DETAILED ACTION
Response to Amendment
1. In response to the amendment received on 11/17/25:
claims 1-20 are presently pending
claims 12-17 are withdrawn
the rejection of claim 18 under 35 USC 112(b) is withdrawn in light of the amendments to the claims
all prior art grounds of rejection are maintained for the reasons set forth below
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.
Claim(s) 1-9, 11 and 18-20 is/are rejected under 35 U.S.C. 103 as being unpatentable over “Understanding Continuous Lithium-Mediated Electrochemical Nitrogen Reduction” by Lazouski et al., Joule 3, pages 1127-1139 (4/17/19) (hereinafter referred to as “LAZOUSKI”) in view of WO2020/075202A1 to Skulason et al., (hereinafter referred to as “SKULASON”).
Regarding claim 1, LAZOUSKI teaches a method for electrochemical ammonia synthesis (see LAZOUSKI at Abstract on cover page and also Summary section on page 1127 discussing a process for the lithium-mediated electrochemical reduction of nitrogen to ammonia; see also LAZOUSKI at Fig. 1 and Results section on pages 1128-1129 teaching the electrochemical approach to ammonia synthesis), comprising the steps of:
providing at least one electrolysis cell (see LAZOUSKI at Fig. 1(B) depicting the electrochemical cell);
contacting a cathode of said electrolysis cell with a source of lithium cations, nitrogen, and protons (see LAZOUSKI at Fig. 1 and page 1128 at para. 2 and Results section under the para. titled “Electrochemical Approach” teaching the cathode in contact with the electrolyte which contains 0.2M lithium perchlorate, i.e. a source of lithium, in the presence of nitrogen gas which is dissolved in the electrolyte, i.e. the nitrogen source, and 1% ethanol which is the proton carrier, i.e. the proton source); and
subjecting the cathode to a potential whereby ammonia is synthesized (see LAZOUSKI at page 1128 and para. 2 and Results section under the para. titled “Electrochemical Approach” teaching the electrolysis resulting in ammonia formation; see also LAZOUSKI at pages 1131-1133 and Fig. 5 teaching the application of current densities ranging from 0.3 mA/cm2 to 25 mA/cm2).
LAZOUSKI fails though to explicitly teach the applied potential being a continuous pulsed potential pulsed between a first cathode potential at a lithium reduction potential and a second cathode potential with the second cathode potential being less negative than the first cathode potential as claimed.
However, SKULASON is related to the electrochemical production of chemicals (see SKULASON at page 1, lines 3-4) and a way to achieve improved current efficiencies and reaction rates (see SKULASON at page 2, lines 1-3). Specifically, SKULASON teaches the use of a varied potential during electrochemical production as a means to provide for increased reaction rate and current efficiency by constantly breaking up the surface double layer of chemical species drawn to the cathode and/or by freeing up catalytic active sites (see SKULASON at page 2, lines 6-14). The varied potential of SKULASON is a square pulse cycle in which the potential is varied between a certain fixed potential level and a replenishment or resting potential (see SKULASON at page 4 line 35-page 5 line 6).
Moreover, SKULASON teaches the varied potential or current as providing for enhanced efficiency and less energy consumption for the electrochemical production of ammonia (see SKULASON at page 4 lines 11-14). SKULASON also teaches that when the reaction in question that takes place at the electrode involves a neutral species, such as N2, that the charged/polar species will be concentrated around the electrode thereby reducing the reaction efficiency (see SKULASON at page 7 lines 5-9) and then states that by alternating the potential as taught that it gives a chance for the neutral species to migrate towards the electrode (see SKULASON at page 7 lines 9-11; see also page 7 lines 12-17 teaching the resting pulse as providing time for the neutral nitrogen time to access the electrode surface). Furthermore, LAZOUSKI teaches the low rate of nitrogen diffusion as being a factor that was found to limit theoretical and practical yields in the lithium-mediated process (see LAZOUSKI at Context & Scale section on page 1127). As such, one of ordinary skill in the art would have recognized the potential benefit in applying a pulsed potential in the process of LAZOUSKI based on the teachings of SKULASON as a way to enhance the efficiency and decrease energy consumption.
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have modified the process of LAZOUSKI so as to incorporate the pulsed potential of SKULASON in an effort to provide enhanced efficiency to the lithium mediated electrochemical nitrogen reduction.
Regarding claim 2, LAZOUSKI as modified by SKULASON teaches the method wherein the cathode potential is pulsed between the lithium reduction potential and the cell OCP (see LAZOUSKI at page 1128 under the Electrochemical Approach section teaching lithium metal being plated onto a metal substrate which would mean a cathodic pulse at or higher than the lithium reduction potential; and see SKULASON at page 7 lines 9-17 teaching the resting, i.e. zero, potential as allowing for a replenishing time on the surface of the electrode of the neutral nitrogen; see also SKULASON at page 8, lines 6-10 teaching for ammonia the pulsing between the negative current and a current close to zero, i.e. 0 mA/cm2).
Regarding claim 3, LAZOUSKI as modified by SKULASON teaches the method wherein a duration of pulses at the first cathode potential is between 0.5-60 minutes (see SKULASON at page 5, lines 31-32 teaching the first pulse being from 0.1 to 30 seconds).
