US 10933370

Here is a concise summary of US patent 10933370:

US Patent 10,933,370 B2

• Title: Sorbents for the oxidation and removal of mercury
• Assignee (Current): Birchtech Corp
• Inventors: Edwin S. Olson, Michael J. Holmes, John H. Pavlish
• Filing Date: April 12, 2018
• Issue Date: March 2, 2021
• Abstract: The patent describes highly reactive, regenerable sorbents and methods for removing pollutants, especially mercury, from gas streams such as flue gas from fossil fuel combustion or product gas from gasification systems. The sorbents are halogen/halide promoted activated carbon, which capture mercury through surface reactions with very short contact times, exhibiting high initial reactivity without an induction period. The invention also covers methods for preparing, regenerating, and reusing these sorbents, including in-flight preparation and injection, and methods for controlling sorbent injection rates based on continuous mercury emission monitoring.

Plain-Language Overview of Independent Claims:

• Independent Claim 1 (Composition Claim): This claim describes a special material called a "promoted carbon sorbent". It's made by taking a basic activated carbon and reacting it with a "promoter," which can be a halogen (like bromine) or a halide, or a combination of these. The key is that the resulting material is effective at removing mercury from a gas stream.
• Independent Claim 12 (Method of Preparation Claim): This claim outlines a method for creating the promoted carbon sorbent. It involves starting with granular activated carbon and making it react with a promoter (again, a halogen, halide, or a combination) to produce the mercury-removing sorbent.
• Independent Claim 22 (Method of Use Claim): This claim details a method for reducing mercury in flue gas. It involves providing the sorbent, injecting it into the mercury-containing flue gas, ensuring that over 70% of the mercury is captured by the sorbent to clean the gas, and then recovering most of the used sorbent from the cleaned gas.
• Independent Claim 27 (Method of Use/Recovery Claim): This claim describes a method for reducing mercury in gas streams that contain both mercury and ash. The distinct feature is using activated carbon sorbent particles that are larger than 40 micrometers. This specific size allows the sorbent particles to be separated from the smaller ash particles based on their size after mercury is captured, and then the sorbent particles can be reused by re-injecting them into the gas stream.

USPTO and CAFC 2026 Docket Information:

As of April 26, 2026, no specific dockets directly related to US Patent 10933370 have been found in the CAFC 2026 dockets. However, the patent is involved in Patent Trial and Appeal Board (PTAB) proceedings. Specifically, PTAB case IPR2025-00688, titled "Pacificorp et al v. Birchtech Corp. IPR of US10933370B2", was filed on March 24, 2025, and an institution decision was made on February 10, 2026. Other listed litigation includes multiple cases in various US District Courts (Kansas, Missouri Eastern, Wyoming, Wisconsin Western, Arizona, Iowa Southern) and other PTAB cases (IPR2025-00687, IPR2025-01324), as well as general "worldwide family litigation," but these do not explicitly show CAFC 2026 docket entries for this specific patent.

Here is a list of known litigation involving US patent 10933370, as of April 26, 2026:

1. IPR2025-01324

• Plaintiff(s): Union Electric Company
• Defendant(s): Birchtech Corp.
• Jurisdiction: Patent Trial and Appeal Board (PTAB)
• Case Number: IPR2025-01324
• Filing Date: July 18, 2025
• Outcome or Current Status: Terminated on November 20, 2025.

2. IPR2025-00688

• Plaintiff(s): Pacificorp et al
• Defendant(s): Birchtech Corp.
• Jurisdiction: Patent Trial and Appeal Board (PTAB)
• Case Number: IPR2025-00688
• Filing Date: March 24, 2025
• Outcome or Current Status: Terminated on February 10, 2026.

3. IPR2025-00687

• Plaintiff(s): Petitioner (specific name unknown)
• Defendant(s): Patent Owner (Birchtech Corp. as assignee, specific name for this case unknown)
• Jurisdiction: Patent Trial and Appeal Board (PTAB)
• Case Number: IPR2025-00687
• Filing Date: Unknown
• Outcome or Current Status: Settlement

4. IN RE: MIDWEST ENERGY EMISSIONS CORP. PATENT LITIGATION (MDL No. 3132)

• Plaintiff(s): Midwest Energy Emissions Corp. (ME2C), now Birchtech Corp.
• Defendant(s): Multiple defendants, including Berkshire Hathaway Energy Company, MidAmerican Energy Company, PacifiCorp, Alliant Energy Corporation, Alliant Energy Corporate Services, Inc., Interstate Power and Light Company, Wisconsin Power and Light Company, Ameren Corp., Union Electric Co. (d/b/a Ameren Missouri), and Salt River Project Agricultural Improvement and Power District.
• Jurisdiction: United States Judicial Panel on Multidistrict Litigation, centralized in the Southern District of Iowa.
• Case Number: MDL No. 3132 (also listed as 4:24-md-03132 in the original patent text).
• Filing Date: Centralization order dated December 12, 2024. Underlying lawsuits filed as early as July 30, 2024.
• Outcome or Current Status: Litigation centralized in the Southern District of Iowa. US10933370B2 is asserted in each action within this MDL, alleging infringement related to mercury capture technologies at coal-fired power plants.

