PTAB

IPR2025-00717

PacifiCorp v. MES Inc

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Key Events
Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Method of separating mercury from a mercury-containing gas
  • Brief Description: The ’218 patent discloses methods for removing mercury from flue gas generated by coal combustion. The methods involve adding hydrogen iodide (HI) or an iodide salt to the coal or directly into the combustion chamber to oxidize mercury, followed by injecting an activated carbon sorbent downstream to adsorb and separate the oxidized mercury from the gas stream.

3. Grounds for Unpatentability

Ground 1: Obviousness over Vosteen589 and Starns - Claims 1-4 and 6-26 are obvious over Vosteen589 in view of Starns.

  • Prior Art Relied Upon: Vosteen589 (Application # 2004/0013589) and Starns (a 2002 conference paper).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Vosteen589 teaches the core inventive concept: adding a halogen compound to coal before combustion to enhance mercury oxidation, making it more readily captured by a downstream sorbent like activated carbon. Vosteen589 primarily discusses bromine but explicitly teaches that iodine compounds are more effective and can be used as a supplement or replacement. Petitioner contended that Starns, a contemporaneous conference paper, supplies the conventional implementation details for the downstream capture step, describing the "most mature, retrofit technology" of activated carbon injection (ACI). Starns discloses the necessary hardware (silos, feeders), control systems, and typical injection rates for a complete ACI system.
    • Motivation to Combine: A POSITA would combine Vosteen589's chemical enhancement process with Starns's well-established ACI technology to create a functional and effective mercury removal system. Vosteen589 provides the chemical basis for improved capture but lacks practical ACI details, which Starns readily supplies as common knowledge in the art.
    • Expectation of Success: A POSITA would have a high expectation of success, as the combination involves implementing a known chemical treatment (halogen addition) with a mature, commercially ready technology (ACI) to achieve the predictable result of improved mercury removal.

Ground 2: Obviousness over Lissianski and Starns - Claims 1, 3, 6-18, and 20-26 are obvious over Lissianski in view of Starns.

  • Prior Art Relied Upon: Lissianski (Patent 7,514,052) and Starns (a 2002 conference paper).

  • Core Argument for this Ground:

    • Prior Art Mapping: Petitioner asserted that Lissianski teaches injecting an ammonium iodide (NH4I) salt solution into a furnace's combustion chamber to oxidize mercury. This oxidized mercury is then captured by an adsorbent in the flue gas. Lissianski discloses that the NH4I thermally decomposes to form HI, directly teaching the use of an iodide salt and HI as claimed. However, like Vosteen589, Lissianski does not provide specific details on the hardware or control processes for the downstream activated carbon injection. Starns was again presented as supplying these missing but conventional details for implementing a standard ACI system.
    • Motivation to Combine: A POSITA seeking to implement the mercury removal process described in Lissianski would be motivated to consult a reference like Starns to supply the practical, well-known details of the ACI hardware and control processes. The combination would simply apply a mature technology (Starns's ACI system) to carry out a disclosed process (Lissianski's iodide-enhanced mercury capture).
    • Expectation of Success: Success would be expected because the combination pairs a disclosed method of mercury oxidation with a standard, reliable method for sorbent injection and capture, yielding predictable improvements in mercury removal efficiency.

  • Additional Grounds: Petitioner asserted additional obviousness challenges, including grounds substituting Mass-EPA (a 2002 Massachusetts Department of Environmental Protection report) for Starns, arguing Mass-EPA similarly taught the conventional nature and implementation of ACI technology. Further grounds combined Lissianski, Starns, and Vosteen589 to argue that adding Vosteen589's teachings on applying additives directly to coal would be an obvious modification to the Lissianski/Starns combination.

4. Key Technical Contentions

  • Claimed Weight Ratio as Routine Optimization: A central technical argument was that the claimed weight ratio of iodide additive to sorbent ("from about 1:100 to about 30:100") is unpatentable because it represents nothing more than the routine optimization of result-effective variables. Petitioner argued that the prior art discloses all general conditions of the claimed method, and discovering the optimal or workable range for conventional materials would have been obvious to a POSITA. Petitioner highlighted that the Patent Owner had previously argued in a related proceeding that a nearly identical 1%-30% ratio was "entitled to no patentable weight." Calculations based on halogen concentrations in Vosteen589/Lissianski and standard ACI rates from Starns/Mass-EPA were shown to fall within or near the claimed range.

5. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 1-4 and 6-26 of the ’218 patent as unpatentable.