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E.I. Dupont De Nemours & Co. v. Synvina C.V.

United States Court of Appeals, Federal Circuit

September 17, 2018

SYNVINA C.V., Appellee

          Appeal from the United States Patent and Trademark Office, Patent Trial and Appeal Board in No. IPR2015-01838.

          Michael J. Flibbert, Finnegan, Henderson, Farabow, Garrett & Dunner, LLP, Washington, DC, argued for appellants. Also represented by Charles Collins-Chase.

          Paul M. Richter, Jr., Pepper Hamilton LLP, New York, NY, argued for appellee. Also represented by Mark Alexander Chapman, Hunton Andrews Kurth LLP, New York, NY.

          Before Lourie, O'Malley, and Chen, Circuit Judges.

          Lourie, Circuit Judge.

         E. I. du Pont de Nemours and Company and Archer-Daniels-Midland Company (collectively, "DuPont") appeal from an inter partes review ("IPR") decision of the United States Patent and Trademark Office Patent Trial and Appeal Board (the "Board"). See DuPont v. Furanix Techs. B.V., No. IPR2015-01838, Paper No. 43, slip op. (P.T.A.B. Mar. 3, 2017) ("Decision"). The Board held that DuPont failed to prove by preponderant evidence that claims 1-5 and 7-9 of U.S. Patent 8, 865, 921 ("'921 patent") would have been obvious at the time of the claimed invention. We conclude that the Board applied the wrong legal standards for obviousness, and reverse.

         I. Background

         Synvina C.V. ("Synvina")[1] owns the '921 patent, directed to a method of oxidizing 5-hydroxymethylfurfural ("HMF") or an HMF derivative, such as 5-methylfurfural ("5MF") or 2, 5-dimethylfuran ("DMF"), under specified reaction conditions to form 2, 5-furan dicarboxylic acid ("FDCA"). '921 patent Abstract; id. col. 7 l. 65. Undisput-edly, the oxidation of HMF and its derivatives to yield FDCA was known at the time of the claimed invention. The main issue on appeal is whether the reaction conditions claimed in the '921 patent-specifically, the choice of temperature, pressure, catalyst, and solvent-would have been obvious to a person of ordinary skill at the time of the invention.


         DuPont and Synvina are competitors in the production of FDCA for industrial use. FDCA has attracted commercial interest because of its potential in the "green" chemical industry. Since FDCA can be produced from sugars using biological or chemical conversion, the U.S. Department of Energy has identified FDCA as a potential "building block[]" for "high-value bio-based chemicals or materials." U.S. Department of Energy, Top Value Added Chemicals from Biomass 1 (2004); see '921 patent col. 1 ll. 34-36.

         The '921 patent claims a method of producing FDCA by oxidizing HMF or an HMF derivative with an oxygen-containing gas such as air. Claim 1 is illustrative and reads as follows:

1. A method for the preparation of 2, 5-furan di-carboxylic acid comprising the step of contacting a feed comprising a compound selected from the group consisting of 5-hydroxymethylfurfural ("HMF"), an ester of 5-hydroxymethylfurfural, 5-methylfurfural, 5-(chloromethyl)furfural, 5-methylfuroic acid, 5-(chloromethyl)furoic acid, 2, 5-dimethylfuran and a mixture of two or more of these compounds with an oxygen-containing gas, in the presence of an oxidation catalyst comprising both Co and Mn, and further a source of bromine, at a temperature between 140° C. and 200° C. at an oxygen partial pressure of 1 to 10 bar, wherein a solvent or solvent mixture comprising acetic acid or acetic acid and water mixtures is present.

'921 patent col. 7 l. 61-col. 8 l. 6 (emphasis added). Thus, claim 1 recites four relevant reaction conditions: (1) a temperature between 140°C and 200°C; (2) an oxygen partial pressure ("PO2")[2] of 1 to 10 bar; (3) a solvent comprising acetic acid; and (4) a catalyst comprising cobalt ("Co"), manganese ("Mn"), and bromine ("Br"). Id.

