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 .
Status of the Claims
This is a final Office action in response to the Applicant’s arguments and amendments filed on 05/28/2026. Claims 1-21 are pending in the current office action. Claims 1-2 and 10 were amended by Applicant.
Status of the Rejection
The rejections of claims 10 and 11 under 35 U.S.C. § 112(a) are withdrawn in view of Applicant’s amendments.
The rejections of claims 2-3 and 5-11 under 35 U.S.C. § 112(b) are withdrawn in view of Applicant’s amendments.
The rejections of claims 1, 4, 12-15, 18, and 20 under 35 U.S.C. § 102(a)(1) are maintained.
The rejections of claims 16-17, 19, and 21 under 35 U.S.C. § 103 are maintained.
The rejections of claims 2-3 and 5 under 35 U.S.C. § 102(a)(1) are withdrawn in view of Applicant’s amendments.
The rejections of claims 6-11 under 35 U.S.C. § 103 are maintained, and modified only as necessitated by Applicant’s amendments.
New rejections of claims 2-3 and 5 under 35 U.S.C. § 103 are necessitated by Applicant’s amendments.
Claim Interpretation
The instant application includes the use of the unit “barg”, which is a unit of gauge pressure, in the claims and/or specification. It is understood by persons of ordinary skill in the art that the gauge pressure indicates the pressure in a system in excess of atmospheric pressure (approximately 1 bar at sea level). For example, a pressure of 1 barg is approximately equivalent to a pressure of 2 bar at sea level. See excerpt below from Towler, et al. (Chemical Engineering Design - Principles, Practice and Economics of Plant and Process Design (2nd Edition) - 1.7 Systems of Units pp. 21 (2013) Elsevier).
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Claim Rejections - 35 USC § 102
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, 4, 12-15, 18, and 20 are rejected under 35 U.S.C. 102(a)(1) as being anticipated by Braun (US Pat. Pub. 2014/0272734) as evidenced by Rackley (“Carbon Capture and Storage - 3.1.5 Rankine Steam Cycle.” (2010) Elsevier) and, in the case of claim 4, Reytier (US Pat. Pub. 2016/0053388).
Regarding claim 1, Braun teaches a method for generating synthesis gas containing hydrogen, carbon monoxide or mixtures of hydrogen, carbon monoxide and carbon dioxide by electrolysis (para. 3),
said method comprising feeding steam (“The polished feed stream may be combined with hydrogen and steam … The preheated polished feed stream may be fed into the SOEC 210 at the cathode 212” Fig. 2 and para. 58) and compressed air (“Air exiting compressor 220 may … be provided to the SOEC 210 at the anode 214” para. 59 and Fig. 2) to a cathode and an anode, respectively, of an electrolysis unit (see Fig. 2), wherein:
the electrolysis unit is operated under an elevated gas pressure (“the SOEC may operate at a pressure between about 1 bar to about 20 bars” para. 36 and see Table 1), and
an oxygen-rich gas leaving the anode is subsequently expanded down to approximately ambient pressure using a gas expander (see below), the gas expander being downstream and not upstream of the electrolysis unit or units (Fig. 2 shows that “heat exchanger 233” i.e., the steam Rankine cycle (SRC) system, is disposed between the electrolysis unit and the exhaust).
Regarding the limitation “an oxygen-rich gas leaving the anode is subsequently expanded down to approximately ambient pressure using a gas expander”. Braun teaches the gas exiting the anode is enriched in oxygen (“oxygen exiting SOEC 210 at anode 214” Table 1). Braun further teaches this gas is passed through “heat exchanger 233”, which is an SRC system (“steam Rankine cycle systems may be utilized to capture some of the syngas sensible and/or latent heat and the LFG combustion gas sensible and/or latent heat to produce electricity (see heat exchangers 225 and 233 respectively)” para. 59 and Fig. 2), wherein the pressure of the oxygen-rich gas is reduced to 100 kPa or about 1 atm i.e., approximately ambient pressure (“exhaust gas exiting SRC 233” Table 1) from 110 kPa (“gas entering SRC 233” Table 1), thereby generating electricity (see Fig. 2). As evidenced by e.g., Rackley, the pressure of a gas stream entering an SRC is reduced by being passed through an expansion turbine to generate electricity (see “From B to C” on p. 36 and Fig. 3.3). Thus, Braun anticipates the limitation “an oxygen-rich gas leaving the anode is subsequently expanded down to approximately ambient pressure using a gas expander”.
Regarding claim 4, Braun anticipates the limitations of claims 1, as described above.
Braun further teaches the synthesis gas is methanol synthesis gas configured for production of methanol (“the syngas may be converted to liquid fuels including, but not limited to, diesel, jet, gasoline, and light fuel gas” para. 41 and see below).
As evidenced by Reytier, the same composition of syngas used to form diesel is used to produce methanol (“Methanol … 1/2” and “Diesel … 1/2” Table 1). Therefore, as Braun teaches the synthesis gas is suitable for forming diesel, the synthesis gas of Braun is suitable for forming methanol.
Regarding claim 12, Braun anticipates the limitations of claim 1, as described above.
Braun further teaches a compressor and the gas expander are connected to different lines (Fig. 2 shows “syngas compressor 228” is on the cathode line, while “heat exchanger 233” i.e., the gas expander, is on the anode line).
Regarding claim 13, Braun anticipates the limitations of claim 1, as described above.
Braun further teaches a compressor and the gas expander are connected to a mutual line (Fig. 2 shows “compressor 220” and “heat exchanger 233” i.e., the gas expander, are both disposed on the anode line).
