Prosecution Insights
Last updated: April 19, 2026
Application No. 17/919,794

ABSORPTION COLUMN COMPRISING A FEED BOX HAVING A SERRATED WEIR AND A STRUCTURED PACKING AND PROCESS FOR THE PRODUCTION OF NITRIC ACID

Final Rejection §103
Filed
Oct 19, 2022
Examiner
MCKENZIE, THOMAS B
Art Unit
1776
Tech Center
1700 — Chemical & Materials Engineering
Assignee
Yara International Asa
OA Round
2 (Final)
57%
Grant Probability
Moderate
3-4
OA Rounds
3y 3m
To Grant
80%
With Interview

Examiner Intelligence

Grants 57% of resolved cases
57%
Career Allow Rate
551 granted / 961 resolved
-7.7% vs TC avg
Strong +23% interview lift
Without
With
+22.9%
Interview Lift
resolved cases with interview
Typical timeline
3y 3m
Avg Prosecution
91 currently pending
Career history
1052
Total Applications
across all art units

Statute-Specific Performance

§101
1.0%
-39.0% vs TC avg
§103
46.5%
+6.5% vs TC avg
§102
17.6%
-22.4% vs TC avg
§112
27.5%
-12.5% vs TC avg
Black line = Tech Center average estimate • Based on career data from 961 resolved cases