         The specification describes the reaction conditions in further detail. We begin with temperature. At several points, the specification refers to the reaction occurring at temperatures "higher than 140° C." Id. Abstract, col. 2 ll. 41-42, col. 2 ll. 57-58, col. 5 ll. 18-19, col. 5 l. 39, col. 5 l. 57. When the specification refers to the temperature range in claim 1, it states that "[t]he temperature of the reaction mixture is at least 140° C., preferably from 140 and 200° C., most preferably between 160 and 190° C." Id. col. 4 ll. 56-58. But "[t]emperatures higher than 180°C. may lead to decarboxylation and to other degradation products." Id. col. 4 ll. 58-59.

         Second, the specification provides the following guidance regarding reaction pressure:

The pressure in a commercial oxidation process may vary within wide ranges. When a diluent is present, and in particular with acetic acid as diluent, the temperature and the pressure in such a process are not independent. The pressure is determined by the solvent (e.g., acetic acid) pressure at a certain temperature. The pressure of the reaction mixture is preferably selected such that the solvent is mainly in the liquid phase.

Id. col. 4 ll. 34-41. Because oxygen functions as the oxidant in the reaction, its partial pressure is particularly relevant. "In the case of continuously feeding and removing the oxidant gas to and from the reactor, the oxygen partial pressure will suitably be between 1 and 30 bar or more preferably between 1 and 10 bar." Id. col. 4 ll. 51-55 (emphasis added).

         Third, as indicated above, "[t]he most preferred solvent is acetic acid." Id. col. 4 ll. 17-18. Fourth, the catalyst is preferably "based on both cobalt and manganese and suitably containing a source of bromine." Id. col. 3 ll. 38-40. The catalyst may also contain "one or more additional metals, in particular [zirconium] and/or [cerium]." Id. col. 3 ll. 57-58.

         Several dependent claims recite narrower conditions than those recited in claim 1. Claims 2-5 each depend from claim 1. Claim 2 limits the starting material to HMF, esters of HMF, and a mixture thereof. Id. col. 8 ll. 7-10. Claims 3 and 4 recite a catalyst with an additional metal, such as zirconium ("Zr") or cerium ("Ce"). Id. col. 8 ll. 11-12, 60-61. And claim 5 recites a narrower temperature range between 160 and 190°C. Id. col. 8 ll. 62-63.

         By conducting the oxidation reaction under the disclosed reaction conditions, the specification states that the inventors "surprisingly" achieved high yields of FDCA, id. col. 2 ll. 39-45, and both Furanix and Synvina have pointed to these yields as objective evidence of nonobviousness. The '921 patent reports yields for several reactions under the claimed conditions. Table 1 summarizes results for oxidizing HMF, an ester of HMF, 5-acetoxymethylfurfural ("AMF"), or a mixture of the two to produce FDCA. Multiple experiments were conducted at a temperature of 180°C and a pressure of 20 bars air in an acetic acid solvent. Id. col. 6 ll. 34-46. The highest yield of 78.08% was obtained with only HMF as a reactant, while the lowest was 46.85% using AMF alone. Id. Table 1.

         Table 2 shows the FDCA yields reported in table 1 for the AMF oxidation reactions compared to prior art processes conducted at lower temperatures and a pressure of 30 bars air. Id. Table 2; id. col. 6 ll. 50-62. FDCA yields achieved using prior art processes were "lower than the results obtained at higher temperature." Id. col. 6 ll. 50- 61.

         Table 3 shows FDCA yields for six experiments when HMF derivatives 5MF or DMF are oxidized with air. The temperature was 180°C, the air pressure was 50 bars, and the solvent was acetic acid. Id. col. 6 l. 66-col. 7 l. 12. Again, the concentration of bromine in the catalyst varied across experiments. Reported FDCA yields for 5MF were 42.62% and 39.94%. Id. Table 3. For DMF, FDCA yields ranged from 7.19% to 16.17%. Id.

         In addition to claiming methods of producing FDCA, the '921 patent also claims certain post-production processes. Claim 7 is independent and recites producing FDCA under the conditions in claim 1, and then "esterify-ing the thus obtained product." Id. col. 9 ll. 1-14. Claims 8 and 9 depend from claim 7 and recite further details of the esterification not relevant to this appeal. Id. col. 9 ll. 15-19. The specification recognizes that "[t]he esterifica-tion of [FDCA] is known." Id. col. 5 ll. 42-48 (citing U.S. Patents 2, 673, 860 and 2, 628, 249); see also id. col. 5 l. 62- col. 6 l. 2 (citing GB 621, 971).


