PTAB

IPR2025-00687

PacifiCorp v. MES Inc

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Key Events
Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Method for Separating Mercury from a Mercury-Containing Gas
  • Brief Description: The ’370 patent discloses methods for removing mercury from flue gas generated by coal combustion. The methods involve adding a halogen-based additive to the coal prior to or during combustion and subsequently injecting an activated carbon sorbent into the resulting flue gas to capture the mercury.

3. Grounds for Unpatentability

Ground 1: Claims 1-8 and 10-18 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 taught the core inventive concept: adding a bromine-containing additive (e.g., HBr, NaBr) to coal before or during combustion to improve mercury removal from flue gas using a downstream activated carbon sorbent. However, Vosteen589 lacked specific implementation details for the sorbent injection. Petitioner asserted that Starns supplied these missing details, describing the "most mature, retrofit technology" for powdered activated carbon (PAC) injection, including the necessary hardware (e.g., bulk-storage silos, blower/feeder trains) and control processes for introducing the sorbent into the flue gas for capture by a particulate control device like an electrostatic precipitator (ESP).
    • Motivation to Combine: A Person of Ordinary Skill in the Art (POSITA) would have been motivated to combine the references to implement Vosteen589’s chemical treatment process using the well-known and mature activated carbon injection (ACI) hardware and methods described in Starns. This combination would yield the predictable result of improved mercury removal.
    • Expectation of Success: A POSITA would have had a reasonable expectation of success because the combination merely applies a known purification technique (ACI from Starns) to a known chemical process (halogen treatment from Vosteen589) to achieve a predictable outcome.
    • Key Aspects: Petitioner contended that the weight ratio limitation of claim 1(c) (1:100 to 30:100 additive-to-sorbent) was obvious. By using the bromine concentration disclosed in Vosteen589 and a routine sorbent injection rate taught by Starns, a POSITA could perform standard calculations to arrive at a ratio falling squarely within the claimed range.

Ground 2: Claims 1-6, 8, and 11 are obvious over Downs-Boiler in view of Starns.

  • Prior Art Relied Upon: Downs-Boiler (Application # 2008/0107579) and Starns (a 2002 conference paper).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner asserted that Downs-Boiler taught adding a bromine-containing reagent (e.g., CaBr₂, HBr, Br₂) to coal or directly into the combustion chamber to enhance mercury capture by a downstream PAC sorbent. Similar to Vosteen589, Downs-Boiler described the chemical process but did not fully detail the PAC injection system. Starns, again, was cited as providing the necessary practical implementation details for a mature ACI system.
    • Motivation to Combine: A POSITA would have combined the teachings of Downs-Boiler with the practical, off-the-shelf ACI technology described in Starns to effectively implement the mercury removal system. The references were directed to the same goal and were interoperable.
    • Expectation of Success: Success was predictable, as the combination involved using a standard injection method to deploy a sorbent whose effectiveness was enhanced by a known chemical promoter.
    • Key Aspects: The argument for the obviousness of the claimed weight ratio was analogous to Ground 1. Petitioner argued a POSITA could use the bromine addition rate from Downs-Boiler (e.g., 375 ppm to coal) and the standard sorbent injection rate from Starns to calculate an additive-to-sorbent ratio within the claimed range through routine unit conversions.

Ground 3: Claims 1, 5-6, and 11 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 argued that Lissianski taught injecting aqueous solutions of ammonium halides (e.g., NH₄Cl, NH₄Br) into a combustion chamber to oxidize mercury, thereby improving its removal by a downstream activated carbon injection system. While Lissianski disclosed the halogen additive, it did not specify the hardware or control processes for the ACI system. Starns was again presented as teaching these missing, well-known details.
    • Motivation to Combine: A POSITA seeking to implement Lissianski’s method would have been motivated to use the mature and widely understood ACI technology detailed in Starns. The combination would have been a straightforward application of a known technique to a compatible process.
    • Expectation of Success: A POSITA would expect predictable results in mercury removal by combining Lissianski’s chemical additive with Starns’s standard sorbent delivery system.
  • Additional Grounds: Petitioner asserted additional obviousness challenges based on substituting Mass-EPA (a 2002 Massachusetts Department of Environmental Protection report) for Starns in the combinations above. Petitioner argued that Mass-EPA, like Starns, described ACI as a mature, well-understood technology and provided an express motivation to improve sorbent efficiency and reduce costs, which would lead a POSITA to combine its teachings with the halogen-based methods of Vosteen589, Downs-Boiler, and Lissianski.

4. Arguments Regarding Discretionary Denial

  • Petitioner argued that the Board should not deny institution under §325(d) because several key prior art references, including Starns and Mass-EPA, were used in every ground and were never cited or considered by the examiner during prosecution. Petitioner claimed the examiner materially erred by overlooking these teachings and allowing the patent based on the weight ratio limitation, which Petitioner contends is unpatentable.
  • Petitioner also argued against discretionary denial under Fintiv, stating that the parallel district court proceeding was in its earliest stages, with a "Trial Ready Date" set for October 12, 2026. A Final Written Decision in the IPR would therefore be expected well before any trial.

5. Relief Requested

  • Petitioner requests institution of inter partes review and cancellation of claims 1-8 and 10-18 of the ’370 patent as unpatentable.