DETAILED ACTION
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 .
Claim Rejections - 35 USC § 102
The following is a quotation of the appropriate paragraphs of 35 U.S.C. 102 that form the basis for the rejections under this section made in this Office action:
A person shall be entitled to a patent unless –
(a)(1) the claimed invention was patented, described in a printed publication, or in public use, on sale, or otherwise available to the public before the effective filing date of the claimed invention.
(a)(2) the claimed invention was described in a patent issued under section 151, or in an application for patent published or deemed published under section 122(b), in which the patent or application, as the case may be, names another inventor and was effectively filed before the effective filing date of the claimed invention.
Claim(s) 1, 4, 5, 10–12, 14, and 15 is/are rejected under 35 U.S.C. 102(a)(1) as being anticipated by Wood (US 2023/0277973 A1).
With respect to claim 1, Wood teaches the claimed carbon-sequestration material (Wood, abstract).
Claim 1 further requires, “A carbon sequestration material, comprising: a gel.” Wood discloses a carbon-dioxide-capture material comprising a hydrogel (Wood, [0090]–[0093], [0146]).
Claim 1 further requires, “a polymeric component that is thermo-responsive and/or hydrophilic.” Wood explains that a hydrogel is a three-dimensional network of cross-linked hydrophilic polymers and specifically forms a cross-linked PEI hydrogel (Wood, [0090]–[0093], [0202]–[0203]).
Claim 1 further requires, “wherein the gel, when in the presence of water, is capable of sequestering and releasing gaseous carbon dioxide.” Wood states that it’s as-prepared PEI hydrogel is swollen with water, captures CO₂ from ambient air, and releases the captured CO₂ by heat, vacuum, dry heat, or steam regeneration (Wood, [0193], [0202]–[0203], [0217]–[0218], [0224]–[0227], [0239]–[0242]). Wood therefore discloses every limitation of claim 1 arranged as claimed.
Regarding claim 4, the claim requires, “wherein the polymeric component comprises a thermo-responsive polymer comprising hydroxypropyl cellulose, poly(N-isopropylacrylamide), and/or poly(N,N-diethylacrylamide).”
Wood teaches cross-linked poly(N-isopropylacrylamide), poly(isopropylacrylamide), and poly(diethylacrylamide) as the hydrophilic polymer of its CO₂-capture hydrogel (Wood, [0131]–[0132]). The expressly selected poly(N-isopropylacrylamide) species necessarily retains its temperature-responsive volume-transition behavior when present as Wood’s cross-linked, water-swollen polymer network; that response is a property of the selected polymer rather than a separately added component. Because claim 4 uses “and/or,” Wood’s poly(N-isopropylacrylamide) species satisfies the recited alternative.
Regarding claim 5, the claim requires, “wherein the polymeric component comprises a carbon dioxide capture medium comprising polyethylenimine, polyamidoamine dendrimers, poly(propylenimine) dendrimers, poly(allylamine), and/or poly(vinyl amine).”
Wood teaches polyethylenimine, polypropylenimine, and polyallylamine as cross-linked hydrophilic polymers and explains that their primary and secondary amines bind CO₂ (Wood, [0131], [0144], [0146]). Wood’s PEI and polyallylamine species satisfy the alternatively recited limitation.
Regarding claim 10, the claim requires “wherein the gel comprises a carbon dioxide capture medium comprising an amine.”
Wood teaches cross-linked polyamine hydrogels, including PEI, PPI, and polyallylamine hydrogels, whose primary and secondary amines bind CO₂ (Wood, [0131], [0144], [0146]). Wood also teaches a cross-linked PEI hydrogel swollen with a liquid containing diethanolamine (Wood, [0244]–[0249]).
Regarding claim 11, the claim requires, “wherein the gel has an amine efficiency of greater than or equal to 0.1 mol CO₂/mol N.”
Wood teaches an amine efficiency of 2–3 mmol CO₂ per gram of amine for the glycol/diethanolamine-swollen, cross-linked PEI hydrogel used with ambient air (Wood, [0249]). Even using the 43.07 g/mol repeat-unit mass of PEI, which contains one nitrogen per repeat unit, the disclosed upper endpoint converts to about 0.129 mol CO₂/mol N (0.003 mol CO₂/g × 43.07 g/mol N-containing repeat unit). That disclosed value is greater than 0.1 mol CO₂/mol N and therefore anticipates claim 11.
Regarding claim 12, the claim requires , “wherein the gel comprises a carbon dioxide capture medium comprising a cationic polymer.”