         DuPont petitioned for IPR of the '921 patent. The petition asserted several grounds of obviousness, two of which are relevant on appeal: (1) claims 1-5 over the '732 publication, [3] alone or in combination with RU '177[4] and the '318 publication;[5] and (2) claims 7-9 over the '732 publication in view of Applicants Admitted Prior Art, or additionally Lewkowksi[6] and/or Oae, [7] and optionally in view of RU '177 and the '318 publication.

         The Board instituted review of claims 1-5 and 7-9 based on grounds 1 and 2 above, but did not institute review of the other claims or grounds.[8] DuPont v. Fu-ranix Techs. B.V., No. IPR2015-01838, Paper No. 10, slip op. at 15, 19 (P.T.A.B. Mar. 9, 2016) ("Institution Decision").

         Each of the three references relevant to claims 1-5 disclosed oxidizing HMF or an HMF derivative to produce FDCA, but did so under somewhat different conditions. First, the '732 publication disclosed oxidizing HMF to FDCA. It included "preferred temperatures" of "about 50° to 250°C, most preferentially about 50° to 160°C." J.A. 2360. Like the '921 patent, the '732 publication indicated that the reaction pressure "is such to keep the solvent mostly in the liquid phase." Id. Specifically, the reference disclosed that an air pressure of 1000 psi "gave good yields of [FDCA]." J.A. 2368. 1000 psi amounts to a PO2 of approximately 14.5 bars. The disclosed solvent was "preferably acetic acid," J.A. 2357, and "the catalyst can be comprised of Co and/or Mn, and Br, and optionally Zr," J.A. 2358. Reported FDCA yields ranged from 14% to 58.8%.

         Second, RU '177 disclosed oxidizing 5MF to form FDCA. It included a method where the oxidation reaction "is conducted at the temperature of 115-140°C and air pressure of 10-50 atm." J.A. 2440. An air pressure of 10- 50 atm roughly corresponds to a PO2 of 2.1-10.5 bars.[9]RU '177 also generally recites an "aliphatic carboxylic acid" as the solvent, and an example in the specification specifically uses acetic acid. Id. The catalyst in RU '177 is "a mixture of cobalt acetate and manganese acetate, as well as bromine-containing compounds, such as ammonium bromide." Id. Purportedly, the process "has a number of advantages compared to prior art: it utilizes readily available and inexpensive reagents as the initial compound and catalysts; [and] the method is a one-step process." J.A. 2439. FDCA yields reportedly ranged from 23-36%.

         Third, the '318 publication taught the oxidation of HMF to make FDCA. The reaction temperature was "from about 50° C. to about 200° C," with a preferred range of 100-160°C. J.A. 2484, 2486. "A preferred pressure can typically be in the range of 150-500 psi," J.A. 2486, corresponding to a PO2 range in air of roughly 2.17- 7.24 bars. Unlike the '921 patent and the other references, the '318 publication taught using water as a solvent and a platinum catalyst.[10] Under these conditions, the '318 publication reported yields "as high as 98%." J.A. 2486.

         The table below summarizes the reaction conditions disclosed in claim 1 of the '921 patent and in the RU '177, '732, and '318 references. For simplicity and to enable comparison between pressure ranges, we restate only the PO2 ranges in bars under the assumption that air is the oxidant.






'921 patent

Between 140-200°C

1-10 bars

Acetic acid


RU '177


2.1-10.5 bars

Acetic acid



50-250°C, preferably 50-160°C

14.5 bars

Acetic acid

Co/Mn/Br, optionally Zr


50-200°C, preferably 100-160°C

2.17-7.24 bars



         Two additional references, Lewkowski and Oae, are relevant to the FDCA esterification claims 7-9. Consistent with the '921 patent's acknowledgment that esterification of FDCA was known at the time of the invention, '921 patent col. 5 l. 42, Lewkowski and Oae both disclosed esterifying FDCA.


         In its final written decision, the Board held the instituted claims not unpatentable as obvious. The Board rejected DuPont's contention that a burden-shifting framework applied, reasoning that our decisions in In re Magnum Oil Tools International, Ltd., 829 F.3d 1364, 1375 (Fed. Cir. 2016), and Dynamic Drinkware, LLC v. National Graphics, Inc., 800 ...

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