Regarding claim 14, Braun anticipates the limitations of claim 1, as described above.
Braun further teaches the gas is further expanded down to a pressure of 100 kPa, or 0 barg, a value within the claimed range, by the gas expander (“exhaust gas exiting SRC 233” Table 1).
Regarding claim 15, Braun anticipates the limitations of claim 1, as described above.
Braun further teaches pre-heating the air in a feed/effluent heat exchanger to a first elevated temperature T1 (“Air exiting compressor 220 may be heated in … heat exchanger 216” para. 59 and Fig. 2, see also Table 1).
Regarding claim 18, Braun further teaches after oxygen-enriched air leaves the SOEC stacks, heat is recuperated in the feed/effluent heat exchanger (Fig. 2 and Table 1 show heat is transferred from the oxygen-enriched air leaving the anode to the air in heat exchanger 216), and wherein the oxygen-enriched air subsequently enters the gas expander (Fig. 2 shows “heat exchanger 233” i.e., the gas expander, is located downstream from “heat exchanger 216”).
Regarding claim 20, Braun teaches a method for generating synthesis gas containing hydrogen, carbon monoxide or mixtures of hydrogen, carbon monoxide and carbon dioxide by electrolysis (para. 3),
said method comprising feeding steam (“The polished feed stream may be combined with hydrogen and steam … The preheated polished feed stream may be fed into the SOEC 210 at the cathode 212” Fig. 2 and para. 58) and compressed air (“Air exiting compressor 220 may … be provided to the SOEC 210 at the anode 214” para. 59 and Fig. 2) to a cathode and an anode, respectively, of an electrolysis unit (see Fig. 2), wherein:
the electrolysis unit is operated under an elevated gas pressure (“the SOEC may operate at a pressure between about 1 bar to about 20 bars” para. 36 and see Table 1), and
an oxygen-rich gas leaving the anode is subsequently expanded down to approximately ambient pressure using a gas expander (see below), the gas expander being downstream and not upstream of the electrolysis unit or units (Fig. 2 shows that “heat exchanger 233” i.e., the steam Rankine cycle system, is disposed between the electrolysis unit and the exhaust),
wherein the compressed air is compressed to a pressure of up to 19 barg, a range within the claimed range (“the SOEC may operate at a pressure between about 1 bar to about 20 bars” para. 36), and
the oxygen-rich gas leaving the anode has a temperature of 800 °C, a value within the claimed range (“Oxygen exiting SOEC 210 at anode 214” Table 1).
Regarding the limitation “an oxygen-rich gas leaving the anode is subsequently expanded down to approximately ambient pressure using a gas expander”. Braun teaches the gas exiting the anode is enriched in oxygen (“oxygen exiting SOEC 210 at anode 214” Table 1). Braun further teaches this gas is passed through “heat exchanger 233”, which is an SRC system (“steam Rankine cycle systems may be utilized to capture some of the syngas sensible and/or latent heat and the LFG combustion gas sensible and/or latent heat to produce electricity (see heat exchangers 225 and 233 respectively)” para. 59 and Fig. 2), wherein the pressure of the oxygen-rich gas is reduced to 100 kPa or about 1 atm i.e., approximately ambient pressure (“exhaust gas exiting SRC 233” Table 1) from 110 kPa (“gas entering SRC 233” Table 1), thereby generating electricity (see Fig. 2). As evidenced by e.g., Rackley, the pressure of a gas stream entering an SRC is reduced by being passed through an expansion turbine to generate electricity (see “From B to C” on p. 36 and Fig. 3.3). Thus, Braun anticipates the limitation “an oxygen-rich gas leaving the anode is subsequently expanded down to approximately ambient pressure using a gas expander”.
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 2-3, 5-9, and 21 are rejected under 35 U.S.C. 103 as being unpatentable over Braun (US Pat. Pub. 2014/0272734) in view of Severinsky (US Pat. Pub. 2006/0211777 A1) and as evidenced by Rackley (“Carbon Capture and Storage - 3.1.5 Rankine Steam Cycle.” (2010) Elsevier), Reytier (US Pat. Pub. 2016/0053388) in the case of claims 5-6, and, Universal Industrial Gases (“Air: Its Composition and Properties” (2019) www.uigi.com/air.html#:~:text=Standard%20dry%20air%2C%20which%20is,recovered%20as%20industrial%20gas%20products) in the case of claim 7.
Regarding claim 2, Braun anticipates the limitations of claim 1, as described in the rejection under 35 U.S.C. § 102(a)(1), above, incorporated herein by reference.
Braun further teaches the electrolysis unit is a solid oxide electrolysis cell (SOEC) (abstract).
Braun does not teach the steam and compressed air are fed to the first electrolysis unit of a series of electrolysis units.
However, Severinsky teaches that using a series of electrolysis units rather than a single electrolysis unit provides the predictable benefits of improving safety and making installation and maintenance more convenient (para. 195).
As Braun teaches a method of producing syngas using an SOEC, Braun is analogous art to the instant invention. As Severinsky teaches a method of producing syngas using a steam electrolyzer (e.g., para. 87), Severinsky is analogous art to the instant invention.
It would therefore have been obvious to a person having ordinary skill in the art before the effective filing date of the instant application to modify the method of Braun, such that the steam and compressed air are fed to the first electrolysis unit in a series of electrolysis units, as taught by Severinsky. A person having ordinary skill in the art would have been motivated to make this modification to achieve the predictable benefits of improved safety and more convenient installation and maintenance, as taught by Severinsky. Furthermore, combining prior art elements according to known methods to yield predictable results establishes a prima facie case of obviousness (MPEP § 2143(I)(A)). Furthermore, duplication of parts, absent evidence of unexpected results, establishes a prima facie case of obviousness (MPEP § 2144.04(VI)(B)).
