Prosecution Insights
Last updated: April 19, 2026
Application No. 18/167,030

PROCESSES FOR REGENERATING SORBENTS, AND ASSOCIATED SYSTEMS

Non-Final OA §103
Filed
Feb 09, 2023
Examiner
NASSIRI MOTLAGH, ANITA
Art Unit
1734
Tech Center
1700 — Chemical & Materials Engineering
Assignee
Massachusetts Institute Of Technology
OA Round
1 (Non-Final)
55%
Grant Probability
Moderate
1-2
OA Rounds
2y 10m
To Grant
80%
With Interview

Examiner Intelligence

Grants 55% of resolved cases
55%
Career Allow Rate
335 granted / 614 resolved
-10.4% vs TC avg
Strong +26% interview lift
Without
With
+25.7%
Interview Lift
resolved cases with interview
Typical timeline
2y 10m
Avg Prosecution
29 currently pending
Career history
643
Total Applications
across all art units

Statute-Specific Performance

§101
0.1%
-39.9% vs TC avg
§103
58.2%
+18.2% vs TC avg
§102
11.9%
-28.1% vs TC avg
§112
25.2%
-14.8% vs TC avg
Black line = Tech Center average estimate • Based on career data from 614 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 . This action is in response to Applicant’s response to election/restriction filed 12/03/2025. Applicant’s election without traverse of Group II, claims 31-36 in the reply filed on 12/03/2025 is acknowledged. Claims 31-50 are pending and being examined. Claims 1-30 are canceled. Claims 37-50 are newly added with no new subject matter being introduced. Claim Rejections - 35 USC § 103 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. The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action: A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made. Claims 31-33, 39, 41-42, 47, and 49 are rejected under 35 U.S.C. 103 as being unpatentable over Schimkat et al. (US 7022168 B2). Considering claim 31, Schimkat teaches a method comprising transporting a fuel and compressed air to a combustion chamber; combusting the natural gas and the compressed air in the combustion chamber to produce flue gas (Schimkat, Col. 3 lines 10-15). Schimkat teaches the burning of fossil fuels such as natural gas, mineral oil and coal (Schimkat, Col. 1 lines 24-28). Therefore, it would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, to transport natural gas with the compressed air to the combustion chamber. One of ordinary skill in the art, before the effective filing date of the claimed invention, would have been motivated to do so because selection of a known material based on its suitability for its intended use is prima facie obvious (see MPEP §2144.07). Schimkat teaches transporting the flue gas (39 of Fig. 1) to an absorber (22 of Fig. 1) comprising sorbent such that carbon dioxide from the flue gas is captured by the sorbent and processed flue gas lean in carbon dioxide (40 of Fig. 1) relative to the flue gas produced in the combustion chamber exits the absorber (Schimkat, Col. 3 lines 39-42 and lines 62-66, Col. 4 lines 10-13, Fig. 1). Schimkat teaches transporting the processed flue gas (40 of Fig. 1) to a heat recovery steam generator (33 of Fig. 1) such that heat recovered from the processed flue gas is used to produce steam (Schimkat, Col. 4 lines 10-13, Fig. 1). Considering claim 32, Schimkat teaches prior to transporting the flue gas to the absorber, transporting the flue gas through a turbine to generate electricity by teaches expanding the hot gas which is formed during the combustion in a gas turbine which via a common rotor drives the air compressor and generates current via a connected first generator (Schimkat, Col. 3 lines 15-18). Considering claim 33, Schimkat teaches compressing air using a gas turbine to generate the compressed air (Schimkat, Col. 3 lines 15-18). Considering claim 39, Schimkat teaches transporting the sorbent comprising the captured carbon dioxide to a desorber, wherein at least a portion of the captured carbon dioxide is separated from the sorbent in the desorber, thereby obtaining separated carbon dioxide (Schimkat, paragraph bridging Col. 3 & 4). Considering claims 41-42, Schimkat teaches a regenerative absorber/desorber for the removal of carbon dioxide from the flue gas (Schimkat, last paragraph of Col. 3). Therefore, it would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, to separate as much of the carbon dioxide including at least 10 mol % and/or 50 mol % from the sorbent in the desorber. One of ordinary skill in the art, before the effective filing date of the claimed invention, would have been motivated to do so in order to free the sorbent of the absorbed carbon dioxide and enable additional carbon dioxide absorption with a reasonable expectation of success. Considering claims 47 and 