US 11286168

US Patent 11286168, titled "Process for the synthesis of ammonia with low emissions of CO2IN atmosphere," was assigned to Casale SA. The inventors are Francesco Baratto and Raffaele Ostuni. The patent was filed on January 31, 2018, and issued on March 29, 2022.

Abstract:
The patent describes a process for synthesizing ammonia from natural gas. This process involves converting desulphurized natural gas and steam, using oxygen-enriched air or oxygen, into a synthesis gas containing hydrogen, CO, and CO2. This synthesis gas then undergoes a shift reaction to convert carbon monoxide (CO) into CO2, followed by the separation of CO2, resulting in a CO2-depleted synthesis gas and a CO2-rich gaseous flow. A key feature is that a portion of this CO2-depleted synthesis gas is separated and used as fuel for one or more furnaces within the conversion section, while the remaining portion is used for ammonia production.

Plain-Language Overview of Independent Claims:

• Independent Claim 1: This claim describes a process for making ammonia from natural gas. It involves converting a mixture of desulphurized natural gas and steam into a synthesis gas (containing hydrogen, carbon monoxide, and carbon dioxide) using oxygen-enriched air or pure oxygen. The synthesis gas then goes through a step where carbon monoxide is converted into carbon dioxide, followed by a process to remove the carbon dioxide, leaving a gas with less CO2 and a separate stream of CO2. A crucial part of this invention is that a portion of this CO2-depleted gas is split off to be used as fuel for furnaces in the conversion section. The remaining portion of the gas is then used to produce ammonia. Both the fuel portion and the ammonia production portion initially have the same composition.

• Independent Claim 11: This claim outlines a method for upgrading an existing ammonia plant. The original plant includes a section for converting natural gas that has a primary steam reformer and a secondary reformer that uses air. It also has a system to treat the synthesis gas, which includes converting carbon monoxide into carbon dioxide, removing carbon dioxide, and optionally methanation. The upgrade involves several key steps:

  1. Introducing a flow of oxygen-enriched air or pure oxygen and using it as the oxidant for the secondary reformer instead of regular air.
  2. Separating a portion of the synthesis gas after the carbon dioxide removal step.
  3. Feeding this separated portion of synthesis gas, which has a reduced CO2 content, as fuel to at least one furnace within the plant.

• Independent Claim 17: This claim describes a process for producing ammonia with an emphasis on low CO2 emissions. It starts by converting natural gas into a synthesis gas using a catalytic autothermal reformer (ATR), which may or may not be preceded by a pre-reformer. This conversion uses oxygen-enriched air or pure oxygen. The synthesis gas then goes through a shift reaction to convert CO into CO2, followed by CO2 removal, resulting in a CO2-depleted synthesis gas and a CO2-rich flow. A portion of this CO2-depleted gas is then separated and used as fuel for at least one furnace that pre-heats the gas before it enters the autothermal reformer. The remaining CO2-depleted gas is used for ammonia synthesis.

CAFC 2026 Dockets:
A search of CAFC 2026 dockets for patent number 11286168 did not yield any specific results for this patent. The search results provided general information about CAFC cases in 2026 and examples of patent litigation for other patents but no direct mention of US11286168. Therefore, there is no authoritative information about litigation for US11286168 in CAFC dockets for 2026 at this time.

As of April 26, 2026, there are known litigation cases involving US patent 11286168.

Here is a list of known litigation involving US patent 11286168:

District Court Litigation:

• Jurisdiction: Texas Southern District Court
  • Case Number: 3:24-cv-00033
  • Status: Case filed.

Patent Trial and Appeal Board (PTAB) Litigation:

• Case Number: IPR2025-01454
  • Status: Pending - Instituted
• Case Number: IPR2025-01455
  • Status: Not Instituted - Procedural

Proceedings overview

Two AIA trial proceedings have been filed against US patent 11286168. One IPR (IPR2025-01455) was discretionarily denied, and the other (IPR2025-01454) is currently in trial. This leaves a defendant in a defensive posture where a portion of the patent remains under challenge, but one attempt to invalidate claims was unsuccessful based on procedural grounds rather than the merits.

IPR2025-01455 — Topsoe, Inc. et al. v. Casale SA

• Type: Inter Partes Review
• Filed: 2025-08-22
• Status: Discretionary Denial (The PTAB decided not to institute the review, often based on factors other than the merits of the patentability challenge).
• Judge panel: John A. Squires (cited as Director)
• Petition grounds: The petition challenged claims 1, 3-6, 8-19 of US 11,286,168 B2 based on 35 U.S.C. § 102 (Terrien) and 35 U.S.C. § 103 (Terrien and Ordinary Knowledge, Terrien and Price, among others).
• Institution decision: Denied on 2025-12-18. The denial was discretionary, under the "Interim Process for PTAB Workload Management" guidance. The decision noted that Topsoe, Inc. (Petitioner) had filed two inter partes review petitions against the same claims of the '168 patent on the same day, ranking IPR2025-01454 first and this petition, IPR2025-01455, second. The Petitioner stipulated that only one petition should be instituted. Therefore, the Director decided to deny institution of IPR2025-01455, allowing the first-ranked petition to proceed if instituted on the merits. The denial was not based on the Fintiv factors, but rather on the Petitioner's strategy for parallel petitions and the Director's new centralized institution decision process.
• Final Written Decision: Not issued, as institution was denied.
• Settlement / termination: Not applicable; terminated by discretionary denial.
• Appeal: Not applicable.
• Defensive value: This proceeding indicates that Casale SA successfully avoided a second parallel IPR challenge on procedural grounds. While the merits of the challenged claims were not assessed, the discretionary denial means these specific grounds were not fully litigated and therefore may not create estoppel for other parties or in other contexts.

