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 .
Status of Claims
Claims 1-8 are pending. This is the first office action on the merits.
Claim Rejections - 35 USC § 103
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 1-6 and 8 are rejected under 35 U.S.C. 103 as being unpatentable over Kuwana (US 2017/0349506 A1, cited in IDS dated 10/31/2024), in view of Savolainen et al. (US 9,682,903 B2).
Regarding claims 1-3 and 6, Kuwana teaches a method for producing high-purity propane by hydrogenation of crude propylene to obtain crude propane containing impurities, followed by an impurity removal step ([0022]), the method comprising treating the crude propane with adsorbents comprising molecular sieve and molecular sieve activated carbon having pores with a pore diameter of 4 angstroms (0.4 nm) ([0054]-[0057]; see also [0098], disclosing activated carbon having a 4A type porous body and a molecular sieve zeolite having a 4A type porous body). Kuwana further teaches removing hydrogen, oxygen, and nitrogen from the propane stream resulting from the adsorption step ([0067]).
Kuwana does not teach removing hydrogen from the crude propane prior to the adsorption.
However, Savolainen teaches a method for treating a gas stream comprising hydrogen and propane with a membrane selectively permeable to hydrogen over propane, thereby producing a propane-containing retentate depleted in hydrogen (Abstract; col. 8, line 20 – col. 9, line 4). The membrane separation is positioned upstream of subsequent propane purification/separation (col. 9, line 35 – co. 10, line 35).
Therefore, before the effective filing date of the instant invention, it would have been obvious to modify Kuwana by removing hydrogen from the crude propane using the hydrogen-selective membrane of Savolainen prior to the adsorption step, because (i) it would have reduced the hydrogen concentration before adsorption and thereby facilitate subsequent removal of nitrogen and oxygen, consistent with the recognized objective of obtaining higher-purity propane, and (ii) this involves application of a known technique to improve a known process to yield predictable result.
Kuwana or Savolainen does not teach hydrogen concentrations of ≤100 ppmv prior to the adsorption and ≤80 ppmv following the adsorption. However, given Kuwana’s objective to obtain high-purity propane with a purity level of 99.999 vol% ([0084]), one would have been motivated to optimize the operating conditions of the membrane separation and the adsorption to effectively remove hydrogen and arrive at the claimed ranges via routine experimentation. It is well established that discovering optimum or workable ranges by routine experimentation is not considered an inventive step when the general conditions of a claim are disclosed in the prior art. MPEP 21144.05 II.
Kuwana, in view of Savolainen, does not teach that the purified propane from the adsorption has a total content of boron, aluminum, phosphorus, sulfur, titanium, vanadium, chromium, and molybdenum of ≤250 ppbm.
However, Kuwana teaches essentially the same adsorbent (i.e.4A molecular zeolite and 4A activated carbon) as an exemplary adsorbent disclosed in the instant invention, where the adsorptions of Kuwana and the invention are operated under the overlapping conditions, including temperature of 5-50° and pressure of 0.1-0.5 MPaG ([0055]-[0060]; see Spec, [0043]-[0044], [0097]; see Example 1-4 and Table 1). While Kuwana discloses the crude propane contains various contaminants, the reference does not expressly identify boron, aluminum, phosphorus, sulfur, titanium, vanadium, chromium, or molybdenum as contaminants of the crude propane. This suggests that these metal contaminants, if present, would be present only in trace amounts. Therefore, it would have been reasonably expected that the adsorption treatment disclosed by Kuwana would reduce any such trace metal contaminants to concentrations comparable to those obtained by the claimed process, including a total content of boron, aluminum, phosphorus, sulfur, titanium, vanadium, chromium, or molybdenum of ≤250 ppbm.
Regarding claim 4, Kuwana, in view of Savolainen, does not explicitly teach that the adsorption step of Kuwana involves adsorbing nitrogen and/or oxygen gas from the crude propane. However, Kuwana teaches essentially the same adsorbent (i.e.4A molecular zeolite and 4A activated carbon) as the instant invention under the overlapping conditions including temperature of 5-50° and pressure of 0.1-0.5 MPaG ([0055]-[0060]; see Spec, [0043]-[0044], [0097]; see Example 1-4 and Table 1). Therefore, it would have been reasonably expected that the adsorption treatment disclosed by Kuwana would adsorb at least some of the nitrogen gas and oxygen gas in the crude propane.
Regarding claim 5, Kuwana, in view of Savolainen, does not explicitly teach that the adsorption step of Kuwana involves adsorbing at least one of boron, aluminum, phosphorus, sulfur, titanium, vanadium, chromium, and molybdenum from the crude propane. However, Kuwana teaches essentially the same adsorbent (i.e.4A molecular zeolite and 4A activated carbon) as the instant invention under the overlapping conditions including temperature of 5-50° and pressure of 0.1-0.5 MPaG ([0055]-[0060]; see Spec, [0043]-[0044], [0097]; see Example 1-4 and Table 1). Therefore, it would have been reasonably expected that the adsorption treatment disclosed by Kuwana would adsorb at least one of boron, aluminum, phosphorus, sulfur, titanium, vanadium, chromium, and molybdenum in the crude propane.
Regarding claim 8, Kuwana’s objective is to provide a high purity propane, and the reference also discloses that high purity propane is useful as a raw material for silicon carbide ([0002], [0012]). Thus, Kuwana is considered to suggest using the high purity propane product in a silicon carbide production method known in the art.
Allowable Subject Matter
Claim 7 is objected to as being dependent upon a rejected base claim, but would be allowable if rewritten in independent form including all of the limitations of the base claim and any intervening claims.
The following is a statement of reasons for the indication of allowable subject matter. The prior art of record fails to teach or suggest the method of claim 1 in combination with the limitations of claim 7. In particular, the prior art fails to provide sufficient teaching or suggestion that would have motivated one of ordinary skill in the art to further include, in addition to the purification steps recited in claim 1, a filtration step for removing at least one of boron, aluminum, phosphorus, sulfur, titanium, vanadium, chromium, and molybdenum from the crude hydrocarbon, the low-hydrogen hydrocarbon, and the high-purity hydrocarbon, wherein the filter medium is at least one filter among a membrane filter, a sintered metal filter, and a filter including a plurality of metal halide pellets. This combination of features is not taught or suggested by the prior art, and the prior art does not provide an adequate rationale for modifying the method of claim 1 to include such a filtration step.
Citation of Pertinent Prior Art
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure. Lee et al. (US 6,190,725 B1) teach using high-purity propane as a carbon source in a chemical vapor deposition method to produce a silicon carbide layer (col. 4, lines 16-42).
Conclusion
Any inquiry concerning this communication or earlier communications from the examiner should be directed to Jason Y Chong whose telephone number is (571)431-0694. The examiner can normally be reached Monday-Friday 9:00am-5:30pm.
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/JASON Y CHONG/Examiner, Art Unit 1772
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