Prosecution Insights
Last updated: April 19, 2026
Application No. 18/263,794

PROCESSES FOR MAKING AND USING SLURRY CATALYST MIXTURES

Non-Final OA §102§103§112
Filed
Aug 01, 2023
Examiner
SASTRI, SATYA B
Art Unit
1762
Tech Center
1700 — Chemical & Materials Engineering
Assignee
ExxonMobil
OA Round
1 (Non-Final)
63%
Grant Probability
Moderate
1-2
OA Rounds
3y 1m
To Grant
93%
With Interview

Examiner Intelligence

Grants 63% of resolved cases
63%
Career Allow Rate
561 granted / 888 resolved
-1.8% vs TC avg
Strong +30% interview lift
Without
With
+29.5%
Interview Lift
resolved cases with interview
Typical timeline
3y 1m
Avg Prosecution
63 currently pending
Career history
951
Total Applications
across all art units

Statute-Specific Performance

§101
0.4%
-39.6% vs TC avg
§103
47.2%
+7.2% vs TC avg
§102
13.3%
-26.7% vs TC avg
§112
24.8%
-15.2% vs TC avg
Black line = Tech Center average estimate • Based on career data from 888 resolved cases

Office Action

§102 §103 §112
DETAILED ACTION The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA . Per preliminary amendment dated 8/1/23, claims 1, 3-21 are currently pending in the application. Restriction Requirement Restriction is required under 35 U.S.C. 121 and 372. This application contains the following inventions or groups of inventions which are not so linked as to form a single general inventive concept under PCT Rule 13.1. In accordance with 37 CFR 1.499, applicant is required, in reply to this action, to elect a single invention to which the claims must be restricted. i. Group I, claim(s) 1, 3-12, drawn to a process of making a slurry catalyst mixture, and ii. Group II, claim(s) 13-21, drawn to a polymerization process. The inventions listed as Groups I and II do not relate to a single general inventive concept under PCT Rule 13.1 because, under PCT Rule 13.2, they lack the same or corresponding special technical features for the following reasons: The technical feature that are common to Groups I and II is the slurry catalyst mixture of claim 1. Regarding this feature, the prior art to Stevens (US2020/0071437 A1) teaches a catalyst comprising metallocene catalysts and slurry thereof prepared in mineral oil, such as SJCS-380, that has been heated to 60oC dried under <3 psi vacuum for 3hrs (Examples, [0302]-[0305]). It is noted that the disclosed conditions fall within the scope of the temperature, vacuum pressure and duration prescribed in the instant disclosure for reducing the moisture concentration to produce a dried mineral oil [0024]-[0025] (elaborated further in the rejection below). Additionally, the essential components of the disclosed slurry catalyst mixture are not taught as necessarily including a wax component. Thus, given that the common technical feature of presently cited claims in Groups I and II fails to define a contribution over the cited art, the common technical feature does not amount to a special technical feature. In light of above, there is lack of unity between the cited groups. During a telephone conversation with Mr. Corey Tumey on 2/3/26, a provisional election was made without traverse to prosecute the invention of Group I, claims 1, 3-12. Affirmation of this election must be made by applicant in replying to this Office action. Claim 13-21 are withdrawn from further consideration by the examiner, 37 CFR 1.142(b), as being drawn to a non-elected invention. Claim Objection Claim 4 is objected to because of the following: The claimed method steps include the following: PNG media_image1.png 74 606 media_image1.png Greyscale Although the claim does not rise to the level of indefiniteness under 112 (b) in view of the disclosure [0025], given that the reducing moisture concentration may be achieved by at least one of the claimed steps, the claim may be amended to improve clarity by reciting “a second inert gas, which may be same or different from the first inert gas,” Appropriate correction and/or clarification is required. Claim Rejections - 35 USC § 112 The following is a quotation of 35 U.S.C. 112(b): (b) CONCLUSION.—The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the inventor or a joint inventor regards as the invention. The following is a quotation of 35 U.S.C. 112 (pre-AIA ), second paragraph: The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the applicant regards as his invention. Claims 1, 3-11 are rejected under 35 U.S.C. 112(b) or 35 U.S.C. 112 (pre-AIA ), second paragraph, as being indefinite for failing to particularly point out and distinctly claim the subject matter which the inventor or a joint inventor (or for applications subject to pre-AIA 35 U.S.C. 112, the applicant), regards as the invention. Claim 1 recites the following step: PNG media_image2.png 68 942 media_image2.png Greyscale The claim indefinite is indefinite. It is not clear as to what degree the moisture concentration in the heated mineral oil is to be reduced to produce a dried mineral oil. The requisite degree is not defined by the claim, the specification does not provide a standard for ascertaining the requisite degree, and one of ordinary skill in the art would not be reasonably apprised of the scope of the invention. Claims 3-11 are subsumed by this rejection because