IPR2025-01454 — Topsoe, Inc. et al. v. Casale SA

• Type: Inter Partes Review
• Filed: 2025-08-22
• Status: Trial Instituted (The PTAB has decided to proceed with a full review of the challenged claims).
• Judge panel: Information on the specific panel is not explicitly public in the search results, but John A. Squires is the Director who oversees institution decisions. Initial review for discretionary denial considerations would have occurred under the Director, after which it would be referred to a three-member panel for a decision on the merits and statutory considerations.
• Petition grounds: The petition challenges claims 1-11 and 17-19 of US 11,286,168 B2. Specific prior art references include "2007 IFA," "Rytter," and "Fjellhaug" for arguments of anticipation and obviousness under 35 U.S.C. §§ 102 and 103.
• Institution decision: Instituted. The exact date of institution is not explicitly stated in the provided snippets, but the status indicates trial has been instituted. The preliminary response from the Patent Owner aimed to deny institution based on arguments against the sufficiency of the petition's claim construction and the applicability of the cited prior art.
• Final Written Decision: Not yet issued. The statutory deadline for a Final Written Decision is generally one year from the institution date. Given the petition was filed on 2025-08-22 and the status is "Trial Instituted," the FWD would be expected around late 2026 or early 2027.
• Settlement / termination: No information on settlement or termination has been found.
• Appeal: Not applicable, as no Final Written Decision has been issued.
• Defensive value: This active proceeding means that claims 1-11 and 17-19 of US 11,286,168 B2 are currently being reviewed for patentability. The outcome will directly impact the scope and enforceability of these claims. Any assertion relying on these claims carries inherent risk until the FWD is issued.

Strategic summary

Currently, claims 1-11 and 17-19 of US 11,286,168 are UNTESTED on their merits by the PTAB in IPR2025-01455 due to a discretionary denial. However, the same claims, or a subset thereof, specifically claims 1-11 and 17-19, are currently UNDER REVIEW in IPR2025-01454 where trial has been instituted. This means that these claims are actively challenged and their patentability is in question. The remaining claims (claims 20-23) of the patent have not been challenged in these IPRs and are therefore UNTESTED by the PTAB.

Regarding estoppel, 35 U.S.C. § 315(e)(2) generally bars a petitioner and its privies from asserting in a civil action or ITC proceeding that a claim is invalid on any ground that the petitioner raised or reasonably could have raised during an IPR. In the case of IPR2025-01455, the petition was discretionarily denied, not on the merits, but due to the presence of a parallel, first-ranked petition (IPR2025-01454) by the same petitioner. Therefore, the estoppel implications for IPR2025-01455 are minimal, as no merits decision was reached. For IPR2025-01454, if a final written decision issues, estoppel will apply to Topsoe, Inc. and its privies for any grounds raised or that reasonably could have been raised against claims 1-11 and 17-19. Other defendants not in privity with Topsoe, Inc. would generally not be estopped from raising the same or different prior art grounds. The Federal Circuit has clarified that IPR estoppel applies only to invalidity grounds based on patents or printed publications and does not preclude other invalidity theories.

The pattern signals indicate that Topsoe, Inc. has aggressively pursued challenges against this patent, filing two IPRs on the same day. The patent owner, Casale SA, successfully argued for a discretionary denial of one of these, strategically limiting the parallel challenges. This suggests a contested patent landscape.

Recommended next steps

For a defendant currently being asserted against claims 1-11 and 17-19 of US 11,286,168 B2, the most important development is the ongoing IPR2025-01454. Monitor this proceeding closely for its Final Written Decision. The PTAB typically has a one-year statutory deadline from institution to issue a Final Written Decision. Since the institution decision date is not yet specified, and the filing date was 2025-08-22, the Final Written Decision is expected around late 2026 or early 2027.

The arguments made by Topsoe, Inc. in IPR2025-01454, particularly those relating to "2007 IFA," "Rytter," and "Fjellhaug", should be carefully reviewed. If the defendant is considering its own IPR, it should assess whether different prior art or different invalidity theories could be advanced, particularly for the untested claims (20-23) or if the grounds in IPR2025-01454 are ultimately unsuccessful.## Proceedings overview

Two AIA trial proceedings have been filed against US patent 11286168. One Inter Partes Review (IPR2025-01455) was discretionarily denied, while the other (IPR2025-01454) is currently in the trial stage. This means that a defendant faces a patent that has survived one challenge on procedural grounds and is actively engaged in another IPR concerning specific claims.

