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 Arguments
Applicant’s amendment was not fully successful in overcoming the rejection grounds under 35 U.S.C. 112(a) set forth in the Office action mailed 6 April 2026. While the amendment did properly limit the supercritical embodiment to hydrogen sulfide in the liquid state, an additional change that was made from the original claims in the amendment filed 14 October 2025 is still present and lacks support in the original specification. The claims currently state that sulfur dioxide is produced from hydrogen sulfide. However, the production of sulfur dioxide is only discussed in the original specification for the aqueous solution of hydrogen sulfide embodiment (see esp. reactions (2a)-(2c) on page 15). The original specification teaches (see reactions (1a)-(1b) on page 7) that the anodic product from electrolysis of hydrogen sulfide in the absence of water was elemental sulfur, not sulfur dioxide. The production of sulfur dioxide at the anode appears to require the presence of water, which is excluded in the supercritical embodiment.
In the interest of achieving compact prosecution, the Office will present additional rejection grounds over the prior art based upon the assumption that Applicant will correct the above written description problem by amending claim 1 to recite “wherein providing power to the electrochemical cell facilitates electrolysis of the hydrogen sulfide to produce sulfur
Claim 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.
The following is a quotation of the first paragraph of pre-AIA 35 U.S.C. 112:
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 of carrying out his invention.
Claims 1-9 and 20-29 are rejected under 35 U.S.C. 112(a) or 35 U.S.C. 112 (pre-AIA ), first paragraph, as failing to comply with the written description requirement. The claim(s) 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, or for applications subject to pre-AIA 35 U.S.C. 112, the inventor(s), at the time the application was filed, had possession of the claimed invention. The specification does not disclose that the anodic product from electrolyzing supercritical hydrogen sulfide was sulfur dioxide. The specification teaches that when hydrogen sulfide (in a liquid state) was provided to the anode, the resulting product was elemental sulfur (see paragraph [0018]). The production of sulfur dioxide is discussed in the specification (see paragraph [0028]) as requiring water (reaction (2a)). Therefore, the instantly claimed invention is not supported by the originally filed application.
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.
Claims 1-9 and 20-29 are rejected under 35 U.S.C. 103 as being unpatentable over Ipsakis et al (“An electrocatalytic membrane-assisted process for hydrogen production from H2S in Black Sea: Preliminary results”) in view of Russ et al (WO 2022/195110 A1).
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Ipsakis et al teach (see abstract, fig. 1) a method comprising:
providing power to an electrochemical cell comprising an anode side and cathode side (fig. 1 and following paragraph “[a]pplication of an electrical potential leads to the electrolysis of H2S”),
flowing hydrogen sulfide to the anode side (fig. 1),
preventing, by a membrane (1) separating the anode side from the cathode side, flow of hydrogen sulfide, water, and sulfur dioxide from passing through the membrane while allowing hydrogen cations to pass through the membrane,
flowing sulfur dioxide out of the anode side, and
flowing hydrogen out of the cathode side.
Ipsakis et al teach that electrolysis of the hydrogen sulfide produced sulfur dioxide and protons on the anode side and the protons were reduced at the cathode side to hydrogen gas.
Ipsakis et al fail to teach maintaining an operating temperature and pressure within the anode side such that the hydrogen sulfide in the anode side was at a supercritical state.
Russ et al teach (see abstract, page 1, third to fifth paragraphs, and page 40, second full paragraph) that operation of an electrolysis cell under supercritical conditions has an advantage of preventing bubble formation on the electrode surfaces that contributed to increased overpotentials. The bubble formation was prevented by the supercritical conditions causing complete miscibility between the electrolyte and the reaction products.
Therefore, it would have been obvious to one of ordinary skill in the art to have modified the process of Ipsakis et al according to the teachings of Russ et al by operating at supercritical conditions in order to prevent unwanted increases in overpotentials caused by bubbles of the sulfur dioxide product becoming attached to the anode surface.
With respect to the claim limitation “preventing, in response to maintaining the operating temperature and the operating pressure within the anode side, such that the hydrogen sulfide in the anode side is at the supercritical state, formation of sulfuric acid in the anode side of the electrochemical cell”, it is noted that the formation of sulfuric acid is discussed by Ipsakis et al as requiring an additional step in the presence of a catalyst (fig. 1). Thus, Ipsakis et al show that sulfuric acid was not formed in the anode side.
Regarding claims 2, 20, and 21, the protons (hydrogen cations) passed through the membrane and reacted at the cathode to form hydrogen. The process included a step of applying a voltage between the anode and cathode.