49, Schimkat teaches the hot gas formed during the combustion is expanded in the gas turbine 16 which via a common rotor drives the compressor and generates current via a connected first generator 13 (Schimkat, Col. 3 lines 10-18). Schimkat also teaches the steam turbine 29 which drives a second generator 28 may be coupled to the gas turbine 16 (Schimkat, Col. 3 lines 33-38). Therefore, it would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, to transport the flue gas to an additional heat recovery steam generator to produce additional steam prior to transporting the flue gas to the absorber. One of ordinary skill in the art, before the effective filing date of the claimed invention, would have been motivated to do so in order to utilize any heat available in the process to generate steam for a more energy efficient process with a reasonable expectation of success. It should be noted that in this embodiment, the additional steam from the additional heat recovery steam generator drives a turbine to generate electricity. Claims 34-36 are rejected under 35 U.S.C. 103 as being unpatentable over Schimkat et al. (US 7022168 B2) in view of Li et al. (US 2010/0139484 A1). Considering claims 34-36, all of the limitations are met by the prior art referenced in meeting claim 31 limitations except for a first, second, third portion of the steam from the heat recovery steam generator driving a first, second, third turbine. Schimkat teaches the heat recovery steam generator turbine usually comprises a plurality of pressure stages (Schimkat, Col. 3 lines 28-37), he does not explicitly teach a first, second, third portion of the steam from the heat recovery steam generator driving a first, second, third turbine. However, Li teaches a power plant integrated with a CO2 capture unit wherein the power plant comprises at least one gas turbine coupled to a heat recovery steam generator unit (Li, abstract). Li teaches the heat recovery steam generator unit can be designed to produced one, two, or three types of steam: high-pressure steam, intermediate pressure steam and low-pressure steam (Li, [0014]). Therefore, it would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, use a first portion of the steam from the heat recovery steam generator to drive a first turbine at a first pressure to generate electricity, use a second portion of the steam from the heat recovery steam generator to drive a second turbine at a second pressure that is higher than the first pressure to generate electricity and use a third portion of the steam from the heat recovery steam generator to drive a third turbine at a third pressure that is higher than the first and second pressure to generate electricity. One of ordinary skill in the art, before the effective filing date of the claimed invention, would have been motivated to do so in order to utilize the steam generated at each stage of the plurality of pressure stages of the heat recovery steam generator turbine and generate electricity with a reasonable expectation of success. Claims 37 and 50 are rejected under 35 U.S.C. 103 as being unpatentable over Schimkat et al. (US 7022168 B2) in view of Olsen (US 2012/0128559 A1). Considering claim 37, all of the limitations are met by the prior art referenced in meeting claim 31 limitations except for the sorbent is in molten form. Schimkat teaches methods of CO2 removal such as liquid absorption and granular metal oxide adsorption (Schimkat, Col. 1 lines 34-63), he does not explicitly teach using a sorbent in molten form. However, Olsen teaches a very efficient capture of CO2 using metal oxides dissolved in salt melts (i.e., sorbent in molten form) (Olsen, abstract, [0015], [0036]). Therefore, it would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, for the sorbent to be in molten form. One of ordinary skill in the art, before the effective filing date of the claimed invention, would have been motivated to do so in order to use a higher efficiency sorbent for the capture of CO2 with a reasonable expectation of success. Considering claim 50, all of the limitations are met by the prior art referenced in meeting claim 39 limitations except for a temperature of the absorber is within 200° C of a temperature of the desorber. Schimkat teaches methods of CO2 removal such as liquid absorption and granular metal oxide adsorption (Schimkat, Col. 1 lines 34-63), he does not explicitly teach a temperature of the absorber is within 200° C of a temperature of the desorber. However, Olsen teaches a very efficient capture of CO2 using metal oxides dissolved in salt melts (i.e., sorbent