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 .
Response to Amendment
The rejection of claims 1-12 and 14-21 under 35 USC § 103 over Wu and Kim is withdrawn by the examiner in view of the amendment filed on 7/01/2026.
Since a new Non-Final Office is follows, applicant’s arguments will not be addressed.
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 1-4, 6, 8, 10, and 14-17 are rejected under 35 U.S.C. 103 as being unpatentable over Ramanujam et al. (US 2015/0283478 A1) in view of Adams et al. (US 5,792,891) and further in view of Kuhlmann et al. (US 5,463,160).
Regarding claim 1, Ramanujam teaches processing a C5 hydrocarbon feed derived from pyrolysis gasoline. In particular, Ramanujam teaches fractionating pyrolysis gasoline to obtain a C5 stream comprising principally five-carbon hydrocarbons and further treating the C5 stream to remove sulfur compounds and hydrogenating undesirable unsaturated contaminants. See ¶¶ [0017]-[0020]. Ramanujam further expressly teaches a process wherein a C5 feedstock is introduced to a deisopentanizer, with a lights fraction containing C4 hydrocarbons and isopentane removed overhead, followed by additional C5 fractionation. See ¶¶ [0049]-[0050], Fig. 1. Thus, Ramanujam establishes that C5 refinery/pyrolysis streams containing isopentane, olefinic C5 components and heavier components were conventionally subjected to sulfur removal, hydrogenation and sequential fractionation. Ramanujam additionally identifies the close-boiling C5 constituents as including pentane, cis-pentene, trans-pentene, 1-pentene, 2-methyl-1-butene and 2-methyl-2-butene.
Ramanujam does not expressly disclose arranging its sulfur-removal/fractionation operations in precisely the claimed sequence or thereafter subjecting the resulting normal-C5 olefin raffinate to skeletal isomerization to manufacture additional isoamylene.
Adams teaches the closely related upgrading of refinery C5 cuts. Adams explains that refinery streams, particularly streams produced by catalytic or thermal cracking, contain saturated hydrocarbons, mono-olefins and diolefins and that C5 streams contain isoamylene together with other C5 olefin isomers. See col. 1, line 55-col. 2, line 13. Adams expressly teaches an integrated C5 process comprising treatment of a C5 stream containing alkanes, normal olefins, diolefins and isoolefins, followed by recovery/separation and isomerization of normal olefins to isoolefins. See col. 2, lines 15-26. Adams further teaches separating a C5-containing fraction from FCC light naphtha and selectively hydrogenating the diolefins before downstream C5 conversion. See col. 2, lines 55-68; col. 3, lines 35-65. Adams further teaches that zeolitic catalysts including ZSM-22, ZSM-23, ZSM-35, ZSM-5, ZSM-11, ZSM-38 and ZSM-48 were known for skeletal isomerization, particularly conversion of normal olefins to more highly branched olefins.
Kuhlmann specifically teaches the missing reaction: skeletal isomerization of n-pentenes to 2-methylbutenes (isoamylenes) using a steam-pretreated zeolite catalyst. Kuhlmann expressly states that a C5 raffinate from a TAME unit containing n-pentenes is converted to additional 2-methylbutenes and identifies an alumina-bound ferrierite zeolite as active and selective for that reaction. Kuhlmann teaches reaction temperatures of 200-550°C and pressures of 0.1-100 atmospheres. Accordingly, Kuhlmann's temperature range overlaps the claimed 100-210°C range at 200-210°C, and its pressure range encompasses the claimed 10-30 barg range.
It would have been obvious to one of ordinary skill in the art before the effective filing date to apply the normal-pentene skeletal-isomerization treatment taught by Adams/Kuhlmann to the olefin-containing C5 stream produced in the Ramanujam processing train because Kuhlmann expressly identifies normal pentenes obtained from steam crackers or catalytic crackers as suitable sources for production of isoamylenes. The modification would predictably convert otherwise less valuable normal C5 olefins to the corresponding branched isoamylenes while retaining Ramanujam's upstream contaminant-removal and C5-separation operations.
Further, selecting operating conditions within the overlapping ranges - i.e., 200-210°C and 10-30 barg - would have been prima facie obvious absent evidence that the claimed overlapping subrange produces an unexpected result. Accordingly, the combination teaches or renders obvious the process of claim 1.
