PacifiCorp v. MES Inc

1. Case Identification

• Case #: IPR2025-00688
• Patent #: 10,933,370
• Filed: March 24, 2025
• Petitioner(s): PacifiCorp, Interstate Power & Light Company, MidAmerican Energy Company, WEC Energy Group, Inc., and Wisconsin Power & Light Company
• Patent Owner(s): Birchtech Corp.
• Challenged Claims: 1-18

2. Patent Overview

• Title: Method for Mercury Separation
• Brief Description: The ’370 patent relates to methods for removing mercury from flue gas generated by coal combustion. The method involves adding a halogen-containing additive to the coal or combustion chamber and subsequently adding a particulate activated carbon sorbent into the resulting mercury-containing gas within a specific weight ratio.

3. Grounds for Unpatentability

Ground 1: Anticipation - Claims 1-4, 6-8, 10-11, and 13-18 are anticipated by Baldrey.

• Prior Art Relied Upon: Baldrey (Application # 2011/0030592).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Baldrey disclosed every element of the challenged claims. Specifically, Baldrey taught a method for mercury removal by adding a halogen-containing additive (chosen from diatomic halogens like Br₂, halide salts like CaCl₂, and combinations) to a coal feed before or during combustion in a furnace. Baldrey then disclosed injecting an activated carbon sorbent into the downstream flue gas. Petitioner asserted that Baldrey explicitly disclosed concentrations for both the additive and the sorbent that, when calculated, resulted in a weight ratio falling within the claimed 1:100 to 30:100 range. Baldrey was also argued to disclose adding the additive as a liquid salt solution and its subsequent vaporization in the flue gas, anticipating various dependent claims.
  • Key Aspects: The anticipation argument hinged on Petitioner's calculation of the additive-to-sorbent ratio based on disclosed concentration ranges in Baldrey, which Petitioner contended inherently met the claimed ratio limitation.

Ground 2: Obviousness over Baldrey in view of Olson-646 - Claims 1-18 are obvious over Baldrey in view of Olson-646.

• Prior Art Relied Upon: Baldrey (Application # 2011/0030592) and Olson-646 (Application # 2006/0048646).
• Core Argument for this Ground:
  • Prior Art Mapping: For any claim elements not anticipated by Baldrey, Petitioner argued Olson-646 rendered them obvious. Olson-646, a publication from the same patent family as the ’370 patent, described the reaction mechanisms between halogens, activated carbon, and mercury. Petitioner contended that Olson-646 explicitly taught the 1:100 to 30:100 ratio of halogen promoter to activated carbon sorbent. It also disclosed the claimed chemical model where carbocations in the activated carbon accept electrons from mercury atoms (claim 5), specific additives like PBr₃ (claim 9), and the co-injection of alkaline components (claim 12) to improve mercury capture.
  • Motivation to Combine: A POSITA would combine Baldrey’s general process with Olson-646’s specific disclosures because both addressed the same problem of mercury removal from flue gas. A POSITA would have looked to Olson-646 to supply specific implementation details, such as optimal sorbent ratios and reaction chemistry, for the system described in Baldrey as a matter of routine optimization.
  • Expectation of Success: Success was expected because the combination involved applying known, conventional ratios and chemical principles (from Olson-646) to a known mercury removal system (from Baldrey) to achieve the predictable result of improved efficiency.

Ground 3: Obviousness over Sjostrom in view of Olson-646 - Claims 1-18 are obvious over Sjostrom in view of Olson-646.

• Prior Art Relied Upon: Sjostrom (a 2005 conference presentation) and Olson-646 (Application # 2006/0048646).

• Core Argument for this Ground:

  • Prior Art Mapping: Petitioner argued Sjostrom, a presentation on full-scale mercury control evaluations, taught the core process. Sjostrom showed adding halogens (Cl, Br, F, I) at three different locations: as a "coal additive" before the boiler (Location 1), directly into the combustion chamber (Location 2), and to the sorbent downstream (Location 3). Sjostrom also taught injecting a powdered activated carbon sorbent downstream of the boiler. Olson-646 was used to supply the specific halogen compounds (e.g., HBr, Br₂) and the claimed weight ratio of additive-to-sorbent (1:100 to 30:100), which Sjostrom lacked.
  • Motivation to Combine: A POSITA would combine the references to implement the general halogen-addition strategy of Sjostrom using the specific, well-defined compounds and ratios taught by Olson-646. This would be a simple substitution of a known element (Sjostrom's generic "Br") with another known, more specific element (Olson-646's HBr or Br₂) to achieve the predictable result of effective mercury removal.
  • Expectation of Success: A POSITA would have had a high expectation of success because the combination applied a known technique (halogen promotion with specific ratios) to a known device (a coal-fired power plant with sorbent injection) for its intended purpose.

• Additional Grounds: Petitioner asserted an additional obviousness challenge (Ground 4) based on Sjostrom and Olson-646, further in view of Eckberg (a 2005 conference presentation). Eckberg was used to provide more specific examples of halogen additives, such as aqueous solutions of calcium bromide and calcium chloride, that a POSITA would have been motivated to use in Sjostrom’s system.

4. Key Technical Contentions (Beyond Claim Construction)

• Priority Date Challenge: A central argument of the petition was that the ’370 patent was not entitled to its claimed priority date of 2004. Petitioner argued that the parent applications in the priority chain taught a different invention: preparing a pre-brominated activated carbon sorbent outside the flue gas and then injecting this single, combined sorbent downstream. Petitioner asserted that the currently claimed method—adding a halogen additive to the coal/combustion chamber separately from the downstream sorbent—was new matter improperly added to the specification in the 2018 application that matured into the ’370 patent. This alleged break in the priority chain was the basis for asserting references like Baldrey (2011), Sjostrom (2005), and Olson-646 (2006) as prior art.

5. Arguments Regarding Discretionary Denial

• Petitioner argued against discretionary denial under Fintiv and §325(d).
  • Fintiv: Petitioner asserted that the parallel district court litigation was in its earliest stages, with a trial date set no earlier than October 2026, well after a Final Written Decision would issue in the IPR.
  • §325(d): Petitioner argued that the examiner did not consider the primary references asserted in the petition (Baldrey, Sjostrom, Eckberg) during prosecution. Therefore, the petition raised new arguments and art that had not been previously evaluated by the USPTO.

6. Relief Requested

• Petitioner requests institution of an IPR and cancellation of claims 1-18 of the ’370 patent as unpatentable.