Wood teaches a water-swollen, cross-linked PEI capture medium having primary and secondary amines that bind CO₂, and Wood further teaches formation of carbonate/bicarbonate species in that PEI gel (Wood, [0144], [0202]–[0203], [0212]).
Regarding claim 14, the claim requires, “wherein at least a portion of the gel is or is derived from biomass.”
Wood teaches forming the hydrogel from natural hydrophilic polymers including chitin and cellulose (Wood, [0132]).
Regarding claim 15, claim 15 further requires, “wherein the gel further comprises one or more additives.”
Wood teaches hydrogels that further contain liquid swelling agents, cross-linking agents, and, optionally, metal salts (Wood, [0145]–[0146], [0158], [0166]–[0179], [0202], [0230])
Claim Rejections - 35 USC § 103
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
The factual inquiries for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows:
1. Determining the scope and contents of the prior art.
2. Ascertaining the differences between the prior art and the claims at issue.
3. Resolving the level of ordinary skill in the pertinent art.
4. Considering objective evidence present in the application indicating obviousness or nonobviousness.
Claim(s) 2, 7, and 16 is/are rejected under 35 U.S.C. 103 as being unpatentable over Wood (US 2023/0277973 A1) as applied to claim 1 above, and further in view of Yue (“Design Rationale of Thermally Responsive Microgel Particle Films That Reversibly Absorb Large Amounts of CO₂: Fine Tuning the pKa of Ammonium Ions in the Particles, 2015” )
With respect to claim 2, Wood teaches a carbon-sequestration gel. Claim 2 requires, “a gel configured such that, when the gel is loaded with carbon dioxide in an amount of at least 0.5 mmol of carbon dioxide (CO₂) per gram of gel.” Wood teaches a gel loaded to 63.02 mg CO₂/g, or about 1.43 mmol CO₂/g (Wood, [0238]).
Claim 2 further requires, “the gel is capable of releasing at least 50% of the carbon dioxide when the gel is at least one temperature of greater than 40 degrees Celsius and less than 100 degrees Celsius and within an environment having an absolute pressure of 1 atm.” Wood teaches operation at approximately 101 kPa and regeneration at 1 bar (Wood, [0194], [0225]), but Wood does not teach “releasing at least 50% of the carbon dioxide when the gel is at least one temperature of greater than 40 degrees Celsius and less than 100 degrees Celsius.” However, Yue teaches a reversible 3.0 mmol CO₂/g capacity and 0.93 mol CO₂/mol amine reversible stoichiometry over a 30–75 °C cycle (Yue, pp. 6120–6122, Figs. 6–7). Applying Yue’s 75 °C phase-transition release to Wood’s gel would predictably release more than 50% of a load exceeding 0.5 mmol/g at the ordinary atmospheric pressure taught by Wood. It would have been obvious to make that modification to reduce regeneration temperature and energy, as Yue expressly teaches for its reversible phase-transition mechanism.
A person of ordinary skill would have had a reasonable expectation of achieving the claimed release because Yue directly demonstrates the amount and 75 °C release in a water-swollen, amine-functionalized NIPAm gel, the same gel chemistry selected for the modification.
Regarding claim 7, the , “wherein the gel is capable of releasing at least 0.3 mmol of gaseous carbon dioxide per gram of gel within 50 minutes when exposed to air comprising 0.01 vol % gaseous carbon dioxide at an absolute pressure of 1 atm, when the gel is at least one temperature of greater than or equal to 40 degrees Celsius and less than 100 degrees Celsius.” Wood teaches the inherited gel, expressly identifies 100 ppm/0.01 vol.% CO₂ as a feed endpoint, operates at approximately 1 atm, and teaches regeneration intervals of 10 or 30 minutes, but Wood’s principal working regenerations use 120 °C (Wood, [0078]–[0079], [0194], [0225], [0239]). Wood does not teach “releasing at least 0.3 mmol of gaseous carbon dioxide per gram of gel within 50 minutes . . . when the gel is at least one temperature of greater than or equal to 40 degrees Celsius and less than 100 degrees Celsius.” However, Yue teaches release at 75 °C, a reversible capacity of 3.0 mmol/g, and a 25-minute desorption interval (Yue, pp. 6120–6122; Yue supplementary information, § 7). Even 10% of Yue’s reported reversible capacity equals the claimed 0.3 mmol/g, and Yue reports substantially higher reversible release.
It would have been obvious to a person of ordinary skill to use Yue’s 75 °C, 25-minute phase-transition desorption in Wood’s 1-atm, low-CO₂ operating environment to reduce regeneration energy. The predictable result meets the claimed amount, time, pressure, feed endpoint, and temperature.
