches the second pH is converted to the third pH in a single step (para [0044], each of the reduction reactions of each individual “complexation agent” considered by Stern is presented as a single step reaction; para [0045], [0082] each describe modifying the pH with a single step of applying suitable reducing potential).
Regarding claim 16, modified Stern renders the method of claim 10 obvious, and Stern further teaches the second pH is converted to the third pH in two or more steps (para [0038]-[0039], “In some cases, a system/method may comprise more than one type of complexation agent (e.g., a first type of complexation agent and a second type of complexation agent different from the first type of complexation agent). Those of ordinary skill in the art will be aware that each type of complexation agent will have a suitable pH range in which it is capable of affecting the pH of a solution to which it is exposed ... In addition, each type of complexation agent may require a different range of electrical potentials to cause association and/or dissociation of an acid and/or base”; it follows that, in the embodiment where two complexation agents (redox active agents) are used, the shift from second pH to third pH entails a first step of reducing one of the agents at a first cathode potential, and a second step of reducing the other of the agents at a second cathode potential).
Regarding claim 17, modified Stern renders the method of claim 10 obvious, and Stern further teaches the method operates continuously (para [0035], “carry out semi-continuous and/or continuous reactions”).
Regarding claim 18, modified Stern renders the method of claim 10 obvious, and Stern further teaches the method operates sequentially (para [0034] discloses the method may be carried out in discrete, isolated batches, i.e. sequentially).
Regarding claim 19, Stern in view of Wedege renders the method of claim 10 obvious, wherein the proton-coupled redox active species incorporated from Orita into Stern is an isoalloxazine (as discussed above with respect to claim 1, it is riboflavin-5’-monophosphate sodium salt; Orita pg 2 left column para 1 – right column para 1, “The planar isoalloxazine ring forms the basic structure for riboflavin, flavin mononucleotide (FMN), and flavin adenine dinucleotide (FAD)”).
Regarding claim 20, modified Stern renders the method of claim 10 obvious, and Stern further teaches the oxidizing in step (b) and/or reducing in step (d) are carried out electrochemically (para [0009], [0026], [0052]).
Regarding claims 21 and 22, modified Stern renders obvious the method of claim 10 and the device of claim 1 respectively, and Stern further teaches the aqueous solution or suspension does not comprise a metal catalyst (metal catalyst is not mentioned anywhere in Stern's disclosure; in para [0074]-[0076], the embodiment of Example 2, include sodium chloride as a supporting electrolyte, and no other metal species; there is no suggestion that the sodium has any catalytic activity; in para [0080]-[0082], the embodiments of examples 4 and 5, the aqueous solution includes sodium and copper ions as components of the capture solution, but does not suggest either of the metals have any catalytic activity).
Regarding claims 23 and 24, modified Stern renders obvious the device of claim 1 and the method of claim 10 respectively. Since the absorption solution of Stern is substantially identical in its composition to the absorption solution recited in the claims, it follows that when CO2 is absorbed by Stern’s solution, it will be dissolved and stored in substantially the same form as when it is absorbed by applicant’s claimed solution, i.e. essentially as dissolved inorganic carbon. Where the claimed and prior art products are identical or substantially identical in structure or composition, or are produced by identical or substantially identical processes, a prima facie case of either anticipation or obviousness has been established. A chemical composition and its properties are inseparable. Therefore, if the prior art teaches the identical chemical structure, the properties applicant discloses and/or claims are necessarily present (see MPEP 2112.01(I-II) and case law discussed therein). Moreover, Stern explicitly teaches that the absorption solution may be a base solution that dissolves and stores CO2 in the form of bicarbonate (para [0045]), i.e. dissolved inorganic carbon.
Regarding claim 25, Stern and Orita render obvious the method of claim 10. Stern further teaches that the concentration of the organic proton-coupled redox active species is between 0.1 M and 5 M, e.g. about 1 M or about 1.5 M (para [0042]), a range of concentrations which overlaps the claimed range of at least 1.0 M.
Orita meanwhile teaches that the aqueous solubility limit of the organic proton-coupled redox active species PMN-Na is about 1.5 M (pg 6 left column para 2), and one may be motivated for the purpose of maximum power density to further pursue PMN-Na solutions with concentrations at or near this limit (pg 6 right column para 2).