Regarding claim 3, Braun further teaches the SOEC stacks operate in thermoneutral mode (see below).
As evidenced by e.g., the instant specification, “thermoneutral mode” refers to operation wherein the influent and effluent of the SOEC have the same temperature (p. 8 line 31 – p. 9 line 7). Braun teaches the influent and effluent from both the anode and cathode sides are each 800 °C (“Heated compressed stream … entering SOEC 210 at cathode 212”, “Syngas stream exiting SOEC 210 at cathode 212”, “heated air to SOEC 210 at anode 214”, and “Oxygen exiting SOEC 210 at anode 214” Table 1).
Thus, Braun teaches the SOEC stack(s) operate in thermoneutral mode.
Regarding claims 5 and 6, modified Braun renders the limitations of claims 2 (claim 5), and 3 (claim 6) obvious, as described above.
Braun further teaches the synthesis gas is methanol synthesis gas configured for production of methanol (“the syngas may be converted to liquid fuels including, but not limited to, diesel, jet, gasoline, and light fuel gas” para. 41 and see below).
As evidenced by Reytier, the same composition of syngas used to form diesel is used to produce methanol (“Methanol … 1/2” and “Diesel … 1/2” Table 1). Therefore, as Braun teaches the synthesis gas is suitable for forming diesel, the synthesis gas of Braun is suitable for forming methanol.
Regarding claim 7, modified Braun renders the limitations of claim 2 obvious, as described above.
Braun does not explicitly teach the air is compressed in an amount sufficient to achieve 50% (v/v) oxygen at an exit of the SOEC stacks.
However, Braun teaches the air is compressed in an amount sufficient to achieve about 48% (v/v) oxygen at an exit of the SOEC stacks (see calculations below), a value not materially different from the claimed value of 50% (v/v). A value very close to a claimed value establishes a prima facie case of obviousness (MPEP § 2144.05).
Calculations: Braun teaches the air is compressed to a pressure of 180 kPa at 800 °C with a flow rate of 4.57 kg/s (see Table 1, annotated below), and the oxygen-enriched stream exits the electrolyzer at a pressure of 170 kPa at 800 °C with a flow rate of 7.21 kg/s (see Table 1, partially reproduced and annotated below).
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Annotated Partial Braun Table 1
As no air is consumed in the electrolyzer, the amount of oxygen in the oxygen-enriched stream is equal to the amount of the oxygen in the air plus the amount of oxygen produced by the electrolyzer. Dry air is 23.20% oxygen by mass, 75.47% nitrogen by mass, and 1.28% argon by mass as evidenced by Universal Industrial Gases (see Table 1, reproduced below). The oxygen-rich output stream of the electrolyzer in Braun thus comprises 3.7 kg/s of oxygen, 3.45 kg/s of nitrogen about 0.06 kg/s of Ar and negligible amounts of other gases (see calculations, below). Dividing the mass of each gas component by their respective molar masses provides the composition of the gas as a molar ratio. As evidenced by Universal Industrial Gases, the molar masses of oxygen, nitrogen, and argon are 32.00, 28.01 and 39.95 g/mol, respectively. The oxygen-rich output stream of Braun thus comprises 115 mol/s O2, 123 mol/s N2 and 1.5 mol/s Ar, or 48% oxygen (mol/mol). The volumetric composition of a gas is directly proportional to its molar composition as shown by the ideal gas law, PV = nRT.
Thus, in the method of Braun, the air is compressed in an amount sufficient to achieve 48% (v/v) oxygen at an exit of the SOEC stacks.
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Universal Industrial Gases Table 1
The masses of the gases in the oxygen-rich stream of Braun were calculated in the following manner. First, the relative masses of the gases in the feed stream were determined to be 1.06 kg/s oxygen, 3.45 kg/s nitrogen and 0.06 kg/s argon by multiplying the mass % the respective gases in air by the flow rate of the feed stream i.e., 4.57 kg/s. The amount of other gases in the feed stream was determined, in the same manner, to be less than 0.01 kg/s and were thus not included in the subsequent analysis. The amount of oxygen added to the stream by the electrolyzer was determined by subtracting the flow rate of the feed stream i.e., 4.57 kg/s, from the flow rate of the output stream i.e., 7.21 kg/s, giving 2.64 kg/s of oxygen added to the flow by the electrolyzer. The mass of nitrogen and argon in the stream is not changed by the electrolyzer, and thus the mass of nitrogen and argon in the oxygen-rich stream is the same as that in the feed stream i.e., 3.45 kg/s and 0.06 kg/s respectively. The mass of oxygen in the oxygen-rich stream is equal to the sum of the mass of oxygen present in the feed stream i.e., 1.06 kg/s, plus that added by the electrolyzer i.e., 2.64 kg/s.
Regarding claim 8, modified Braun renders the limitations of claim 2, obvious, as described above.
Braun further teaches the steam is mixed with hydrogen (“The polished feed stream may be combined with hydrogen and steam” para. 58 and “H2” Fig. 2) and pre-heated in a feed/effluent heat exchanger on a cathode side of the SOEC stacks (“which may have been previously processed in heat exchanger 224” Id.).
Braun does not, in the embodiment depicted in Fig. 2, teach the hydrogen is recycled hydrogen.