Regarding claim 4, LAZOUSKI as modified by SKULASON teaches the method wherein the duration of pulses at the second cathode potential is between 1-120 minutes and/or wherein the pulses at a first cathodic current load has a duration of between 0.5-60 minutes (see SKULASON at page 5, lines 37-38 teaching the resting pulse, i.e. second cathode potential, ranging in time from 1 to 180 seconds).
Regarding claim 5, LAZOUSKI as modified by SKULASON teaches the method wherein the pulses at a second cathodic current load has a duration of between 1-120 minutes (see SKULASON at page 5, lines 37-38 teaching the resting pulse, i.e. second cathode potential, ranging in time from 1 to 180 seconds).
Regarding claim 6, LAZOUSKI as modified by SKULASON teaches the method wherein the pulsed cathodic current load is pulsating DC and/or pulsating AC (see SKULASON at page 4, lines 20-36 teaching the pulse being a square pulse cycle or a sinusoidal varied potential).
Regarding claim 7, LAZOUSKI as modified by SKULASON teaches the method wherein the pulses at a first cathodic current load has a current density below -1 mA/cm2 and/or wherein the pulses at a second cathodic current load has a current density above -0.5 mA/cm2 (see SKULASON at page 7 lines 9-17 teaching the resting, i.e. zero, potential as allowing for a replenishing time on the surface of the electrode of the neutral nitrogen; see also SKULASON at page 8, lines 6-10 teaching for ammonia the pulsing between the negative current and a current close to zero, i.e. 0 mA/cm2, which is a current density above -0.5 mA/cm2 as claimed).
Regarding claim 8, LAZOUSKI as modified by SKULASON teaches the method wherein the source of Li ions is selected from the group consisting of: molten Li salt, Li solutions, and combination thereof (see LAZOUSKI at page 1128, second paragraph teaching the electrolyte solution including a THF solution of the lithium perchlorate, ethanol, and nitrogen so as to be a lithium solution as claimed).
Regarding claim 9, LAZOUSKI as modified by SKULASON teaches the method wherein the source of nitrogen is selected from the group consisting of: gaseous N2, liquidly dissolved N2, and combinations thereof (see LAZOUSKI at Fig. 1 on page 1129 teaching the addition of N2 gas, which would to some degree also dissolve in the THF based solution).
Regarding claim 11, LAZOUSKI as modified by SKULASON teaches the method wherein the electrolysis cell is selected from the group consisting of: single compartment cells, and flow cells (see LAZOUSKI at Fig. 1 on page 1129 teaching the nitrogen gas flowing through the electrochemical cell so as to be a flow cell as claimed).
Regarding claim 18, LAZOUSKI as modified by SKULASON teaches the method wherein the solution has a Li concentration below 3M or 1M (see LAZOUSKI at page 1128, second paragraph teaching the electrolyte solution including 0.2M lithium perchlorate).
Regarding claim 19, LAZOUSKI as modified by SKULASON teaches the method wherein the source of protons is selected from the group consisting of: gaseous H2, liquidly dissolved H2, aprotic solvents, ethanol, alkyl alcohols, tert-butanol, perfluorinated alcohols, polyethyleneglycols, ethanethiol, alkyl thiols, alkyl ketones, alkyl esters and combinations thereof (see LAZOUSKI at page 1128, second paragraph teaching the electrolyte solution including ethanol).
Regarding claim 20, LAZOUSKI as modified by SKULASON teaches the method wherein the temperature is between 10-150 °C and/or wherein the pressure is equal to or below 20 bar (see LAZOUSKI at page 1128, para. 2 teaching the desire to run the process at ambient temperatures and pressures; see also LAZOUSKI at page 1137, in the Conclusion section stating the process allowing for the formation of ammonia at room temperature and ambient pressure).
Claim(s) 10 is/are rejected under 35 U.S.C. 103 as being unpatentable over LAZOUSKI in view of SKULASON as applied to claim 1 above, and further in view of US Pub. No. 2001/0028977 to Kazacos et al., (hereinafter referred to as “KAZACOS”).
Regarding claim 10, while LAZOUSKI as modified by SKULASON teaches the method with the source of protons combined with a separator membrane (see LAZOUSKI at Fig. 1 depicting the electrochemical cell with a DARAMIC separator), LAZOUSKI in view of SKULASON fails to explicitly teach the membrane being a proton exchange membrane.
However, KAZACOS teaches that for membrane-type electrochemical cells it is known to use various types of membranes to provide separation in electrochemical cells and lists microporous DARAMIC separators and proton exchange polymer membranes as ionically conducting separators known in the art (see KAZACOS at ¶242).
As such, one of ordinary skill in the art would have recognized that the microporous separator of LAZOUSKI could be replaced with other known separator membrane materials such as a proton exchange membrane as taught by KAZACOS.
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have replaced the DARAMIC separator of LAZOUSKI with a proton exchange membrane as taught by KAZACOS to provide the separation between the anode and cathode portions of the electrochemical cell so as to arrive at a method as claimed.