Given the teachings of Stern regarding a concentration range of 0.1 M and 5 M, e.g. about 1 M or about 1.5 M, for the proton-coupled redox active species (para [0042]), it would have been obvious to have selected and utilized a concentration within the disclosed range, including those amounts that overlap within the claimed range of at least 1.0 M. A concentration in the claimed range could be achieved in predictable fashion with reasonable expectation of success, based on Orita’s disclosure that the organic redox active species that is being used in the method of modified Stern (PMN-Na) is soluble in the relevant solvent system (aqueous base) at concentrations of up to 1.5 M. The court has held that obviousness exists where the claimed ranges overlap or lie inside ranges disclosed by the prior art; see MPEP 2144.05 (I).
Claim 11 is rejected under 35 U.S.C. 103 as being obvious over Stern and Orita as applied to claim 10 above, in further view of Kohl et al (US 2,926,751 A) and Volkamer et al (US 4,553,984 A).
Regarding claim 11, modified Stern renders the method of claim 10 obvious. Stern teaches carrying out their method of capturing CO2 using a device for capturing CO2 comprising a liquid flow path (abstract, para [0008]-[0009], [0022]), said device comprising:
a) a first region (figure 6, column 202; para [0052]) comprising a first inlet and a first outlet (figure 6, column 202 comprises inlet 200 and outlet 201) and an aqueous solution or suspension comprising a proton-coupled redox active species (Stern discloses various “complexation agents” (redox active species) in para [0036]-[0039], [0044]-[0045], [0052], [0054], [0074]-[0076], some of which are proton-coupled; in the example of para [0037] and [0074]-[0076], the redox species is a quinone, and para [0037], [0075] illustrates how the redox reaction is proton-coupled; para [0054], the species is provided as an aqueous solution), wherein the first region is configured to receive a gas comprising CO2 via the first inlet, allow the gas to contact the aqueous solution or suspension, and to release the gas depleted of CO2 via the first outlet (per figure 6 and para [0052], a gas mixture comprising CO2 and other gases is introduced via inlet 200, contacts the solution of active species in column 202, CO2 is absorbed into solution, and feed gas depleted of CO2 is released at outlet 201) ;
b) a second region fluidically connected to the first region and comprising at least one electrode (figure 6, anode chamber 204 is a second region, fluidically connected to first region 202 via conduit 208, and comprising anode 206; para [0052]);
c) a third region fluidically connected to the second region and comprising a second outlet, wherein the third region is configured to release CO2 outgassing from the aqueous solution or suspension via the second outlet (per figure 6 and para [0052], flash tank 218 is a third region, connected via conduit 216 to the second region (anode chamber 204), and comprises outlet 210 configured to release CO2 outgassing from the aqueous solution); and
d) a fourth region fluidically connected to the first and third regions and comprising at least one electrode (per figure 6 and para [0052], cathode chamber 212 is a fourth region, fluidically connected to the third region (flash tank 218) via conduit 218, and to the first region (absorption column 202) via conduit 220, and cathode chamber 212 comprises cathode 214).
Stern does not teach the third region comprises a second inlet fluidically connected to the second outlet, wherein the second inlet is connected to a carrier gas source.
Kohl teaches a method and system for removing CO2 from a mixed gas stream (col 1 ln 14-32) by contacting the gas stream in an absorption column with an absorbent solvent that dissolves CO2 (figure 1, feed gas passes into column 11 and is mixed with solvent introduced at inlet 12; col 3 ln 24-59), then passing the resulting solution to a flash desorption chamber (figure 1, flash chamber 20) to separate the CO2 from the solvent (col 3 ln 62 - col 4 ln 15). Kohl further teaches that a portion of the dissolved CO2 remains dissolved after the flash desorption, and that the amount of CO2 recovered from the solution can be further increased by contacting the solution with a stripping gas (col 4 ln 12-25; col 5 ln 21-26). The stripping takes place in a chamber that comprises a second inlet fluidically connected to its liquid outlet, wherein the second inlet is connected to a carrier gas source (figure 1, air stripping chamber 24 comprises solvent inlet 25, solvent outlet 26, carrier gas inlet 27, gas outlet 28).