Regarding claim 16, the claim requires, “wherein the thermo-responsive polymer undergoes a phase change at a phase change temperature, wherein the phase change temperature is greater than 40 degrees Celsius.” Wood teaches poly(N-isopropylacrylamide) for its water-swollen CO₂-capture hydrogel, but Wood does not teach “wherein the thermo-responsive polymer undergoes a phase change at a phase change temperature, wherein the phase change temperature is greater than 40 degrees Celsius” (Wood, [0131]–[0132]). However, Yue teaches NIPAm-containing, amine-functionalized gel particles having volume-phase-transition temperatures that are tunable through composition and reports a D30B2 composition having a volume-phase-transition temperature above 60 °C (Yue, pp. 6116–6118, Fig. 3c). Yue further teaches that transition temperature controls the pKa shift and reversible CO₂ capture/release behavior of the gel particles (Yue, pp. 6116–6119, Scheme 3).
It would have been obvious to select Yue’s disclosed NIPAm/DMAPM composition and monomer ratio for Wood’s expressly permitted NIPAm hydrogel because Yue teaches that composition is used to tune the phase-transition temperature governing reversible CO₂ capture and release, thereby producing a Wood-type thermo-responsive gel with a phase transition above 40 °C. A person of ordinary skill would have had a reasonable expectation of obtaining that phase transition because Yue directly measures it in the same water-swollen NIPAm/amine-gel system rather than in a materially different polymer class. Claim 16 would have been obvious.
Claim(s) 3, 9, 13, and 17 is/are rejected under 35 U.S.C. 103 as being unpatentable over Wood (US-20230277973-A1) and Yue (“Design Rationale of Thermally Responsive Microgel Particle Films That Reversibly Absorb Large Amounts of CO₂: Fine Tuning the pKa of Ammonium Ions in the Particles, 2015”) as applied to claims 1 and 2 above, and further in view of Chintapalli (2021/0370226 A1).
With respect to claim 3, the claim requires, “a gel capable of: sequestering at least 0.5 mmol of gaseous carbon dioxide (CO₂) per gram of the gel when the gel is at least one temperature of greater than 0 degrees Celsius and less than or equal to 40 degrees Celsius, when the gel is exposed to air comprising 0.01 vol % gaseous carbon dioxide at an absolute pressure of 1 atm, and when the air is at least one relative humidity of greater than or equal to 30%; and/or releasing at least 0.3 mmol of gaseous carbon dioxide per gram of gel when exposed to air comprising 0.01 vol % gaseous carbon dioxide at an absolute pressure of 1 atm, when the gel is at least one temperature of greater than 40 degrees Celsius and less than 100 degrees Celsius.” Because the claim uses “and/or,” the capture and release clauses are alternatives. The capture alternative is addressed below. Wood teaches 100 ppm/0.01 vol.% CO₂, 15–30 °C, approximately 101 kPa, and relative humidity of 30% or higher (Wood, [0078]–[0079], [0194], [0198]). Wood further teaches about 1.43 mmol/g capacity for its DAC PEI gel but does not teach “sequestering at least 0.5 mmol of gaseous carbon dioxide (CO₂) per gram of the gel . . . when the gel is exposed to air comprising 0.01 vol % gaseous carbon dioxide” at the single 100 ppm endpoint (Wood, [0238]). However, Chintapalli teaches more than 1 mmol/g at a CO₂ concentration below 1000 ppm and temperatures above 0 °C, together with greater-than-4-mmol/g DAC embodiments (Chintapalli, Table 1, [0017]–[0023], claims 11–14).
It would have been obvious to select Chintapalli’s high accessible amine loading and thin pore walls for Wood’s 100 ppm embodiment because Chintapalli teaches those features to improve dilute-DAC capacity, thereby predictably maintaining at least 0.5 mmol/g. A person of ordinary skill would have had a reasonable expectation of success because both references report capacities comfortably above 0.5 mmol/g at direct-air-capture concentrations.
Regarding claim 9, the carbon sequestration material of claim 1 has been discuss above.
