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 .
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and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114.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 2 Jul. 2026 has been entered.
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.
This application currently names joint inventors. In considering patentability of the claims the examiner presumes that the subject matter of the various claims was commonly owned as of the effective filing date of the claimed invention(s) absent any evidence to the contrary. Applicant is advised of the obligation under 37 CFR 1.56 to point out the inventor and effective filing dates of each claim that was not commonly owned as of the effective filing date of the later invention in order for the examiner to consider the applicability of 35 U.S.C. 102(b)(2)(C) for any potential 35 U.S.C. 102(a)(2) prior art against the later invention.
Claims 1-12 and 28-30 are rejected under 35 U.S.C. 103 as being unpatentable over Koros et al. WO 2020/251937 published 17 Dec. 2020and further in view of Ahmad et al. “Novel MMM using CO2 selective SSZ-16 and high-performance 6FDA-polyimide for CO2/CH4 separation” published 1 Jan. 2021 Separation and Purification Technology Volume 254, 117582 (hereafter Ahmad) and Qiu et al. “Gas separation performance of 6FDA-based polyimides with different chemical structures” published 19 Sep. 2013 Polymer 54 6226-6235 (hereafter Qiu).
Regarding claim 1, Koros teaches a method of separating carbon dioxide (CO2) and hydrogen sulfide (H2S) from natural gas (¶38), comprising:
providing a polymer membrane comprising a polymer comprising 6FDA-DAM/DABA (¶42-43, ¶47);
introducing a natural gas stream to the polymer membrane, wherein the natural gas stream comprises CO2, H2S, and methane (CH4), and the natural gas stream comprises at least about 5% H2S by volume (¶29-31, MPEP 2144.05 I where it would have been obvious to choose the overlapping portion of the ranges of the claimed at least 5% and the prior art 0.23 to 15 bar partial pressure at between 20 to 80 bar total pressure); and
removing carbon dioxide (CO2) and hydrogen sulfide (H2S) from the natural gas (¶38).
Koros does not teach providing a polymer membrane comprising a polymer selected from 6FDA-DAM/DABA (3:1) and 6FDA-DAM/DABA (5:1).
Ahmad teaches CO2/methane membrane separation with 6FDA-DAM/DABA (3:1) because of the good CO2/methane selectivity and good CO2 permeability (pages 6-7 section 3.2).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify the 6FDA-DAM/DABA (3:2) of Koros by using the 6FDA-DAM/DABA (3:1) of Ahmad because of the good CO2/methane selectivity and good CO2 permeability (pages 6-7 section 3.2).
Qiu teaches CO2/methane membrane separation with 6FDA-DAM/DABA (abstract) where the permeation and selectivity can be adjusted by adjusting the monomer ratio (page 6231 column 1; page 3234 section 5).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify the 6FDA-DAM/DABA (3:2) of Koros by optimizing the monomer ratio such as to 3:1 or 5:1 in order to affect the permeation and selectivity (Qiu page 6231 column 1; page 3234 section 5). See MPEP 2144.05 II.
The modification would have resulted in wherein the polymer membrane exhibits an increase in H2S permeability, CO2 permeability, and H2S/CH4 selectivity as compared to the same polymer membrane comprising 6FDA-DAM/DABA (3:2) polymer because the properties of the polymer of the prior art would be expected to have the same properties of the claimed invention with the same composition.
Regarding claim 2, Koros in view of Ahmad and Qiu teach all the limitation of claim 1.
Koros teaches a H2S 0.23 to 15 bar partial pressure at between 20 to 80 bar total pressure (¶29-31).
Koros does not teach wherein the natural gas stream comprises about 5% to about 30% H2S by volume, about 5% to about 25% H2S by volume, about 5% to about 20% H2S by volume, about 5% to about 18% H2S by volume, about 5% to about 16% H2S by volume, about 5% to about 14% H2S by volume, about 5% to about 12% H2S by volume, about 5% to about 10% H2S by volume, about 10% to about 20% H2S by volume, about 12% to about 20% H2S by volume, about 14% to about 20% H2S by volume, about 16% to about 20% H2S by volume, about 18% to about 20% H2S by volume, or about 18% to about 22% H2S by volume.
