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 25-36 are rejected under 35 U.S.C. §103 as being unpatentable over Malaty et al. (US 2012/0053383 A1) in view of Van Willigenburg (US 2020/0290939 A1). Malaty discloses a refinery off-gas stream comprising hydrogen and light hydrocarbons including methane, ethane, propane, propylene, butanes, butenes, carbon monoxide, and carbon dioxide (¶[0034]). Malaty further teaches that such off-gas streams may be provided to a pyrolysis furnace (¶[0042]) and may be used alone or in combination with conventional hydrocarbon feeds such as ethane or propane (¶[0043]). Malaty teaches that thermal cracking of such feeds produces olefins including ethylene and propylene (¶[0045]). Malaty additionally Hydrogen-containing lighter gases act as diluents that reduce hydrocarbon partial pressure and improve ethylene selectivity ([0010]). Accordingly, Malaty teaches providing a thermal cracking feed containing hydrogen and propane and subjecting the feed to thermal cracking to obtain an effluent comprising ethylene propane-containing feeds are thermally cracked to olefins. Van Willigenburg discloses combining a hydrocarbon feedstream with a hydrogen gas feedstream (¶[0023]), wherein the hydrocarbon feedstream may comprise light hydrocarbons including ethane and propane (¶[0026]). Van Willigenburg further teaches subjecting the combined stream to thermal treatment at elevated temperatures, including reactor temperatures in the range of about 700°C to about 880°C, to produce olefin products (¶[0041]) and hydrogen is deliberately supplied as a cracking diluent; hydrogen dilution increases olefin yield in its disclosed hydropyrolysis comparison and expressly suppresses coke formation ([0022], [0055]).
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 Malaty to include controlled addition of hydrogen gas as taught by Van Willigenburg in order to improve olefin selectivity and reduce coke formation during thermal cracking.
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 Malaty by optimizing the relative amounts of propane and hydrogen, including the claimed propane concentration and propane-to-hydrogen ratio, since Malaty teaches feeds containing propane and hydrogen (¶[0034]) and Van Willigenburg teaches controlling hydrogen addition (¶[0023]), and such parameters are result-effective variables that would have been routinely optimized to achieve desired olefin yield and reduced coking (In re Aller).
Claim 26
Malaty teaches propane-containing feeds (¶[0034], ¶[0043]). 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 Malaty by adjusting propane concentration and propane-to-hydrogen ratio within narrower ranges (e.g., 15–50 mol% propane; ratio 0.10–2.2) as a matter of routine optimization.
Claim 27
Malaty teaches feeds comprising C2+ hydrocarbons including ethane, propane, and butane together with hydrogen (¶[0034]).
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 Malaty by controlling the ratio of C2+ hydrocarbons to hydrogen within the claimed range as a result-effective variable.
Claim 28
Malaty teaches the presence of C4 hydrocarbons including butanes and butenes (¶[0034]).
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 Malaty by adjusting the amount of C4 hydrocarbons to 1–8 mol% as part of routine feed composition optimization.
Claim 29
Malaty teaches feeds comprising ethane and propane (¶[0034], ¶[0043]).
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 Malaty by including ethane in an amount of 0–10 mol% as a conventional steam cracking feed component.
Claim 30
Malaty teaches hydrogen-containing feeds (¶[0034]) and Van Willigenburg teaches hydrogen co-feeding (¶[0023]).
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 Malaty by adjusting hydrogen concentration within the claimed range as a result-effective variable.
Claim 31
Malaty teaches refinery off-gas streams comprising methane, CO, CO₂, and other components (¶[0034]).
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 Malaty by controlling impurity levels within the claimed range as part of routine process optimization.
Claim 32
Van Willigenburg teaches hydrogen integration with hydrocarbon processing (¶[0023]).
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 Malaty to employ renewable-derived hydrocarbon feeds having biogenic carbon content, as such feeds are known in the art.
Claim 33
Malaty teaches pyrolysis (steam cracking) (¶[0042]).
Claim 34
Van Willigenburg teaches reactor temperatures of about 700°C to about 880°C (¶[0041]) and Malaty teaches steam cracking furnace operation (¶[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 Malaty to operate within the claimed temperature, pressure, and dilution ranges, as these are conventional steam cracking conditions.
