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
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.
Claim(s) 1-13 is/are rejected under 35 U.S.C. 103 as being unpatentable over Bhise (2012/0041217 A1), and further in view of Lauritzen (US 4,761,394).
Claim 1 requires "metal oxide promoter" in a solution that is combined with a porous support and a catalyst metal. Bhise teaches impregnating a porous catalyst support, preferably alpha-alumina, with a silver-containing solution and promoters, including rhenium and alkali-metal promoters (Bhise, [0002], [0022]–[0025], [0028]–[0037]). Bhise does not explicitly teach "metal oxide promoter" as claimed.
Claim 1 further requires the promoter and catalyst metal to have the stated surface-free-energy relationship. Lauritzen teaches ammonium perrhenate as the preferred soluble rhenium compound and rhenium heptoxide as a suitable alternative that hydrolyzes in water to perrhenate (Lauritzen, col. 8, l. 55–col. 9, l. 17). The Applicant’s Specification teaches surface free energies of 1302 ergs/cm² for silver and about 38 ergs/cm² for rhenium heptoxide (Specification, [0031], [0034]). The same chemical materials necessarily possess those intrinsic properties in the prior-art process. See MPEP § 2112.
Claim 1 further requires co-impregnation and at least 1.2 μmol of promoter per gram of catalyst. Bhise teaches promoter deposition with silver and teaches rhenium loadings of 0.1–10 μmol/g, preferably 0.2–5 μmol/g and more preferably 0.5–4 μmol/g (Bhise, [0032], [0035]–[0036]). Lauritzen’s Catalyst B adds NH₄ReO₄ and CsOH to the same silver impregnating solution before impregnating a porous carrier (Lauritzen, col. 16, ll. 20–34; col. 17, ll. 1–15). Its reported 372 ppm Re equals 1.998 μmol/g catalyst, above the claimed lower bound (Lauritzen, col. 17, ll. 27–32).
Claim 1 further requires a first calcination at 250°C or higher and a second calcination at a higher temperature. Bhise applies two calcinations, with the first including about 250°C and excursions to 270°C and the second using higher temperatures within disclosed ranges including 250–500°C and 235–450°C (Bhise, [0043]–[0047]).
It would have been obvious before the effective filing date to use Lauritzen’s same-solution perrhenate co-impregnation procedure and promoter loading when preparing Bhise’s silver/rhenium/alkali catalyst, and then to apply Bhise’s two-stage calcination. Bhise expressly cites Lauritzen for impregnation procedures and authorizes promoter co-deposition (Bhise, [0032]). A skilled artisan would have been motivated to do so because Lauritzen attributes improved ethylene-oxide selectivity to the combined silver/alkali/rhenium catalyst, while Bhise teaches that its second calcination reduces residual organics and manufacturing time (Lauritzen, col. 2, ll. 1–22; Bhise, [0006]–[0007], [0056]–[0057]).
The modification would have yielded the predictable result of a porous silver catalyst co-impregnated with a promoting concentration of perrhenate and then subjected to Bhise’s two established calcinations. The references concern the same catalyst system, Bhise expressly adopts Lauritzen-type impregnation procedures, and each step performs its known function. Lauritzen’s worked preparation and Bhise’s worked two-stage calcination provide a reasonable expectation of success. Accordingly, claim 1 would have been obvious.
Claim 2 requires "Group IB" metal. Bhise expressly uses silver as the catalytic metal throughout (Bhise, [0002], [0009], [0028]–[0034]). Silver is a Group IB metal.
Claim 3 requires "silver." Bhise teaches impregnation of the support with silver or a silver-containing compound and converts it to active silver during calcination (Bhise, [0009], [0028]–[0034], [0043])..
Claim 4 requires "rhenium oxide" as one alternative in its open list of rhenium, molybdenum, tungsten, and sulfur oxides. Lauritzen teaches perrhenates and rhenium oxides in the silver impregnating solution, including rhenium heptoxide, and explains that Re₂O₇ hydrolyzes in water to perrhenate (Lauritzen, col. 8, l. 55–col. 9, l. 17). Bhise also teaches rhenium as a preferred promoter (Bhise, [0036]).
Claim 5 requires "ReO₄−" as one alternative in its open list of promoter oxyanions. Lauritzen teaches use of NH₄ReO₄ in Catalyst B and explains that aqueous Re₂O₇ forms perrhenate (Lauritzen, col. 8, l. 55–col. 9, l. 17; col. 16, ll. 20–28).