Response to Arguments
Applicant's arguments filed 11/17/25 have been fully considered but they are not persuasive.
Applicant argues that the grounds of rejection does not provide a reasonable suggestion or motivation to modify LAZOUSKI by SKULASON so as to use a varied cathode potential as claimed (see Remarks at pages 6-8). However, for at least the following reasons, the examiner respectfully disagrees. As set forth in the grounds of rejection, LAZOUSKI teaches nitrogen diffusion rate as being a factor found to limit yields, i.e. ammonia production, in the lithium-mediated process (see LAZOUSKI at “Context & Scale” section on page 1127). SKULASON specifically mentions that when a neutral species, such as nitrogen, is involved in a reaction at an electrode, that the charged/polar species will concentrate around the electrode and reduce the reaction efficiency (see SKULASON at page 7 lines 5-9). As a result, SKULASON teaches the application of an alternating, i.e. pulsed, potential as a way to increase reaction efficiency by allowing for the reactive species, here the nitrogen, to migrate/move towards the electrode (see SKULASON at page 7 lines 9-11).
While the examiner acknowledges that SKULASON is specifically directed towards the towards the electrolytic reduction of nitrogen on a catalytic electrode and not the lithium-mediated nitrogen reduction of LAZOUSKI, one of ordinary skill in the art would have still have been motivated to want to increase the reaction efficiency and would have looked to implement means to achieve enhanced efficiencies. Moreover, the fact that both reaction mechanisms require the presence of nitrogen gas at the electrode would have led one of ordinary skill in the art to use the teachings of SKULASON showing the use of a pulsed potential to allow for increase efficiency through the replenishment of the nitrogen at the electrode in an effort to increase efficiency at the electrode of LAZOUSKI which, after having lithium deposited thereon, requires nitrogen gas to react with the lithium to form lithium nitride and then eventually ammonia as shown in the reaction pathway for the lithium-mediated electrochemical nitrogen reduction reaction (see LAZOUSKI at page 1129, Fig. 1A).
Consequently, applicant’s arguments that there is no evident reason to modify LAZOUSKI by SKULASON so as to arrive at the limitations of claim 1 are not found persuasive.
Applicant also argues that SKULASON “contravenes the general principle of lithium ion reduction and metal formation based on a cited teaching from SKULASON that teaches the resting potential as “pushing the positively charged ion and polar compounds away from the surface” (see Remarks at page 7 line 28-page 8 line 4). However, for at least the following reasons the examiner respectfully disagrees that the citation would contradict or prevent the lithium deposition of LAZOUSKI. Specifically, it is noted that this citation must be understood in the context of what is occurring and in accordance with what one of ordinary skill in the art would understand. For example, while SKULASON does use the term “pushing”, since there is no potential being applied to the electrodes during the resting time, the driver for the migration or movement of the charged and polar compounds is from the concentration gradient. As such, all lithium ions would not be expelled from the electrode but rather the concentration during the rest period would trend to go back to the overall concentration within the electrolyte. Likewise, the concentration of nitrogen that would decrease during the period when potential is being applied, would likewise be able to increase to the general concentration of nitrogen within the electrolyte during the rest period. Therefore, the application of the teachings of SKULASON to the lithium-mediated electrochemical reduction process of LAZOUSKI would be seen by one of ordinary skill in the art as completely compatible and allowing for the further reaction of nitrogen with the deposited lithium and not as preventing future lithium deposition.
Applicant also argues that the prior art fails to teach the limitation as claimed and seems to assert that the claim requires ammonia to be synthesized at two distinct pulsed cathode potentials (see Remarks at page 9 lines 3-16). However, the examiner respectfully disagrees with this characterization of the claim limitations. Specifically, it is noted that the claim limitation at issue merely requires the subjecting of the cathode to a continuous pulsed cathode potential including the first and second cathode potentials as recited, which results in ammonia being synthesized or made. The claim doesn’t specify anything more than this and as such ammonia being produced at any time during the application of the pulsed cathode potential would read on the claim as presently presented.
Furthermore, while the applicant asserts that LAZOUSKI teaches that ammonia can only be generated under current load (see Remarks at page 8 lines 20-21), there is no citation given for this statement. Furthermore, the reaction pathway taught by LAZOUSKI would seem to contradict this assertion. LAZOUSKI teaches the reaction scheme on page 1134. The scheme depicts the reaction starting with the reduction of lithium on the cathode (see LAZOUSKI at page 1134, Scheme 1 showing Li+ goes to Li). However, this initial step is the only portion requiring the application of current. Thereafter, the deposited lithium metal can react with nitrogen to form lithium nitride which then is quickly protonated by the proton carrier to form ammonia. As such, LAZOUSKI would seem to indicate that even after the removal of the current that any lithium metal that has been deposited can still potentially form ammonia.
Conclusion
THIS ACTION IS MADE FINAL. 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 Bryan D. Ripa whose telephone number is (571)270-7875. The examiner can normally be reached Mon-Fri 8:00AM-4:00PM ET.
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/BRYAN D. RIPA/Primary Patent Examiner, Art Unit 1794