Union Electric Co v. MES Inc

1. Case Identification

• Case #: IPR2025-01117
• Patent #: 10,596,517
• Filed: June 6, 2025
• Petitioner(s): Union Electric Company
• Patent Owner(s): Birchtech Corporation
• Challenged Claims: 1-15, 17-30

2. Patent Overview

• Title: Method for Mercury Removal from Flue Gas
• Brief Description: The ’517 patent discloses a two-step method for removing mercury from flue gas generated by coal combustion. The method involves (1) adding a bromine-containing species (e.g., Br₂, HBr, or a bromide compound) to the coal or combustion chamber to oxidize mercury, and (2) subsequently adding an activated carbon sorbent downstream to collect the oxidized mercury. A core contention of the petition is that the challenged claims lack written description support in the priority applications for adding the bromine promoter to the coal, and therefore, the claims are only entitled to the 2018 filing date of the application, making the cited references valid prior art.

3. Grounds for Unpatentability

Ground 1: Obviousness over Downs and Altman - Claims 1-15 and 17-30 are obvious over Downs in view of Altman

• Prior Art Relied Upon: Downs (Application # 2008/0107579) and Altman (Patent 5,827,352).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Downs taught the first step of the claimed method: adding a bromine-containing reagent (including Br₂, HBr, and bromide compounds like calcium bromide) to coal before combustion or directly into the furnace to enhance mercury oxidation. Downs also disclosed using a downstream sorbent injection system with powdered activated carbon (PAC) to remove the oxidized mercury. Petitioner asserted that Altman provided a detailed, well-known system for the second step: injecting an activated carbon sorbent into a flue gas stream to adsorb mercury and using a downstream particulate collector, such as an electrostatic precipitator (ESP), to collect the sorbent.
  • Motivation to Combine: A POSITA would combine Downs and Altman to implement a known, effective mercury removal strategy. Downs taught the benefit of pre-combustion bromine addition for mercury oxidation, and Altman provided a known, conventional system for post-combustion sorbent injection and collection. A POSITA would have been motivated to use Altman's detailed sorbent injection and capture system to implement the downstream collection step generally disclosed in Downs, as both references addressed the same problem using standard industry components.
  • Expectation of Success: A POSITA would have had a reasonable expectation of success because combining the known technique of bromine-enhanced oxidation (Downs) with the known technique of activated carbon injection and collection (Altman) involved using predictable technologies for their intended purposes.

Ground 2: Obviousness over Vosteen and Altman - Claims 1-15 and 17-30 are obvious over Vosteen in view of Altman

• Prior Art Relied Upon: Vosteen (Application # 2004/0013589) and Altman (Patent 5,827,352).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner contended that Vosteen, like Downs, disclosed the first key step of the claimed method by teaching the addition of bromine or bromide compounds (e.g., sodium bromide) to the furnace or to the coal upstream of combustion to achieve substantial oxidation of mercury. Vosteen also taught using downstream emissions control systems, including ESPs and scrubbers with activated carbon, to remove the mercury. The argument leveraged Altman, as in Ground 1, to provide a specific, exemplary implementation of the activated carbon injection and collection system that Vosteen described more generally.
  • Motivation to Combine: The motivation was similar to Ground 1. A POSITA seeking to implement Vosteen’s mercury control process would have looked to known systems like Altman’s for injecting activated carbon and collecting it in an ESP. Petitioner argued this was a simple substitution of one known flue gas treatment system for another to achieve a predictable result.
  • Expectation of Success: Success was expected because Vosteen demonstrated that bromine addition effectively oxidized mercury, and Altman demonstrated that activated carbon injection effectively captured it. Combining these known processes would predictably result in an effective two-step mercury removal method.

Ground 3: Obviousness over Blankinship and Vosteen/Olson-235 - Claims 1-15 and 17-30 are obvious over Blankinship in view of Vosteen or Olson-235

• Prior Art Relied Upon: Blankinship (a 2009 journal article), Vosteen (Application # 2004/0013589), and Olson-235 (Patent 8,652,235).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Blankinship disclosed a complete two-step mercury removal process, describing Alstom’s KNX™ system where a bromide compound (calcium bromide) is added to the boiler or coal pre-combustion, followed by a post-combustion activated carbon injection system (MER-CURE™) upstream of a particulate control device. For claim limitations related to process control (e.g., claims 8, 10, 20), Petitioner combined Blankinship with Vosteen, which taught continuously measuring mercury content and controlling the amount of bromine fed in response. For limitations on sorbent composition (claim 5), Petitioner combined Blankinship with Olson-235, which explicitly disclosed a promoted sorbent comprising 1 to 30 grams of promoter per 100 grams of base sorbent.
  • Motivation to Combine: A POSITA would combine Blankinship with Vosteen to optimize the amount of bromine additive, a known process variable, to improve efficiency and reduce cost, which Vosteen explicitly taught. A POSITA would have been motivated to use the specific sorbent composition of Olson-235 in the Blankinship system as a known and effective option for mercury capture.
  • Expectation of Success: A POSITA would expect success in optimizing the Blankinship process using the feedback controls taught by Vosteen, as this was a routine optimization. Similarly, using the specific sorbent ratios from Olson-235 was expected to work predictably within the known framework of activated carbon sorbents.
• Additional Grounds: Petitioner asserted anticipation of various claims over Downs (Ground 1) and Blankinship (Ground 4), arguing these single references disclosed every element of the claimed methods.

4. Arguments Regarding Discretionary Denial

• Petitioner argued against discretionary denial under §314(a), asserting that the co-pending district court litigation is in its very early stages, with no depositions taken and claim construction briefs not due until October 2025, meaning a Final Written Decision (FWD) from the IPR would issue well before trial.
• Petitioner also argued against denial under §325(d), stating that the Examiner did not consider key prior art, such as Blankinship, during prosecution. Further, while other references like Downs were cited, they were not used in any substantive rejection, so the Board would be considering the art in a new light.

5. Relief Requested

• Petitioner requests institution of an inter partes review and cancellation of claims 1-15 and 17-30 of the ’517 patent as unpatentable.