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 Objections
Claims 4, 6, 7 and 8 are objected to under 37 CFR 1.75(c) as being improper form because multiple dependent claims cannot depend on any other multiple dependent claims. See MPEP § 608.01(n).
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.
Claims 1-9 are rejected under 35 U.S.C. 103 as being unpatentable over Krapchetov et al (US 2020/0199059 A1) in view of Limbach et al (US 2020/0157035 A1).
Applicants’ claimed invention is directed to a process for producing methyl methacrylate by oxidative esterification in a reactor system comprising one or more reactors, the process comprising: feeding methanol, methacrolein, and an oxygen containing gas to a first reactor, wherein the first reactor comprises a heterogeneous noble metal-containing catalyst; introducing a base material at a position external to the first reactor and mixing the base material with one or more reactants to form a base-containing stream; and feeding the base-containing stream to the first reactor, wherein the pH in the first reactor is between 4 and 10.
Krapchetov teaches a method for preparing methyl methacrylate from methacrolein and methanol. The method comprises contacting in a tubular reactor having at least four zones a mixture comprising methacrolein, methanol, oxygen and a base with a catalyst bed of heterogeneous catalyst comprising a support and a noble metal, wherein reaction zones comprising catalyst beds alternate with mixing zones not comprising catalyst beds. See abstract.
Krapchetov teaches bases include alkali metal hydroxides and C1-C4 alkoxides, preferably sodium and potassium hydroxide and sodium or potassium methoxide or ethoxide, preferably sodium hydroxide or sodium methoxide. Preferably, base is added as a solution, preferably in methanol, ethanol or water, preferably methanol or water. Preferably, alkoxides are added in methanol or ethanol. Preferably, the concentration of base in the solution is from 50 to 1 wt %, preferably from 45 to 2 wt %, preferably from 40 to 5 wt %. See paragraph 0008.
Krapchetov teaches Preferably, pH in the catalyst bed is from 4 to 10; preferably at least 5, preferably at least 5.5; preferably no greater than 9, preferably no greater than 8, preferably no greater than 7.5. Preferably, the catalyst bed is in a tubular continuous reactor. See paragraph 0020.
Krapchetov teaches that the first zone is a mixing zone into which fresh reactants are fed. Preferably, base is also fed to the first mixing zone, either with the reactants or separately. In a preferred embodiment of the process, base, oxygen or both are fed to at least one subsequent mixing zone as well as the first mixing zone. Preferably, a portion of the reaction mixture is recycled to the first mixing zone from subsequent mixing zones. See paragraph 0005.
The primary difference is that the current claim explicitly requires introducing and mixing the base at a location external to the first reactor vessel, whereas Krapchetov teaches introducing the base into a first mixing zone “either with the reactants or separately) without explicitly defining that zone as physically external to the reactor. This difference is rendered obvious because a person skilled in the art, prior to the effective filing date of the claimed invention, guided by Limbach’s feed streams, would view an external arrangement as a predictable engineering layout of Krapchetov’ s process; moving the mixing point upstream into an external pipe or manifold represents routine optimization to ensure the stream is thoroughly mixed and uniformly balanced to a safe pH of 4 to 10 before it contacts the sensitive catalyst, thereby avoiding destructive chemical “hot spots.”
Limbach teaches the time to reach 95% homogeneity is calculated by the following equation for stirred reactors in turbulent flow, in which time to reach 95% homogeneity is no greater than 4 minutes. See paragraph 0006 and claim 9.
The prior art reports that addition of base to the reactor to raise pH increases catalyst life and may reduce selectivity. The solution to this problem has been to mix the base into a portion of the reaction mixture or reactants in a separate vessel, see, e.g., U.S. Pub. No. 2016/0251301. However, there is a need for a more efficient process which can provide improved selectivity. See paragraph 0002.
The claims further differ require reaching at least 95% homogeneity within a strict 2-minute window, whereas Krapchetov is entirely silent on mixing uniformity and Limbach teaches a broader threshold of achieving 95% homogeneity withing 4 minutes; however, this limitation is rendered obvious because the claimed 2-minute target falls completely within Limbach’s disclosed 4-minute range(as any process completing mixing in 2 minutes inherently satisfies a 4-minute maximum constraint). Thus, a person having ordinary skill in the art, before the effective filing date of the claimed invention would see accelerating the mixing timeframe as routine optimization of a result-effective variable, motivated to achieve faster uniformity to further protect the sensitive catalyst from destructive localized pH spikes.
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/JAFAR F PARSA/Primary Examiner, Art Unit 1692
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