PTAB

IPR2015-01838

E.I. du Pont de Nemous and Company v. FURANIX TECHNOLOGIES B.V.

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1. Case Identification

2. Patent Overview

  • Title: Method for the Preparation of 2,5-Furandicarboxylic Acid and for the Preparation of the Dialkyl Ester of 2,5-Furandicarboxylic Acid
  • Brief Description: The ’921 patent describes a method for preparing 2,5-furandicarboxylic acid (FDCA) or its dialkyl ester. The process involves the catalytic oxidation of a furan-based derivative feed, such as 5-hydroxymethylfurfural (HMF), using an oxygen-containing gas in the presence of an oxidation catalyst comprising Cobalt (Co), Manganese (Mn), and a bromine source, within specific temperature and pressure ranges.

3. Grounds for Unpatentability

Ground 1: Obviousness over '732, RU '177, and '318 - Claims 1-5 are obvious over the '732 publication, alone or combined with RU '177 and the '318 publication.

  • Prior Art Relied Upon: '732 publication (WO 01/072732), RU '177 (USSR Patent 448177A1), and '318 publication (Application # 2008/0103318).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that the '732 publication, which the Patent Owner admitted is the closest prior art, discloses nearly all elements of independent claim 1. This includes the oxidation of HMF to FDCA using a Co/Mn/Br catalyst in an acetic acid solvent. The '732 publication’s disclosed temperature range (up to 160°C) overlaps with the claimed range (140-200°C), and its disclosed oxygen partial pressure (~14.5 bar) is close enough to the claimed 1-10 bar range that a person of ordinary skill in the art (POSA) would have expected similar results. For dependent claims, '732 teaches using zirconium (Zr), mapping to claims 3 and 4, and a temperature of 150°C, which is close to the 160-190°C range of claim 5.
    • Motivation to Combine: A POSITA would have been motivated to modify the '732 process using the teachings of RU '177 and '318 to optimize reaction conditions, particularly to lower the pressure. Both RU '177 and '318 teach liquid-phase oxidation of similar furanic compounds at lower pressures that fall within the claimed 1-10 bar range. The motivation would be to reduce process costs and improve safety, which are standard considerations in chemical process design.
    • Expectation of Success: A POSITA would have a reasonable expectation of success because all references are in the same technical field, address the same problem of producing FDCA, and use similar catalytic systems. The '732 publication explicitly suggests optimizing reaction parameters like temperature and pressure to maximize yield, guiding a POSITA toward such modifications.

Ground 2: Obviousness over '732 and '018 - Claims 6 and 10 are obvious over the '732 publication in view of the '018 patent.

  • Prior Art Relied Upon: '732 publication (WO 01/072732) and '018 patent (Patent 8,558,018).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground targets claim 6, which recites using an ester of HMF as the starting feed. Petitioner asserted that while '732 teaches the base oxidation process starting with HMF, the '018 patent explicitly discloses using an ester of HMF (specifically an acetate ester) as the starting material for oxidation to FDCA. Claim 10 adds that the HMF ester is obtained from a carbohydrate source, which is also taught by '732 and '018.
    • Motivation to Combine: A POSITA would combine these references to achieve a known benefit. The '018 patent explicitly teaches that using an HMF ester derivative is advantageous because it is more soluble and easier to purify than HMF, leading to improved handling and potentially higher overall yields. A POSITA would therefore be motivated to substitute the HMF starting material in the '732 process with the improved HMF ester taught by '018.
    • Expectation of Success: Success would be expected because the substitution is straightforward, involving replacing a known starting material with a known, improved alternative within a well-understood catalytic oxidation process.

Ground 3: Obviousness over Partenheimer, '732, and '018 - Claims 1-4 are obvious over Partenheimer in view of the '732 publication, optionally combined with the '018 patent.

  • Prior Art Relied Upon: Partenheimer (a 2001 journal article), '732 publication (WO 01/072732), and '018 patent (Patent 8,558,018).

  • Core Argument for this Ground:

    • Prior Art Mapping: Petitioner contended that Partenheimer independently teaches the core elements of claim 1, including the Co/Mn/Br catalyzed oxidation of HMF to FDCA. Partenheimer's reaction conditions (temperatures up to 125°C and pressure of ~14.5 bar oxygen partial pressure) are close to the claimed ranges.
    • Motivation to Combine: A POSITA would be motivated to increase the temperature of the Partenheimer process into the claimed 140-200°C range. Partenheimer itself states that yield increases with temperature, providing a direct motivation for this modification. The '732 publication reinforces this by teaching that higher temperatures lead to higher FDCA yields. Further, the '018 patent teaches lower pressure ranges that overlap with the claimed range, motivating a reduction in pressure.
    • Expectation of Success: A POSITA would expect that increasing the temperature would, as taught by the prior art, increase the reaction yield. Routine experimentation would be sufficient to determine the optimal temperature within the workable range disclosed by the art.

  • Additional Grounds: Petitioner asserted additional obviousness challenges, including that claims 7-9 are obvious over the '732 publication combined with Applicants' Admitted Prior Art and publications like Lewkowski or Oae, which teach the well-known esterification of FDCA. A further ground asserted that claim 1 is obvious over RU '177 alone.

4. Key Claim Construction Positions

  • “oxygen partial pressure of 1 to 10 bar”: Petitioner argued this limitation is not critical to patentability and was added during prosecution simply to overcome a rejection. The petition noted that the '921 patent itself discloses a broader suitable range of 1-30 bar, suggesting the claimed 1-10 bar range is merely a preference. This construction supports the argument that prior art with slightly higher pressures (e.g., 14.5 bar in '732) is legally relevant and renders the claims obvious under the "close enough" standard.
  • Transitional term “comprising”: Petitioner argued that the use of "comprising" for the catalyst and solvent limitations means the claims are open-ended and do not exclude additional, unrecited elements. For example, the catalyst can include metals other than Co and Mn (such as Zr or Ce, which are in the dependent claims). This construction broadens the claim scope, making it easier to find prior art that discloses the claimed elements.

5. Key Technical Contentions (Beyond Claim Construction)

  • Flaws in Patent Owner's "Unexpected Results" Data: Petitioner contended that the Patent Owner's evidence of unexpected results (i.e., higher FDCA yields), which was used to overcome rejections during prosecution, was technically flawed and insufficient. The argument was twofold: (1) the Patent Owner's data was not compared against the closest prior art ('732 publication), and (2) the data was not commensurate with the full scope of the claims, as it showed results for only a single starting material (HMF) at a single temperature (180°C) and pressure, whereas the claims cover a broad Markush group of starting materials and wide ranges of temperature and pressure.

6. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 1-10 of the '921 patent as unpatentable under 35 U.S.C. §103.