PacifiCorp et al. v. MES, Inc.

Petition

Petition summary

Invalidity analysis

Prosecution analysis

Examiner search

## 1. Case Identification
- Case Number: [IPR2025-00717](https://ai-lab.exparte.com/case/ptab/IPR2025-00717)
- Patent #: 10,926,218
- Filed: April 8, 2025
- Petitioner(s): [PacifiCorp](https://ai-lab.exparte.com/party/pacificorp), Interstate Power & Light Company, [MidAmerican Energy Company](https://ai-lab.exparte.com/party/midamerican-energy-co), [WEC Energy Group, Inc.](https://ai-lab.exparte.com/party/wec-energy-group-inc), and Wisconsin Power & Light Company
- Patent Owner(s): Birchtech Corp.
- Challenged Claims: 1-4, 6-26

## 2. Patent Overview
- Title: Method of Separating Mercury from a Mercury-Containing Gas
- Brief Description: The [’218 patent](https://ai-lab.exparte.com/case/ptab/IPR2025-00717/doc/1001) discloses methods for removing mercury from flue gas generated by coal combustion. The claimed methods involve adding hydrogen iodide (HI) or an iodide salt to the coal or combustion chamber, and subsequently injecting an activated carbon sorbent downstream to capture the mercury for separation.

## 3. Grounds for Unpatentability

#### Ground 1: Claims 1-4 and 6-26 are obvious over Vosteen589 in view of Starns.
- **Prior Art Relied Upon:** Application # 2004/0013589 (“[Vosteen589](https://ai-lab.exparte.com/case/ptab/IPR2025-00717/doc/1005)”), [Starns](https://ai-lab.exparte.com/case/ptab/IPR2025-00717/doc/1008) (“Full-Scale Test of Mercury Control with Sorbent Injection,” June 2002).
- **Core Argument for this Ground:**
    - **Prior Art Mapping:** Petitioner argued that [Vosteen589](https://ai-lab.exparte.com/case/ptab/IPR2025-00717/doc/1005) discloses the fundamental process for mercury removal from flue gas at coal-fired power stations. [Vosteen589](https://ai-lab.exparte.com/case/ptab/IPR2025-00717/doc/1005) teaches adding a halide (specifically bromine compounds) to coal before combustion to oxidize mercury, making it more easily captured downstream by an activated carbon sorbent. Petitioner asserted that [Vosteen589](https://ai-lab.exparte.com/case/ptab/IPR2025-00717/doc/1005) explicitly suggests substituting or supplementing bromine with more effective (though costlier) iodine compounds, rendering the use of HI or an iodide salt (as claimed) obvious. While [Vosteen589](https://ai-lab.exparte.com/case/ptab/IPR2025-00717/doc/1005) discloses the core chemical process, [Starns](https://ai-lab.exparte.com/case/ptab/IPR2025-00717/doc/1008), a publicly available conference paper, provides the well-known and mature implementation details for activated carbon injection (ACI) that [Vosteen589](https://ai-lab.exparte.com/case/ptab/IPR2025-00717/doc/1005) lacks. [Starns](https://ai-lab.exparte.com/case/ptab/IPR2025-00717/doc/1008) teaches the specific hardware (e.g., silos, feeders) and processes for injecting powdered activated carbon (PAC) upstream of a particulate collector like an electrostatic precipitator (ESP) to capture mercury, as claimed.
    - **Motivation to Combine:** A person of ordinary skill in the art (POSITA) would combine the teachings of [Vosteen589](https://ai-lab.exparte.com/case/ptab/IPR2025-00717/doc/1005) and [Starns](https://ai-lab.exparte.com/case/ptab/IPR2025-00717/doc/1008) to implement a complete and effective mercury removal system. A POSITA looking to apply [Vosteen589](https://ai-lab.exparte.com/case/ptab/IPR2025-00717/doc/1005)’s halide-addition method would naturally turn to a well-documented, mature technology like the ACI system detailed in [Starns](https://ai-lab.exparte.com/case/ptab/IPR2025-00717/doc/1008) to implement the downstream sorbent injection and collection steps.
    - **Expectation of Success:** A POSITA would have a high expectation of success, as the combination involves using a standard ACI system ([Starns](https://ai-lab.exparte.com/case/ptab/IPR2025-00717/doc/1008)) to carry out a sorbent capture step already contemplated by the primary reference ([Vosteen589](https://ai-lab.exparte.com/case/ptab/IPR2025-00717/doc/1005)). The combination merely applies known techniques for their intended purpose to achieve predictable results.
    - **Key Aspects:** Petitioner contended the claimed weight ratio of halide-to-sorbent (claim 1(d)) is not a patentable distinction but an obvious parameter derived from routine optimization. Petitioner demonstrated that by combining the halide concentrations taught by [Vosteen589](https://ai-lab.exparte.com/case/ptab/IPR2025-00717/doc/1005) with the standard sorbent injection rates taught by [Starns](https://ai-lab.exparte.com/case/ptab/IPR2025-00717/doc/1008), a POSITA would arrive at a ratio falling within the claimed range.