5. United States District Court for the Southern District of Iowa (Underlying MDL Cases)

• Plaintiff(s): Midwest Energy Emissions Corp. (ME2C Environmental), now Birchtech Corp.
• Defendant(s): Berkshire Hathaway Energy Company, MidAmerican Energy Company, PacifiCorp, Alliant Energy Corporation, Interstate Power and Light Company, and Wisconsin Power and Light Company.
• Jurisdiction: Iowa Southern District Court
• Case Number(s): 4:24-cv-00243, 4:24-cv-00446, 4:24-cv-00447.
• Filing Date: July 30, 2024.
• Outcome or Current Status: Centralized as part of MDL No. 3132 in the Southern District of Iowa as of December 12, 2024.

6. United States District Court for the Eastern District of Missouri (Underlying MDL Case)

• Plaintiff(s): Midwest Energy Emissions Corp. (ME2C Environmental), now Birchtech Corp.
• Defendant(s): Ameren Corp. and Union Electric Co.
• Jurisdiction: Missouri Eastern District Court
• Case Number: 4:24-cv-00980.
• Filing Date: July 30, 2024.
• Outcome or Current Status: Centralized as part of MDL No. 3132 in the Southern District of Iowa as of December 12, 2024.

7. United States District Court for the District of Arizona (Underlying MDL Case)

• Plaintiff(s): Midwest Energy Emissions Corp. (ME2C Environmental), now Birchtech Corp.
• Defendant(s): Tucson Electric Power Co., San Carlos Resources, Inc., Salt River Project Agricultural Improvement and Power District, Tri-State Generation and Transmission Association, Inc., Springerville Unit 3 Holding LLC, and Springerville Unit 3 Partnership LP.
• Jurisdiction: Arizona District Court
• Case Number: 3:24-cv-08145.
• Filing Date: July 30, 2024.
• Outcome or Current Status: Centralized as part of MDL No. 3132 in the Southern District of Iowa as of December 12, 2024.

8. United States District Court for the Western District of Missouri

• Plaintiff(s): Birchtech Corp.
• Defendant(s): Evergy, Inc., Evergy Metro Inc., Evergy Missouri West, Inc., and Evergy Kansas Central, Inc.
• Jurisdiction: Missouri Western District Court
• Case Number: 4:25-cv-00050.
• Filing Date: January 23, 2025.
• Outcome or Current Status: Transferred to the U.S. District Court for the Southern District of Iowa. (Likely part of the ongoing MDL).

Other Cases from Patent Text (Details Unknown from Search Results):
The following cases are listed in the original patent document under "Family has litigation" but specific plaintiff, defendant, filing date, and detailed outcome/status information were not found in the search results to confirm their relation to US10933370B2 or provide full details:

• Kansas District Court: Case Number: 5:25-cv-04033
• Wyoming District Court: Case Number: 2:25-cv-00015
• Wyoming District Court: Case Number: 1:25-cv-00015
• Wisconsin Western District Court: Case Number: 3:25-cv-00026
• Iowa Southern District Court: Case Number: 4:25-cv-00154
• Iowa Southern District Court: Case Number: 4:25-cv-00046
• Iowa Southern District Court: Case Number: 4:25-cv-00037

Note on Patent Expiration:
US Patent 10933370 expired on April 24, 2026. This means that while ongoing litigation for past infringement may continue, new infringement actions cannot be filed for acts occurring after this date.

Proceedings overview

One AIA trial proceeding is on file for US patent 10933370, which resulted in a discretionary denial of institution. This outcome means the patent's claims have not undergone a full merits review at the PTAB, suggesting the patent has not been substantively challenged and its claims remain intact.

IPR2025-01324 — UNION ELECTRIC COMPANY et al. v. Birchtech Corp.

• Type: Inter Partes Review
• Filed: 2025-07-18
• Status: Discretionary Denial. This indicates that the Patent Trial and Appeal Board (PTAB) chose not to institute an inter partes review trial, likely based on procedural or policy considerations, rather than a comprehensive review of the patentability merits. The proceeding was officially terminated on 2025-11-20.
• Judge panel: The institution decision was likely issued by the Director of the USPTO, John Squires. Around the time of this decision (late 2025), the Director had taken personal control over institution decisions, often issuing summary denials without specifying a panel of Administrative Patent Judges.
• Petition grounds: Specific claims challenged, prior art cited, and the statutory bases (§ 102 / § 103 / § 112) for the challenge are not publicly detailed in the context of a discretionary denial.
• Institution decision: Denied on 2025-11-20. The denial was procedural, consistent with a broader trend at the PTAB at that time to deny institution on discretionary grounds, often citing factors like parallel district court litigation, proximity of trial dates, or policies concerning multiple petitions.
• Final Written Decision (if issued): Not applicable, as institution of the trial was denied.
• Settlement / termination: The proceeding terminated with the denial of institution on 2025-11-20.
• Appeal: Institution decisions are generally final and non-appealable.
• Defensive value: For a defendant, this means that the claims of US10933370 have not been invalidated by the PTAB through this proceeding. While the specific grounds raised by UNION ELECTRIC COMPANY et al. (and their privies) may be estopped in future proceedings or litigation, the scope of estoppel from a discretionary denial is typically narrower than from a full merits review.

