PTAB

IPR2025-00424

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 by coal combustion. The methods involve combusting coal with a bromine-containing additive and pyrolysis char, followed by adding a particulate activated carbon sorbent into the resulting gas stream to capture mercury.

Prior Art Relied Upon: Vosteen589 (Application # 2004/0013589) and Starns (a 2002 conference paper on mercury control).
Core Argument for this Ground:
- Prior Art Mapping: Petitioner argued that Vosteen589 teaches the core chemical process: adding a bromine-containing additive (e.g., HBr, NaBr) to coal before it enters a combustion chamber and using a downstream dry emission control system with an activated carbon sorbent to remove mercury. Petitioner contended that the claimed "pyrolysis char" is an inherent byproduct of combusting coal, as taught by Vosteen589. Starns was asserted to supply the well-known implementation details for the sorbent addition step, describing the use of powdered activated carbon (PAC) injection equipment upstream of a particulate control device, such as an electrostatic precipitator (ESP), which Vosteen589 also discloses.
- Motivation to Combine: A POSITA would combine the teachings of Vosteen589 with Starns to implement Vosteen589’s chemical treatment method using the mature, commercially available, and practical hardware and control processes for activated carbon injection (ACI) that Starns describes in detail.
- Expectation of Success: Because Starns described ACI as the "most mature, retrofit technology available," a POSITA would have had a high expectation of success in combining it with Vosteen589's process to achieve predictable mercury removal.

Prior Art Relied Upon: Vosteen589 (Application # 2004/0013589) and Mass-EPA (a Dec. 2002 government report on mercury emissions).
Core Argument for this Ground:
- Prior Art Mapping: The mapping for Vosteen589 is identical to that in Ground 1. Petitioner argued that Mass-EPA, like Starns, provides the necessary details for implementing ACI. Mass-EPA describes ACI using PAC as the most likely candidate for commercialization and discusses its use with particulate control devices like ESPs.
- Motivation to Combine: A POSITA would have been motivated to combine the references because Mass-EPA provides an express reason to do so: improving the efficiency of activated carbons to reduce injection rates and control costs. A POSITA would have understood that adding halogens as taught by Vosteen589 would achieve this stated goal when combined with the ACI technology detailed in Mass-EPA.
- Expectation of Success: Mass-EPA's finding that ACI was ready for commercialization by 2002 would have provided a POSITA with a strong expectation that combining it with Vosteen589's halogen treatment would be successful.

Prior Art Relied Upon: Downs-Boiler (Application # 2008/0107579).
Core Argument for this Ground:
- Prior Art Mapping: Petitioner asserted that Downs-Boiler discloses every element of the challenged claims in a single reference. It teaches a method for mercury removal from flue gas by adding bromine-containing reagents (including HBr, Br₂, and bromide compounds) to coal upstream of or directly into a combustion chamber (a boiler/furnace). Petitioner argued this process inherently creates and combusts pyrolysis char along with the coal and additive. Downs-Boiler further discloses injecting a particulate PAC sorbent into the flue gas downstream of the combustor, which is then removed by particulate collectors (e.g., an ESP or fabric filter), and explicitly shows test data achieving 77% mercury removal, satisfying the "greater than 70 wt %" limitation.
Additional Grounds: Petitioner asserted additional obviousness challenges based on Downs-Boiler in view of Starns (Ground 4) and Downs-Boiler in view of Mass-EPA (Ground 5). These grounds argued that Starns and Mass-EPA provide further details, support, and motivation for implementing the specific ACI system disclosed in Downs-Boiler.

Petitioner adopted the construction for "pyrolysis char" from a parallel district court proceeding. This construction allows for the pyrolysis char to be created within the combustor as a result of coal combustion, rather than requiring it to be a separately added ingredient. This position is critical to Petitioner's arguments that the presence of pyrolysis char is inherent in any prior art process that combusts coal.

A central technical contention advanced across multiple grounds was the inherent formation of pyrolysis char during coal combustion. Petitioner argued that, based on well-established principles of coal chemistry, pyrolysis char is an unavoidable and necessary byproduct of the combustion process. Therefore, any prior art reference teaching the combustion of coal in a furnace inherently discloses the presence of pyrolysis char in the mixture being combusted.

Petitioner argued that the Board should not deny institution under 35 U.S.C. §314(a) based on Fintiv factors because the parallel district court litigation is in its nascent stages, with no scheduling orders or trial dates set.
Petitioner also argued against denial under 35 U.S.C. §325(d), asserting that the primary secondary references for its obviousness grounds (Starns and Mass-EPA) were never presented to or considered by the USPTO examiner. Furthermore, while the primary references Vosteen589 and Downs-Boiler were listed on the face of the ’225 patent, the examiner did not use them in any substantive rejection, which Petitioner characterized as a material error.

Petitioner requests institution of an inter partes review and cancellation of claims 1-2, 5-15, 17-20, and 22-29 of Patent 10,589,225 as unpatentable.