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 .
Response to Amendment
The rejection of claims 1-6 under 35 USC § 112 is withdrawn by the examiner in view of the amendment filed on 4/14/2026.
Claim Rejections - 35 USC § 103
In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis (i.e., changing from AIA to pre-AIA ) for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status.
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 1-6 are rejected under 35 U.S.C. 103 as being unpatentable over Uchida et al. “Two-step formation of methane–propane mixed gas hydrates in a batch-type reactor,” AIChE Journal, Vol. 50, pp. 518–523, 2004 in view of Baek et al. “Enhanced methane hydrate formation with cyclopentane hydrate seeds” (Applied Energy 202, 32–41, 2017).
Uchida discloses a method for forming methane-containing hydrates from methane and propane under controlled temperature and pressure conditions in a batch-type reactor (Abstract; Experimental Methods). Uchida discloses that structure II methane-containing hydrates crystallize in a first step and that structure I methane hydrates form in a second step, as confirmed by X-ray diffraction and Raman spectroscopy (Abstract; Results and Discussion; Figs. 2–5). Uchida further discloses that methane participates in the initial structure II hydrate phase and subsequently forms structure I methane hydrate under continued hydrate-forming conditions. Uchida discloses hydrate formation at approximately 274.0 ± 0.1 K and pressures of approximately 5–7 MPa (Experimental Methods; Table 1).
Baek discloses that cyclopentane is a thermodynamic additive that forms structure II hydrates and regulates methane hydrate formation behavior through structure II hydrate systems and hydrate seed promotion. Baek further teaches methane hydrate crystal regulation utilizing structure II hydrate-forming thermodynamic additives.
Uchida does not expressly disclose generating a “II-type pure methane hydrate.” However, it would have been obvious to one having ordinary skill in the art before the effective filing date of the claimed invention to regulate methane hydrate crystal structure in the methane-containing hydrate systems of Uchida by utilizing the thermodynamic additive-based hydrate regulation teachings of Baek in order to obtain methane-dominant structure II hydrate phases and subsequent transformation to structure I methane hydrate, because both references teach methane hydrate formation behavior associated with structure II hydrate systems under controlled hydrate-forming conditions.
Claim 1 further recites controlling the temperature to 274.15–288.15 K. Uchida et al. disclose hydrate formation at approximately 274.0 ± 0.1 K, immediately adjacent to the claimed range. Adjusting the operating temperature upward within the hydrate stability region to obtain the same hydrate phase-transition behavior would have been an obvious matter of routine optimization of a result-effective variable.
Regarding claim 2, Uchida et al. expressly disclose propane as a thermodynamic additive, while Baek et al. disclose cyclopentane as a thermodynamic additive for methane hydrate crystal regulation. Accordingly, the thermodynamic additives recited in claim 2 would have been obvious.
Regarding claim 3, neither Uchida et al. nor Baek et al. expressly disclose the claimed additive-to-water volume ratio of (15–24):(76–85). However, selection of a particular additive-to-water ratio would have been an obvious matter of routine optimization of a result-effective variable in hydrate formation systems.
Regarding claim 4, Baek et al. teach cyclopentane as a structure II hydrate-forming thermodynamic additive for methane hydrate regulation. It would have been obvious to substitute cyclopentane for propane in the methane-containing hydrate system of Uchida et al. because both are known structure II hydrate-forming thermodynamic additives used to regulate methane hydrate phase behavior. Uchida et al. already disclose hydrate formation pressures overlapping the claimed range of 7–9 MPa. Adjusting the operating temperature slightly upward within the hydrate stability region to the claimed range of 274.15–288.15 K would have been an obvious matter of routine optimization of a result-effective variable.
Regarding claim 5, Uchida et al. disclose propane-containing hydrate systems at pressures overlapping the claimed range of 5–7 MPa. Adjusting the operating temperature upward within the hydrate stability region to the claimed range of 276.15–283.15 K would have been an obvious modification representing routine optimization of operating conditions.
Regarding claim 6, Uchida et al. expressly disclose that gas hydrates are useful for natural gas storage and transportation (Introduction; Conclusions). Therefore, the additional limitation of claim 6 constitutes an intended use that would have been obvious.
Response to Arguments
Applicant’s arguments have been fully considered but are not persuasive.
Applicant argues that Uchida does not disclose a “II-type pure methane hydrate” because Uchida expressly characterizes the first-step hydrate as a methane–propane mixed structure II hydrate. Applicant further argues that Baek concerns cyclopentane-associated hydrate systems rather than pure methane structure II hydrates. These arguments are acknowledged. However, the rejection does not rely on either reference expressly disclosing an independently stable isolated pure methane structure II hydrate. Rather, the rejection relies on the collective teachings of the references concerning methane hydrate crystal regulation through structure II hydrate-forming thermodynamic additive systems.
Uchida expressly teaches that methane participates in structure II hydrate phases and subsequently forms structure I methane hydrate under continued hydrate-forming conditions. Baek further teaches regulating methane hydrate formation behavior utilizing thermodynamic additives that form structure II hydrate systems, including cyclopentane. The combined teachings therefore reasonably suggest regulating methane hydrate crystal structures through thermodynamic additive selection and hydrate-forming conditions in order to obtain desired methane hydrate phase behavior, including methane-dominant structure II hydrate phases and subsequent methane structure I hydrate formation.
Applicant additionally argues that combining Uchida with Baek would change the principle of operation of Uchida et al. or destroy its intended functionality. This argument is not persuasive because both references are directed to methane hydrate formation behavior associated with structure II hydrate systems and thermodynamic hydrate regulation. The proposed combination merely applies known structure II hydrate-forming thermodynamic additives and hydrate regulation techniques to known methane-containing hydrate systems in order to influence methane hydrate crystal structure and hydrate phase behavior. Such substitution and optimization constitute no more than the predictable use of prior art elements according to their established functions.
Applicant further argues that the inventors recognized a previously unidentified gas storage capacity problem associated with thermodynamic additives. However, the presently pending claims do not recite any quantitative gas storage capacity threshold, occupancy parameter, or structural limitation distinguishing over the methane-containing hydrate systems disclosed by the cited references. Accordingly, the rejection remains based upon the expressly recited process limitations, which would have been obvious over the cited references.
Conclusion
Applicant's amendment necessitated the new ground(s) of rejection presented in this Office action. Accordingly, THIS ACTION IS MADE FINAL. See MPEP § 706.07(a). Applicant is reminded of the extension of time policy as set forth in 37 CFR 1.136(a).
A shortened statutory period for reply to this final action is set to expire THREE MONTHS from the mailing date of this action. In the event a first reply is filed within TWO MONTHS of the mailing date of this final action and the advisory action is not mailed until after the end of the THREE-MONTH shortened statutory period, then the shortened statutory period will expire on the date the advisory action is mailed, and any nonprovisional extension fee (37 CFR 1.17(a)) pursuant to 37 CFR 1.136(a) will be calculated from the mailing date of the advisory action. In no event, however, will the statutory period for reply expire later than SIX MONTHS from the mailing date of this final action.
Any inquiry concerning this communication or earlier communications from the examiner should be directed to TAM M NGUYEN whose telephone number is (571)272-1452. The examiner can normally be reached Mon - Frid.
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/TAM M NGUYEN/Primary Examiner, Art Unit 1771
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