Strategic summary

All claims of US10933370 remain UNTESTED by the PTAB on their merits, as the single inter partes review proceeding (IPR2025-01324) resulted in a discretionary denial of institution. No claims have been canceled or formally sustained through a Final Written Decision.

The estoppel landscape for IPR2025-01324 is that UNION ELECTRIC COMPANY et al. and their privies may be estopped from asserting the specific prior-art grounds raised in their petition in subsequent litigation or PTAB proceedings, pursuant to 35 U.S.C. § 315(e)(2). However, because institution was denied on discretionary grounds rather than a decision on the merits, the breadth of this estoppel can be a complex legal question, potentially leaving other, non-raised prior-art grounds open. Other non-privy defendants are generally not affected by this estoppel.

The pattern signals indicate that this denial occurred during a period (late 2025) when USPTO Director John Squires frequently issued summary discretionary denials, often without extensive explanation, potentially to manage the PTAB's caseload or to address concerns about parallel litigation. Birchtech Corp. is an active patent owner, known for its intellectual property portfolio in activated carbon technologies and has been involved in multiple patent infringement lawsuits, securing settlements and significant verdicts. The denial of this IPR petition suggests a strategy by the patent owner to defend its patents against PTAB challenges, or reflects a broader PTAB policy favoring such denials in certain contexts, rather than a definitive test of the patent's validity.

Recommended next steps

As a defendant facing assertion of US10933370 today, it is crucial to recognize that no claims of this patent have been invalidated by the PTAB. The discretionary denial of IPR2025-01324 means that the patent's claims have not undergone a substantive validity review at the PTAB. Any consideration of a new IPR challenge should include a thorough analysis of the specific grounds for the discretionary denial in IPR2025-01324, an assessment of the current PTAB discretionary denial policies (such as the Fintiv factors), and a strategy to present new prior art or distinct non-estoppeled grounds that might overcome these policies, especially if there is ongoing parallel district court litigation.

Inventors

• Edwin S. Olson: Midwest Energy Emissions Corp. (implied by original assignee)
• Michael J. Holmes: Midwest Energy Emissions Corp. (implied by original assignee)
• John H. Pavlish: Midwest Energy Emissions Corp. (implied by original assignee)

No unusual patterns, such as all inventors departing the original assignee within 12 months of filing, are immediately apparent from the provided information.

Original assignee

The original assignee, as listed on the issued patent, is Midwest Energy Emissions Corp.. Their primary line of business, based on the patent's subject matter, is likely related to environmental technologies, specifically mercury removal from gas streams, suggesting they shipped products or provided services embodying the claims. As of November 7, 2024, Midwest Energy Emissions Corp. reassigned the patent to Birchtech Corp..

Assignment timeline

• 2019-09-23 (executed) / recorded 2019-09-23

  • Conveyance: Assignment of Assignors Interest
  • Assignor: PAVLISH, JOHN H.
  • Assignee: ENERGY AND ENVIRONMENTAL RESEARCH CENTER FOUNDATION
  • Correspondent: Not specified in Google Patents, but likely the attorney for the Energy and Environmental Research Center Foundation.
  • Context: Transfer from individual inventor to research institution.

• 2019-09-23 (executed) / recorded 2019-09-23

  • Conveyance: Assignment of Assignors Interest
  • Assignor: HOLMES, MICHAEL J.
  • Assignee: ENERGY AND ENVIRONMENTAL RESEARCH CENTER FOUNDATION
  • Correspondent: Not specified in Google Patents, but likely the attorney for the Energy and Environmental Research Center Foundation.
  • Context: Transfer from individual inventor to research institution.

• 2019-09-23 (executed) / recorded 2019-09-23

  • Conveyance: Assignment of Assignors Interest
  • Assignor: OLSON, EDWIN S.
  • Assignee: ENERGY AND ENVIRONMENTAL RESEARCH CENTER FOUNDATION
  • Correspondent: Not specified in Google Patents, but likely the attorney for the Energy and Environmental Research Center Foundation.
  • Context: Transfer from individual inventor to research institution.

• 2019-09-23 (executed) / recorded 2019-09-23

  • Conveyance: Assignment of Assignors Interest
  • Assignor: ENERGY AND ENVIRONMENTAL RESEARCH CENTER FOUNDATION
  • Assignee: MIDWEST ENERGY EMISSIONS CORP.
  • Correspondent: Not specified in Google Patents, but likely the attorney for Midwest Energy Emissions Corp.
  • Context: Transfer from research institution to original assignee.

• 2024-11-07 (executed) / recorded 2024-11-07

  • Conveyance: Change of Name
  • Assignor: MIDWEST ENERGY EMISSIONS CORP.
  • Assignee: BIRCHTECH CORP.
  • Correspondent: Not specified in Google Patents, but likely the attorney for Birchtech Corp.
  • Context: Corporate name change from Midwest Energy Emissions Corp. to Birchtech Corp.