Claim 35
Malaty teaches refinery off-gas streams (¶[0034]) and Van Willigenburg teaches hydrogen integration (¶[0023]).
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 Malaty by deriving the cracking feed from hydrotreatment of renewable oxygen-containing hydrocarbons, as such processes are known to produce hydrogen and light hydrocarbons.
Claim 36
Malaty teaches production of ethylene and propylene (¶[0045]).
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 Malaty by separating ethylene and propylene and subjecting them to polymerization, as such downstream processing is conventional in petrochemical systems.
Response to Arguments
Applicant's arguments filed in response to the rejection under 35 U.S.C. § 103 have been fully considered but are not persuasive.
Applicant argues that neither Malaty nor Van Willigenburg teaches the claimed propane concentration of 10–60 mol-% or the claimed propane-to-hydrogen molar ratio of 0.10–2.5, and that the cited references do not identify these parameters as result-effective variables. Applicant further argues that the claimed ranges are critical because they provide unexpectedly improved propane conversion, ethylene selectivity, and reduced coke formation.
With respect to Malaty, Applicant's assertion that hydrogen is merely an incidental component having no recognized relationship to ethylene production is not persuasive. Malaty expressly teaches obtaining refinery off-gas containing ethane and/or propane, combining the off-gas with a pyrolysis-furnace ethane or propane feed, cracking the resulting stream in a downstream pyrolysis furnace, and recovering products including ethylene and propylene (Malaty, ¶[0009]). More significantly, Malaty expressly teaches that the lighter gases contained in the feed, “mainly hydrogen and methane,” function as diluents which lower hydrocarbon partial pressure and improve yield selectivity toward the desired ethylene, while only slightly reducing propylene (Malaty, ¶[0010]). Malaty further teaches operation at coil outlet pressures of 2.4–2.8 bara and steam-to-hydrocarbon ratios of 0.1–0.3 while achieving optimum yield and energy efficiency. Malaty also expressly teaches that its off-gas may be used alone or combined with a typical propane feed and sent to a pyrolysis system without further fractionation (¶[0024]), and that the pyrolysis furnace may be a conventional tubular steam cracking furnace for producing olefins (¶[0025]). Thus, contrary to Applicant's argument, Malaty recognizes a technical relationship between hydrogen-containing dilution of a propane-capable cracking feed and the desired result of improved ethylene selectivity.
With respect to Van Willigenburg, Applicant's assertion that Van is concerned only with energy-recovery equipment and does not provide a relevant teaching concerning hydrogen dilution is likewise not persuasive. Van expressly teaches producing olefins by combining a hydrocarbon feedstream with a separate hydrogen gas feedstream and feeding the combined stream to a reactor; Van further expressly identifies propane as a suitable hydrocarbon feed component (Van, ¶[0007]; claims 1 and 3). Van's Example further employs a deliberate hydrogen feed, specifically cracking 10 t/h of kerosene mixed with 1.0 t/h hydrogen at hydropyrolysis conditions (¶[0053]). Most importantly, Van expressly teaches that hydrogen may be used as the diluent instead of steam, that hydrogen dilution increases the yield of ethylene and propylene relative to the disclosed steam-cracking comparison, and that hydrogen dilution suppresses coke formation in the reactor tube (¶[0055], Table 1).
Accordingly, the rejection does not rely merely on the fact that hydrogen and propane appear somewhere in the cited references. Malaty expressly recognizes that the amount of hydrogen-containing dilution affects hydrocarbon partial pressure and ethylene selectivity, while Van expressly recognizes hydrogen dilution as affecting olefin yield and coke formation. A variable is result-effective where the prior art recognizes that the variable affects the relevant property or result; the prior art need not disclose the claimed optimum value itself. MPEP § 2144.05(II)(C) explains that recognition in the prior art that a property is affected by the variable is sufficient to establish the variable as result-effective.
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 Malaty by controlling the amount of hydrogen dilution in the propane-containing cracking feed, as taught by Van Willigenburg, because Malaty expressly teaches that hydrogen-containing dilution lowers hydrocarbon partial pressure and improves ethylene selectivity, while Van expressly teaches deliberate hydrogen dilution for olefin production and identifies suppression of coke formation as an additional benefit. A person of ordinary skill seeking the known benefits of hydrogen dilution would therefore have had reason to adjust the relative amounts of hydrocarbon feed and hydrogen diluent to obtain a workable balance between hydrocarbon throughput, ethylene selectivity, and coke suppression. Selection of workable or optimum proportions under such circumstances is within the ordinary optimization contemplated by MPEP § 2144.05.