However, Braun further teaches, in a second embodiment, that hydrogen produced by the SOEC stack may suitably be recycled into the steam fed to the cathode (“The polished carbon dioxide feed stream may then be mixed with steam stream 107 and/or hydrogen recycle gas stream 109 to produce an enriched feed stream.” para. 57 and Fig. 1).
As Braun teaches a method of producing syngas in an SOEC, Braun is analogous art to the instant invention.
It would therefore have been obvious to a person having ordinary skill in the art before the effective filing date of the instant application to modify the method of Braun, such that at least a portion of the hydrogen supplied to the cathode is recycled hydrogen. A person having ordinary skill in the art would have been motivated to make this modification because Braun suggests using recycled hydrogen as at least a portion of the hydrogen added to the cathodic feed stream.
Regarding claim 9, Braun further teaches on the cathode side, steam is electrolyzed and oxygen ions are transported across an electrolyte to an anode side of the SOEC stacks (because the anode output is oxygen and the cathode input is steam, see Fig. 1, oxygen is necessarily transported across the electrolyte to the anode side of the SOEC stacks).
Regarding claim 21, Braun teaches a method for generating synthesis gas containing hydrogen, carbon monoxide or mixtures of hydrogen, carbon monoxide and carbon dioxide by electrolysis (para. 3),
said method comprising feeding steam (“The polished feed stream may be combined with hydrogen and steam … The preheated polished feed stream may be fed into the SOEC 210 at the cathode 212” Fig. 2 and para. 58) and compressed air to a cathode and an anode, respectively (“Air exiting compressor 220 may … be provided to the SOEC 210 at the anode 214” para. 59 and Fig. 2), of an electrolysis unit (see Fig. 2), wherein:
the electrolysis unit is operated under an elevated gas pressure (“the SOEC may operate at a pressure between about 1 bar to about 20 bars” para. 36 and Table 1), and
an oxygen-rich gas leaving the anode is subsequently expanded down to approximately ambient pressure using a gas expander (see below), the gas expander being downstream and not upstream of the electrolysis unit or units (Fig. 2 shows that “heat exchanger 233” i.e., the steam Rankine cycle system, is disposed between the electrolysis unit and the exhaust).
Regarding the limitation “an oxygen-rich gas leaving the anode is subsequently expanded down to approximately ambient pressure using a gas expander”. Braun teaches the gas exiting the anode is enriched in oxygen (“oxygen exiting SOEC 210 at anode 214” Table 1). Braun further teaches this gas is passed through “heat exchanger 233”, which is an SRC system (“steam Rankine cycle systems may be utilized to capture some of the syngas sensible and/or latent heat and the LFG combustion gas sensible and/or latent heat to produce electricity (see heat exchangers 225 and 233 respectively)” para. 59 and Fig. 2), wherein the pressure of the oxygen-rich gas is reduced to 100 kPa or about 1 atm i.e., approximately ambient pressure (“exhaust gas exiting SRC 233” Table 1) from 110 kPa (“gas entering SRC 233” Table 1), thereby generating electricity (see Fig. 2). As evidenced by e.g., Rackley, the pressure of a gas stream entering an SRC is reduced by being passed through an expansion turbine to generate electricity (see “From B to C” on p. 36 and Fig. 3.3). Thus, Braun anticipates the limitation “an oxygen-rich gas leaving the anode is subsequently expanded down to approximately ambient pressure using a gas expander”.
Braun does not teach the electrolysis unit is a first electrolysis unit of a series of electrolysis units.
However, Severinsky teaches that using a series of electrolysis units rather than a single electrolysis unit provides the predictable benefits of improving safety and making installation and maintenance more convenient (para. 195).
As Braun teaches a method of producing syngas using an SOEC, Braun is analogous art to the instant invention. As Severinsky teaches a method of producing syngas using a steam electrolyzer (e.g., para. 87), Severinsky is analogous art to the instant invention.
It would therefore have been obvious to a person having ordinary skill in the art before the effective filing date of the instant application to modify the method of Braun, such that the electrolysis unit is a first electrolysis unit of a series of electrolysis units, as taught by Severinsky. A person having ordinary skill in the art would have been motivated to make this modification to achieve the predictable benefits of improved safety and more convenient installation and maintenance, as taught by Severinsky. Furthermore, combining prior art elements according to known methods to yield predictable results establishes a prima facie case of obviousness (MPEP § 2143(I)(A)). Furthermore, duplication of parts, absent evidence of unexpected results, establishes a prima facie case of obviousness (MPEP § 2144.04(VI)(B)).
Claim 10 is rejected under 35 U.S.C. 103 as being unpatentable over Braun in view of Severinsky, as applied to claim 8, above, and further in view of Rueger (US Pat. Pub. 2018/0287179).
Regarding claim 10, modified Braun renders the limitations of claim 8 obvious, as described above.
Braun further teaches a second stream of hydrogen mixed with steam i.e., the cathodic effluent (see Fig. 2), is passed through the feed/effluent heat exchanger (“The syngas enters a heat-exchanger 224 where steam is produced and may be provided to the polished feed stream.” para. 58 and Fig. 2, note the syngas is the effluent of the SOEC and comprises of a mixture of hydrogen and leftover steam).
Braun does not teach the second stream of hydrogen mixed with steam is subsequently further cooled down by generating high pressure steam.
Braun instead teaches the second stream is subsequently cooled down in an expansion turbine to generate electricity (“steam Rankine cycle systems may be utilized to capture some of the syngas sensible and/or latent heat … to produce electricity (see heat exchangers 225 …” para. 59 and Fig. 2).