Timeline diagram

timeline
    title Ownership of US 10933370
    2018 : Filed by Midwest Energy Emissions Corp
    2019 : Inventors assigned to EERC Foundation
         : EERC Foundation assigned to Midwest Energy Emissions Corp
    2021 : Issued
    2024 : Midwest Energy Emissions Corp changed name to Birchtech Corp

NPE / troll-pattern signals

1. Shell-entity transfer — Unclear. While Birchtech Corp. could potentially be a licensing entity, there is no explicit evidence in the provided data (e.g., registered-agent address, explicit statement of no products) to confirm it is a shell entity. The conveyance type is "Change of Name", suggesting a rebranding or corporate restructuring of an existing operating company rather than a transfer to a new, separate shell.

2. Known asserter in the chain — Not present. None of the assignees (Midwest Energy Emissions Corp., Energy and Environmental Research Center Foundation, Birchtech Corp.) are listed as known NPEs in common directories based on the provided information.

3. Repeat correspondent across the chain — Unclear. The provided Google Patents data does not include correspondent information for the assignment records, making it impossible to assess this signal.

4. Cascading transfers — Not present. There are two transfers in 2019, from individual inventors to a foundation, and then from the foundation to Midwest Energy Emissions Corp., both occurring on the same day. This suggests an internal organizational or IP management process rather than a rapid, speculative transfer through multiple LLCs.

5. Pre-litigation transfer — Unclear. The earliest listed litigation (IPR2025-00688) was filed on March 24, 2025. The most recent assignment (change of name) occurred on November 7, 2024, which is within six months of the IPR filing. However, an IPR is a patent validity challenge, not an infringement suit, and the "Change of Name" conveyance type does not suggest a transfer specifically to enable litigation.

6. Bankruptcy fire-sale — Not present. No evidence of bankruptcy proceedings for Midwest Energy Emissions Corp. or Birchtech Corp. is provided.

7. Privateering — Not present. No information suggests an operating company transferred the patent to an NPE for assertion against competitors.

8. Defensive aggregator (anti-NPE) — Not present. The chain does not terminate at a known defensive aggregator.

Verdict

Insufficient data. While there is litigation activity related to the patent (multiple district court cases and PTAB challenges), the provided assignment records primarily show a transfer from inventors to a research foundation, then to an operating company, followed by a corporate name change. The lack of correspondent information and explicit evidence for shell entities or known NPEs in the chain prevents a confident determination of NPE activity.

USPTO Assignment Center search page: https://assignmentcenter.uspto.gov/ (Search for patent number 109333370)

To identify the most relevant prior art for US patent 10933370, I will refer to the citations listed within the patent itself, as this is typically the most direct way to ascertain the prior art considered by the patent examiner.

According to 35 U.S.C. § 102, a patent claim is anticipated if every element of the claim is found, either explicitly or inherently described, in a single prior art reference that predates the effective filing date of the patent.

Below are the most relevant prior art references cited in US10933370B2, along with their publication/filing dates, a brief description, and which claims they potentially anticipate.

Cited US Patent References:

• U.S. Pat. No. 4,786,483

  • Publication Date: November 22, 1988 (Approximate, exact filing date not readily available from provided text, but publication date is critical for prior art analysis).
  • Description: This patent describes porous beds containing a mercury oxidizing reagent, specifically peroxomonosulfate, on a solid support for the removal of mercury from gas streams.
  • Potential Anticipation: This reference could potentially anticipate aspects of claims related to sorbent compositions and methods for mercury removal (e.g., Independent Claims 1, 12, 22) to the extent that it discloses a supported reagent for mercury oxidation. However, US10933370B2 specifically distinguishes itself by claiming a "halogen/halide promoted activated carbon" that forms a chemical compound with the carbon, and also highlights regenerability. The '483 patent's reagent material is noted as being "destroyed either by reaction with the flue gas during sorption or by attempts to regenerate the sorbent," suggesting a difference in regenerability that could differentiate US10933370's claims.

• U.S. Pat. No. 3,194,629

  • Publication Date: July 13, 1965 (Approximate, exact filing date not readily available from provided text).
  • Description: This patent is cited in the context of porous beds containing a mercury oxidizing reagent on a solid support, specifically mentioning triiodide or other mixed halogens, or sulfur, for mercury removal from gas streams.
  • Potential Anticipation: Similar to '483, this patent might anticipate broader aspects of sorbent compositions and mercury removal methods (e.g., Independent Claims 1, 12, 22). However, US10933370B2 emphasizes a reactive compound produced by the reaction of bromine (or halide or other halogen) with the carbon and notes that its sorbent is regenerable. The '629 patent's reagent material is also stated to be destroyed, indicating a potential distinction in regenerability. Furthermore, US10933370B2 notes that the sorbent it produces from halogen and activated carbon "does not represent a molecular halogen form, but rather a new chemically modified carbon (or halocarbon) structure," which may differentiate it from prior art involving molecular halogen complexes on a support.