Applicant's argument that Malaty would have led one of ordinary skill toward ethane-rich feeds rather than propane-rich feeds is also not persuasive. Although Malaty's prophetic ethane-furnace example reports a higher ethylene concentration than its propane-furnace example, Malaty expressly identifies both ethane and propane as suitable cracking feeds and expressly teaches separate cracking of an ethane-rich gas stream and of propane and heavier components to achieve optimum olefin yield (Malaty, ¶[0030]). The disclosure of an alternative or preferred embodiment does not constitute a teaching away unless the reference criticizes, discredits, or otherwise discourages the claimed alternative. MPEP § 2145 instructs that the mere disclosure of alternatives does not constitute teaching away. Malaty does not criticize or discourage cracking propane; rather, it expressly provides for propane cracking.
Applicant's contention that Malaty teaches away from controlled hydrogen addition because Malaty emphasizes little or no initial pretreatment is likewise not persuasive. Malaty's statement in ¶[0008] concerns avoiding extensive pretreatment of refinery off-gas before its use as a cracking feed. Addition or adjustment of a hydrogen diluent is not the pretreatment that Malaty seeks to avoid. Moreover, Malaty affirmatively recognizes the beneficial diluent function of hydrogen in ¶[0010]. Thus, Malaty does not criticize, discredit, or discourage the proposed use or control of hydrogen dilution.
Applicant's allegation of impermissible hindsight is also not persuasive. The proposed modification does not originate from Applicant's disclosure. Malaty itself supplies the teaching of propane-containing feeds, cracking to obtain ethylene, and improved ethylene selectivity resulting from hydrogen-containing dilution, while Van independently supplies the teaching of deliberately combining hydrogen with a hydrocarbon cracking feed and the recognized benefit of reduced coke formation. Thus, the reason for adjusting hydrogen dilution is found in the prior art itself rather than in Applicant's specification.
Applicant's evidence concerning unexpected results and criticality has also been considered but does not outweigh the evidence of obviousness. Applicant relies upon the specification's comparison of feeds F1–F4 and asserts that feed F3, which satisfies the claimed feed criteria, provides improved propane conversion, increased selectivity toward ethylene, and reduced coke formation. However, the asserted advantages of hydrogen dilution are at least qualitatively expected from the cited prior art. Malaty expressly teaches improved ethylene selectivity resulting from hydrogen-containing dilution (¶[0010]), while Van expressly teaches that hydrogen dilution suppresses coke formation and increases ethylene/propylene yield (¶[0055]). Thus, improved ethylene selectivity and reduced coking are not, by themselves, results contrary to what one of ordinary skill would have expected from hydrogen dilution.
Further, the evidence relied upon does not establish that the claimed numerical boundaries themselves are critical throughout the scope of claim 25. Applicant identifies F3 as falling within the claimed region, but the comparisons principally involve individual compositions rather than feeds positioned at or near the claimed boundaries of 10 and 60 mol-% propane or propane₂ ratios of 0.10 and 2.5. Moreover, Applicant acknowledges that both hydrogen-containing F3 and nitrogen-substituted F4 exhibited improved ethylene selectivity relative to the higher-propane feeds F1 and F2. Thus, the reported improvement in ethylene selectivity is not shown on this record to result uniquely from the claimed propane-to-H₂ ratio rather than from dilution and reduced propane concentration more generally.
The evidence of unexpected results must be considered and given appropriate weight, but it must also bear a sufficient nexus to the claimed invention and be reasonably commensurate in scope with the claims. MPEP § 2145 explains that evidence directed to only a portion of a claimed range may establish nonobviousness where the evidence demonstrates a trend that one skilled in the art could reasonably extend across the claimed scope; conversely, isolated results need not establish unexpected performance throughout a substantially broader claimed range. Here, Applicant has not adequately demonstrated that the specific boundaries recited in claim 25 define a critical region producing results different in kind, rather than degree, from the known effects of hydrogen dilution taught by Malaty and Van.
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.
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 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.
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.
/TAM M NGUYEN/Primary Examiner, Art Unit 1771
Prosecution Insights