Regarding claims 3 and 22, Ipsakis et al discusses (see Materials and methods section on page 7532) electrolysis of hydrogen sulfide to generate hydrogen, wherein the volumetric flow rate of the hydrogen sulfide was kept constant achieving a space velocity (“GHSV” = gas hourly space velocity) of 13500 per hour.
Regarding claims 4 and 23, from fig. 1, and the first paragraph of the “Materials and methods” section, the thickness of the membrane of Ipsakis et al is considered to inherently fall within the claimed range. Fig. 1 shows the membrane (1) being thicker than any adjoining layer (anode 2, cathode 3 or support 4). The discussion teaches that the cathode had a thickness of about 15 mm. Thus, the membrane of Ipsakis et al must have a thickness larger than 15 mm.
Regarding claims 5 and 24, Ipsakis et al teach (see first paragraph of “Materials and methods” section) using Y-doped barium zirconate proton-conducting solid electrolyte, BaZr0.85Y0.15O3-d as the membrane. Perovskite materials have the general formula ABO3. Thus, the Y-doped barium zirconate material of Ipsakis et al was a perovskite.
Regarding claims 6-8 and 25-27, it would have been within the ordinary level of skill in the art to have performed routine experimentation to determine suitable temperature and pressure conditions in order to maintain the hydrogen sulfide of Ipsakis et al in a supercritical state.
Regarding claims 9 and 28, although Ipsakis et al fail to teach the exact voltage applied, it would have been within the ordinary level of skill in the art to have performed routine experimentation to determine suitable voltage value for driving the electrolytic reaction.
Regarding claim 29, it is noted that the formation of sulfuric acid is discussed by Ipsakis et al as requiring an additional step in the presence of a catalyst (fig. 1). Thus, Ipsakis et al show that sulfuric acid was not formed in the anode side.
The following grounds of rejection are applied against the claims assuming that the claims are amended from “sulfur dioxide” to “sulfur” as discussed in paragraph 3 above.
Claims 1, 2, 20-21, and 25-29 are rejected under 35 U.S.C. 103 as being unpatentable over Gregory et al (“Electrolysis of liquid hydrogen sulphide”) in view of Lupton et al (US 2022/0205113) and Russ et al (WO 2022/195110 A1).
Gregory et al teach (see abstract, figs. 1-2, section 2) a method comprising providing power to an electrochemical cell that included an anode side and a cathode side, flowing hydrogen sulfide in a liquid state to the electrochemical cell (including the anode side), wherein providing power to the electrochemical cell facilitated electrolysis of the hydrogen sulfide to produce sulfur and protons on the anode side and reduction of protons to produce hydrogen on the cathode side, and flowing sulfur out of the anode side and flowing hydrogen out of the cathode side.
Note that “anode side” is interpreted as being the portion of the electrochemical cell closer to the anode and “cathode side” as being the portion closer to the cathode.
Gregory fails to teach (1) a step of preventing, by a membrane separating the anode side from the cathode side, flow of hydrogen sulfide and sulfur and (2) maintaining operating temperature and pressure such that the hydrogen sulfide is at a supercritical state.
Regarding (1), Lupton et al teach (see abstract, paragraphs [0004], [0014]-[0017] and [0020]-[0021]) that a membrane may be provided between an anode/anode side and a cathode/cathode side of an electrochemical cell used to decompose hydrogen sulfide into hydrogen gas and liquid sulfur, and that the membrane had the effect of separating the hydrogen gas product from the sulfur product.
Therefore, it would have been obvious to one of ordinary skill in the art at the time of filing to have modified the method of Gregory by adding a step of preventing, by use of a membrane separating the anode side from the cathode side, flow of hydrogen sulfide and sulfur from passing through the membrane while allowing hydrogen cations (protons) to pass through the membrane as taught by Lupton et al because Lupton et al teach that a membrane positioned between the anode and cathode permitted separate recovery of the anode product (sulfur) from the cathode product (hydrogen).
Regarding (2), Russ et al teach (see abstract, page 1, third to fifth paragraphs, and page 40, second full paragraph) that operation of an electrolysis cell under supercritical conditions has an advantage of preventing bubble formation on the electrode surfaces that contributed to increased overpotentials. The bubble formation was prevented by the supercritical conditions causing complete miscibility between the electrolyte and the reaction products.
Therefore, it would have been obvious to one of ordinary skill in the art to have modified the process of Gregory according to the teachings of Russ et al by operating at supercritical conditions in order to prevent unwanted increases in overpotentials caused by bubbles of products becoming attached to the electrode surfaces.