• U.S. Pat. No. 3,662,523

  • Publication Date: May 16, 1972 (Approximate, exact filing date not readily available from provided text).
  • Description: This patent is also cited for porous beds containing a mercury oxidizing reagent on a solid support, specifically mentioning triiodide or other mixed halogens.
  • Potential Anticipation: Similar to '483 and '629, this could broadly anticipate claims related to mercury removal using supported halogen-based reagents (e.g., Independent Claims 1, 12, 22). The same distinctions regarding the chemical modification of the carbon structure and regenerability made for the '629 patent would likely apply here.

• U.S. Pat. No. 4,101,631

  • Publication Date: July 18, 1978 (Approximate, exact filing date not readily available from provided text).
  • Description: Cited for porous beds containing sulfur on a solid support for mercury removal.
  • Potential Anticipation: This could potentially anticipate aspects of claims (e.g., Independent Claims 1, 12) if they broadly cover sulfur-containing sorbents for mercury removal. However, US10933370B2 focuses on halogen/halide promoted activated carbon and describes a specific chemical reaction to form a reactive compound, which may differentiate it. Also, US10933370B2 mentions adding a "mercury-stabilizing reagent selected from the group consisting of S, Se, H2S, SO2, H2Se, SeO2, CS2, P2S5, and combinations thereof" as an additional component, implying that sulfur alone as the primary active component might be distinct from the core halogen/halide promoted carbon.

• U.S. Pat. No. 4,708,853

  • Publication Date: November 24, 1987 (Approximate, exact filing date not readily available from provided text).
  • Description: Also cited for porous beds containing sulfur on a solid support for mercury removal.
  • Potential Anticipation: Similar to '631, this could anticipate claims (e.g., Independent Claims 1, 12) related to sulfur-based sorbents. The same distinctions as for '631 would likely apply.

• U.S. Pat. No. 4,814,152 (Yan)

  • Publication Date: March 21, 1989 (Approximate, exact filing date not readily available from provided text).
  • Description: Describes a Hg sorbent comprising elemental sulfur and a metal catalyst on a carbon support. The patent explicitly notes that "This method did not appear to employ a halide."
  • Potential Anticipation: This patent might anticipate aspects of claims (e.g., Independent Claims 1, 12) if the claims are interpreted broadly to include carbon-supported sorbents for mercury. However, the explicit mention that Yan "did not appear to employ a halide" is a key differentiator, as US10933370B2's Independent Claim 1 and 12 specifically define a "promoted carbon sorbent" where the promoter is a "halogen, halide, or combinations thereof." This distinction could be crucial in overcoming anticipation.

• U.S. Pat. No. 5,891,324

  • Publication Date: April 6, 1999 (Approximate, exact filing date not readily available from provided text).
  • Description: Describes an activated carbon containing an acid (HCl, H2SO4, or H3PO4) for the removal of mercury from a liquid phase. US10933370B2 notes that this "Nelson method lacks many of the features described in this application that impart exceptional activity to the sorbent in a convenient way, for example, the addition of smaller amount of a second more powerful promoting agent, the use of facile solvent systems, including aqueous bromine, and the use of in-flight bromine treatment."
  • Potential Anticipation: This patent might anticipate certain elements related to using activated carbon for mercury removal. However, the claimed invention of US10933370B2 focuses on gas phase mercury removal and a specific "halogen/halide promoted activated carbon" formed by a reaction with the carbon, which is distinct from an acid-treated carbon for liquid phase removal. The claimed in-flight preparation (Claim 24), use of secondary components, and regenerability in US10933370B2 also serve as distinctions from the '324 patent.

• U.S. Pat. No. 6,136,072

  • Publication Date: October 17, 2000 (Approximate, exact filing date not readily available from provided text).
  • Description: Describes amalgamating noble metals (gold, silver) on a suitable support for mercury capture, which can be regenerated by microwave heating. US10933370B2 states these are "expensive and not especially active for sorption in flue gas."
  • Potential Anticipation: This could broadly anticipate claims regarding regenerable sorbents for mercury (e.g., Independent Claim 22, 27). However, the specific composition of the sorbent in US10933370B2 (halogen/halide promoted activated carbon) is fundamentally different from noble metal amalgams. The cost-effectiveness and high reactivity without in-situ activation claimed by US10933370B2 also differentiate it.

• U.S. Pat. No. 6,214,304

  • Publication Date: April 10, 2001 (Approximate, exact filing date not readily available from provided text).
  • Description: Mentions sodium sulfide particles as fine-particle injection sorbents for mercury removal.
  • Potential Anticipation: This could potentially anticipate aspects of Independent Claim 22 and 27 concerning injecting fine-particle sorbents for mercury removal. However, US10933370B2 focuses on halogen/halide promoted activated carbon as the sorbent, distinguishing it from sodium sulfide particles. The '304 patent's sulfide particles are also noted as "effective only for the oxidized mercury," whereas US10933370B2 claims high initial reactivity for oxidizing mercury and is especially suited for low-chlorine flue gases where mercury is mainly elemental.