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify the H2S 0.23 to 15 bar partial pressure at between 20 to 80 bar total pressure (¶29-31) of Koros to choose the overlapping portion of the claimed range of about 5% to about 30% H2S by volume and the prior art range as a prima facie case of obviousness. See MPEP 2144.05 I.
Regarding claim 3, Koros in view of Ahmad and Qiu teach all the limitation of claim 1.
Koros teaches a H2S 0.23 to 15 bar partial pressure at between 20 to 80 bar total pressure (¶29-31).
Koros does not teach the natural gas stream comprises about 20% or more H2S by volume.
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify the H2S 0.23 to 15 bar partial pressure at between 20 to 80 bar total pressure (¶29-31) of Koros to choose the overlapping portion of the claimed range of about 20% or more H2S by volume and the prior art range as a prima facie case of obviousness. See MPEP 2144.05 I.
Regarding claim 4, Koros in view of Ahmad and Qiu teach all the limitation of claim 1.
Koros teaches a H2S 0.23 to 15 bar partial pressure and a CO2 1.4 to 20 bar partial pressure at between 20 to 80 bar total pressure (¶29-31).
Koros does not teach wherein the natural gas stream comprises about 5% to about 20% H2S and about 3% to about 15% CO2 by volume.
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify the H2S 0.23 to 15 and CO2 1.4 to 20 bar partial pressures at between 20 to 80 bar total pressure (¶29-31) of Koros to choose the overlapping portion of the claimed range of about 5% to about 20% H2S and about 3% to about 15% CO2 by volume and the prior art ranges as a prima facie case of obviousness. See MPEP 2144.05 I.
Regarding claim 5, Koros in view of Ahmad and Qiu teach all the limitation of claim 1.
Koros further teaches wherein the natural gas stream further comprises ethane (C2H6), ethylene (C2H4), C3+ hydrocarbons, nitrogen (N2), water (H2O), and combinations thereof (¶3, further where one of ordinary skill would expect that ethylene and C3+ hydrocarbons would be present in natural gas).
Regarding claim 6, Koros in view of Ahmad and Qiu teach all the limitation of claim 1.
Koros teaches wherein the natural gas stream has a pressure of 20 to 80 bar (¶29-31).
Koros does not teach wherein the natural gas stream has a pressure of at least about 800 psig.
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify the 20 to 80 bar natural gas stream pressure (¶29-31) of Koros to choose the overlapping portion of the claimed range of at least about 800psig and the prior art range as a prima facie case of obviousness. See MPEP 2144.05 I.
Regarding claim 7, Koros in view of Ahmad and Qiu teach all the limitation of claim 1. Koros further teaches wherein the polymer membrane is thermally treated (¶29 where the membrane is treated with gas at up to 90C).
Regarding claim 8, Koros in view of Ahmad and Qiu teach all the limitation of claim 1. Koros further teaches wherein the H2S/CH4 selectivity is about 15 to about 27 (¶29).
Regarding claim 9, Koros in view of Ahmad and Qiu teach all the limitation of claim 1.
Koros does not teach wherein the polymer membrane exhibits: (i) an H2S permeability increase of about 140% to about 310%; (ii) an H2S/CH4 selectivity increase of about 10% to about 35%; and/or (iii) a CO2 permeability increase of about 30% to about 230%; as compared to the same polymer membrane comprising 6FDA-DAM/DABA (3 :2) polymer.
