Union Electric Co v. MES Inc

1. Case Identification

• Case #: IPR2025-01322
• Patent #: 10,668,430
• Filed: July 18, 2025
• Petitioner(s): Union Electric Company
• Patent Owner(s): Birchtech Corporation
• Challenged Claims: 1-4, 6-29

2. Patent Overview

• Title: Method for Mercury Removal from Flue Gas
• Brief Description: The ’430 patent discloses methods for removing mercury from a mercury-containing gas, such as flue gas from coal combustion. The method involves adding a bromine-containing additive to the coal or combustion chamber and injecting an activated carbon sorbent downstream to capture the mercury for later separation.

3. Grounds for Unpatentability

Ground 1: Claims 1-4, 6-9, 15-16, 18-19, and 21-28 are anticipated by Downs.

• Prior Art Relied Upon: Downs (Application # US 2008/0107579).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Downs disclosed every element of the challenged claims. Downs taught a method of removing mercury from coal combustion flue gases by adding a bromine-containing reagent (such as HBr, Br2, or bromide compounds like calcium bromide) to the incoming coal or directly into the boiler combustion furnace. Downs further disclosed injecting a powdered activated carbon (PAC) sorbent into the flue gas downstream of the combustion chamber to adsorb the mercury, which was then removed by particulate collectors like electrostatic precipitators (ESPs) or fabric filters. The petition asserted that Downs reported achieving 77% mercury removal, satisfying the limitation of claims 15-16.

Ground 2: Claims 1-4 and 6-29 are obvious over Vosteen in view of Altman.

• Prior Art Relied Upon: Vosteen (Application # US 2004/0013589) and Altman (Patent 5,827,352).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner contended that Vosteen taught adding a bromine additive (including Br2, HBr, or bromide compounds like sodium bromide) to coal upstream of the furnace or directly into the combustion chamber to achieve "substantial, essentially complete, oxidation of the mercury." Altman taught a known system for mercury removal by injecting an activated carbon sorbent into flue gas downstream of a coal-fired boiler and using a wet ESP to capture the sorbent. The combination of these references, Petitioner argued, rendered the claims obvious.
  • Motivation to Combine: A POSITA would combine Vosteen’s upstream chemical addition with Altman’s downstream sorbent injection system. Both references addressed the same problem of mercury removal from flue gas. Petitioner argued a POSITA would have found it obvious to use Altman’s well-established sorbent injection and capture system to remove the oxidized mercury species generated by Vosteen’s process, as Vosteen itself suggested using known downstream cleanup systems like ESPs.
  • Expectation of Success: The combination involved applying known techniques (chemical oxidation and sorbent capture) to achieve the predictable result of enhanced mercury removal.

Ground 3: Claims 1-4 and 6-29 are obvious over Blankinship in view of Vosteen or Olson-235.

• Prior Art Relied Upon: Blankinship (a 2009 Power Engineering article), Vosteen (Application # US 2004/0013589), and Olson-235 (Patent 8,652,235).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner asserted Blankinship disclosed Alstom’s KNX™ process, which involved adding a calcium bromide solution to the boiler or coal pre-combustion to oxidize mercury, followed by a post-combustion activated carbon injection system to capture the mercury. To meet the limitations of claims 10 and 12 (measuring mercury and modifying inputs), Petitioner combined Blankinship with Vosteen, which taught continuously measuring mercury content in flue gas and controlling the amount of bromine fed in response to that measurement.
  • Motivation to Combine: A POSITA would be motivated to incorporate Vosteen’s feedback control loop into Blankinship’s two-step process. This modification represented a simple application of a known optimization strategy to improve efficiency, reduce the cost of consumables (bromine and sorbent), and ensure compliance with emission limits—all predictable outcomes.
  • Expectation of Success: Implementing a feedback control loop to optimize a chemical process was a routine engineering task, and a POSITA would have a high expectation of success in applying Vosteen's control method to Blankinship's system.
• Additional Grounds: Petitioner asserted additional challenges, including that claims 1-4 and 6-29 are obvious over Downs in view of Altman and Nelson, and that claims 1-4, 6-9, 15-16, and 18-28 are anticipated by Blankinship.

4. Key Technical Contentions (Beyond Claim Construction)

• Lack of Priority Date Entitlement: A central contention of the petition was that the ’430 patent was not entitled to its claimed priority date earlier than its 5/8/2018 filing date. Petitioner argued that the parent applications in the priority chain lacked written description support for the key limitation of adding a bromine-containing promoter to the coal. The petition asserted that the priority applications only disclosed preparing a promoted sorbent outside the flue gas and then injecting that promoted sorbent downstream. Because the prior art references (Downs, Vosteen, etc.) were published before this 2018 filing date, Petitioner argued they qualify as prior art.

5. Arguments Regarding Discretionary Denial

• §314(a) / Fintiv: Petitioner argued against discretionary denial because the parallel district court litigation was in a very early stage. The case had been consolidated into an MDL proceeding where no depositions had occurred, and a trial date was not expected until well after a Final Written Decision in the IPR would issue.
• §325(d): Petitioner argued denial was inappropriate because the primary prior art was not meaningfully considered by the Examiner. Specifically, Blankinship was never presented to the USPTO, and while Downs and Altman were cited on the face of the patent, they were part of a list of over 100 references and were not used in any substantive rejection during prosecution.

6. Relief Requested

• Petitioner requested the institution of an inter partes review and the cancellation of claims 1-4 and 6-29 of the ’430 patent as unpatentable.