However, Rueger teaches a method for recovering thermal energy in an SOEC (“electrolytic cell 5” Fig. 3 and abstract), wherein a cathodic effluent comprising hydrogen and steam (“hot hydrogen-steam mixture 4” Fig. 3 and para. 82) is passed through a feed/effluent heat exchanger (“recuperative preheater 3” para. 92 and Fig. 3), and is subsequently further cooled down by generating high pressure steam (“e hydrogen-steam mixture 17 cooled in the heat exchanger 3 is optionally further cooled in a heat exchanger 18.” para. 85 and “To reduce the external steam requirement 1, the heat exchangers 18 and 35 can be used, instead of providing heat for external users, to generating steam.” para. 115 and Fig. 3), which provides the predictable benefit of reducing the steam required by the SOEC (Id.).
As Rueger teaches a for recovering thermal energy in an electrolyzer configured to produce hydrogen, Rueger is analogous art to the instant invention.
It would therefore have been obvious to a person having ordinary skill in the art before the effective filing date of the instant application to modify the method of Braun, by adding a step of further cooling down the second stream of hydrogen mixed with steam by generating high pressure steam after the second stream of hydrogen mixed with steam is passed through the feed/effluent heat-exchanger, as taught by Rueger. A person having ordinary skill in the art would have been motivated to make this modification to achieve the predictable benefit of reducing the amount of steam required by the SOEC, as taught by Rueger. A person having ordinary skill in the art would have had a reasonable expectation of success making this modification, because Braun teaches the second stream of hydrogen mixed with steam retains sufficient sensible and/or latent heat to use generating electricity. Furthermore, simple substitution of one known element for another (i.e., a step of cooling down and generating steam as taught by Ruger rather than a step of cooling down and generating electricity as taught by Braun) to achieve predictable results (reducing the amount of steam required by the system/method) establishes a prima facie case of obviousness (MPEP § 2143(I)(B)).
Claim 11 is rejected under 35 U.S.C. 103 as being unpatentable over Braun in view of Severinsky and Rueger, as applied to claim 10, and further in view of Boardman (WO 2008/154257 A2).
Regarding claim 11, modified Braun renders the limitations of claim 10 obvious, as described above.
Braun further teaches, in a second embodiment, splitting the second stream into a recycle hydrogen stream and a residual stream (“The heated dry syngas stream may then be split using a splitter 132 to produce a syngas side-stream and a main syngas stream” and “The hydrogen recycle stream 109 from the pressure swing adsorption (PSA) system 138 may be a recycle stream derived from the syngas produced by the SOEC 110” para. 57 and see Fig. 1).
It would therefore have been obvious to a person having ordinary skill in the art before the effective filing date of the instant application to modify the method of Braun, such that the second stream is split into a recycle hydrogen stream and a residual stream. A person having ordinary skill in the art would have been motivated to make this modification because it is suggested by Braun.
Braun does not teach the residual stream is sent to ammonia synthesis. Braun instead teaches the residual stream is sent to “gas-to-liquid conversion process 134 that produces the liquid fuels (e.g. Fisher-Tropsch process)” (para. 57).
However, Boardman teaches hydrogen generated from high-temperature steam electrolysis may be reacted with nitrogen to produce ammonia (“Hydrogen produced by the electrolysis of water may also be combined with nitrogen to produce ammonia.” abstract and see para. 33).
Both the residual stream of Braun and the hydrogen stream of Boardman serve the same, predictable, art-recognized purpose as a starting material for the synthesis of chemical products.
As Boardman teaches a method for generating hydrogen by electrolysis, Boardman is analogous art to the instant invention.
It would therefore have been obvious to a person having ordinary skill in the art before the effective filing date of the instant application to modify the method of Braun, such that the residual stream is sent to an ammonia synthesis process, as taught by Boardman, rather than the liquid fuel synthesis process of Braun. A person having ordinary skill in the art would have been motivated to make this modification to achieve the predicable benefit of synthesizing ammonia, as taught by Boardman. A person having ordinary skill in the art would have had a reasonable expectation of success for making this modification as both the residual streams of Braun and Boardman comprise hydrogen gas. Furthermore, simple substitution of a known step (the liquid fuel production process of Braun) for another known step (the ammonia production step of Boardman) to obtain predictable results establishes a prima facie case of obviousness (MPEP § 2143(I)(B)).
Claims 16 and 17 are rejected under 35 U.S.C. 103 as being unpatentable over Braun in view of Rueger (US Pat. Pub. 2018/0287179).
Regarding claim 16, Braun anticipates the limitations of claim 15, as detailed in the rejection under 35 U.S.C. § 102(a)(1), above, incorporated herein by reference.
Modified Braun does not teach that, following pre-heating, the pre-heated air enters an electrical pre-heater which heats the air to a second elevated temperature T2, wherein T2>T1.
Braun instead teaches a step wherein following pre-heating, the pre-heated air enters a second heat exchanger which heats the air to a second elevated temperature T2, wherein T2>T1 (“Air exiting compressor 220 may be heated in heat-exchanger 218” para. 59 and Fig. 2, see also Table 1).
However, Rueger teaches a method for recovering thermal energy in an electrolyzer (“electrolytic cell 5” Fig. 3), wherein an air feed (“Purge air 9” Fig. 3) is pre-heated in a feed/effluent heat exchanger (“heat exchanger 11” Fig. 3) to a first elevated temperature T1 (see e.g., para. 137) and, following pre-heating, the pre-heated air enters an electrical pre-heater (“heater 13” and “electric energy 14” Fig. 3 and para. 83) which heats the air to a second elevated temperature T2, wherein T2>T1 (“In the heater 13, the further heating of the scavenging air with electric energy 14 takes place up to the electrolysis cell inlet temperature” Id.).