Ahmad teaches where 6FDA-DAM/DABA (3:1) has good selectivity and permeability compared to 6FDA-DAM/DABA (3:2).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention for the 6FDA-DAM/DABA (3:1) of Ahmad substituting for the 6FDA-DAM/DABA (3:2) in the membrane of Koros to have the polymer membrane exhibit a CO2 permeability increase of about 30% to about 230% as compared to the same polymer membrane comprising 6FDA-DAM/DABA (3:2) polymer, where Ahmad teaches increased CO2 permeability compared to 6FDA-DAM/DABA (3:2). The method of Koros measures permeability at 20% H2S, 20% CO2, and 60% CH4 feed at 35C and 46 bar (¶47) while the method of Ahmad measures permeability at equimolar CO2/CH4 between 6.9 and 20 bar and 25-35C (pages 6-7 section 3.2) and thus a direct comparison of the performance cannot be accurately determined based on the disclosures.
Regarding claim 10, Koros in view of Ahmad and Qiu teach all the limitation of claim 1. Koros further teaches wherein the CO2/CH4 selectivity is about 15 to about 40 wherein the natural gas stream comprises at least about 20% H2S by volume (¶47).
Regarding claim 11, Koros in view of Ahmad and Qiu teach all the limitation of claim 1.
Koros does not teach wherein the natural gas stream comprises at least about 20% H2S by volume and the polymer membrane exhibits: (i) an H2S permeability increase of about 65% to about 320%; and/or (ii) a CO2 permeability increase of about 150% to about 270%; as compared to the same polymer membrane comprising 6FDA-DAM/DABA (3:2) polymer.
Koros teaches CO2 permeability at 20% H2S, 20% CO2, and 60% CH4 feed at 35C and 46 bar (¶47).
Ahmad teaches CO2 permeability at equimolar CO2/CH4 between 6.9 and 20 bar and 25-35C (pages 6-7 section 3.2).
Thus, a direct comparison of the performance cannot be accurately determined based on the disclosures.
Ahmad teaches where 6FDA-DAM/DABA (3:1) has good selectivity and permeability compared to 6FDA-DAM/DABA (3:2).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention for the 6FDA-DAM/DABA (3:1) of Ahmad substituting for the 6FDA-DAM/DABA (3:2) in the membrane of Koros to have the polymer membrane exhibit a CO2 permeability increase of about 150% to about 270% as compared to the same polymer membrane comprising 6FDA-DAM/DABA (3:2) polymer, where Ahmad teaches increased CO2 permeability compared to 6FDA-DAM/DABA (3:2). The method of Koros measures permeability at 20% H2S, 20% CO2, and 60% CH4 feed at 35C and 46 bar (¶47) while the method of Ahmad measures permeability at equimolar CO2/CH4 between 6.9 and 20 bar and 25-35C (pages 6-7 section 3.2) and thus a direct comparison of the performance cannot be accurately determined based on the disclosures.
Regarding claim 12, Koros in view of Ahmad and Qiu teach all the limitation of claim 1.
Koros does not teach wherein the natural gas stream comprises at least about 20% H2S by volume and the polymer membrane exhibits: (i) an H2S/CH4 selectivity increase of about 1 % to about 15%; and/or (ii) a CO2/CH4 selectivity increase of about 40% to about 60%; as compared to the same polymer membrane comprising 6FDA-DAM polymer.
Koros teaches CO2 selectivity at 20% H2S, 20% CO2, and 60% CH4 feed at 35C and 46 bar (¶47).
Ahmad teaches CO2 selectivity at equimolar CO2/CH4 between 6.9 and 20 bar and 25-35C (pages 6-7 section 3.2).
Thus, a direct comparison of the performance cannot be accurately determined based on the disclosures.
Ahmad teaches where 6FDA-DAM/DABA (3:1) has good selectivity and permeability compared to 6FDA-DAM/DABA (3:2).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention for the 6FDA-DAM/DABA (3:1) of Ahmad substituting for the 6FDA-DAM/DABA (3:2) in the membrane of Koros to have the polymer membrane exhibit a CO2 selectivity increase of about 40% to about 60% as compared to the same polymer membrane comprising 6FDA-DAM polymer, where Ahmad teaches increased CO2 permeability compared to 6FDA-DAM/DABA (3:2) and where Ahmad does not teach comparing to 6FDA-DAM.
