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
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.
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.
Claims 1-17, 20, and 21 are rejected under 35 U.S.C. 103 as being unpatentable over Washburn et al. (WO 2020/197890 A1) in view of Dorsi et al. (US 2021/0122688 A1).
Washburn teaches a process for producing p-xylene by methylation of benzene and/or toluene with methanol and/or dimethyl ether in the presence of a zeolitic methylation catalyst, including MWW-type zeolites, under methylation conditions of temperature and pressure consistent with those recited in the claims (See [0089]-[0094], [0090]-[0091]).
Washburn further teaches:
operation in fixed-bed reactors, including multiple catalyst beds arranged in series ([0083]-(0084);
staged addition of methylating agent and/or aromatic feed ([0091]);
formation of water as a reaction by-product of methylation ([0031]); and
removal of water and other components from methylation effluent using conventional separation techniques, producing aromatic-rich stream ([0095]-[0096]).
Accordingly, Washburn teaches the core methylation process of claims 1, 3–5, 10–15, and
18–19, except for the specific interstage processing and recycle architecture recited in certain
dependent claims.
Dorsi teaches an integrated methylation process for producing p-xylene from benzene and/or
toluene with methanol and/or dimethyl ether, including:
fixed-bed methylation reactors ([0034], [0035];
operating temperatures (200–500 °C) and pressures (100–8,500 kPa) ([0031]-[0032]);
aqueous/oil phase separation of methylation effluent to remove reaction water ([0042], [0049]);
recovery of DME-rich, methanol-rich, and aromatics-rich streams ([0043]-[0047];
recycling of DME, methanol, benzene, and/or toluene to the methylation reactor ([0043], [0047], [0049], [0050]; and
heat exchange (cooling/heating) of reactor effluent prior to separation ([0078]-[0081]).
Dorsi therefore expressly teaches interstage separation, conditioning, and recycle of methylation effluent streams.
It would have been obvious to one having ordinary skill in the art before the effective filing date of the claimed invention to incorporate the effluent separation, water removal, and recycle techniques of Dorsi into the methylation process of Washburn because:
Both references are in the same field (benzene/toluene methylation to p-xylene using methanol/DME and zeolitic catalysts);
Both recognize water and unreacted methylating agent as normal products/by-products of methylation;
Removal of water and recycling of unreacted methanol/DME and aromatics are well-known process-efficiency and catalyst-protection measures; and
The modification represents a predictable combination of known process steps yielding expected benefits (improved catalyst life, improved feed utilization, reduced separation load).
Claim 2
Washburn teaches a multi-stage methylation process employing staged reactors and temperature control of methylation effluent prior to downstream handling and separation (¶¶ [0093], [0095]–[0096]). However, Washburn does not expressly quantify an interstage temperature differential.
Dorsi explicitly teaches cooling methylation effluent using heat exchangers prior to further processing, including cooling prior to separation and recycle, which necessarily results in a temperature reduction between reaction stages (¶¶ [0078]–[0081], [0034]–[0036]).
It would have been obvious to one having ordinary skill in the art before the effective filing date of the claimed invention to apply the effluent cooling techniques of Dorsi to the staged methylation process of to control reaction severity and catalyst performance, thereby arriving at the claimed interstage temperature reduction, which represents a result-effective variable.
Claim 3
Washburn explicitly teaches methylation reaction temperatures within 200–500 °C (¶¶ [0089]–[0091]).
Claim 4
Washburn discloses preferred methylation temperatures within sub-ranges overlapping 250–400 °C (¶¶ [0089]–[0090]).
Claim 5
Washburn teaches staged addition of methylating agent to control reaction severity and selectivity (¶ [0093]). Injection of a methylating agent at a lower temperature than the reactor bed inherently produces a temperature differential, with the specific ΔT being a result-effective variable.
Claims 6–9
Washburn teaches that methylation produces water as a by-product and that methylation effluent is subjected to separation to remove water and other components (¶¶ [0095]–[0096]).
Dorsi explicitly teaches:
cooling methylation effluent prior to separation using heat exchangers (¶¶ [0034]–[0035], [0078]–[0081]);
aqueous/oil phase separation to remove water (¶¶ [0034]–[0036]).
It would have been obvious to one having ordinary skill in the art before the effective filing date of the claimed invention to have modified the process of Washburn by combining these teachings to achieve predication removal of water and conditioning of efferent stream.
Claims 10–15
Washburn teaches:
fixed-bed methylation reactors (¶¶ [0083]–[0084]);
pressures within 100–8,500 kPa (¶ [0091]);
zeolitic methylation catalysts including MWW-type and ZSM-5 (¶¶ [0093]–[0094]);
aromatic-to-methylating-agent molar ratios overlapping the claimed ranges (¶ [0091]).