in molten form) (Olsen, abstract, [0015], [0036]). Olsen teaches absorption at approximately 700-800° C and desorption at approximately 950° C (Olsen, [0031]). Therefore, it would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, to use Olsen’s molten sorbent process wherein a temperature of the absorber is within 200° C of a temperature of the desorber. One of ordinary skill in the art, before the effective filing date of the claimed invention, would have been motivated to do so in order to use a higher efficiency sorbent for the capture of CO2 with a reasonable expectation of success. Claim 38 is rejected under 35 U.S.C. 103 as being unpatentable over Schimkat et al. (US 7022168 B2) in view of Harada et al. (US 2018/0354807 A1). Considering claim 38, all of the limitations are met by the prior art referenced in meeting claim 31 limitations except for the sorbent comprises an alkali metal borate. Schimkat does not explicitly teach the sorbent comprises an alkali metal borate. However, Harada teaches post combustion carbon dioxide removal using a sequestration material comprising lithium borate; the sequestration material can capture large amount of carbon dioxide per mass of the sequestration material and can be cycled repeatedly while losing little if any ability to sequester carbon dioxide (Harada, [0005]). Therefore, it would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, to use a sorbent comprising an alkali metal borate such as lithium borate. One of ordinary skill in the art, before the effective filing date of the claimed invention, would have been motivated to do so in order to sequester large amounts of carbon dioxide per mass of the sequestration material and cycle the material repeatedly while losing little if any ability to sequester carbon dioxide with a reasonable expectation of success. Claims 40 and 48 are rejected under 35 U.S.C. 103 as being unpatentable over Schimkat et al. (US 7022168 B2) in view of Boulet et al. (US 2019/0262767 A1). Considering claim 40, all of the limitations are met by the prior art referenced in meeting claim 39 limitations except for a portion of the steam from the heat recovery steam generator is directed to the desorber and is used to separate the at least the portion of the captured carbon dioxide from the sorbent. Schimkat teaches heating the circulating carbon dioxide in the first heat exchanger in order to keep the desorption in progress in the absorber/desorber (Schimkat, Col. 4 lines 19-21), he does not explicitly teach using a portion of the generated steam for desorption. However, Boulet teaches an adsorptive gas separation method using temperature swing adsorption in a contactor for CO2 separation using a steam purge gas to desorb the carbon dioxide; he also teaches a heat transfer fluid such as a carbon dioxide enriched product gas stream can be used in addition to or in place of a purge gas (Boulet, [0067]-[0068]). Therefore, it would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, to direct a portion of the steam from the heat recovery steam generator to the desorber and use it to separate the at least the portion of the captured carbon dioxide from the sorbent. One of ordinary skill in the art, before the effective filing date of the claimed invention, would have been motivated to do so because the use of steam as a purge stream for desorption of carbon dioxide can be used in addition to or in place of a heat transfer fluid such as carbon dioxide enriched product gas stream. Considering clam 48, Schimkat teaches transporting the sorbent comprising the captured carbon dioxide to a desorber wherein at least a portion of the captured carbon dioxide is separated from the sorbent in the desorber by teaching a coated regenerative heat exchanger which rotates about an axis of rotation to move the sorbent between absorption/desorption (Schimkat, paragraph bridging Col. 3 & 4). Schimkat teaches heating the circulating carbon dioxide in the first heat exchanger in order to keep the desorption in progress in the absorber/desorber (Schimkat, Col. 4 lines 19-21), he does not explicitly teach using a portion of the generated steam for desorption. However, Boulet teaches an adsorptive gas separation method using temperature swing adsorption in a contactor for CO2 separation using a steam purge gas to desorb the carbon dioxide; he also teaches a heat transfer fluid such as a carbon dioxide enriched product gas stream can be used in addition to or in place of a purge gas (Boulet, [0067]-[0068]). Therefore, it would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, to direct