AEP Generation Resources Inc. v. Midwest Energy Emissions Corp.

1. Case Identification

• Case #: IPR2020-01296
• Patent #: 8,168,147
• Filed: July 15, 2020
• Petitioner(s): Aep Generation Resources Inc., Aep Texas Inc. and Southwestern Energy Power Co.
• Patent Owner(s): Midwest Energy Emissions Corp.
• Challenged Claims: 1-2, 4-6, 9-24

2. Patent Overview

• Title: Method for Mercury Removal from Flue Gas
• Brief Description: The ’147 patent relates to methods for removing mercury from flue gas streams, such as those from coal-fired power plants. The invention purports to improve upon known mercury control methods by using exceptionally reactive, bromide-promoted carbon sorbents with specific surface structures and chemical reaction properties.

3. Grounds for Unpatentability

Ground 1: Obviousness over Nelson and Olson-Paper - Claims 1-2, 4-6, 9-17, and 20-24 are obvious over Nelson in view of Olson-Paper.

• Prior Art Relied Upon: Nelson (Patent 6,953,494) and Olson-Paper ("Chemical mechanisms in mercury emission control technologies," a 2003 publication).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Nelson disclosed a method of remediating mercury from coal-fired power plants by preparing a promoted-brominated sorbent from powdered activated carbon (PAC) and a bromine promoter (HBr/Br2). The only allegedly novel feature of the ’147 patent, which overcame a rejection during prosecution, was the limitation that the activated carbon contains "graphene sheets having carbene species edge sites." Petitioner asserted that Olson-Paper, which was not before the examiner, explicitly disclosed that the specific brand of PAC used in Nelson (Norit Darco FGD) inherently contains these exact carbene structures at the edges of its graphene layers.
  • Motivation to Combine: A Person of Ordinary Skill in the Art (POSITA) would combine Nelson, which taught a practical implementation, with Olson-Paper, which detailed the underlying chemical-reaction mechanisms for the same technology. Both references taught using halogens to improve mercury removal with activated carbon, and both specifically referenced using Norit Darco FGD sorbent. A POSITA would have recognized the teachings of chlorine-based reactions in Olson-Paper as applicable to the bromine-based system in Nelson, as chlorine and bromine are well-known chemical equivalents in the halogen group.
  • Expectation of Success: A POSITA would have a high expectation of success because the combination amounted to confirming the scientific basis for a known, working process. The combination did not require modifying Nelson's process but merely provided a more detailed chemical explanation for its effectiveness.

Ground 2: Obviousness over Nelson, Olson-Paper, and Lissianski-Patent - Claims 11-12 and 17-20 are obvious over Nelson and Olson-Paper in view of Lissianski-Patent.

• Prior Art Relied Upon: Nelson (Patent 6,953,494), Olson-Paper (a 2003 publication), and Lissianski-Patent (Patent 7,514,052).
• Core Argument for this Ground:
  • Prior Art Mapping: This ground built upon the combination of Nelson and Olson-Paper by adding the teachings of Lissianski-Patent. Lissianski-Patent disclosed injecting a halogen agent (e.g., from ammonium bromide, which decomposes into HBr) into a flue gas stream upstream of a sorbent injection. This process was taught to enhance mercury oxidation and, critically, to improve NOx reduction in plants equipped with a selective catalytic reduction (SCR) unit. The combination would result in a system where the pre-brominated sorbent from Nelson was injected into a flue gas stream that was already being treated with an upstream halogen injection per Lissianski-Patent.
  • Motivation to Combine: A POSITA would combine Lissianski-Patent with the Nelson/Olson-Paper system to achieve multi-pollutant control, simultaneously improving both mercury and NOx removal. Since both Nelson and Lissianski-Patent contemplated use in power plants with SCR units, combining the teachings was a natural and predictable step for process optimization. The additional upstream halogen from Lissianski-Patent would further promote the sorbent from Nelson, enhancing mercury capture without increasing the sorbent injection rate.

Ground 3: Obviousness over Downs-Halogenation and Olson-Paper - Claims 1-2, 4-6, 11-12, 15-16, and 21-24 are obvious over Downs-Halogenation in view of Olson-Paper.

• Prior Art Relied Upon: Downs-Halogenation (Application # 2007/0180990) and Olson-Paper (a 2003 publication).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Downs-Halogenation, like Nelson, taught a method for mercury removal using brominated sorbents but through a different process. Downs-Halogenation disclosed an "in-flight" system where PAC sorbent and a bromine-containing reagent were separately injected into a transport gas line, allowing them to react and form a promoted sorbent before injection into the main flue gas. As with the Nelson-based grounds, Petitioner contended that Downs-Halogenation did not detail the surface chemistry, which was supplied by Olson-Paper's disclosure of carbene edge sites on PAC.
  • Motivation to Combine: The motivation was identical to Ground 1: a POSITA would look to Olson-Paper to understand the underlying chemical mechanisms of the process taught in Downs-Halogenation. Both references involved using halogens to promote PAC for mercury removal, making the combination logical for a skilled artisan seeking to understand and optimize the technology.
• Additional Grounds: Petitioner asserted additional obviousness challenges in Ground 4, arguing claims 17-20 were obvious over the combination of Downs-Halogenation, Olson-Paper, and Lissianski-Patent, relying on similar motivations for multi-pollutant control and enhanced mercury removal as described in Ground 2.

4. Key Technical Contentions (Beyond Claim Construction)

• The central technical contention was that the examiner allowed the ’147 patent claims based on the applicants’ argument that the prior art of record did not disclose “activated carbon containing graphene sheets having carbene species edge sites.” Petitioner argued that Olson-Paper, which was not before the examiner, explicitly described this exact feature in the same commercial sorbent (Norit Darco FGD) used in the primary references, thereby negating the patentable distinction upon which the patent was granted.

5. Arguments Regarding Discretionary Denial

• Petitioner argued that the Board should not exercise discretionary denial under §314(a) (Fintiv) because the co-pending district court litigation was in its infancy, with a trial date nearly two years away. An FWD would therefore conclude long before trial.
• Petitioner also argued that denial under §325(d) would be inappropriate because the petition presented prior art and arguments not previously considered by the USPTO. Specifically, the examiner was never presented with Olson-Paper, which disclosed the dispositive "carbene edge sites" limitation, or Downs-Halogenation, which formed the basis of separate grounds.

6. Relief Requested

• Petitioner requested institution of an inter partes review and cancellation of claims 1-2, 4-6, and 9-24 of Patent 8,168,147 as unpatentable.