they depend on rejected base claim 1. For the purpose of examination, in view of the disclosure (PGPUB-[0026]), examiner interprets the moisture concentration in the dried mineral oil to mean <100 ppm. Claim 11 recites the limitation “the first catalyst or the second catalyst”. The claim is indefinite because there is insufficient antecedent basis for “the first catalyst” and “the second catalyst”. Claim Rejections - 35 USC § 102 and 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. Claims 1, 4, 5 and 9 are rejected under 35 U.S.C. 102(a)(1) as being anticipated by Stevens et al. (US2020/0071437 A1). Stevens teaches a catalyst component for gas phase reactor comprising two catalysts, and providing a slurry thereof in a diluent, such as mineral oil [0145]. Disclosed mineral oils have a density of from 0.85 to 0.9 g/cm3 at 25° C per ASTM D4052, a kinematic viscosity @ 25° C. of from 150 cSt to 200 cSt per ASTM 341and an average molecular weight of from 400 g/mol to 600 g/mol per ASTM D 2052, such as HYDROBRITE® 380 PO White Mineral Oil (“HB380”) [0135]. Disclosed Example teaches a method comprising: preheating a mixer to 60oC and adding mineral oil, applying <3 psi vacuum (60oC, 3h) and refilling the mixer with nitrogen, i.e., capable of reducing moisture, adding a dual solid catalyst and agitating the mixture for 2 hrs [0302]-[0305]. It is noted that the disclosed vacuum pressure/temperature/duration fall within the scope of the temperature, vacuum pressure and duration prescribed in the instant disclosure for reducing the moisture concentration to produce a dried mineral oil [0024]-[0025]. Given that Stevens teaches a method of preparing a catalyst slurry mixture comprising steps as in the claimed method, and noting that Stevens does not teach any of the catalyst slurry components as necessarily including wax, that wax may be optionally added as an additional component [0135], [0151], the disclosed method must inherently provide for a catalyst slurry mixture having claimed wax content. Regarding claim 9, it is noted that the claimed limitation “the slurry catalyst mixture is produced at a manufacturing facility” is a product-by-process limitation nested in the process claim that is not seen as limiting the structure of the product in any way. Therefore, claim 9 is not seen as necessarily limiting the scope of claim 1. In light of above, presently cited claims are anticipated by the reference. Claims 3, 7, 8, 10 and 11 are rejected under 35 U.S.C. 103 as being unpatentable over Stevens et al. (US2020/0071437 A1). The discussion on Stevens from paragraph 11 above is incorporated herein by reference. Regarding claim 3, Stevens teaches that the oil is agitated under vacuum before the addition of the catalyst, and after the solid catalyst is added to provide for a well-mixed slurry [0305]. Regarding claim 7, Stevens teaches a solid catalyst mixture comprising hafnocene and zircocene, i.e., metallocene catalysts, and silica [0302]-[0305], and that an activator, such as aluminoxane may be included in the slurry catalyst mixture [0118], [0145]. Regarding claim 8, Stevens teaches rac/meso Me2Si(Me3SiCH2Cp)2HfMe2 (reads on dimethylsilylbis[(trimethylsilyl)methyl)cyclopentadienyl]hafnium dimethyl) [0101] and rac/meso bis(1-methylindenyl)zirconium dimethyl [0112]. Regarding claim 10, Stevens prescribes a shorter time when combining the catalysts with other components, such as a support or an activator, immediately prior to a polymerization reactor, e.g., less than 1h, as being more effective in providing for faster flow rates [0155]. Regarding claim 11, Stevens teaches that the catalyst component slurry can be combined in-line with a catalyst component solution to form a final catalyst composition, wherein the catalyst component solution is prepared by mixing a solvent and at least one catalyst compound, for use in a gas phase polymerization reactor [0145], [0150]-[0155]. Stevens further teaches that time dependent parameters may be adjusted, such as changing relative feed rates of slurry or solution, changing the mixing time, the temperature and/or mixing time of the slurry and solution in-line etc., and that any combination of these adjustments may be used to control the properties of the final product [0169]. Stevens is silent on a method of preparing a slurry catalyst mixture comprising the claimed step and/or the claimed component in one single embodiment as in the claimed invention. Given the teaching on preparing a well-mixed slurry catalyst, the teaching on suitable metallocene catalysts and use thereof as a combination of two or more in the slurry mixture, and aluminoxane and silica as further components of the slurry catalyst, it would have been obvious to one of ordinary skill in the art, as of the effective filing date of the claimed invention to (a) agitate the heated mineral oil upon introducing into a heated mixer so as to heat the mineral oil uniformly (claim 3), or (b) prepare a catalyst mixture slurry comprising a first and second metallocene catalyst, silica, and aluminoxane activator, or (c) a catalyst mixture slurry comprising claimed compounds. In the case where the claimed ranges "overlap or lie inside ranges disclosed by