a portion of the steam from the additional heat recovery steam generator to the desorber and use it to separate the at least the portion of the captured carbon dioxide from the sorbent. One of ordinary skill in the art, before the effective filing date of the claimed invention, would have been motivated to do so because the use of steam as a purge stream for desorption of carbon dioxide can be used in addition to or in place of a heat transfer fluid such as carbon dioxide enriched product gas stream. Claims 43-46 are rejected under 35 U.S.C. 103 as being unpatentable over Schimkat et al. (US 7022168 B2) in view of Boulet et al. (US 2019/0262767 A1) and Olsen (US 2012/0128559 A1). Considering claims 43-44, Schimkat teaches a stream comprising the separated carbon dioxide exits the desorber (Schimkat, Col. 4 lines 10-21). It has already been established to direct a portion of the steam from the heat recovery steam generator to the desorber and use it to separate the at least the portion of the captured carbon dioxide from the sorbent; thus, it would be expected that the stream comprising the separated carbon dioxide exiting the desorber would also comprise a portion of the steam from the heat recovery steam generator. Schimkat teaches methods of CO2 removal such as liquid absorption and granular metal oxide adsorption (Schimkat, Col. 1 lines 34-63) wherein his main embodiment uses a coated regenerative heat exchanger which rotates about an axis of rotation to move the sorbent between absorption/desorption (Schimkat, paragraph bridging Col. 3 & 4), he does not explicitly teach using a stream comprising the sorbent exiting the desorber. However, Olsen teaches a very efficient capture of CO2 using metal oxides dissolved in salt melts (i.e., sorbent in molten form) (Olsen, abstract, [0015], [0036]). Olsen teaches an absorber wherein the molten salts absorb carbon dioxide and a desorber that is heated to release the carbon dioxide (Olsen, [0031]). Olsen teaches the regenerated molten salts are reintroduced into the absorber (Olsen, [0032]). Therefore, it would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, to use Olsen’s molten salt process for carbon dioxide capture wherein a stream comprising the sorbent exits the desorber and is directed back to the absorber to capture additional carbon dioxide. One of ordinary skill in the art, before the effective filing date of the claimed invention, would have been motivated to do so in order to use a higher efficiency sorbent for the capture of CO2 with a reasonable expectation of success. Considering claims 45-46, Schimkat teaches pumping back condensed steam into the feed-water tank used for steam generation (Schimkat, Col. 3 lines 33-36). Boulet teaches when using steam as a purge gas to regenerate sorbent, the steam component of the recovered carbon dioxide is condensed in order to remove it from the product stream resulting in increased purity of the carbon dioxide (Boulet, [0068]). Therefore, it would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, to cool the second stream comprising carbon dioxide and condense the portion of the steam from the heat recovery steam generator in the second stream to obtain water from which addition steam is generated. One of ordinary skill in the art, before the effective filing date of the claimed invention, would have been motivated to do so in order to obtain a higher purity carbon dioxide product stream in addition to recovering water for generation of additional steam with a reasonable expectation of success. Conclusion Any inquiry concerning this communication or earlier communications from the examiner should be directed to ANITA NASSIRI-MOTLAGH whose telephone number is (571)270-7588. The examiner can normally be reached M-F 6:30-3:00. 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, Jonathan Johnson can be reached at 571-272-1177. 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. /ANITA NASSIRI-MOTLAGH/Primary Examiner, Art Unit 1734
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Prosecution Timeline

Feb 09, 2023
Application Filed
Dec 10, 2025
Non-Final Rejection — §103
Mar 12, 2026
Interview Requested
Mar 19, 2026
Examiner Interview Summary
Mar 19, 2026
Applicant Interview (Telephonic)

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Prosecution Projections

1-2
Expected OA Rounds
55%
Grant Probability
80%
With Interview (+25.7%)
2y 10m
Median Time to Grant
Low
PTA Risk
Based on 614 resolved cases by this examiner. Grant probability derived from career allow rate.

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