Volkamer is directed to a system and method for removing CO2 from a mixed gas stream, by contacting the gas stream in an absorption column with an aqueous absorbent solution that dissolves CO2 (col 4 ln 11-23 and figure 1, gas stream 1 and absorption liquid stream 3 are contacted in absorption column 2, forming scrubbed gas stream 13 and CO2-laden liquid solution 4; col 2 ln 34-46, Volkamer's absorbent is an aqueous solution of alkanolamine), then passing the resulting solution to a desorption chamber to separate the CO2 from the solvent (col 4 ln 24 - 38 and figure 1, solution 4 is passed to flash desorption chamber 6 where it is partially desorbed to form a gas stream 7 comprising CO2 and a liquid solution 8; solution 8 is then passed to a second flash desorption chamber 10 to desorb more CO2 into gas stream 11). Kohl further teaches that some of the water in the aqueous solution is volatilized during CO2 desorption and lost, and that the lost water is compensated for by feeding makeup water into the circuit in the form of steam (col 4 ln 38-43 and figure 1, steam stream 14 is fed in at desorption stage 10 to compensate for water losses; per col 3 ln 44-68, the steam stream functions both to make up lost water and to make up lost heat).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Stern by including, at the third region, a gas stripping stage including a second gas inlet connected to a carrier gas source and fluidically connected to the second outlet, in order to increase the amount of CO2 removed from solution at the third region as taught in Kohl (col 4 ln 12-25; col 5 ln 21-26), and thereby increase the amount of CO2 that is recovered in each pass through Stern’s CO2 recovery system.
It would have been obvious to a person having ordinary skill in the art before the effective filing date of the claimed invention to further modify Stern by including a makeup stream to replace water that is lost to evaporation in the flash desorption module, based on Volkamer's teaching that water is in fact lost during the flash desorption of aqueous CO2 absorption solutions, and that the lost water can be compensated by a makeup stream (col 3 ln 44-68, col 4 ln 38-43, figure 1).
Response to Arguments
Applicant’s arguments (see Remarks filed 15 April 2026) are not persuasive with respect to claim 1, and the previously applied grounds of rejections are maintained. However, Applicant’s argument is persuasive to establish that the previously applied references do not render new claim 25 obvious. To address claim 25, new grounds of rejection are presented in this action in view of Orita.
Applicant argues that the Office’s reliance on Stern as the base reference of the rejection is misplaced because, in addition to the portions of Stern which Examiner cited in the grounds of rejection, Stern also discloses other different proton-coupled redox active species that do not read on the claim, including some in which the redox active species is not organic, and some in which CO2 is stored in the solution as carbamate complexes rather than as dissolved inorganic carbon. Applicant argues that one skilled in the art, directed to using Stern’s device and method of CO2 capture, would have relied on Stern’s other embodiments, which are already effective at higher pH and higher mediator concentration, rather than modify Stern’s benzoquinone embodiment to achieve higher pH and higher mediator concentration.
Applicant’s argument is unpersuasive because "[t]he prior art’s mere disclosure of more than one alternative does not constitute a teaching away from any of these alternatives because such disclosure does not criticize, discredit, or otherwise discourage the solution claimed" (In re Fulton, 391 F.3d 1195, 1201, 73 USPQ2d 1141, 1146 (Fed. Cir. 2004)). Stern’s disclosure of other embodiments, e.g. embodiments wherein CO-2 is captured as an amine complex or wherein the redox active species is copper ion, do not negate or discredit the embodiment of Stern that uses a benzoquinone as the redox active species to enact a pH swing, because a reference may be relied upon for all that it would have reasonably suggested to one having ordinary skill in the art (ibid; see also Merck & Co. v. Biocraft Labs., Inc. 874 F.2d 804, 10 USPQ2d 1843 (Fed. Cir. 1989)).
Applicant argues that the use of Wedege’s redox active species in Stern’s device is nonobvious because Wedege’s redox active species has an aqueous solubility limit below 1 M, and Stern does not suggest their device can make use of a redox active species at a concentration of less than 1 M.
This argument is unpersuasive with respect to claim 1 because Stern at paragraph [0040] explicitly teaches that their method can be practiced using redox active species concentrations as low as 0.1 M. However, this argument does persuasively establish that one would not reasonably expect the redox active species of Wedege could be used successfully at a concentration of at least 1.0 M in the method of Stern. Therefore the subject matter of claim 25 is not obvious over Stern and Wedege.
The previous rejections of record are maintained. Since the references relied on in the previous grounds of rejection do not suggest the subject matter of claim 25, new grounds of rejection based on Orita are introduced in this action to address claim 25. In the interest of compact prosecution, the new grounds are also applied to all of the other claims.
Conclusion
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/ANDREW KOLTONOW/Examiner, Art Unit 1795
/LUAN V VAN/Supervisory Patent Examiner, Art Unit 1795
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