Prosecution Insights
Last updated: April 19, 2026
Application No. 18/691,643

PYROLYSIS GAS TREATMENT INCLUDING CAUSTIC SCRUBBER

Final Rejection §102§103
Filed
Mar 13, 2024
Examiner
OLADAPO, TAIWO
Art Unit
1771
Tech Center
1700 — Chemical & Materials Engineering
Assignee
ExxonMobil
OA Round
2 (Final)
53%
Grant Probability
Moderate
3-4
OA Rounds
3y 2m
To Grant
64%
With Interview

Examiner Intelligence

Grants 53% of resolved cases
53%
Career Allow Rate
605 granted / 1144 resolved
-12.1% vs TC avg
Moderate +11% lift
Without
With
+11.4%
Interview Lift
resolved cases with interview
Typical timeline
3y 2m
Avg Prosecution
89 currently pending
Career history
1233
Total Applications
across all art units

Statute-Specific Performance

§101
0.9%
-39.1% vs TC avg
§103
52.8%
+12.8% vs TC avg
§102
16.2%
-23.8% vs TC avg
§112
15.9%
-24.1% vs TC avg
Black line = Tech Center average estimate • Based on career data from 1144 resolved cases

Office Action

§102 §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 § 102/103 The following is a quotation of the appropriate paragraphs of 35 U.S.C. 102 that form the basis for the rejections under this section made in this Office action: A person shall be entitled to a patent unless – (a)(1) the claimed invention was patented, described in a printed publication, or in public use, on sale, or otherwise available to the public before the effective filing date of the claimed invention. 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. This application currently names joint inventors. In considering patentability of the claims the examiner presumes that the subject matter of the various claims was commonly owned as of the effective filing date of the claimed invention(s) absent any evidence to the contrary. Applicant is advised of the obligation under 37 CFR 1.56 to point out the inventor and effective filing dates of each claim that was not commonly owned as of the effective filing date of the later invention in order for the examiner to consider the applicability of 35 U.S.C. 102(b)(2)(C) for any potential 35 U.S.C. 102(a)(2) prior art against the later invention. Claim 1, 4 – 9, 11 – 17, 20 are rejected under 35 U.S.C. 102(a)(1) as anticipated by Bitting et al. (WO 2021/163113A1) or, in the alternative, under 35 U.S.C. 103 as obvious over Bitting et al. (WO 2021/163113 A1) In regards to claim 1, Bitting teaches chemical recycling of plastic derived streams to a cracker separation zone, wherein a waste plastic source is fed into a pretreatment system, then to a pyrolysis feed system, then to a pyrolysis reactor, then to a solids separator which separates out pyrolysis residue, then to a gas separation unit which separates out pyrolysis gas and pyrolysis oil according to a)i) of the claim (abstract, Fig 1). The gas is pyrolysis gas is cooled to obtain pyrolysis gas (pygas) and pyrolysis oil (pyoil) according to aii) and aiii) of the claim [0182]. The CO2, sulfur, and the halogens in the pyrolysis gas can each be at most 100 ppm [0015, 0159]. The gas is sent to a dehalogenation unit to remove halogen (fig 2). The pyrolysis gas is also goes to a gasifier comprising a caustic scrubber etc., unit to remove CO2 etc. according to b), c) of the claim [0221, 0391]. The pyrolysis oil is sent to a POX unit which is part of a cracker facility and comprises a furnace wherein the oil is heated according to b), d) of the claim [fig 3 & fig 4 and 0194]. Pygas is combined with effluent from the cracker furnace [0391]. In regards to claim 4, Bitting teaches the process wherein pygas is treated to remove CO2 and halogen as previously stated according to a) of the claim. A portion of the dehalogenated gas is sent to the gasifier (i.e., comprising the caustic scrubber etc.) according to b) of the claim [0006]. In regards to claim 5, Bitting teaches the process wherein carbon dioxide is removed from the absorber system as previously stated according to i), and wherein halogens are removed from the pygas in a halogen removal system (i.e., providing the halogen removal material) according to (iii) as claimed. Thus, since at least i) and ii) are taught, the claimed limitation allowing for alternatives is provided. In regards to claim 6, Bitting teaches the process wherein the carbon dioxide is removed in the scrubber and thus intrinsically provides the treated pygas stream and the caustic spent stream in the caustic scrubber comprising the carbon dioxide. In regards to claim 7, Bitting teaches the process which provides acid gas removal [0220 – 0223]. Since it is a similar process, the formation of acids such as HCL of the claim would be expected and the removal by any conventional means including neutralization would be obvious to persons of ordinary skill in the art. While the specific use of spent caustic components are not taught for neutralizing the acids, recycling of components is generally taught by Bitting and thus would make it obvious to persons of ordinary skill in the art to have provided acid removal including by neutralization using recycled material such as caustic materials. Generally, recycling of ingredients from one station to another for reuse would not be considered innovative. Neutralization of acids using caustic components is a conventional chemical process. In regards to claim 8, Bitting teaches the process wherein recycled pyrolysis gas (r-pyrolysis gas) is dehalogenated then sent to the compression unit where it is cooled and sent into a separation unit to produce recycled products such as olefins, paraffins, gasoline etc., (i.e., r-olefin) as end products according to limitation ii) of the claim [figs 2, 5, 6, and 0182, 0323 – 0326]. Dehydration of the gas is also performed in a H2O removal step according to limitation i) of the claim (fig 11A). While cryogenic cooling is not particularly recited, the means and/or rate of cooling are process parameters that would routinely be optimized by persons ordinary skill in the art and therefore do not carry patentable weight, or are obvious. Generally, differences in temperature will not support the patentability of subject matter encompassed by the prior art unless there is evidence indicating such temperature is critical. “[W]here 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.” In re Aller, 220 F.2d 454, 456, 105 USPQ 233, 235 (CCPA 1955). In regards to claim 9, Bitting teaches the process which combines cracker effluent with pygas prior and thus forming a combined stream that is sent to scrubber according to limitations a) and b) of the claim [0391 and Figs 4 – 6]. In regards to claim 11, Bitting teaches sending a portion of pyoil to the cracker as previously stated, and which would provide effluent from the cracker. Cracking may be made by steam cracking [0334]. In regards to claims 12 – 16, Bitting teaches the process wherein the pygas has the CO2 content of the claims as previously discussed. Before the scrubber it has CO2 of about 100ppm or less as previously discussed. After the scrubber it is depleted of CO2. In regards to claims 17, 20, Bitting teaches the process comprising the steps of treating pygas in fractionation columns comprising stripper, absorber etc., wherein pygas is introduced into the caustic scrubber and stripped of CO as previously discussed [also 0365]. The scrubber is a caustic scrubber and appears that it would contain caustic solvent such as KOH (potassium hydroxide) [0517]. Conclusion Any inquiry concerning this communication or earlier communications from the examiner should be directed to TAIWO OLADAPO whose telephone number is (571)270-3723. The examiner can normally be reached 8-5pm. 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, Prem Singh can be reached at 571-272-6381. 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. /TAIWO OLADAPO/Primary Examiner, Art Unit 1771
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Prosecution Timeline

Mar 13, 2024
Application Filed
Nov 10, 2025
Non-Final Rejection — §102, §103
Jan 20, 2026
Response Filed
Apr 10, 2026
Final Rejection — §102, §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

3-4
Expected OA Rounds
53%
Grant Probability
64%
With Interview (+11.4%)
3y 2m
Median Time to Grant
Moderate
PTA Risk
Based on 1144 resolved cases by this examiner. Grant probability derived from career allow rate.

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