Both the second heat exchanger in the method of modified Braun and the electrical pre-heater in the method of Rueger serve the same, predictable purpose of heating the air to a second elevated temperature, wherein the second temperature (T2) is greater than the temperature of the air leaving the (first) feed/effluent heat exchanger (T1).
As Rueger teaches a for recovering thermal energy in an electrolyzer configured to produce hydrogen, Rueger is analogous art to the instant invention.
It would therefore have been obvious to a person having ordinary skill in the art before the effective filing date of the instant application to modify the method of Braun by using an electric pre-heater in place of the second heat exchanger, as taught by Rueger. A person having ordinary skill in the art would have been motivated to make this modification because Rueger teaches an electric pre-heater is a suitable means for further increasing the temperature of a pre-heated air stream supplied to the anode of an SOEC. Simple substitution of one known element for another to achieve predictable results establishes a prima facie case of obviousness (MPEP § 2143(I)(B)).
Regarding claim 17, Braun further teaches the second elevated temperature T2 is an inlet temperature of the SOEC stacks (Table 1, para. 59, and Fig. 2 show the air is supplied directly from “heat exchanger 218” to the anode side of the SOEC).
Claim 19 is rejected under 35 U.S.C. 103 as being unpatentable over Braun (US Pat. Pub. 2014/0272734).
Regarding claim 19, Braun anticipates the limitations of claim 1, as detailed in the rejection under 35 U.S.C. § 102(a)(1), above, incorporated herein by reference.
Braun further teaches the compressed air is compressed to up to 19 barg (“a pressure between about 1 bar to about 20 bars” para. 33), a range close to the claimed range. A claimed range that does not overlap with, but is close to, a range disclosed in the prior art establishes a prima facie case of obviousness (MPEP § 2144.05(I)).
Response to Arguments
Applicant’s arguments, see Remarks p. 8, filed 05/28/2026, with respect to the rejections of claims 10 and 11 under 35 U.S.C. § 112(a) have been fully considered, and are persuasive. The rejections of claims 10 and 11 under 35 U.S.C. § 112(a) have been withdrawn.
Applicant’s arguments, see Remarks p. 9, filed 05/28/2026, with respect to the rejections of claims 2-3 and 5-11 under 35 U.S.C. § 112(b) have been fully considered, and are persuasive. The rejections of claims 2-3 and 5-11 under 35 U.S.C. § 112(b) have been withdrawn.
Applicant’s arguments, see Remarks p. 9-10, filed 05/28/2026, with respect to the rejections of claims 1 and 20 under 35 U.S.C. § 102(a)(1) have been fully considered, but they are not persuasive.
Applicant’s arguments, see Remarks p. 10-16, filed 05/28/2026, with respect to the rejections of claims 7-8, 10-11, 16-17, 19, and 21 under 35 U.S.C. § 103 have been fully considered, but they are not persuasive.
Applicant’s Argument #1
Applicant argues on p. 9-10 and 16-17 that Braun does disclose reasonably disclose a gas expander acting on the oxygen-rich anode exhaust, and therefore does not anticipate (in the case of claims 1 and 20) or render obvious (in the case of claim 21) the limitation “an oxygen-rich gas leaving the anode is subsequently expanded down to approximately ambient pressure using a gas expander”.
Specifically, Applicant acknowledges that Braun discloses the oxygen-rich anode exhaust is expanded to approximately ambient pressure. However, Applicant argues that because this expansion is performed in a steam Rankine cycle system, it cannot be considered “purposeful expansion through a work-recovering gas expander”.
Examiner’s Response #1
Examiner respectfully disagrees. In response to applicant's argument that the references fail to show certain features of the invention, it is noted that the features upon which applicant relies (i.e., recovery of work by the gas expander) are not recited in the rejected claim(s). Although the claims are interpreted in light of the specification, limitations from the specification are not read into the claims. See In re Van Geuns, 988 F.2d 1181, 26 USPQ2d 1057 (Fed. Cir. 1993).
In the instant case, Applicant has argued that the steam Rankine cycle system of Braun does not read on “a gas expander”, because the system does not recover the expansion energy as work. However, the claim, as currently drafted, does not require any work/energy to be recovered by the gas expander, it merely requires the gas be expanded in a gas expander.
Furthermore, as evidenced by e.g., Rackley, the expansion turbine of a steam Rankine cycle system generates work by expanding and cooling a high-temperature gas stream comprising steam. Thus, even under Applicant’s more narrow definition, the expansion turbine of Braun would read on the limitation “a gas expander”. Therefore, the step of feeding the oxygen-rich anode exhaust through the expansion turbine recovers work as electricity, and Braun reads on the limitation “an oxygen-rich gas leaving the anode is subsequently expanded down to approximately ambient pressure using a gas expander” even under Applicant’s preferred construction.
Applicant’s argument is therefore not persuasive.
Applicant’s Argument #2
Applicant argues on p. 11 that Braun does not render obvious the limitation “the air is compressed in an amount sufficient to achieve 50% (v/v) oxygen at an exit of the SOEC stacks” as recited in claim 7.
Specifically, Applicant argues that Examiner’s calculation of 48% (v/v) oxygen at the exit of the SOEC stacks relies on “Examiner-selected table entries and assumptions regarding air composition and anode-side mass addition, which are unsupported by the record”, and therefore cannot be relied upon for calculations.