Regarding claim 2, Adams expressly teaches separating reaction products and unreacted C5 materials and recycling an isomerization product into the integrated C5 conversion process. See col. 3, lines 1-8.
Kuhlmann likewise teaches that skeletal isomerization of the n-pentenes in a C5 raffinate generates additional 2-methylbutenes/isoamylenes.
It would have been obvious to separate the isomerization effluent into an isoamylene-enriched product and a remaining C5 recycle stream so that unconverted C5 material could be recovered rather than discarded.
Regarding claim 3, Ramanujam expressly teaches that the C5 raffinate containing principally alkanes is returned for re-cracking or alternatively gasoline blending. See ¶ [0050].
Recycling the C5 recycle stream to the cracker furnace assembly would have been an obvious implementation of Ramanujam's express teaching to return C5 raffinate for re-cracking.
Regarding claim 4. Adams teaches a recycle C5 stream 118 that is recycled to the TAME reactor (col. 12-13, Fig. 1; see also discussion of stream 118), and Table IV reports recycle stream 118/134 as containing 0 wt.% isopentane, which falls within the claimed limitation of less than or equal to 16 wt.% isopentane. Accordingly, claim 4 is rendered obvious by the references applied to claim 3 further in view of Adams.
Regarding claim 6: The processes of Ramanujam, Adams, and Kuhlmann are as discussed above. Adams teaches separation of C5 hydrocarbon streams comprising isopentane, pentane and pentenes and further teaches C5 recycle streams 134 and 118 containing essentially no isopentane (Adams, Fig. 1; Table IV). Thus, Adams demonstrates separation of isopentane from the remaining C5 hydrocarbons. One of ordinary skill in the art would have understood that the resulting isopentane-rich separated C5 stream would also contain other C5 hydrocarbons, including pentane and pentenes, depending upon the selected fractionation conditions and separation cut.
Adams does not expressly disclose that the separated stream comprises 68-75 wt.% isopentane, 5-10 wt.% pentane, and 15-25 wt.% pentene. However, once separation of these known C5 components into an isopentane-rich fraction is taught, the relative concentrations of the components in the separated fraction would have been determined by the degree of separation and the selected fractionation cut. It would have been within the ordinary skill in the art to adjust the known C5 separation conditions to obtain a desired balance of isopentane recovery and accompanying C5 hydrocarbons, thereby obtaining a separated stream having the claimed composition.
Regarding claim 8, Ramanujam expressly states that pyrolysis gasoline is produced by thermal cracking in the presence of steam of petroleum fractions including LPG, naphtha, diesel and heavier fractions to produce ethylene and/or propylene. See ¶ [0046]. Thus, forming the claimed C5 feed from a portion of cracker-furnace effluent is taught or at minimum directly suggested.
Regarding claim 9, Kuhlmann does not expressly disclose heating the raffinate stream via a heater assembly to a temperature of 70-160°C prior to passing the raffinate stream to the reactor assembly. However, it would have been obvious to one of ordinary skill in the art to provide a conventional heater upstream of the reactor and preheat the C5 raffinate to an appropriate reactor-feed temperature, including a temperature within the claimed range of 70-160°C, in order to bring the feed toward the required reaction temperature and facilitate operation of the elevated-temperature skeletal-isomerization reactor. Selection of the particular preheat temperature would have been within the ordinary skill in the art based on the desired reactor inlet conditions and heating duty.
Regarding claim 10, Ramanujam expressly teaches treatment of the C5 stream to remove sulfur compounds and selective hydrogenation of acetylene compounds before subsequent C5 separation. See ¶¶ [0018]-[0019], [0049]. Ramanujam's Fig. 1 further expressly removes a lights fraction containing C4 hydrocarbons from the C5 processing train. The reference does not expressly establish H₂S as part of that same separated stream.
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 Ramanujam by removing
sulfur as H₂S following hydrogenative sulfur conversion, together with removal of light C4 components, would have been a predictable conventional implementation of sulfur-removal/hydrogenation and fractionation of the disclosed cracked C5 stream.