Claim 9 further requires “wherein the gel has a sequestration capacity of greater than or equal to 3.6 mmol CO₂ per gram of the gel.” Wood teaches up to about 1.43 mmol/g for its water-swollen PEI gel and does not teach “a sequestration capacity of greater than or equal to 3.6 mmol CO₂ per gram of the gel” (Wood, [0238]). However, Chintapalli teaches equilibrium CO₂ loadings for its aminopolymer aerogel embodiments of greater than 1, greater than 3, and greater than 4 mmol/g under DAC conditions; paragraph [0021] likewise discloses a capacity in the range of 4 mol CO₂/kg, which equals 4 mmol CO₂/g (Chintapalli, Table 1, [0017]–[0023]). It would have been obvious to incorporate Chintapalli’s high backbone-integrated amine content, small pore walls, and accessible surface area into Wood’s porous polyamine gel because Chintapalli expressly teaches that those features increase loading (Chintapalli, [0017]–[0023]). The predictable 4 mmol/g result exceeds 3.6 mmol/g. Claim 9 would have been obvious.
A person of ordinary skill would have had a reasonable expectation of reaching the claimed capacity because Chintapalli reports the 4 mmol/g result under DAC conditions in the aminopolymer architecture being adopted and identifies high amine content and accessibility as the features producing that result (Chintapalli, [0017]–[0023]).
Regarding claim 13, the carbon sequestration material of claim 1 has been discussed above.
Claim 13 further requires “wherein the gel comprises a porous network comprising pores having a pore diameter of greater than or equal to 100 nm and less than or equal to 300 micrometers.”
Wood supplies claim 1 and describes porous hydrogel particles and liquid-filled interstitial spaces that improve CO₂ access to amine sites, but Wood does not teach “pores having a pore diameter of greater than or equal to 100 nm and less than or equal to 300 micrometers” (Wood, [0090]–[0094], [0132]–[0144]). However, Chintapalli teaches aminopolymer gel-derived aerogels having pore-size ranges of 10–1000 nm and, alternatively, 1–500 nm (Chintapalli, [0017], [0023]). Those ranges overlap claim 13 from 100 to 1000 nm and from 100 to 500 nm, respectively. Chintapalli also teaches that the accessible pore network increases gas-sorbent interaction and loading/unloading rates (Chintapalli, [0017]–[0023]).
It would have been obvious to use Chintapalli’s taught pore-size distribution in Wood’s polyamine gel because Chintapalli identifies pore size as a controllable parameter affecting CO₂ access and diffusion, thereby predictably forming a porous Wood-type gel having pores inside the claimed range. The claimed endpoints are not shown to be critical, and the art expressly discloses overlapping ranges for the same CO₂-transport purpose. Claim 13 would have been obvious.
Regarding claim 17, the carbon sequestration material of claim 1 has been discussed above.
claim 17 further requires, “wherein the gel is capable of the sequestering at least 0.5 mmol or gaseous carbon dioxide (CO₂) per gram of the gel when the gel is at least one temperature of greater than or equal to 15 degrees Celsius and less than or equal to 30 degrees Celsius, when the gel is exposed to air comprising 0.01 vol % gaseous carbon dioxide at an absolute pressure of 1 atm, and when the air is at least one relative humidity of greater than or equal to 30%.”
Wood teaches 100 ppm/0.01 vol.% CO₂, 15–30 °C, approximately 101 kPa, and relative humidity of 30% or higher (Wood, [0078]–[0079], [0194], [0198]), but Wood does not teach “sequestering at least 0.5 mmol or gaseous carbon dioxide (CO₂) per gram of the gel . . . when the gel is exposed to air comprising 0.01 vol % gaseous carbon dioxide” at that endpoint. However, Chintapalli teaches greater than 1 mmol/g below 1000 ppm and greater-than-4-mmol/g DAC embodiments, together with the accessible-amine and pore features that produce those results (Chintapalli, Table 1, [0017]–[0023], claims 11–14).
It would have been obvious to use Chintapalli’s high accessible amine loading and thin pore walls in Wood’s disclosed 100 ppm, 15–30 °C, humid, 1-atm embodiment because Chintapalli teaches those features to preserve capacity in dilute DAC service, thereby predictably retaining at least 0.5 mmol/g. A person of ordinary skill would have had a reasonable expectation of success because both Wood and Chintapalli report capacities above 0.5 mmol/g in DAC service and Wood already supplies the claimed 100 ppm, temperature, humidity, and pressure conditions. Claim 17 would have been obvious.
Claim(s) 6 is/are rejected under 35 U.S.C. 103 as being unpatentable over Wood (US 2023/0277973 A1) and Yue (2021/0370226 A1) as applied to claims 1-3 above, and further in view of Liu (“Radiation-Initiated High Strength Chitosan/Lithium Sulfonate Double Network Hydrogel/Aerogel with Porosity and Stability for Efficient CO₂ Capture, 2021” ).
Regarding claim 6, the carbon sequestration material of claim 1 as discussed above,
Claim 6 further requires “wherein the polymeric component comprises a hydrophilic material comprising konjac glucomannan, gelatin, chitosan, and/or polyvinyl alcohol.”
