Prosecution Insights
Last updated: April 17, 2026
Application No. 18/186,365

SYSTEM AND METHOD FOR DIRECT AIR CAPTURE OF CARBON DIOXIDE UTILIZING A MICROWAVE DESORPTION TECHNIQUE

Non-Final OA §103
Filed
Mar 20, 2023
Examiner
BUI, DUNG H
Art Unit
1773
Tech Center
1700 — Chemical & Materials Engineering
Assignee
unknown
OA Round
2 (Non-Final)
78%
Grant Probability
Favorable
2-3
OA Rounds
2y 7m
To Grant
99%
With Interview

Examiner Intelligence

Grants 78% — above average
78%
Career Allow Rate
962 granted / 1227 resolved
+13.4% vs TC avg
Strong +24% interview lift
Without
With
+24.4%
Interview Lift
resolved cases with interview
Typical timeline
2y 7m
Avg Prosecution
85 currently pending
Career history
1312
Total Applications
across all art units

Statute-Specific Performance

§103
48.1%
+8.1% vs TC avg
§102
26.8%
-13.2% vs TC avg
§112
18.8%
-21.2% vs TC avg
Black line = Tech Center average estimate • Based on career data from 1227 resolved cases

Office Action

§103
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 . In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis (i.e., changing from AIA to pre-AIA ) for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status. 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. Claim(s) 1-13 are rejected under 35 U.S.C. 103 as being unpatentable over Ruettinger et al (US 20230233972; hereinafter Ruettinger) in view of Gaur et al (US 20210046417; hereinafter Gaur). As regarding claim 1, Ruettinger discloses the claimed invention for a direct air capture of CO2 ([0005]) system, comprising: a chamber defining a microwave cavity and having an upstream end and an opposing downstream end (figs. 2-3; no number); a microwave heating unit (203, 303, [0056] and [0059]) coupled to the chamber in electromagnetic communication with the microwave cavity; a sorbent structure ([0044]) carried within and filling the chamber. Ruettinger does not disclose the sorbent structure including one or more porous support structures each carrying nanoparticles of CO2 adsorbent material, the one or more porous support structures having a plurality of pores and channels formed therethrough providing a large area of surfaces coated by the CO2 adsorbent material. Gaur teaches the sorbent structure including one or more porous support structures each carrying nanoparticles ([0059], claim 1; figs. 1 and 9) of CO2 adsorbent material, the one or more porous support structures having a plurality of pores and channels formed therethrough providing a large area of surfaces coated by the CO2 adsorbent material. Both Ruettinger and Gaur are directed to carbon dioxide adsorption. It would have been obvious to one having ordinary skill in the art before the effective filing date of the invention was made to provide the sorbent structure including one or more porous support structures each carrying nanoparticles of CO2 adsorbent material, the one or more porous support structures having a plurality of pores and channels formed therethrough providing a large area of surfaces coated by the CO2 adsorbent material as taught by Gaur in order to maximize accessible surface area and adsorption sites, accelerate CO2 capture and release, and improve mass and heat transfer efficiency. Ruettinger as modified discloses a motor fan (Gaur - 440) coupled to the downstream end of the chamber to create an air flow from the upstream end to the downstream end and draw air through the chamber and the sorbent structure carried therein. As regarding claim 2, Ruettinger as modified discloses all of limitations as set forth above. Ruettinger as modified discloses the claimed invention for wherein the CO2 adsorbent material are hybrid amines, consisting of at least two amine or polyamine components chosen from the list of monoethanolamine, methyldiethanolamine, diethanolamine, ethylenediamine, aminomethyl propanol, diisopropylamine, triethylenetetramine, diethylenetriamine, triethanolamine, tetraethylenepentamine, piperazine, as well as amino group containing polymers including polyethyleneimine, polyacrylamide and chitosan ([0044]-[0045]). Alternatively, Ruettinger as modified does not disclose wherein the CO2 adsorbent material are hybrid amines, consisting of at least two amine or polyamine components chosen from the list of monoethanolamine, methyldiethanolamine, diethanolamine, ethylenediamine, aminomethyl propanol, diisopropylamine, triethylenetetramine, diethylenetriamine, triethanolamine, tetraethylenepentamine, piperazine, as well as amino group containing polymers including polyethyleneimine, polyacrylamide and chitosan. It would have been obvious to one having ordinary skill in the art before the effective filing date of the invention was made to provide wherein the CO2 adsorbent material are hybrid amines, consisting of at least two amine or polyamine components chosen from the list of monoethanolamine, methyldiethanolamine, diethanolamine, ethylenediamine, aminomethyl propanol, diisopropylamine, triethylenetetramine, diethylenetriamine, triethanolamine, tetraethylenepentamine, piperazine, as well as amino group containing polymers including polyethyleneimine, polyacrylamide and chitosan in order to enhance direct air capture system performance, since it was known in the art as shown in Masoudi et