#### Ground 2: Claims 1-4 and 6-26 are obvious over Vosteen589 in view of Mass-EPA.
- **Prior Art Relied Upon:** [Vosteen589](https://ai-lab.exparte.com/case/ptab/IPR2025-00717/doc/1005), [Mass-EPA](https://ai-lab.exparte.com/case/ptab/IPR2025-00717/doc/1009) (“Evaluation of the Technological and Economic Feasibility of Controlling and Eliminating Mercury Emissions,” Dec. 2002).
- **Core Argument for this Ground:**
    - **Prior Art Mapping:** This ground is substantially similar to Ground 1, but substitutes the [Mass-EPA](https://ai-lab.exparte.com/case/ptab/IPR2025-00717/doc/1009) government report for the [Starns](https://ai-lab.exparte.com/case/ptab/IPR2025-00717/doc/1008) conference paper. Petitioner argued [Mass-EPA](https://ai-lab.exparte.com/case/ptab/IPR2025-00717/doc/1009), like [Starns](https://ai-lab.exparte.com/case/ptab/IPR2025-00717/doc/1008), describes ACI as a mature, well-understood technology for mercury control. It provides detailed information on injecting activated carbon sorbent, its effectiveness at different concentrations, and its use with ESPs. The core teachings of [Vosteen589](https://ai-lab.exparte.com/case/ptab/IPR2025-00717/doc/1005) regarding halide addition to enhance mercury oxidation remain the same.
    - **Motivation to Combine:** The motivation is analogous to Ground 1. A POSITA implementing [Vosteen589](https://ai-lab.exparte.com/case/ptab/IPR2025-00717/doc/1005)’s process would have been motivated to consult a comprehensive government report like [Mass-EPA](https://ai-lab.exparte.com/case/ptab/IPR2025-00717/doc/1009) for data and best practices on the ACI portion of the system. [Mass-EPA](https://ai-lab.exparte.com/case/ptab/IPR2025-00717/doc/1009) provides an express motivation by stating a goal of improving mercury adsorption efficiency and reducing costs, which aligns with [Vosteen589](https://ai-lab.exparte.com/case/ptab/IPR2025-00717/doc/1005)’s teaching of using more effective halides.
    - **Expectation of Success:** Success would be expected for the same reasons as in Ground 1; the combination integrates known technologies to achieve a predictable outcome.