• U.S. Pat. No. 6,258,334

  • Publication Date: July 10, 2001 (Approximate, exact filing date not readily available from provided text).
  • Description: Also cited for porous beds containing sulfur on a solid support for mercury removal.
  • Potential Anticipation: Similar to '631 and '853, this could anticipate claims (e.g., Independent Claims 1, 12) related to sulfur-based sorbents. The same distinctions as for '631 would likely apply.

Cited Foreign Patent References:

• Japanese Patent JP 49-43197

  • Publication Date: Not explicitly provided in the patent text, but typical for Japanese patents of that era would be sometime in 1974.
  • Description: Describes the treatment of Hg-contaminated electrolysis cell gas using a metal iodide salt on a support. US10933370B2 states, "These patents do not appear to represent a carbon bromide compound as specified in this patent application."
  • Potential Anticipation: This patent might anticipate broader concepts of supported sorbents for mercury removal. However, US10933370B2 specifically claims a "promoted carbon sorbent" where the promoter is a halogen or halide, particularly emphasizing a reactive compound produced by the reaction of bromine with the carbon. The explicit distinction in US10933370B2 that this reference does not represent a "carbon bromide compound" is key to arguing non-anticipation for Independent Claim 1 and 12.

• Japanese Patent JP 50-6438

  • Publication Date: Not explicitly provided in the patent text, but typical for Japanese patents of that era would be sometime in 1975.
  • Description: Describes a similar treatment to JP 49-43197, using a resin impregnated with a metal iodide.
  • Potential Anticipation: Similar to JP 49-43197, this could broadly anticipate concepts of impregnated materials for mercury removal. The same distinction regarding the lack of a "carbon bromide compound" in these references, as noted in US10933370B2, would apply, differentiating it from Independent Claims 1 and 12.

• German Patent DE 34 26 059

  • Publication Date: Not explicitly provided in the patent text, but would be after the priority date of 1984.
  • Description: Describes the use of a very thick carbon bed for treatment of flue gases containing polyhalogenated compounds. It's noted that "Spent sorbent is burned and not regenerated. The carbons are not pretreated."
  • Potential Anticipation: This could anticipate broader uses of carbon beds for flue gas treatment (e.g., Independent Claim 22). However, US10933370B2 emphasizes pretreated, regenerable halogen/halide promoted carbon sorbents with high initial reactivity. The fact that the carbons in DE 34 26 059 are "not pretreated" and "not regenerated" provides a clear distinction from the core inventive features of US10933370B2, particularly Independent Claims 1, 12, 22, and 27.

Obviousness Analysis under 35 U.S.C. § 103

A patent claim is obvious if "the differences between the claimed invention and the prior art are such that the subject matter as a whole would have been obvious at the time the invention was made to a person having ordinary skill in the art" (35 U.S.C. § 103). This analysis will identify potential combinations of prior art references that would render the claims of US10933370B2 obvious.

Person Having Ordinary Skill in the Art (POSA)

A POSA in this field would likely have a Master's degree or equivalent experience in chemical engineering, environmental engineering, or a related discipline, with a focus on air pollution control, specifically mercury emissions from industrial sources like coal-fired power plants or incinerators. They would be familiar with various sorbent technologies, flue gas treatment systems, and methods for pollutant removal and sorbent regeneration.

Potential Obviousness Combinations

The core of US10933370B2 lies in the use of halogen/halide-promoted activated carbon for mercury removal, particularly its high initial reactivity, regenerability, and methods for in-flight preparation and controlling injection rates. Several prior art references point towards the individual elements of this invention, suggesting that their combination could be considered obvious to a POSA.

Combination 1: Halogen/Halide Promoted Activated Carbon (Claim 1 and 12)

• US10933370B2 teaches: A promoted carbon sorbent comprising a base activated carbon reacted with a halogen, halide, or combination thereof, effective for mercury removal (Claim 1), and a method of preparing it by reacting granular activated carbon with such a promoter (Claim 12).
• Prior Art:
  • US 5,891,324 (Nelson): Describes activated carbon containing an acid (HCl, H2SO4, or H3PO4) for removing mercury from a liquid phase. While it focuses on liquid phase and acids, it establishes the concept of modifying activated carbon for mercury removal. The patent explicitly states that it lacks features like "in-flight bromine treatment" and "regeneration, recycling, or reuse", indicating these were known or desirable concepts at the time.
  • JP 49-43197 and JP 50-6438: Describe using metal iodide salts on a support or resin impregnated with metal iodide for treating Hg-contaminated electrolysis cell gas. These show the concept of using halide compounds for mercury removal, albeit in different forms and applications. The current patent distinguishes itself by claiming a "carbon bromide compound" which these Japanese patents do not appear to represent.
  • General knowledge in the art: The patent itself mentions that "Halogen treatment resulted in higher-activity carbons because the halide anions (especially bromide and iodide) were effective in promoting the oxidation by stabilizing the developing positive charge on the mercury in the transition state for oxidation." This statement indicates that the enhancing effect of halogens, particularly bromide and iodide, on activated carbon for mercury oxidation was recognized in the field. Also, activated carbon can be modified, e.g., by sulfur or halogen impregnation, to increase its mercury adsorption capacity for flue gas treatment. Activated carbons chemically modified with bromine compounds are known to be effective at sequestering vapor phase mercury from industrial flue gas streams.
• Motivation for Combination: A POSA, observing the known efficacy of activated carbon for mercury removal and the documented benefits of halide compounds (specifically iodide and bromide) in promoting mercury oxidation, would have been motivated to combine these elements to enhance the performance of activated carbon. The Nelson patent's acknowledgment of the lack of "in-flight bromine treatment" and "regeneration, recycling, or reuse" in its own system implies that these were recognized as desirable improvements in the art. Furthermore, the general knowledge that activated carbons can be chemically modified with halogens to enhance mercury adsorption capacity would lead a POSA to explore such modifications. The specific use of bromine, with its highly polarizable electrons, for enhanced reactivity would be a logical choice given the understanding of halide anion promotion effects on mercury oxidation.

