NRG Energy Inc v. Midwest Energy Emissions Corp

1. Case Identification

• Case #: IPR2020-00928
• Patent #: 8,168,147
• Filed: May 27, 2020
• Petitioner(s): NRG Energy, Inc., Talen Energy Corporation, and Vistra Energy Corp.
• Patent Owner(s): Midwest Energy Emissions Corp.
• Challenged Claims: 18-19

2. Patent Overview

• Title: Sorbents for the Oxidation and Removal of Mercury
• Brief Description: The ’147 patent relates to methods for removing mercury from flue gas. The technology involves using promoted carbon sorbents, specifically by treating activated carbon with a bromine-containing promoter to improve mercury capture.

3. Grounds for Unpatentability

Ground 1: Claims 18-19 are obvious over Lissianski-Presentation in view of Olson-646

• Prior Art Relied Upon: Lissianski-Presentation (a 2006 conference presentation) and Olson-646 (Application # 2006/0048646).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Lissianski-Presentation disclosed a system for mercury control in low-rank coals that meets the limitations of the challenged claims. This system involved injecting bromine-containing promoters and activated carbon sorbent separately into a mercury-containing flue gas stream, followed by particulate removal with an electrostatic precipitator (ESP) or fabric filter. Olson-646 was argued to supply the underlying chemical theory absent from Lissianski-Presentation, teaching that the activated carbon sorbent ("Darco FGD," the same brand used in Lissianski) contains graphene sheets with carbene edge sites. Olson-646 further explained that a bromine promoter (like HBr) reacts with these sites to form a promoted sorbent with a carbocation, which then chemically reacts with and captures elemental mercury. Together, the references were asserted to teach every limitation of claims 18 and 19.
  • Motivation to Combine: A Person of Ordinary Skill in the Art (POSITA) would combine the references because they address the identical technical problem (mercury removal from flue gas) using the same core components (bromine promoters and activated carbon). A POSITA reviewing the practical system in Lissianski-Presentation would have been motivated to consult a reference like Olson-646 to understand the underlying chemical reactions and optimize the process, such as by selecting specific bromine compounds (HBr or Br₂) taught by Olson-646.
  • Expectation of Success: A POSITA would have a reasonable expectation of success because the combination involved applying the known chemical principles from Olson-646 to explain and optimize the known mercury control system of Lissianski-Presentation.

Ground 2: Claims 18-19 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 asserted that Sjostrom disclosed enhancing mercury removal from flue gas in coal-fired power plants by injecting halogens (including bromine) and an activated carbon sorbent. Sjostrom's diagrams showed flexibility in injection points, including injecting bromine into the boiler (Location 2) and injecting the sorbent downstream. This taught the claimed separate injection into a mercury-containing gas stream. The flue gas acts as a transport gas for the in-flight reaction. As in Ground 1, Olson-646 was used to provide the detailed chemical mechanisms, teaching the reaction between the bromine promoter and the carbene sites on the activated carbon to form a promoted sorbent that captures mercury.
  • Motivation to Combine: The motivation was argued to be the same as in Ground 1. A POSITA would combine Sjostrom's disclosure of a full-scale mercury control system with Olson-646's theoretical explanation to better understand the reaction mechanisms and improve the system's effectiveness. Both references teach using the same commercial sorbent (Darco FGD), reinforcing the rationale for combination.
  • Expectation of Success: A POSITA would have a high expectation of success, as Olson-646's teachings on bromine-carbon chemistry were directly applicable to the bromine and carbon injection system disclosed by Sjostrom to achieve predictable results in mercury capture.

4. Key Technical Contentions (Beyond Claim Construction)

• Priority Date Challenge: A central argument of the petition was that claims 18-19 are not entitled to the priority date of the 2004 provisional application. Petitioner contended that the intervening parent applications fail to provide written description support for the key limitations of claims 18-19: separately injecting a promoter and sorbent into a mercury-containing gas.
• Petitioner argued the parent applications only disclosed combining the promoter and sorbent in a common transport line containing no mercury before injecting the mixture into the flue gas. Because priority was allegedly broken, the effective filing date for claims 18-19 is no earlier than April 6, 2009, making the Lissianski-Presentation (2006) and Sjostrom (2005) references available as prior art under 35 U.S.C. §102.

5. Arguments Regarding Discretionary Denial

• Against §314(a) (Fintiv): Petitioner argued that denial would be inappropriate because the parallel district court proceeding was in its earliest stages. At the time of filing, multiple motions to dismiss were pending, Petitioners had not answered the complaint, no trial schedule was set, and discovery had not commenced. Therefore, a Final Written Decision in the IPR would likely issue well before any trial.
• Against §325(d): Petitioner contended that denial would be improper because the primary references, Lissianski-Presentation and Sjostrom, were never considered by the USPTO during prosecution. While Olson-646 was of record, it was not applied in a substantive rejection. Thus, the petition raised art and arguments not previously before the Office.

6. Relief Requested

• Petitioner requests institution of inter partes review and cancellation of claims 18 and 19 of the ’147 patent as unpatentable.