Regarding claim 28, Koros in view of Ahmad and Qiu teach all the limitation of claim 1.
Koros does not teach wherein the polymer membrane comprises 6FDA-DAM/DABA (3:1).
Ahmad teaches CO2/methane membrane separation with 6FDA-DAM/DABA (3:1) because of the good CO2/methane selectivity and good CO2 permeability (pages 6-7 section 3.2).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify the 6FDA-DAM/DABA (3:2) of Koros by using the 6FDA-DAM/DABA (3:1) of Ahmad because of the good CO2/methane selectivity and good CO2 permeability (pages 6-7 section 3.2).
Qiu teaches CO2/methane membrane separation with 6FDA-DAM/DABA (abstract) where the permeation and selectivity can be adjusted by adjusting the monomer ratio (page 6231 column 1; page 3234 section 5).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify the 6FDA-DAM/DABA (3:2) of Koros by optimizing the monomer ratio such as to 3:1 in order to affect the permeation and selectivity (Qiu page 6231 column 1; page 3234 section 5). See MPEP 2144.05 II.
Regarding claim 29, Koros in view of Ahmad and Qiu teach all the limitation of claim 1.
Koros does not teach wherein the polymer membrane comprises 6FDA-DAM/DABA (5:1).
Ahmad teaches CO2/methane membrane separation with 6FDA-DAM/DABA (3:1) because of the good CO2/methane selectivity and good CO2 permeability (pages 6-7 section 3.2).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify the 6FDA-DAM/DABA (3:2) of Koros by using the 6FDA-DAM/DABA (3:1) of Ahmad because of the good CO2/methane selectivity and good CO2 permeability (pages 6-7 section 3.2).
Qiu teaches CO2/methane membrane separation with 6FDA-DAM/DABA (abstract) where the permeation and selectivity can be adjusted by adjusting the monomer ratio (page 6231 column 1; page 3234 section 5).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify the 6FDA-DAM/DABA (3:2) of Koros by optimizing the monomer ratio such as to 5:1 in order to affect the permeation and selectivity (Qiu page 6231 column 1; page 3234 section 5). See MPEP 2144.05 II.
Regarding claim 30, Koros in view of Ahmad and Qiu teach all the limitation of claim 1. Koros further teaches wherein the natural gas stream has a pressure of 20 to 80 bar (¶29; 290 to 1160 psig).
Koros does not teach wherein the natural gas stream has a pressure of at least 500 psig.
MPEP
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify the 290 to 1160 psig pressure (¶29) of Koros to choose the overlapping portion of the claimed range of at least 500 to 1160 psig as a prima facie case of obviousness. See MPEP 2144.05 I.
Response to Arguments
The following is a response to Arguments filed 2 Jul. 2026:
Applicant argues that the sour gas environment of at least about 5% H2S would not have led one of ordinary skill in the art to look to the polymers of Ahmad and Qiu.
Examiner disagrees. The 3:2 6FDA-DAM/DABA of Koros is taught to be suitable in the sour gas environment of the claimed process. The polymers of Ahmad and Qiu, while different ratios, would not be expected to be unsuitable in the sour gas environment because the components are taught in Koros to be suitable. Applicant must provide further evidence that increasing the percentage of 6FDA-DAM would not have been expected to survive the 5% H2S process.
Applicant argues that the instant application demonstrates unexpected and superior results.
Examiner disagrees. Applicant has not cited any particular section of the instant application which would support the argument.
Further, Examiner notes that superior results are not the same as unexpected results. Superior results may or may not be predicted. Unexpected results are when one of ordinary skill would expect one result based some rationale, but where experimental results show a different result was achieved.
Conclusion
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/STEPHEN HOBSON/Examiner, Art Unit 1776
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