Regarding claim 11, the processes of Ramanujam, Adams, and Kuhlmann are as discussed above. Ramanujam teaches fractionation of hydrocarbon streams comprising C5 hydrocarbons and separation of the C5 components from other hydrocarbon components (Ramanujam, Fig. 1; ¶¶ [0049]-[0050]). The references do not expressly disclose that the third separated stream comprises 15 to 28 wt.% C6+ hydrocarbons. However, the concentration of C6+ hydrocarbons in a separated hydrocarbon stream is dependent upon the selected fractionation cut and degree of separation. It would have been obvious to one of ordinary skill in the art to adjust the known fractionation conditions and cut point to obtain a desired distribution of C5 and C6+ hydrocarbons, including a third separated stream comprising 15 to 28 wt.% C6+ hydrocarbons, as a matter of routine process design and optimization.
Regarding claim 14, Adams teaches normal pentenes in the C5 stream and their conversion to branched C5 olefins. Kuhlmann is even more specific: its skeletal-isomerization feed contained 35.83% n-pentenes, 8.21% isoamylenes and 55.96% pentanes, and its reported n-pentene conversions include values of approximately 62-81%, thereby encompassing conversion of at least 58%. Claim 14 is therefore rendered obvious.
Regarding claims 15 and 17, Adams expressly recognizes diolefins as undesirable constituents of C5 refinery cuts and teaches their selective hydrogenation to mono-olefins.
Ramanujam similarly performs selective hydrogenation of undesirable highly unsaturated C5 constituents while preserving desired olefinic material. Accordingly, reducing the residual diene/diolefin concentration to no more than 5 wt.% before skeletal isomerization would have been an obvious degree of the expressly taught selective removal of these undesirable constituents.
Regarding claim 16, Ramanujam expressly identifies 1-pentene and other pentenes among the close-boiling C5 constituents. Kuhlmann expressly subjects n-pentenes to skeletal isomerization to form isoamylenes. The claimed raffinate comprising pentene, wherein the pentene comprises at least one of 1-pentene or 2-pentene, is therefore rendered obvious.
Regarding claim 18, Kuhlmann further teaches skeletal isomerization of a C5 olefin feed comprising pentenes to produce isoamylenes (Kuhlmann, col. 9, lines 20–28 and 52–64; col. 10, line 29 through col. 11, line 13). Kuhlmann's exemplified pentene feed does not identify dienes or diolefins as components thereof (see Example 2). Thus, Kuhlmann teaches a raffinate/reactor feed having no disclosed dienes or diolefins, i.e., an amount within the claimed ≤5 wt.% range.
Regarding claim 20, the processes of the references applied to claim 6 are as discussed above. Kuhlmann teaches skeletal isomerization of a C5 olefin feed comprising pentenes to produce isoamylenes (Kuhlmann, col. 9, lines 20–28 and 52–64; col. 10, line 29 through col. 11, line 13). Kuhlmann's exemplified pentene feed does not identify dienes or diolefins as components thereof (see Example 2). Further, the process applied to claim 1 subjects the C5 hydrocarbon feed to upstream hydrotreatment/hydrodesulfurization before the C5 raffinate is passed to the downstream zeolite-based reactor. It would have been obvious to one of ordinary skill in the art to operate the upstream hydrogen-treatment conditions so as to reduce undesirable dienes/diolefins in the downstream C5 raffinate to a low concentration, including ≤5 wt.%, because diolefins are more readily hydrogenated than the desired mono-olefins and reducing such reactive species protects the downstream catalytic processing.
Regarding claim 21, the processes of the references applied to claim 1 are as discussed above. Adams further teaches C5 stream 134 being passed to skeletal-isomerization unit 60 to produce stream 118. Adams' Table IV discloses that stream 134 contains 0 wt% 2-methyl-2-butene (isoamylene), which falls within the claimed range of 0–1 wt% isoamylene, whereas the resulting stream 118 contains approximately 3.4 wt% 2-methyl-2-butene, evidencing production of isoamylene in unit 60 (Adams, Fig. 1; Table IV).
Adams does not expressly disclose that the reactor-feed C5 stream contains 1-5 wt.% isopentane and 90–98 wt.% other C5 hydrocarbons excluding isopentane and isoamylene. However, Adams teaches separation of isopentane from the C5 stream before skeletal isomerization, with stream 134 containing essentially no isopentane. The amount of residual isopentane remaining in the C5 raffinate is dependent upon the degree of isopentane separation and the selected fractionation cut. It would have been obvious to one of ordinary skill in the art to operate the known C5 separation at a degree of separation providing a small residual amount of isopentane, including 1-5 wt%, while retaining predominantly the other C5 hydrocarbons in the raffinate, thereby obtaining 90–98 wt% other C5 hydrocarbons, as a matter of routine optimization of isopentane recovery versus raffinate composition.