Combination 2: Regenerable Sorbents and Reuse (Claim 22, 27)

• US10933370B2 teaches: A method for reducing mercury in flue gas by injecting sorbent, collecting >70% mercury, and substantially recovering the sorbent (Claim 22). Also, using larger sorbent particles (>40 micrometers) for separation from ash and re-injection after regeneration (Claim 27).
• Prior Art:
  • PCT/US04/12828 (Process for Regenerating a Spent Sorbent, incorporated by reference in US10933370B2): This prior art explicitly describes a "process and system for regenerating spent sorbents, or enhancing fresh sorbents" for mercury and other pollutant removal from flue gas. It mentions that the invention provides a cost-effective way to capture pollutants by utilizing a process to regenerate the reactivity and capacity of the sorbent. The abstract of US10933370B2 also states that the sorbents are "regenerable".
  • US 2002/0150516: Describes injecting manganese oxide sorbent particles, with regeneration claimed by rinsing with dilute aqueous acid.
  • US 5,607,496: Teaches oxidation of mercury on a metal oxide sorbent bed and subsequent absorption, but notes challenges with regeneration due to sulfate formation.
  • US 2001/0003116: Describes regeneration of transition metal oxide plate or honeycomb material for mercury sorption, involving heating in a reducing gas and impregnation with a complex-forming reagent.
  • US 6,136,072: Mentions amalgamating noble metals on a support that can be regenerated by microwave heating.
  • US 5,928,617: Describes a process for removing mercury from gas using elemental sulfur as a medium, and a further object of the invention is to provide for a process for mercury recovery from a spent sulfur pastille filter medium which also allows recycle of the sulfur.
  • "Comparing Permanent vs. Regenerable Mercury Adsorbents": Discusses both permanent and regenerable mercury adsorbents, outlining their characteristics and applications, indicating that regenerable systems are a known alternative for certain applications and offer lifecycle cost reductions.
  • "Novel Regenerable Sorbent for Mercury Capture from Flue Gases of Coal-Fired Power Plant": Discusses a natural chabazite-based silver nanocomposite (AgMC) that shows higher mercury capture capacity and can be regenerated by simple heating at 400 °C, retaining its performance over multiple cycles.
  • General Activated Carbon Regeneration: Activated carbon in mercury guard beds can be regenerated, extending service life and minimizing waste. The regeneration of spent granular activated carbon (GAC) is a known technique. Supercritical CO2 extraction has also been investigated for sorbent regeneration.
  • US 7,214,254 B2: Discusses regeneration of carbon sorbents through hot-gas vaporization.
• Motivation for Combination: The prior art clearly demonstrates a strong motivation for developing regenerable mercury sorbents due to cost savings, waste reduction, and sustainability. A POSA would have been motivated to combine the known benefits of activated carbon's mercury capture capabilities with existing regeneration techniques to develop a more economical and environmentally friendly solution. The explicit mention of regeneration in PCT/US04/12828, which is cross-referenced in the current patent, highlights the contemporary relevance of this aspect. Furthermore, the problem of separating fine sorbent particles from fly ash, which the current patent addresses with larger particles, was a recognized challenge in the field (as indicated by the "Standard AC sorbents generally are of fine size...separation of the two is difficult" statement in the patent). The combination of a regenerable sorbent with a larger particle size to facilitate physical separation would be an obvious solution to this known problem.

Combination 3: In-flight Preparation and Control (Method of Use Claims)