With respect to the claim limitation “preventing, in response to maintaining the operating temperature and the operating pressure within the anode side, such that the hydrogen sulfide in the anode side is at the supercritical state, formation of sulfuric acid in the anode side of the electrochemical cell”, it is noted that the formation of sulfuric acid requires the presence of water. Since Gregory et al and Lupton et al do not teach the presence of water in the electrochemical cell, formation of sulfuric acid was avoided. Applicant has failed to show that the supercritical state was capable of preventing the formation of sulfuric acid when the anode reactant was hydrogen sulfide in the liquid state.
Regarding claim 2, the hydrogen cations (protons) passed through the membrane of Lupton et al. Both Gregory and Lupton et al teach that the hydrogen cations are reduced at the cathode to hydrogen gas.
Regarding claim 20, the membrane of Lupton et al was a cation exchange membrane, which means that it was inherently configured to allow the protons to pass from the anode to the cathode. Both Gregory et al and Lupton et al teach applying a voltage across the anode and the cathode to produce hydrogen at the cathode.
Regarding claim 21, the process as taught by Gregory et al and Lupton et al included reduction of the protons to hydrogen gas at the cathode.
Regarding claim 25-27, it would have been within the ordinary level of skill in the art to have performed routine experimentation to determine suitable temperature and pressure conditions in order to maintain the hydrogen sulfide of Gregory et al in a supercritical state.
Regarding claim 28, Gregory et al fail to teach the voltage utilized in the electrolysis process. Lupton et al teach (see paragraph [0024]) applying voltages in the range of 1 to 1.5 volts to cause the electrolytic reduction of H-2S to hydrogen and sulfur. One of ordinary skill in the art at the time of filing would have looked to other hydrogen sulfide electrolysis decomposition methods to establish a workable range of voltage in the process of Gregory et al as claimed.
Regarding claim 29, Russ et al suggests conducting electrolysis under supercritical conditions. With respect to the claim limitation “prevent formation of sulfuric acid in the anode side of the electrochemical cell”, it is noted that the formation of sulfuric acid requires the presence of water. Since Gregory et al and Lupton et al do not teach the presence of water in the electrochemical cell, formation of sulfuric acid was avoided. Applicant has failed to show that the supercritical state was capable of preventing the formation of sulfuric acid when the anode reactant was hydrogen sulfide in the liquid state.
Claims 3 and 22 are rejected under 35 U.S.C. 103 as being unpatentable over Gregory et al (“Electrolysis of liquid hydrogen sulphide”) in view of Lupton et al (US 2022/0205113) and Russ et al (WO 2022/195110) as applied to claims 2 and 21, respectively, above, and further in view of Ipsakis et al (“An electrocatalytic membrane-assisted process for hydrogen production from H2S in Black Sea: Preliminary results”).
Gregory et al and Lupton et al are silent with respect to the space velocity of the hydrogen sulfide to the anode side.
Ipsakis et al discusses (see Materials and methods section on page 7532) electrolysis of hydrogen sulfide to generate hydrogen, wherein the volumetric flow rate of the hydrogen sulfide was kept constant achieving a space velocity (“GHSV” = gas hourly space velocity) of 13500 per hour.
Therefore, in the absence of secondary considerations, it would have been obvious to one of ordinary skill in the art at the time of filing to have looked to other hydrogen sulfide electrolysis decomposition methods to establish a workable range of flow rate of the hydrogen sulfide to achieve a space velocity as claimed.
Claim 4 is rejected under 35 U.S.C. 103 as being unpatentable over Gregory et al (“Electrolysis of liquid hydrogen sulphide”) in view of Lupton et al (US 2022/0205113), Russ et al (WO 2022/195110) and Ipsakis et al (“An electrocatalytic membrane-assisted process for hydrogen production from H2S in Black Sea: Preliminary results”) as applied to claim 3 above, and further in view of He et al (“Physicochemical properties of phosphoric acid doped polybenzimidazole membranes for fuel cells”).
Lupton et al fail to teach the thickness of the phosphoric acid doped PBI membrane.
He et al describe the physical and chemical properties of conventional phosphoric acid doped PBI membrane. Typical membranes of this type possessed a dry thickness of 35-50 μm. Even with swelling caused by the acid doping (see section 3.1) or by adsorption of water during use, the conventional membrane would have been expected to inherently possess a thickness within the claimed range.