Examiner’s Response #2
Examiner respectfully disagrees. At issue is whether or not Braun discloses, explicitly, implicitly, or inherently, the composition of the gas at an exit of the SOEC stacks is 48% (v/v) oxygen (MPEP § 2112).
As agreed upon by both Examiner and Applicant, Braun does not explicitly disclose the composition of the gas exiting the SOEC stack in terms of percentage (v/v). Braun does, however, teach the flow rate and pressure of the air fed to the SOEC stack, and the flow rate and pressure of the gas exiting the SOEC stack. It is therefore possible to determine the composition of the gas exiting the SOEC stack based on the composition of air and conservation of mass, as detailed in the rejection of claim 7.
While Applicant has characterized the reported values in Braun, the composition of air as evidenced by Universal Industrial Gases, and/or the presumption that mass is conserved during electrolysis as “assumptions … which are unsupported by the record”, Applicant has not provided any evidence as to why these values are not reliable, or why mass would not be conserved during the electrolysis.
Applicant’s argument is therefore not persuasive.
Applicant’s Argument #3
Applicant argues on p. 11 that Braun does not render obvious the limitation “the air is compressed in an amount sufficient to achieve 50% (v/v) oxygen at an exit of the SOEC stacks” as recited in claim 7.
Specifically, Applicant argues that even if Braun discloses a value of about 48% (v/v) oxygen at an exit of the SOEC stacks, this would not render a value of 50% (v/v) oxygen obvious, because a person having ordinary skill in the art would have had no particular motivation to modify a value of about 48% (v/v) to be exactly 50% (v/v) as required by the claim.
Examiner’s Response #3
Examiner respectfully disagrees. At issue is whether Braun’s prior art teaching of compressing air to an amount sufficient to achieve 48% (v/v) oxygen at an exit of the SOEC stacks reasonably renders obvious the limitation “wherein the air is compressed in an amount sufficient to achieve 50% (v/v) oxygen at an exit of the SOEC stacks”.
Determination of obviousness of similar amounts and proportions is highly fact dependent (MPEP § 2144.05(I)). In general, a prima facie case of obviousness exists when claimed ranges or amounts do not overlap with the prior art but are merely close. In particular, a rejection under 35 U.S.C. § 103 is considered appropriate when a person having ordinary skill in the art would have expected no notable difference between the prior art and claimed values.
In the instant case, it is considered that the prior art value of about 48% (v/v) disclosed by Braun would not be materially different or, equivalently, would not require any materially different manipulations to achieve, than the claimed value of 50% (v/v), at least because the values are approximately equal. It is therefore considered that Braun renders the limitation “the air is compressed in an amount sufficient to achieve 50% (v/v) oxygen at an exit of the SOEC stacks” prima facie obvious.
While this finding of prima facie obviousness may be rebutted by evidence demonstrating a material difference between the prior art and the claimed range, no such evidence has been made of record.
Absent such evidence, Applicant’s argument cannot be persuasive.
Applicant’s Argument #4
Applicant argues on p. 12 that a person having ordinary skill in the art would not have been motivated to combine the hydrogen recycle from the embodiment of Braun depicted in Fig. 1 with the embodiment of Braun depicted in Fig. 2. Specifically, Applicant appears to argue that a suggestion in the prior art to make a modification does not render such modification obvious.
Examiner’s Response #4
Examiner respectfully disagrees. At issue is whether a teaching, suggestion or motivation to combine is sufficient to establish a prima facie case of obviousness.
While a prima facie case of obviousness may be established on a variety of grounds, it is considered that a teaching, motivation, or suggestion in the prior art to obtain an art-recognized advantage is the strongest rationale on which obviousness can be established (MPEP § 2144(II)).
In the instant case, Braun suggests making the proposed modification, because this allows the SOEC to use recycled hydrogen as a feed. Therefore, it is considered that the proposed modification is rendered obvious by Braun.
Applicant’s argument is therefore not persuasive.
Applicant’s Argument #5
Applicant argues on p. 12 that Braun’s disclosure of “up to 19 barg” does not reasonably render the claimed range of “20 to 40 barg” obvious, and that Braun therefore does not render claim 19 obvious.
Specifically, Applicant argues that “19” is not close to “20”.
Examiner’s Response #5
Examiner respectfully disagrees. At issue is whether Braun’s teaching of a pressure of up to 19 barg reasonably renders a pressure range of 20 to 40 barg obvious.
Determination of obviousness of similar amounts and proportions is highly fact dependent (MPEP § 2144.05(I)). In general, a prima facie case of obviousness exists when claimed ranges or amounts do not overlap with the prior art but are merely close. In particular, a rejection under 35 U.S.C. § 103 is considered appropriate when a person having ordinary skill in the art would have expected no notable difference between the prior art and claimed values.
In the instant case, Braun teaches pressures in bar (e.g., para. 29), and indicates the values in increments of 5 bar when the pressure is above 10 bar. It is therefore considered that a person having ordinary skill in the art would expect a change of about 5 bar to be necessary to produce a materially different result when starting from a pressure of 19 barg. The lower bounds of Applicant’s claimed range is 20 barg, a pressure 1 bar greater than Braun’s highest reported pressure. It is therefore considered that a person having ordinary skill in the art would not have expected any material difference between the highest pressure taught by Braun and the lowest pressure claimed by Applicant, because this difference is less than 5 bar.