Office Action

§103
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 . Claim Rejections - 35 USC § 103 The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action: A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made. The factual inquiries for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows: 1. Determining the scope and contents of the prior art. 2. Ascertaining the differences between the prior art and the claims at issue. 3. Resolving the level of ordinary skill in the pertinent art. 4. Considering objective evidence present in the application indicating obviousness or nonobviousness. Claims 1–3, 6, 8, 9, 20 and 22 are rejected under 35 U.S.C. 103 as being unpatentable over Suchak et al., US 2014/0065025 A1 in view of Friese et al., WO 2008/132096 A11. Regarding claim 1, Suchak teaches a packed column scrubber 10 for absorption of nitrogen oxides from a feed gas 26 comprising nitrogen oxides into an aqueous solution comprising dissolved nitrogen oxide. See Suchak Fig. 3, [0035]–[0036]. The packed column scrubber 10 reads on the claimed “vertical adsorption column for absorption of nitrogen oxides from a process gas comprising said nitrogen oxides into water for production of an aqueous nitric acid solution.” The scrubber 10 comprises a packed bed 24, which reads on the “structured packing.” See Suchak Fig. 3, [0035]. The scrubber 10 also comprises a spray nozzle 22, located directly above the packed bed 24 for distributing liquid within the scrubber 10. See Suchak Fig. 3, [0035]. The scrubber 10 further comprises an inlet for the addition of ozone 28 into a lower part of the scrubber 10, which reads on the “inlet for an addition of oxygen to a lower part of the vertical adsorption column.” See Suchak Fig. 3, [0036]. The scrubber 10 also comprises an inlet for feed gas 26 comprising nitrogen oxides at the lower part of the scrubber 10, which reads on the “inlet for the process gas comprising nitrogen oxides.” See Suchak Fig. 3, [0035]. Note that the limitation indicating that the feed gas is “from an ammonia oxidation process” fails to further limit the scope of the claim because it describes the manner of operating the device rather than its structure. See MPEP 2114, subsection II (manner of operating the device does not differentiate apparatus claim from the prior art). The scrubber 10 further comprises a pipe 19 for an aqueous solution at an upper part of the scrubber 10, which reads on the “inlet for an aqueous solution at an upper part of the vertical absorption column.” See Suchak Fig. 3, [0035]. The scrubber 10 also comprises a pipe 13 that is capable of discharging nitric acid with the pipe 13 being located at a bottom of the scrubber 10. See Suchak Fig. 3, [0035]. The pipe 13 reads on the “at least one nitric acid outlet at a bottom of the vertical absorption column.” The scrubber 10 further comprises an outlet 40 that is capable of discharging tail gas comprising nitrogen oxides at a top of the scrubber 10. See Suchak Fig. 3, [0047]. The outlet 40 reads on the “outlet for tail gas comprising nitrogen oxides at a top of the vertical absorption column.” PNG media_image1.png 785 745 media_image1.png Greyscale Suchak differs from claim 1 because, while it teaches the spray nozzle 22 being located directly above the packed bed 24, as claimed, it is silent as to the spray nozzle 22 having the same structure as the claimed “liquid distributor.” Suchak also differs from claim 1 because it is silent as to the scrubber 10 comprising a plate packing comprising a plurality of horizontal plates provided with cooling means. But the spray nozzle 22 is provided for distributing liquid onto the packed bed 24. See Suchak Fig. 3, [0035]. Also, ozone is introduced into the aqueous medium 12 in the lower portion of the scrubber 10 for oxidation of nitrogen oxide impurities dissolved in the aqueous medium, which is exothermic. Id. at [0036]. With this in mind, Friese teaches a column that can be used as an absorbing for nitrogen oxides, where the column comprises a liquid feed device 3, 4, 5 for distributing liquid into a lower part of the column beneath the device 3, 4, 5. See Friese Fig. 1, p. 3. The column also comprises transverse flow trays (having heat exchange coils 7 provided on them) submerged in liquid that accumulates in the lower part of the column. Id. The liquid feed device 3, 4, 5 comprises a downcomer 3 that supplies liquid into an inner box 4 so that the liquid can flow over serrations 10 at the top of the inner box 4 into an outer box 5 and then through rows of holes 6 in the bottom of the outer box 5 and into the lower part of the column. Id. Note that it would have been obvious2 for the bottom of the outer box 5 to be manufactured from two separable sections (each having rows of holes) because this would merely represent making separable otherwise integrated parts. See MPEP 2144.04, subsection V, C. The liquid feed device 3, 4, 5 is beneficial because it provides uniform distribution of liquid into the column. See Friese 4. The transverse trays (with cooling coils 7) are beneficial because the heat exchange coils 7 remove heat from the liquid in the lower part of the column generated by the oxidation of nitrogen oxides to move the equilibrium of the reaction to a suitable equilibrium. Id. PNG media_image2.png 759 706 media_image2.png Greyscale It would have been obvious to modify the scrubber 10 of Suchak to use the liquid feed device 3, 4, 5 of Friese (in place of the spray nozzle 22) to provide uniform distribution of liquid into the scrubber 10. It also would have been obvious to modify the scrubber of Suchak to include the transverse flow trays (having heat exchange coils 7 provided on them) in the lower part of the scrubber 10 so that the trays are submerged in the liquid that accumulates to remove heat generated by the oxidation reactions to move the equilibrium to a suitable equilibrium. With this modification, the liquid feed device 3, 4, 5 of Friese reads on the “liquid distributor, located directly above” the packed bed 24 (the “structured packing”) of Suchak. The bottom of the outer box 5 (the two pieces of material, each having rows of holes 6 as explained above) reads on the “perforated trays.” The inner box 4 reads on the “feed box” and the serrations 10 at the top of the inner box 4 read on the “serrated weir for distribution of a liquid through upward-pointing serrations of the serrated weight into the perforated trays.” Also with this modification, the transverse flow trays (having heat exchange coils 7 provided on them) read on the “plate packing comprising a plurality of horizontal plates, provided with cooling means.” Regarding claim 2, Suchak as modified teaches that the oxygen is ozone gas, which reads on “oxygen gas.” See Suchak [0036]. Note also that the claimed “oxygen gas” fails to further limit the claim because it is not a positively recited element of the claimed “vertical absorption column.” See MPEP 2115 (a claim is only limited by positively recited elements). Regarding claim 3, Suchak as modified teaches that the liquid feed device 3, 4, 5 of Friese (the “liquid distributor”) and the packed bed 24 of Suchak (the “structured packing”) are arranged between the pipe 19 (the “inlet for the aqueous solution”) and an uppermost horizontal plate of the transverse flow trays (having heat exchange coils 7 provided on them) of Friese (the “plate packing”), as seen in Fig. 3 of Suchak where the spray nozzle 22 and packed bed 24 is between the pipe 19 and the lower portion of the tank 12 where liquid collects (which contains the transverse flow trays). Regarding claim 6, Suchak as modified teaches that the heat exchange coils 7 of Friese are “cooling coils” comprising a cooling medium superposed on a horizontal plane of the transverse flow trays (the “plate