Claims 5-9 are rejected under 35 U.S.C. 103 as being unpatentable over Gregory et al (“Electrolysis of liquid hydrogen sulphide”) in view of Lupton et al (US 2022/0205113), Russ et al (WO 2022/195110), Ipsakis et al (“An electrocatalytic membrane-assisted process for hydrogen production from H2S in Black Sea: Preliminary results”) and He et al (“Physicochemical properties of phosphoric acid doped polybenzimidazole membranes for fuel cells”) as applied to claim 4 above, and further in view of Shnell et al (“Supercritical Geothermal Cogeneration: Combining Leading-Edge, Highly-Efficient Energy and Materials Technologies in a Load-Following Renewable Power Generation Facility”) and Bi et al (“Steam electrolysis by solid oxide electrolysis cells (SOECs) with proton-conducting oxides”).
Regarding claim 5, Lupton et al and He et al teach the membrane being polybenzimidazole (PBI) not a perovskite oxide proton-exchange membrane.
In view of the supercritical fluid conditions suggested by Russ et al, one of ordinary skill in the art would have sought to ensure that the membrane separating the anode and cathode were capable of operating at the temperatures and pressures of the supercritical fluid.
Shnell et al (see sections 2 and 3) performing electrolysis under supercritical conditions, wherein a proton conducting ceramic was utilized because of the temperature of operation with the supercritical fluids.
Bi et al teach (see abstract, section 2) that perovskite-type oxides possessed high proton conductivity and were widely used as a proton exchange membrane under high temperature conditions.
Therefore, it would have been obvious to one of ordinary skill in the art at the time of filing to have substituted a perovskite oxide proton-exchange membrane as taught by Bi et al for the PBI membrane of Lupton et al when operating the cell under supercritical conditions due to the temperature resistance of the ceramic proton exchange membranes recognized by Shnell et al.
Regarding claims 6-8, it would have been within the ordinary level of skill in the art to have performed routine experimentation to determine suitable temperature and pressure conditions in order to maintain the hydrogen sulfide of Gregory et al in a supercritical state.
Regarding claim 9, Gregory et al fail to teach the voltage utilized in the electrolysis process. Lupton et al teach (see paragraph [0024]) applying voltages in the range of 1 to 1.5 volts to cause the electrolytic reduction of H-2S to hydrogen and sulfur. One of ordinary skill in the art at the time of filing would have looked to other hydrogen sulfide electrolysis decomposition methods to establish a workable range of voltage in the process of Gregory et al as claimed.
Claim 23 is rejected under 35 U.S.C. 103 as being unpatentable over Gregory et al (“Electrolysis of liquid hydrogen sulphide”) in view of Lupton et al (US 2022/0205113) and Russ et al (WO 2022/195110) as applied to claim 20 above, and further in view of He et al (“Physicochemical properties of phosphoric acid doped polybenzimidazole membranes for fuel cells”).
Lupton et al fail to teach the thickness of the phosphoric acid doped PBI membrane.
He et al describe the physical and chemical properties of conventional phosphoric acid doped PBI membrane. Typical membranes of this type possessed a dry thickness of 35-50 μm. Even with swelling caused by the acid doping (see section 3.1) or by adsorption of water during use, the conventional membrane would have been expected to inherently possess a thickness within the claimed range.
Claim 24 is rejected under 35 U.S.C. 103 as being unpatentable over Gregory et al (“Electrolysis of liquid hydrogen sulphide”) in view of Lupton et al (US 2022/0205113) and Russ et al (WO 2022/195110) as applied to claim 20 above, and further in view of Ipsakis et al (“An electrocatalytic membrane-assisted process for hydrogen production from H2S in Black Sea: Preliminary results”).
Lupton et al teach using a polymeric cation exchange membrane for transporting the protons from the anode to the cathode.
Lupton et al thus fail to teach using a perovskite ceramic membrane.
Ipsakis et al teach (see abstract, fig. 1) that ceramic membranes that supported proton conduction were compatible with performing electrolysis of hydrogen sulfide. Ipsakis et al teach (see first paragraph of “Materials and methods” section) using a Y-doped barium zirconate proton-conducting solid electrolyte, BaZr0.85Y0.15O3-d. Perovskite materials have the general formula ABO3. Thus, the Y-doped barium zirconate material of Ipsakis et al was a perovskite. Ipsakis et al teach (see third paragraph of “Introduction” section) that the moderate temperatures of the H2S electrolysis process were benefited by using the ceramic membrane material (as opposed to polymeric membranes that had lower maximum operating temperatures).
Therefore, it would have been obvious to one of ordinary skill in the art at the time of filing to have substituted the ceramic membrane taught by Ipsakis et al in place of the polymeric membrane taught by Lupton et al for the purpose of increasing the maximum operating temperature of the membrane, in order to make the membrane more resistant to the temperature and pressure necessary for supercriticalness of the hydrogen sulfide.
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.
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/HARRY D WILKINS III/Primary Examiner, Art Unit 1794
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