Claim 6 requires "metal oxide promoter comprising as rhenium sesquioxide, rhenium dioxide, rhenium trioxide, perrhenate, rhenium heptoxide, or any combination thereof." as one alternative in its open list of rhenium species. Lauritzen expressly prefers ammonium perrhenate, identifies alkali-metal and silver perrhenates, and uses ammonium perrhenate in Catalyst B (Lauritzen, col. 8, l. 55–col. 9, l. 17; col. 16, ll. 20–28).
Claim 7 requires "the solution further comprising an alkali metal salt or hydroxide, an alkaline earth metal salt or hydroxide, or any combination thereof.” Bhise teaches alkali-metal-containing promoters dissolved in the impregnation solvent and permits simultaneous impregnation with silver and rhenium (Bhise, [0037]–[0039]). Lauritzen further teaches Catalyst B being added with aqueous CsOH to the same silver/NH₄ReO₄ impregnating solution (Lauritzen, col. 16, ll. 20–34).
Claim 8 requires "nitrate salt" as one of the recited alternatives.
The applied claim 7 embodiment using CsOH does not explicitly teach "nitrate salt." However, Lauritzen teaches soluble alkali-metal nitrates and states that the most preferred cesium promoter may be applied as aqueous cesium nitrate or cesium hydroxide (Lauritzen, col. 11, ll. 28–63). Lauritzen further recommends cesium nitrate instead of cesium chloride when silver nitrate is used, to avoid premature silver-chloride precipitation (Lauritzen, col. 12, ll. 1–19).
It would have been obvious to substitute Lauritzen’s expressly recommended cesium nitrate for cesium hydroxide in the co-impregnation solution because both are disclosed carriers of the same cesium promoter and the nitrate avoids the identified precipitation problem in silver-ion solutions. The substitution would have predictably delivered cesium during impregnation without premature AgCl formation success because Lauritzen teaches both choices for this same impregnation system and recommends nitrate for compatibility.
Claim 9 requires "2 μmol/g-cat" or greater alkali- or alkaline-earth loading. Lauritzen reports 420 ppm Cs for Catalyst B (Lauritzen, col. 17, ll. 27–32). That amount is 0.420 g Cs/kg ÷ 132.905 g/mol = 3.160 mmol/kg = 3.160 μmol/g catalyst, above the recited lower bound.
Claim 10 requires "alumina" as one alternative in its open list of support materials. Bhise teaches porous alpha-alumina as the preferred support and also lists silica, zirconia, and titania (Bhise, [0022]–[0025]).
Claim 11 requires "between" ordering of the support surface free energy relative to those of the catalyst metal and metal-oxide promoter. The applied combination uses silver, rhenium heptoxide/perrhenate, and alumina. Applicant’s Specification reports 1302 ergs/cm² for silver, about 38 ergs/cm² for Re₂O₇, and 805 ergs/cm² for alumina (Specification, [0031], [0034], [0041]).
Claim 12 requires "270°C" or higher for the second calcination. Bhise teaches that the second calcination is higher than the first and discloses 200–600°C, 250–500°C, 350–400°C, and 235–450°C ranges; Example 1 reaches 400°C in the second calcination (Bhise, [0047], [0056]).
Claim 13 requires "275°C to 300°C" for the second calcination. Bhise does not explicitly teach "275°C to 300°C" as a preferred subrange. However, Bhise teaches second-calcination ranges of 250–500°C and 235–450°C, both of which fully encompass the claimed interval, and states that the second temperature is higher than the first (Bhise, [0047]).
It would have been obvious to select a second-calcination temperature within 275–300°C while using Bhise’s approximately 250°C first calcination because the selected interval lies wholly inside Bhise’s expressly useful ranges. Bhise teaches that calcination temperature and time are correlated to convert the silver compound to active silver and remove organics and volatiles (Bhise, [0043], [0048]). The expected result—additional conversion and volatile removal at a second temperature higher than the first—would have been predictable, and Bhise’s disclosed ranges provide a reasonable expectation of success. See MPEP § 2144.05; In re Peterson, 315 F.3d 1325, 1330 (Fed. Cir. 2003).
Conclusion
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/STARFARI TESHAWN MCCLAIN/Examiner, Art Unit 1736
/ANTHONY J ZIMMER/Supervisory Patent Examiner, Art Unit 1736
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