packing”), as claimed. See Friese Fig. 1, p. 3. Note that the limitation indicating that “an initial temperature of the cooling medium in the cooling coils is between 5 to 45°C” fails to patentably distinguish over the prior art because it describes the manner of operating the vertical adsorption column (a device) rather than its structure. See MPEP 2114, subsection II (manner of operating the device does not differentiate apparatus claim from the prior art). Note also that it would have been obvious to use routine experimentation to determine the optimal temperature of the cooling medium of the coils 7 because the temperature is result effective as it impacts the ability of the coils to maintain suitable equilibrium. See Friese p. 4; MPEP 2144.05, subsection II (where the general conditions of a claim are disclosed in the prior art, it is not inventive to discover the optimal or workable ranges by routine experimentation). Regarding claims 8 and 22, Suchak as modified teaches the limitations of claim 1, as explained above. Suchak as modified differs from claims 8 and 22 because it is silent as to number of holes 6 per square meter (drip-point density per m2) in the bottom of the outer box 5 of Friese. Therefore, the reference fails to provide enough information to teach that the liquid feed device 3, 4, 5 (the “liquid distributor”) has a drip-point density of at least 30 drippings per m2 or 60 to 200 dripping points per m2, as claimed. But Friese teaches that the dimensions of the holes 6 (including size and number) can be adjusted depending on the amount of liquid to be distributed. See Friese p. 3. Therefore, it would have been obvious to use routine experimentation to determine the optimize number of holes 6 per unit area depending on the amount of liquid to be distributed. See MPEP 2144.05, subsection II (where the general conditions of a claim are disclosed in the prior art, it is not inventive to discover the optimum or workable ranges by routine experimentation). Regarding claim 9, Suchak teaches that all components of the scrubber 10 (including the packed bed 24) can be made of polypropylene, which is an acid-compatible material. See Suchak [0035]. Regarding claim 20, Suchak teaches that the inlet for the feed gas 26 (the “process gas”) and the inlet for ozone 30 (the “oxygen”) are separate inlets, as seen in Fig. 3. Claims 7 and 21 are rejected under 35 U.S.C. 103 as being unpatentable over Suchak et al., US 2014/0065025 A1 in view of Friese et al., WO 2008/132096 A1 and in further view of Chen et al., US 2014/0158519 A1. Regarding claims 7 and 21, Suchak as modified teaches the limitations of claims 7 and 21, as explained above. Suchak as modified differs from claims 7 and 21 because it is silent as to the surface area of the packed bed 24 (the “structured packing”). Therefore, the reference fails to provide enough information to teach the packed bed 24 has a surface area density of at least 250 m2/m3 or between 450 to 750 m2/m3, as claimed. But Chen teaches that the density of a structured packing is result effective because it impacts the flow rate through a column. See Chen [0004]. Chen also teaches that a conventional structured packing has a density of 750 m2/m3. As such, it would have been obvious to use routine experimentation to determine the optimal surface area density of the of the packed bed 24 of Suchak to determine the optimal flow rate through the material. See MPEP 2144.05, subsection II (where the general conditions of a claim are disclosed in the prior art, it is not inventive to discover the optimum or workable ranges by routine experimentation). A person of ordinary skill in the art would have had a reasonable expectation of success in achieving the claimed range of at least 250 m2/m3 and between 450 to 750 m2/m3 because Chen teaches a conventional structured packing material with a density of 750 m2/m3. Allowable Subject Matter Claims 4 and 5 are objected to as being dependent upon a rejected base claim, but would be allowable if rewritten in independent form including all of the limitations of the base claim and any intervening claims. Claim 4 is allowable over Suchak in view of Friese because the prior art combination fails to teach the liquid feed device 3, 4, 5 of Friese (the “liquid distributor”) and the packed bed 24 of Suchak (the “structured packing”) being arranged between a lowermost horizontal plate of the transverse trays (with coils 7) of Friese (the “plate packing”) and the inlet of the feed gas 26 (the “process gas”), as claimed. Instead, Suchak illustrates that the packed bed 24 is above both the inlet of the feed gas 26 and the lower part of the scrubber 10 where liquid 12 accumulates (which contains the transverse trays). Claim 5 is allowable because it depends from claim 4. Response to Arguments Claim Objections The Examiner withdraws the claim objection to claim 6 in light of the amendments. 35 U.S.C. 112(f) Interpretation The Examiner withdraws the previous 35 U.S.C. 112(f) claim interpretation for claim 5 in light of the amendments. 35 U.S.C. 112(b) Rejections The Examiner withdraws the previous 35 U.S.C. 112(b) rejections in light of the amendments. 35 U.S.C. 103 Rejections Applicant’s arguments with respect to the pending claims have been considered but are moot because the new ground of rejection does not rely on any reference applied in the prior rejection of record for any teaching or matter specifically challenged in the argument. 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 T. BENNETT MCKENZIE whose telephone number is (571)270-5327. The examiner can normally be reached Mon-Thurs 7:30AM-6:00PM. Examiner interviews are available via telephone, in-person, and video conferencing using a USPTO supplied web-based collaboration tool. To schedule an interview, applicant is encouraged to use the USPTO Automated Interview Request (AIR) at http://www.uspto.gov/interviewpractice. If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Jennifer Dieterle can be reached at 571-270-7872. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300. Information regarding the status of published or unpublished applications may be obtained from Patent Center. Unpublished application information in Patent Center is available to registered users. To file and manage patent submissions in Patent Center, visit: https://patentcenter.uspto.gov. Visit https://www.uspto.gov/patents/apply/patent-center for more information about Patent Center and https://www.uspto.gov/patents/docx for information about filing in DOCX format. For additional questions, contact the Electronic Business Center (EBC) at 866-217-9197 (toll-free). If you would like assistance from a USPTO Customer Service Representative, call 800-786-9199 (IN USA OR CANADA) or 571-272-1000. T. BENNETT MCKENZIE Primary Examiner Art Unit 1776 /T. BENNETT MCKENZIE/Primary Examiner, Art Unit 1776 1 An original, untranslated copy of Friese is in the record as the 20-page Foreign Reference filed December 03, 2025. A translation is provided with this communication. The rejection cites to the original, untranslated copy for figures and the translation for text. 2 Note that throughout the rejection, the statement of “it would have been obvious” refers to being obvious to a person of ordinary skill in the art before the effective filing date of the claimed invention.
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Prosecution Timeline

Oct 19, 2022
Application Filed
Oct 20, 2025
Non-Final Rejection — §103
Feb 23, 2026
Response Filed
Mar 23, 2026
Final Rejection — §103 (current)

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Prosecution Projections

3-4
Expected OA Rounds
57%
Grant Probability
80%
With Interview (+22.9%)
3y 3m
Median Time to Grant
Moderate
PTA Risk
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