PTAB

IPR2025-00425

PacifiCorp v. MES Inc

Key Events

Petition

petition

Title: Method for Treating a Mercury-Containing Gas
Brief Description: The ’225 patent discloses methods for removing mercury from flue gas generated during fossil fuel combustion. The claimed methods involve combusting a mixture of coal, pyrolysis char, and a bromine-containing additive to form a mercury-containing gas, and subsequently adding a particulate activated carbon sorbent into that gas.

Prior Art Relied Upon: Sjostrom (a 2005 conference presentation on mercury control) and Eckberg (a 2005 conference presentation on halogen injection).
Core Argument for this Ground:
- Prior Art Mapping: Petitioner argued that Sjostrom taught the fundamental claimed process: adding a generic bromine-containing substance ("Br") to coal or directly into the combustion chamber (locations 1 and 2) and subsequently injecting an activated carbon sorbent downstream to capture mercury. Eckberg disclosed the specific implementation details that Sjostrom lacked, namely the use of an aqueous calcium bromide (CaBr₂) solution as the "Br" additive injected into the boiler.
- Motivation to Combine: A POSITA would combine the references because they address the same problem of mercury removal, use complementary techniques, and were presented consecutively in the same technical session at the 2005 Electric Utilities Environment Conference (EUEC). Eckberg provided a clear, practical solution (using CaBr₂) for implementing Sjostrom's more general disclosure, representing a simple substitution of a known component.
- Expectation of Success: Given that both references described proven techniques for mercury removal and were presented as complementary, a POSITA would have had a high expectation of success in achieving predictable, high-efficiency mercury removal.

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 while Sjostrom taught the overall system, Olson-646 provided key enabling details. Olson-646 specifically taught using gaseous hydrogen bromide (HBr) or molecular bromine (Br₂) as the promoter additive and explained the chemical mechanisms by which these promoters enhance mercury capture on activated carbon. Olson-646 also disclosed using a continuous emissions monitor in a feedback loop to control the sorbent injection rate, mapping to dependent claims 6 and 24.
- Motivation to Combine: A POSITA would have been motivated to consult Olson-646 to understand the underlying chemistry of the process described in Sjostrom and to select a specific, effective promoter (HBr or Br₂) to implement Sjostrom's system. This combination represented a routine optimization of a known process to achieve predictable results.
- Expectation of Success: Olson-646’s detailed explanation of the reaction mechanisms and its use of the same commercial activated carbon sorbent as Sjostrom would have provided a POSITA with a strong and reasonable expectation of success.

Prior Art Relied Upon: Olson-235 (Patent 8,652,235).
Core Argument for this Ground:
- Prior Art Mapping: Based on the argument that the ’225 patent’s priority date is no earlier than May 15, 2015, the February 2014 issuance of Olson-235 makes it an anticipatory reference. Petitioner argued Olson-235 discloses every limitation of the challenged claims. Specifically, Olson-235 teaches introducing a halogen promoter (e.g., gaseous HBr or Br₂) into a combustion chamber that combusts coal, which inherently produces pyrolysis char. Downstream, a particulate activated carbon sorbent is injected into the mercury-containing gas. Olson-235 also explicitly discloses using feedback control, particulate separators like ESPs, and specific coal types (subbituminous, lignite), anticipating numerous dependent claims.

Petitioner adopted the Patent Owner's construction from co-pending district court litigation for the term "pyrolysis char." This construction allows for the pyrolysis char to be created in situ within the combustor from the combustion of coal, rather than requiring it to be a separately added component. This position is central to Petitioner's arguments that the presence of pyrolysis char is an inherent and obvious result of combusting coal as taught by the prior art.

A central contention underpinning all grounds is that the ’225 patent is not entitled to a priority date earlier than May 15, 2015. Petitioner argued that prior to a preliminary amendment on that date, the patent’s specification and its entire non-provisional priority chain lacked written description support for the key limitation of adding specific bromine-containing additives (HBr, bromide compounds) directly to the coal or into the combustion chamber. Petitioner asserted the prior applications were exclusively directed to a different process: pre-treating an activated carbon sorbent with bromine outside the flue gas stream and then injecting the pre-treated sorbent downstream of combustion. This alleged break in the priority chain makes references published between 2005 and 2014 valid prior art against the challenged claims.

Petitioner argued against discretionary denial under §314(a) and the Fintiv factors, asserting that the parallel district court litigation is in its earliest stages, with no scheduling orders or trial dates set. Petitioner also contended that denial under §325(d) is inappropriate because the patent examiner never considered the primary references (Sjostrom and Eckberg) during prosecution. Furthermore, Petitioner argued the examiner erred by not re-evaluating priority and applying intervening prior art after the 2015 claim amendments fundamentally changed the nature of the claimed invention.

Petitioner requests institution of an inter partes review and cancellation of claims 1-2, 5-15, 17-20, and 22-29 of the ’225 patent as unpatentable.