Union Electric Co v. MES Inc

1. Case Identification

• Case #: IPR2025-01118
• Patent #: 10,343,114
• Filed: June 6, 2025
• Petitioner(s): Union Electric Company
• Patent Owner(s): Birchtech Corporation
• Challenged Claims: 1-30

2. Patent Overview

• Title: Method of Separating Mercury from a Mercury-Containing Gas
• Brief Description: The ’114 patent describes methods for removing mercury from flue gas generated by coal combustion. The claimed method involves adding a bromine-containing promoter (e.g., HBr, Br₂) to the coal or combustion chamber to oxidize mercury, followed by injecting an activated carbon sorbent downstream to capture the oxidized mercury.

3. Grounds for Unpatentability

Ground 1: Claims 1-30 are obvious over Downs in view of Altman

• Prior Art Relied Upon: Downs (Application # US 2008/0107579) and Altman (Patent 5,827,352).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Downs taught all elements of the independent claims except for a specific downstream sorbent injection and collection system. Downs disclosed adding bromine-containing reagents (including HBr, Br₂, and calcium bromide) to coal or a combustion furnace to enhance mercury oxidation, followed by removal using downstream pollution control devices like particulate collectors. Altman was argued to supply the missing element by teaching a system for injecting an activated carbon sorbent into a flue gas stream downstream of a boiler, followed by separating the mercury-laden sorbent using a wet electrostatic precipitator (ESP).
  • Motivation to Combine: A POSITA would combine Downs and Altman to improve mercury capture efficiency. Downs taught that bromine addition increases oxidized mercury, which is more readily captured. Altman provided a known and effective method for injecting sorbent and capturing particulate matter downstream. Petitioner asserted it would have been obvious to use Altman’s efficient sorbent injection and capture system to remove the oxidized mercury generated by the process taught in Downs.
  • Expectation of Success: The combination was asserted to be a predictable application of known technologies. A POSITA would have reasonably expected that injecting Altman’s activated carbon sorbent into the bromine-treated flue gas from Downs’ process would effectively capture the resulting oxidized mercury.

Ground 2: Claims 1-30 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: This ground is similar to Ground 1, but with Vosteen serving as the primary reference. Petitioner argued Vosteen disclosed adding bromine or bromide compounds (e.g., sodium bromide) to the furnace or coal to achieve substantial oxidation of mercury in flue gas. Vosteen further taught using downstream emission control systems, including scrubbers and ESPs. As in Ground 1, Altman was cited for its specific method of injecting activated carbon into a chamber upstream of a wet ESP for efficient sorbent-based mercury capture.
  • Motivation to Combine: A POSITA would have been motivated to combine Vosteen’s mercury oxidation method with Altman’s sorbent capture system. Vosteen’s process created oxidized mercury, and Altman provided a well-understood and effective system for removing such species using an injected sorbent, which was known to be an improvement over static packed-bed systems.
  • Expectation of Success: A POSITA would have had a reasonable expectation of success because combining a known oxidation step (Vosteen) with a known sorbent capture step (Altman) was a common and predictable approach to mercury removal from flue gas.

Ground 3: Claims 23, 25-27 are anticipated by Blankinship

• Prior Art Relied Upon: Blankinship (“A Variety of Hg Capture Solutions Are Available,” Power Engineering, Jan. 2009).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner contended that Blankinship, a trade journal article, described a commercially available two-part mercury removal process from Alstom that met every limitation of claims 23 and 25-27. The process involved adding a calcium bromide solution (a bromide compound) to the coal or boiler pre-combustion (meeting limitations 23(b) and 25(b)) and injecting activated carbon sorbent downstream of combustion to capture the mercury (meeting limitations 23(c) and 25(c)). The system then used a particulate control device to separate the sorbent composition from the gas (meeting limitations 23(e) and 25(e)).

Ground 4: Claims 1-30 are obvious over Blankinship in view of Olson-235

• Prior Art Relied Upon: Blankinship (as above) and Olson-235 (Patent 8,652,235).
• Core Argument for this Ground:
  • Prior Art Mapping: This ground built upon Blankinship's disclosure of adding a bromide compound to coal and injecting activated carbon downstream. To the extent any claim limitations were not explicitly met by Blankinship (such as the specific promoter-to-sorbent ratio of claim 4), Petitioner argued Olson-235 supplied the teaching. Olson-235 disclosed an in-flight method for preparing a promoted sorbent, teaching a promoter-to-sorbent ratio of about 1 to 30 grams of promoter per 100 grams of base sorbent, which directly corresponded to the ratio recited in the claims.
  • Motivation to Combine: A POSITA reviewing the Alstom process in Blankinship would be motivated to optimize the sorbent performance and usage. Olson-235 provided known and effective parameters for promoting sorbents, making it a natural and obvious resource for a POSITA seeking to implement or improve the system described in Blankinship.

4. Key Technical Contentions (Beyond Claim Construction)

• Lack of Priority Date Entitlement: A central argument of the petition was that the ’114 patent was not entitled to any priority date before its filing on May 14, 2018. Petitioner asserted that none of the parent applications in the priority chain provided written description support for the key limitation of adding a bromine promoter directly to the coal. The prior applications allegedly only disclosed injecting a pre-promoted sorbent or injecting a promoter into the flue gas stream, but not adding it to the coal feed. Petitioner also argued there was a break in the priority chain due to improper incorporation by reference of an essential provisional application. This argument, if successful, establishes that all cited references qualify as prior art.

5. Arguments Regarding Discretionary Denial

• Arguments Against Fintiv Denial: Petitioner argued against discretionary denial under §314(a), asserting that the co-pending district court litigation was in a very early stage, with no depositions taken and a trial date more than two years away. It was argued that a Final Written Decision would issue well before any trial.
• Arguments Against §325(d) Denial: Petitioner contended that denial under §325(d) would be improper because the core prior art references, namely Blankinship and Downs, were never substantively considered by the Examiner during prosecution. While the references were listed in an IDS, they were not applied in any rejection, meaning the Patent Office had not previously considered the specific invalidity arguments presented in the petition.

6. Relief Requested

• Petitioner requested institution of an inter partes review and cancellation of claims 1-30 of the ’114 patent as unpatentable.