the prior art" a prima facie case of obviousness exists. In re Wertheim, 541 F.2d 257, 191 USPQ 90 (CCPA 1976). See MPEP § 2144.05. Additionally, it would have been obvious to one of ordinary skill in the art, as of the effective filing date of the claimed invention, to use shorter mixing times immediately prior to a polymerization reactor, e.g., less than 1h, for providing slurry catalyst mixtures having faster flow rates (claim 10), or, to contact a slurry catalyst mixture and a solution catalyst mixture to form a slurry/solution catalyst mixture, wherein each of the constituent mixtures comprise one or more of any of the disclosed catalysts, for introducing into the gas phase polymerization reactor. Claim 6 is rejected under 35 U.S.C. 103 as being unpatentable over Stevens et al. (US2020/0071437 A1), in view of Abe et al. (JP 2001-347152 A, machine translation). The discussion on Stevens from paragraph 11 above is incorporated herein by reference. Stevens is silent on agitating with a rotatable mixing apparatus as in the claimed invention. The secondary reference to Abe teaches mixing and defoaming performed by supplying a material to a rotation / revolution type mixing and defoaming apparatus capable of improving stability, stabilizing manufacturing quality with improved efficiency of mixing and defoaming (Overview, [0013]), wherein said material may be a slurry for a catalyst, [0014], and wherein the rotation speed may be controlled [0082]. Given the teaching in Abe on advantages of the disclosed apparatus, it would have been obvious to one of ordinary skill in the art, as of the effective filing date of the claimed invention, to perform the steps of agitation during the heating of the mineral oil, applying vacuum, introducing the solid catalyst and mixing in an apparatus as taught by Abe at a rotation speed, including at the claimed rpm range, so as to provide for optimal improvements in stability, manufacturing quality and mixing and defoaming efficiency, absent evidence to the contrary. Claim 12 is rejected under 35 U.S.C. 103 as being unpatentable over Stevens et al. (US2020/0071437 A1), alone, or in view of Wang et al. (CN 1485350 A, machine translation). The discussion on Stevens from paragraph 11 above is incorporated herein by reference. Although Stevens is silent on a method wherein the dried mineral has a moisture content as in the claimed invention, given the teaching on applying a vacuum of <3 psi vacuum at 60oC for 3h, on the mineral oil, i.e., conditions that fall within the scope of the conditions prescribed in the instant disclosure, it would have been obvious to one of ordinary skill in the art, as of the effective filing date of the claimed invention, to apply a vacuum of <3 psi vacuum, i.e., pressure ranging between 0 and 3 psi, reasonably expect a moisture content to be < 50 ppm as in the claimed invention, absent evidence to the contrary. In the alternative, the secondary reference to Wang teaches is in a related field and teaches a catalyst slurry for gas phase polymerization comprising a pure mineral oil that is dehydrated to below 5.0 ppm as being capable of improving the performance of the catalyst and protecting the catalyst activity (lines 234-254, ref. claim 6). In view of the disclosed advantages, it would have been obvious to one of ordinary skill in the art, as of the effective filing date of the claimed invention, to reduce the moisture level of mineral oil in Steven’s slurry catalyst mixtures to below 5 ppm. Conclusion Any inquiry concerning this communication or earlier communications from the examiner should be directed to Satya Sastri at (571) 272 1112. The examiner can normally be reached Monday-Friday, 9 AM - 5 PM EST. If attempts to reach the examiner by telephone are unsuccessful, the examiner's supervisor, Mr. Robert Jones can be reached at (571)-270- 7733. The fax phone number for the organization where this application or proceeding is assigned is (571) 273 8300. Information regarding the status of an application may be obtained from the Patent Application Information Retrieval (PAIR) system. Status information for published applications may be obtained from either Private PAIR or Public PAIR. Status information for unpublished applications is available through Private PAIR only. For more information about the PAIR system, see https://ppair-my.uspto.gov/pair/PrivatePair. Should you have questions on access to the Private PAIR system, contact the Electronic Business Center (EBC) at 866-217-9197 (toll- free). If you would like assistance from a USPTO Customer Service Representative or access to the automated information system, call 800-786-9199 (IN USA OR CANADA) or 571-272- 1000. /Satya B Sastri/ Primary Examiner, Art Unit 1762
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Prosecution Timeline

Aug 01, 2023
Application Filed
Feb 18, 2026
Non-Final Rejection — §102, §103, §112 (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

1-2
Expected OA Rounds
63%
Grant Probability
93%
With Interview (+29.5%)
3y 1m
Median Time to Grant
Low
PTA Risk
Based on 888 resolved cases by this examiner. Grant probability derived from career allow rate.

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