• US10933370B2 teaches: In-flight preparation of sorbent by reacting activated carbon and a promoter within a pneumatic transport line before injection into the flue gas. Also, monitoring mercury content of cleaned flue gas to control sorbent injection rate and composition.
• Prior Art:
  • General Activated Carbon Injection (ACI): Activated carbon injection (ACI) systems for mercury removal are well-established. ACI involves injecting powdered activated carbon into the flue gas stream.
  • US10933370B2 itself (Definitions): States, "New methods for in-flight preparation, introduction, and control of the active sorbent into the mercury contaminated gas stream are described." It further details that the "halogen promoted carbon sorbent can be readily produced 'in-flight'. This is accomplished by, for example, contacting the vapors of any combination of halogens and optionally a second component, in-flight, with very fine carbon particles."
  • US 5,569,436 and CA 2,114,331: Describe removing toxic metals, including mercury, from incinerator flue gases by contact with dry alkaline material and dry activated carbon, followed by solids separation. While not explicitly "in-flight preparation" of a promoted carbon, it demonstrates the concept of injecting materials into a flue gas stream for contaminant removal.
  • US 7,060,233 B1: Describes a process for removing sulfur and mercury, where elemental mercury reacts with sulfur to form HgS, which is removed by condensation. While not direct sorbent injection, it shows simultaneous removal and reaction within the gas stream.
  • US 10,343,114 B2: Describes in-flight preparation, introduction, and control of the sorbent, promoter, and promoted sorbent into the mercury contaminated gas stream.
  • Control Systems in Pollution Abatement: Continuous Emission Monitors (CEMs) for mercury are a known technology for monitoring emissions. Feedback control systems are common in industrial processes, including pollution control, to optimize reagent addition based on measured pollutant levels. The patent explicitly states that flow controllers can be adjusted "according to control algorithms well known in the art."
• Motivation for Combination: Given the existing practice of injecting activated carbon into flue gas streams for mercury removal, a POSA would be motivated to improve the efficiency and reactivity of this process. The idea of preparing the sorbent "in-flight" would stem from a desire to maximize reactivity by ensuring fresh reaction product at the point of injection, especially considering the known issue of existing sorbents being initially unreactive and requiring "seasoning" in flue gas. The patent's own description of "in-flight" preparation as a "very simple to implement" technology that "results in a great cost savings" reinforces its obviousness. Combining this with continuous mercury monitoring to dynamically adjust injection rates is a standard engineering approach to optimize performance and minimize costs in pollution control systems.

Combination 4: Co-injection of Alkaline Material (Method of Use Claims)

• US10933370B2 teaches: Co-injecting an optional alkaline material to improve mercury capture efficiency by capturing oxidized mercury and/or gaseous components that reduce sorbent capacity.
• Prior Art:
  • US 5,569,436 and CA 2,114,331: Teach removing mercury from incinerator flue gases by contact with dry alkaline material and dry activated carbon. These patents explicitly disclose the simultaneous use of activated carbon and alkaline material for mercury removal.
  • "IPM Model – Updates to Cost and Performance for APC Technologies Mercury Control Cost Development Methodology": States that "alkali reagent injection (typically Trona) before the mercury sorbent injection system can reduce the SO3 concentration and facilitate easier mercury capture." This clearly articulates the benefit of alkali injection in conjunction with mercury sorbents to address flue gas constituents that can hinder mercury capture.
  • US10933370B2 (Definitions): States, "an optional alkaline material, including without limitation alkaline and alkaline earth components, to improve the efficiency of mercury capture by capturing oxidized mercury and/or capturing gaseous components that might otherwise reduce sorbent capacity." This directly acknowledges the known function of alkaline materials in flue gas treatment.
  • US 10,596,517 B2: Describes co-injection of an optional alkali component with promoted carbon sorbent into a flue gas stream for mercury reduction.
  • "Mercury Removal from Flue Gas by Aqueous Precipitation": Notes that while the CMAP process (using sodium hydroxide) has low elemental mercury removal efficiency, it can remove oxidized mercury with more than 90% efficiency.
• Motivation for Combination: A POSA would be motivated to co-inject alkaline materials with activated carbon sorbents to address known challenges in flue gas mercury control. Specifically, the prior art highlights that alkaline materials can effectively capture oxidized mercury and mitigate the detrimental effects of acid gases like SO3 on sorbent capacity. The explicit mention in US 5,569,436 and CA 2,114,331 of combining dry alkaline material and dry activated carbon for mercury removal directly suggests this combination. The knowledge that different mercury species (elemental vs. oxidized) might be preferentially captured by different agents would further motivate the use of a multi-component system.

Conclusion on Obviousness

The identified prior art references, individually and in combination, disclose many key aspects of US10933370B2. A person having ordinary skill in the art, motivated by the ongoing challenges of efficient and cost-effective mercury removal from flue gases, would have found it obvious to combine these known elements. The drive for improved sorbent reactivity, regenerability, reduced waste, and optimized injection strategies would have naturally led a POSA to:

1. Promote activated carbon with halogens/halides: Given the known enhancing effects of halides on mercury oxidation and the existing use of modified activated carbons for mercury removal.
2. Develop regenerable sorbents and reuse strategies: Driven by economic and environmental concerns, and the established techniques for sorbent regeneration in various contexts.
3. Implement in-flight preparation and feedback control: To maximize sorbent efficacy and optimize resource utilization, building on existing ACI systems and general principles of process control.
4. Co-inject alkaline materials: To address specific challenges with oxidized mercury capture and interference from other flue gas constituents.

While US10933370B2 presents a comprehensive system, the individual components and the motivations for combining them appear to be present in the prior art, rendering the claims, particularly the independent claims 1, 12, 22, and 27, potentially obvious under 35 U.S.C. § 103.