While this determination may be rebutted by evidence of a material difference between pressures of 19 and 20 barg, no such evidence has been made of record.
Applicant’s argument is therefore not persuasive.
Applicant’s Argument #6
Applicant argues on p. 13 that Braun in view of Rueger does not reasonably render the limitation “a second stream of hydrogen mixed with steam is passed through the feed/effluent heat exchanger prior to being further cooled down by generating high pressure steam” as required by claim 10.
Specifically, Applicant argues that because Braun already teaches means for recovering heat from the second stream, a person having ordinary skill in the art would not have had a motivation to modify the heat recovery of system Braun such that further uses the second stream of hydrogen to generate high pressure steam as taught by Rueger.
Applicant further argues that any such modification in view of Rueger would potentially prevent Braun’s system from operating as intended.
Examiner’s Response #6
Examiner respectfully disagrees. At issue is whether a person having ordinary skill in the art would have been motivated to modify the second hydrogen stream of Braun, such that a portion of the heat thereof is used to generate steam as taught by Rueger.
In the instant case, Rueger teaches that the heat from a hydrogen stream may suitably be used to generate steam for use in the SOEC, thereby saving energy. It is therefore considered that a person having ordinary skill in the art would have had a motivation to modify the system of Braun such that the second stream of hydrogen is further cooled down by generating high pressure steam, because Rueger teaches that this provides an art-recognized benefit. A teaching, motivation, or suggestion in the prior art to obtain an art-recognized advantage is the strongest rationale on which obviousness can be established (MPEP § 2144(II)).
It is therefore considered that a person having ordinary skill in the art would have found it obvious to modify the system of Braun based on the teachings of Rueger.
While Applicant has asserted that this modification would prevent Braun’s system from operating as intended i.e., from electrolyzing oxygen and hydrogen, Applicant has not provided any rationale as to why this would be the case, or evidence in support thereof.
Applicant’s argument is therefore not persuasive.
Applicant’s Argument #7
Applicant argues on p. 14 that Braun in view of Rueger does not reasonably render obvious the limitation “an electrical pre-heater” as required by claim 16. Specifically, Applicant argues that replacing the heat exchanger of Braun for an electrical heater as taught by Rueger is more than a simple substitution of one known element for another to obtain predictable results, because it would change the principle of operation of Braun.
Examiner’s Response #7
Examiner respectfully disagrees. At issue is whether the limitation “an electrical pre-heater” as recited in claim 16 is reasonably rendered obvious by Braun in view of Rueger.
For a modification of the prior art to be considered prima facie obvious on the basis of a simple substitution of one known element for another to obtain predictable results (MPEP § 2143(I)(B)), it must be established that: (1) the prior art contains a device/method that differs from the claimed device/method by substitution of some components/steps; (2) that the substituted components/steps and their functions were known in the prior art; (3) that a person having ordinary skill in the art would have been capable of substituting the components/steps, and that the results of said substitution would have been predictable to said person having ordinary skill in the art; and (4) additional findings based on the Graham factual inquiries if necessary in view of the facts.
In the instant case, (1) Braun teaches a method that differs from the claimed method in that a heat exchanger is used in place of the claimed electric heater to heat the air provided to the anode of the SOEC to the electrolyzer operating temperature; (2) Rueger teaches that an electric heater may be used to heat air provided to the anode of an SOEC to the electrolyzer operating temperature; (3) based on the disclosures of Braun and Rueger it is considered that a person having ordinary skill in the art would have been capable of substituting the heat exchanger of Braun for the electric heater of Rueger (MPEP § 2141.03(II)), and the results of this substitution would have been predictable i.e., heating the air provided to the anode of the SOEC to the electrolyzer operating temperature. Thus, the modification of Braun based on the teachings of Rueger is clearly a simple substitution of one known element for another to obtain predictable results.
While Applicant further argues that this modification would alter the principle upon which Braun operates, and is therefore not able to establish a prima facie ground of obviousness, it is not clear on what basis Applicant makes this assertion. Specifically, Braun’s principle of operation is considered to be the electrochemical production of syngas from carbon dioxide. It is unclear how the particular means used to heat the sweep gas fed to the anode in the system could alter this principle of operation.
Applicant’s argument is therefore not persuasive.
Applicant’s Argument #8
Applicant argues on p. 15 that Braun in view of Rueger and Boardman does not reasonably render the limitation “a residual stream sent to ammonia synthesis”.
Specifically, Applicant appears to argue that a person having ordinary skill in the art would not have recognized production of ammonia as a desirable outcome based on the teachings of Boardman.
Examiner’s Response #8
Examiner respectfully disagrees. At issue is whether a person having ordinary skill in the art would have found it obvious to modify the method of Braun such that the hydrogen is provided to ammonia synthesis, as taught by Boardman, rather than a hydrocarbon synthesis, as taught by Braun.
In the instant case, Boardman teaches that hydrogen from an electrolyzer can suitably be used to generate ammonia. It is considered that Boardman implicitly teaches ammonia production is desirable, because it is the topic of Boardman’s disclosure. Therefore, it is considered that a person having ordinary skill in the art would have been motivated to modify the method of Braun, such that the hydrogen produced by the electrolysis is used to generate ammonia as taught by Boardman.
Applicant’s argument is therefore not persuasive.
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 ALEXANDER R PARENT whose telephone number is (571)270-0948. The examiner can normally be reached M-F 11:00 AM - 6 PM EST.
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/ALEXANDER R. PARENT/Examiner, Art Unit 1795
/LUAN V VAN/Supervisory Patent Examiner, Art Unit 1795
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