Claims 16–17
Washburn teaches controlling aromatic-to-methylating-agent ratios during methylation (¶ [0091]).
Dorsi explicitly teaches recycling methanol, DME, benzene, and/or toluene from separation units back to the methylation reactor to maintain desired feed ratios (¶¶ [0034]–[0039], [0040]–[0042]).
It would have been obvious to one having ordinary skill in the art before the effective filing date of the claimed invention to have modified the process of Washburn by recycling streams as suggested by Dorsi to maintain desired ratio ratios (claimed ratio).
Claim 19
Washburn teaches multiple catalyst beds arranged in series, either within a single reactor or in separate vessels, for methylation reactions ([0083]-[0084]).
Claim 20
Washburn teaches staged methylation reactors with downstream separation of methylation effluent ([0095]–[0096]).
Dorsi explicitly teaches:
separation of methylation effluent into aqueous and hydrocarbon phases (¶¶ [0034]–[0036]);
recovery of aromatics-rich streams (¶ [0033]);
recycle of benzene/toluene-rich streams to the methylation reactor (¶¶ [0039]–[0042], [0040]–[0041]).
It would have been obvious to one having ordinary skill in the art before the effective filing date of the claimed invention to have modified the process of Washburn by incorporating these known separation and recycle steps of Dorsi into the methylation process of Washburn to improve efficiency and catalyst utilization.
Claim 21
Dorsi explicitly teaches operating methylation processes with an aromatic-to-methylating agent molar ratio greater than 1 (e.g., 2–20; ¶ [0091]), which necessarily corresponds to an amount of benzene and/or toluene being in stoichiometric excess relative to the methylating agent. It would have been obvious to employ such ratios in the process of Washburn to suppress over-alkylation and improve xylene selectivity.
Response to Arguments
Applicant argues that the combination fails to teach: (i) “producing a mixture feed having a second temperature T2 via reducing the temperature of the first methylation product mixture,” and (ii) “contacting the mixture feed with a second methylation catalyst in a second fixed bed.” These arguments are not persuasive. First, with respect to temperature reduction / cooling, Dorsi explicitly teaches cooling/conditioning of methylation effluent prior to downstream processing and/or further handling using heat exchange and separation systems (see, e.g., ¶¶ [0034]–[0036], [0078]–[0081]). Cooling of reactor effluent prior to subsequent processing is a conventional and necessary operation in hydrocarbon processing, including methylation systems, to control reaction severity, protect downstream equipment, and enable separation. As such, reducing the temperature of a first methylation product stream to form a subsequent feed stream constitutes no more than routine process optimization of a result-effective variable (temperature), which would have been obvious to one of ordinary skill in the art.
Applicant’s assertion that Dorsi does not explicitly describe “cooling effluent 135” is not persuasive because the cited disclosure of heat exchange and separation inherently requires temperature reduction of process streams prior to separation, particularly where aqueous/organic phase separation and light-ends recovery are performed. See (Applicant acknowledges reliance on ¶¶ [0078]–[0081] but mischaracterizes their teaching). The law does not require verbatim recitation where the feature is necessarily present or inherent in the disclosed operation.
Second, with respect to the second fixed bed / staged contacting, Washburn teaches methylation in fixed-bed systems including multiple catalyst beds arranged in series (see, e.g., ¶¶ [0083]–[0084]). It would have been obvious to one having ordinary skill in the art before the effective filing date of the claimed invention to operate such beds under different conditions and with interstage conditioning (including cooling and/or feed adjustment) to improve selectivity (e.g., p-xylene) and catalyst performance. The use of interstage cooling and/or feed staging between catalyst beds is a well-known technique in exothermic catalytic processes and represents a predictable variation.
Applicant’s argument that Washburn allegedly includes “only a single input stream” is not persuasive. Even assuming arguendo a single feed introduction, it would have been obvious to modify the process to include staged feeds and/or interstage conditioning as taught by Dorsi and as commonly practiced in catalytic reactor design to control temperature profiles and improve selectivity. The claimed “mixture feed” is therefore nothing more than a process stream resulting from routine interstage conditioning, which would have been obvious.
Third, Applicant’s reliance on purported advantages (e.g., improved p-xylene selectivity via cooling) does not overcome the rejection. Discovery of an optimization benefit of a known variable does not render the claimed process nonobvious where the underlying modification itself is obvious. See KSR.
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 TAM M NGUYEN whose telephone number is (571)272-1452. The examiner can normally be reached Mon - Frid.
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If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Prem C Singh can be reached at 571-273-6381. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300.
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/TAM M NGUYEN/Primary Examiner, Art Unit 1771
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