al (US 20210349065; hereinafter Masoudi; [0118], [0125], [0127] and [0178]). As regarding claim 3, Ruettinger as modified discloses all of limitations as set forth above. Ruettinger as modified discloses the claimed invention except for wherein the one or more porous support structures include microwave absorptive materials, chosen from activated carbon, silicon carbide or both. It would have been obvious to one having ordinary skill in the art before the effective filing date of the invention was made to provide wherein the one or more porous support structures include microwave absorptive materials, chosen from activated carbon, silicon carbide or both in order to enhance direct air capture system performance, since it was known in the art as shown in Yeh et al (US 20200164339; hereinafter Yeh; [0034]). As regarding claim 4, Ruettinger as modified discloses all of limitations as set forth above. Ruettinger as modified discloses the claimed invention except for wherein the one or more porous support structures further include structure strengthening materials chosen from alumina, silica, magnesium oxide, cerium oxide, zeolite, cordierite or combinations thereof, which are generally transparent to microwave energy. It would have been obvious to one having ordinary skill in the art before the effective filing date of the invention was made to provide wherein the one or more porous support structures further include structure strengthening materials chosen from alumina, silica, magnesium oxide, cerium oxide, zeolite, cordierite or combinations thereof, which are generally transparent to microwave energy in order to enhance direct air capture system performance, since it was known in the art as shown in Kimura et al (US 20180050322; hereinafter Kimura; claim 29). As regarding claim 5, Ruettinger as modified discloses all of limitations as set forth above. Ruettinger as modified discloses the claimed invention for a shutter assembly (fig. 2; no number) coupled to the upstream end of the chamber, the shutter assembly movable between an open position allowing air to the upstream end, and a closed position, preventing air from entering the upstream end. Alternative, it is well-known in the art before the effective filing date of the invention to provide a vale upstream (shutter assembly) of the chamber in order to control the fluid flow into the chamber. As regarding claim 6, Ruettinger as modified discloses all of limitations as set forth above. Ruettinger as modified discloses the claimed invention for wherein the one or more porous support structures are pellets, granules, or a honeycomb structure ([0044]). As regarding claim 7, Ruettinger as modified discloses all of limitations as set forth above. Ruettinger as modified discloses the claimed invention except for wherein the microwave heating unit generates microwaves at 915 MHz or 2.45 GHz frequency for selective heating of the CO2 adsorbent material. It would have been obvious to one having ordinary skill in the art before the effective filing date of the invention was made to provide wherein the microwave heating unit generates microwaves at 915 MHz or 2.45 GHz frequency for selective heating of the CO2 adsorbent material in order to enhance system performance, since it has been held that where the general conditions of a claim are disclosed in the prior art, discovering the optimum or workable ranges involves only routine skill in the art. In re Aller, 105 USPQ 233. As regarding claim 8, Ruettinger as modified discloses all of limitations as set forth above. Ruettinger as modified discloses the claimed invention for a duct (figs. 2-3; 201 or 202) having an inlet end and an outlet end, the chamber carried within the duct intermediate the inlet end and the outlet end, the motor fan a motor fan (Gaur - 440) carried by the duct proximate the outlet end and adjacent the downstream end of the chamber. Claims 9-13 are likewise rejected for reasons analogous to those outlined with respect to claims 1-8 above. Response to Arguments Applicant’s arguments with respect to claim(s) 1-13 have been considered but are moot because of the new ground of rejection. Conclusion Any inquiry concerning this communication or earlier communications from the examiner should be directed to DUNG H BUI whose telephone number is (571)270-7077. The examiner can normally be reached Monday-Friday 8:00 - 4:30 ET. 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, Magali Slawski can be reached at (571) 270-3960. 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. /DUNG H BUI/ Primary Examiner, Art Unit 1773
Read full office action

Prosecution Timeline

Mar 20, 2023
Application Filed
Aug 13, 2025
Non-Final Rejection — §103
Nov 15, 2025
Response Filed
Jan 07, 2026
Non-Final Rejection — §103 (current)

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Study what changed to get past this examiner. Based on 5 most recent grants.

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Prosecution Projections

2-3
Expected OA Rounds
78%
Grant Probability
99%
With Interview (+24.4%)
2y 7m
Median Time to Grant
Moderate
PTA Risk
Based on 1227 resolved cases by this examiner. Grant probability derived from career allow rate.

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