Wood teaches cross-linked natural hydrophilic polymers, including polysaccharides and chitin, for the CO₂-capture hydrogel (Wood, [0132]). Wood does not teach “a hydrophilic material comprising konjac glucomannan, gelatin, chitosan, and/or polyvinyl alcohol.” However, Liu teaches the exact chitosan species: Liu describes chitosan as a natural biopolymer, forms a water-swollen chitosan physical hydrogel and chitosan double-network hydrogel, and evaluates the porous gel-derived material for CO₂ capture (Liu, pp. 20486–20488, Abstract, §§ 1, 2.2).
It would have been obvious to select Liu’s chitosan as Wood’s natural hydrophilic polysaccharide network because Liu teaches that chitosan forms a water-swollen gel and provides a CO₂-philic, porous capture structure. The substitution is between expressly suggested natural hydrophilic gel polymers and predictably preserves Wood’s water-assisted CO₂ capture.
Claim(s) 8 is/are rejected under 35 U.S.C. 103 as being unpatentable over Wood (US 2023/0277973 A1) and Yue (“Design rationale of thermally responsive microgel particle films that reversibly absorb large amounts of CO2: fine tuning the pKa of ammonium ions in the particles,” 2015) as applied to claim 1 above, and further in view of Chintapalli (2021/0370226 A1).
Regarding claim 8, the carbon sequestration material of claim 1 has been discussed above “wherein the gel is capable of undergoing at least 10 sequestration/regeneration cycles wherein: for each sequestration cycle, the carbon sequestration material sequesters at least 0.5 mmol or gaseous carbon dioxide (CO₂) per gram of the gel when the gel is at least one temperature of greater than 0 degrees Celsius and less than or equal to 40 degrees Celsius, when the gel is exposed to air comprising 0.01 vol % gaseous carbon dioxide at an absolute pressure of 1 atm, and when the air is at least one relative humidity of greater than or equal to 30%; and for each regeneration cycle, the carbon sequestration material releases at least 0.3 mmol of gaseous carbon dioxide per gram of gel when exposed to air comprising 0.01 vol % gaseous carbon dioxide at an absolute pressure of 1 atm, when the gel is at least one temperature of greater than 40 degrees Celsius and less than 100 degrees Celsius.”
Wood supplies claim 1, the 100 ppm/0.01 vol.% endpoint, approximately 1-atm pressure, 15–30 °C capture, relative humidity of 30% or higher, and ten-cycle capture/regeneration operation (Wood, [0078]–[0079], [0194], [0198], [0239]–[0241], Figs. 19–20). Wood does not teach “for each sequestration cycle, the carbon sequestration material sequesters at least 0.5 mmol or gaseous carbon dioxide (CO₂) per gram of the gel” at 0.01 vol.% CO₂ or “for each regeneration cycle, the carbon sequestration material releases at least 0.3 mmol of gaseous carbon dioxide per gram of gel” below 100 °C.
However, Yue teaches the missing sub-100 °C release and cycling features. Yue’s optimized gel has a reversible capacity of 3.0 mmol/g, releases at 75 °C over a 25-minute desorption interval, and is operated through ten release/capture cycles (Yue, pp. 6120–6122, Fig. 7; Yue supplementary information, § 7). After the tenth cycle, the reversible stoichiometry remains 0.71 mol CO₂/mol amine, well above the fraction needed to release 0.3 mmol/g from the reported 3.0 mmol/g first-cycle capacity (Yue, p. 6121, Fig. 7).
Chintapalli further teaches the missing low-concentration capacity feature by reporting greater than 1 mmol/g below 1000 ppm and high-capacity DAC embodiments, with the accessible-amine and thin-pore-wall features that produce the result (Chintapalli, Table 1, [0017]–[0023], claims 11–14).
It would have been obvious to combine Chintapalli’s low-concentration, high-accessibility aminopolymer architecture and Yue’s 75 °C reversible phase-transition cycling with Wood’s humid, 1-atm, 100 ppm, ten-cycle protocol. The references address the same DAC sorbent variables, and each modification is used for its expressly taught purpose: Chintapalli to preserve capacity at dilute CO₂ and Yue to lower regeneration temperature while maintaining reversible cycling. The predictable result meets the capture and release thresholds for at least ten cycles. Claim 8 would have been obvious.
.
Conclusion
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/STARFARI TESHAWN MCCLAIN/ Examiner, Art Unit 1736
/DANIEL C. MCCRACKEN/ Primary Examiner, Art Unit 1736
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