#### Ground 3: Claims 1, 3, 6-18, and 20-26 are obvious over Lissianski in view of Starns.
- **Prior Art Relied Upon:** Patent 7,514,052 (“[Lissianski](https://ai-lab.exparte.com/case/ptab/IPR2025-00717/doc/1014)”), [Starns](https://ai-lab.exparte.com/case/ptab/IPR2025-00717/doc/1008).
- **Core Argument for this Ground:**
    - **Prior Art Mapping:** Petitioner argued this combination also renders the claims obvious. [Lissianski](https://ai-lab.exparte.com/case/ptab/IPR2025-00717/doc/1014) is presented as a stronger primary reference than [Vosteen589](https://ai-lab.exparte.com/case/ptab/IPR2025-00717/doc/1005) because it explicitly teaches injecting an iodide salt (ammonium iodide, NH4I) into the combustion chamber. [Lissianski](https://ai-lab.exparte.com/case/ptab/IPR2025-00717/doc/1014) explains this salt decomposes into HI, which oxidizes mercury to improve its subsequent capture by ACI. Therefore, [Lissianski](https://ai-lab.exparte.com/case/ptab/IPR2025-00717/doc/1014) teaches the core inventive concept. As in Ground 1, [Starns](https://ai-lab.exparte.com/case/ptab/IPR2025-00717/doc/1008) provides the necessary, well-known implementation details for the ACI system (hardware, injection location, and ESP-based collection) that are described functionally but not structurally in [Lissianski](https://ai-lab.exparte.com/case/ptab/IPR2025-00717/doc/1014).
    - **Motivation to Combine:** A POSITA would combine [Lissianski](https://ai-lab.exparte.com/case/ptab/IPR2025-00717/doc/1014) and [Starns](https://ai-lab.exparte.com/case/ptab/IPR2025-00717/doc/1008) because [Lissianski](https://ai-lab.exparte.com/case/ptab/IPR2025-00717/doc/1014) teaches the "what" (use iodide salt and ACI) and [Starns](https://ai-lab.exparte.com/case/ptab/IPR2025-00717/doc/1008) teaches the "how" (practical implementation of a mature ACI system). This represents a straightforward combination of a specific chemical treatment with its standard application hardware.
    - **Expectation of Success:** A POSITA would have a high expectation of success in combining the specific halogen agent taught by [Lissianski](https://ai-lab.exparte.com/case/ptab/IPR2025-00717/doc/1014) with the standard ACI system detailed in [Starns](https://ai-lab.exparte.com/case/ptab/IPR2025-00717/doc/1008).

- **Additional Grounds:** Petitioner asserted additional obviousness challenges, including:
    - - Claims 1, 3, and 6-26 are obvious over [Lissianski](https://ai-lab.exparte.com/case/ptab/IPR2025-00717/doc/1014) in view of [Mass-EPA](https://ai-lab.exparte.com/case/ptab/IPR2025-00717/doc/1009) (Ground 4), which relies on the same logic as Ground 3 but uses [Mass-EPA](https://ai-lab.exparte.com/case/ptab/IPR2025-00717/doc/1009) as the source for ACI implementation details.
    - - Claims 2, 4, 6, and 23-25 are obvious over [Lissianski](https://ai-lab.exparte.com/case/ptab/IPR2025-00717/doc/1014) and [Starns](https://ai-lab.exparte.com/case/ptab/IPR2025-00717/doc/1008)/[Mass-EPA](https://ai-lab.exparte.com/case/ptab/IPR2025-00717/doc/1009), further in view of [Vosteen589](https://ai-lab.exparte.com/case/ptab/IPR2025-00717/doc/1005) (Grounds 5 and 6). These grounds argued that [Vosteen589](https://ai-lab.exparte.com/case/ptab/IPR2025-00717/doc/1005)’s teaching of adding halides directly to coal pre-combustion would have been an obvious modification to [Lissianski](https://ai-lab.exparte.com/case/ptab/IPR2025-00717/doc/1014)’s system to improve mixing and residence time.

## 4. Relief Requested
- Petitioner requested institution of an inter partes review and cancellation of claims 1-4 and 6-26 of the [’218 patent](https://ai-lab.exparte.com/case/ptab/IPR2025-00717/doc/1001) as unpatentable under 35 U.S.C. §103.

Flue gas mercury removal patent challenged: Lissianski & Starns prior art supports obviousness of 25 claims using iodide & activated carbon injection.

IPR2025-00717

PacifiCorp v. MES, Inc.