Claims 5 and 19 are rejected under 35 U.S.C. 103 as being unpatentable over the references applied to claim 2 above, further in view of Barias et al. (US 2022/0135496 A1).
The references applied to claim 2 are as discussed above but do not expressly disclose that the product stream comprises 98 to 99.9 wt.% isoamylene.
Barias teaches separating an isoamylene-containing reactor effluent to obtain an isoamylene product stream (¶¶ [0032]-[0034]) and expressly teaches that the recovered isoamylene fraction may contain greater than 98, 98.5, 99, 99.1, or 99.5 wt.% isoamylene, and may have a purity of at least 99.9 wt% (¶ [0035]). Barias further expressly claims an isoamylene product stream comprising at least 99.8 wt% isoamylene (claim 5).
Regarding claim 5, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to further separate/purify the isoamylene-containing product stream of the references applied to claim 2 according to Barias in order to obtain a high-purity isoamylene product suitable for petrochemical applications, thereby obtaining an isoamylene product having a purity within the claimed range of 98 to 99.9 wt%.
Regarding claim 19, Kuhlmann further teaches skeletal isomerization of a C5 olefin feed comprising pentenes to produce isoamylenes (Kuhlmann, col. 9, lines 20–28 and 52–64; col. 10, line 29 through col. 11, line 13), and the exemplified pentene feed does not identify dienes or diolefins as components thereof (see Example 2). Accordingly, the C5 feed disclosed by Kuhlmann satisfies or renders obvious a diene/diolefin content of ≤5 wt.%.
Claim 7 is rejected under 35 U.S.C. 103 as being unpatentable over references as applied to claim 1 above, and further in view of Bedenko et al. "Optimization of technological regimes of the deisopentanizer column for the preparation of the feed stream of the low-temperature isomerization unit PGI-DIG/280-NK" 2023, pages 204-211.
The references applied to claim 1 are as discussed above.
Bedenko further teaches a deisopentanizer for removing isopentane from a C5 hydrocarbon feed and determines that the column should contain 63 theoretical plates to achieve substantially complete isopentane recovery. Bedenko specifically models a deisopentanizer containing 80 plates, which falls within the claimed range of 70 to 88 stages, and further recognizes that implementation of the calculated temperature profile along the height of the column is important to achieving the desired isopentane separation (see abstract).
Although Bedenko does not expressly disclose a top temperature of 50-60°C and a bottom temperature of 70-85°C, the temperatures at the top and bottom of a distillation column are conventional operating parameters dependent upon the composition being separated, operating pressure, reflux and desired degree of separation. Because the reference expressly teaches separating the same C5/isopentane system and recognizes the column temperature profile as a parameter affecting that separation, it would have been obvious to one of ordinary skill in the art to select and adjust the top and bottom temperatures to provide the desired isopentane separation, including temperatures within the claimed ranges, through routine process design and optimization.
Claim 12 is rejected under 35 U.S.C. 103 as being unpatentable over the references applied to claim 1, further in view of Vermeiren et al., “Impact of Zeolites on the Petroleum and Petrochemical Industry,” Topics in Catalysis, Vol. 52, pp. 1131–1161 (2009) (“Vermeiren”).
The processes of the references applied to claim 1 are as discussed above, but do not expressly disclose that the raffinate stream comprising C5 hydrocarbons is withdrawn from a side of the deisopentanizer assembly.
Vermeiren teaches a light-naphtha hydroisomerization process employing a deisopentanizer (DIP) and shows withdrawal of the C5-containing stream from the side of the DIP for passage to the isomerization reactor (Vermeiren, Fig. 5; §5.1).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify the deisopentanizer of the references applied to claim 1 according to Vermeiren by withdrawing the C5 raffinate from the side of the deisopentanizer, because Vermeiren teaches this configuration for recovering the C5 fraction for subsequent isomerization.
Conclusion
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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/TAM M NGUYEN/Primary Examiner, Art Unit 1771
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