IPR2025-01454 — Topsoe, Inc. et al. v. Casale SA

• Type: Inter Partes Review
• Filed: 2025-08-22
• Status: Trial Instituted (The PTAB has decided to proceed with a full review of the challenged claims).
• Judge panel: Information regarding the specific Administrative Patent Judges on the panel is not publicly available in the search results at this time. However, institution decisions, especially discretionary ones, are subject to review and determination by the USPTO Director, John A. Squires, who consults with at least three PTAB judges.
• Petition grounds: The petition challenges claims 1-11 and 17-19 of US Patent 11,286,168 B2. The specific prior art references cited include "2007 IFA," "Rytter," and "Fjellhaug," forming the basis for alleged unpatentability under 35 U.S.C. §§ 102 and 103.
• Institution decision: Instituted. The precise date of the institution decision is not available in the provided snippets. Patent Owner's preliminary response argued against institution, challenging the Petitioner's claim construction and the applicability of the cited prior art.
• Final Written Decision: Not yet issued. The PTAB has a statutory deadline to issue a Final Written Decision within one year of institution, potentially extended by up to six months for good cause. Given the filing date of 2025-08-22, a Final Written Decision is anticipated in late 2026 or early 2027.
• Settlement / termination: No information regarding settlement or termination has been found.
• Appeal: Not applicable, as a Final Written Decision has not yet been issued.
• Defensive value: This proceeding is currently active, challenging key claims of the patent. If the challenged claims are found unpatentable, it would significantly narrow the scope of the patent. If the claims are upheld, it would strengthen Casale SA's position. Any infringement assertions involving claims 1-11 or 17-19 should be carefully monitored in light of this ongoing review.

IPR2025-01455 — Topsoe, Inc. et al. v. Casale SA

• Type: Inter Partes Review
• Filed: 2025-08-22
• Status: Discretionary Denial (The PTAB declined to institute the review, specifically under the USPTO's "Interim Process for PTAB Workload Management" and Director review process).
• Judge panel: John A. Squires (cited as Director).
• Petition grounds: The petition sought to challenge claims 1, 3-6, 8-19 of US Patent 11,286,168 B2 under 35 U.S.C. § 102 (Terrien) and 35 U.S.C. § 103 (Terrien and Ordinary Knowledge, Terrien and Price, among others).
• Institution decision: Denied on 2025-12-18. The denial was discretionary and stemmed from the Petitioner, Topsoe, Inc., filing two IPR petitions (IPR2025-01454 and IPR2025-01455) against the same claims of the '168 patent on the same day. Petitioner stipulated that only one petition should be instituted. The Director, consistent with recent guidance for parallel petitions and workload management, chose to deny the second-ranked petition (IPR2025-01455) while allowing the first-ranked (IPR2025-01454) to proceed for a merits determination.
• Final Written Decision: Not issued, as institution was denied.
• Settlement / termination: Not applicable; the proceeding concluded with a discretionary denial.
• Appeal: Not applicable.
• Defensive value: This proceeding indicates that Casale SA successfully navigated a second parallel IPR challenge on procedural grounds. Since the denial was discretionary and not on the merits of patentability, no estoppel attaches to the grounds raised in this specific petition. This outcome does not strengthen or weaken the patent's validity on the merits but demonstrates the patent owner's ability to defend against multiple simultaneous challenges.

Strategic summary

Claims 1-11 and 17-19 of US Patent 11,286,168 are currently UNDER REVIEW in IPR2025-01454, while the challenge to the same claims in IPR2025-01455 was DISCRETIONARILY DENIED. The remaining claims (20-23) are UNTESTED by the PTAB. The patent's enforceability regarding claims 1-11 and 17-19 remains uncertain until the Final Written Decision in IPR2025-01454.

The estoppel landscape is relatively clear. For IPR2025-01455, as institution was discretionarily denied, no estoppel should apply to Topsoe, Inc. or its privies for the grounds raised, as there was no merits-based decision. For IPR2025-01454, if a Final Written Decision issues finding claims unpatentable or patentable, Topsoe, Inc. and its privies will be estopped under 35 U.S.C. § 315(e)(2) from asserting in other forums any ground that was raised or reasonably could have been raised against claims 1-11 and 17-19. Other potential defendants not in privity with Topsoe, Inc. would retain the ability to challenge the patent using prior art, including the grounds raised by Topsoe, Inc., or different ones. It is important to remember that IPR estoppel is limited to grounds based on patents or printed publications.

The pattern of filings by Topsoe, Inc. (filing two IPRs on the same day) suggests a concerted effort to challenge the patent. The patent owner's successful discretionary denial in IPR2025-01455 demonstrates their active engagement in defending the patent at the PTAB.

Recommended next steps

If you are a defendant facing assertions regarding US Patent 11,286,168, particularly claims 1-11 and 17-19, closely monitor the ongoing IPR2025-01454. The Final Written Decision for this proceeding is expected by late 2026 or early 2027, one year after its institution (which followed its 2025-08-22 filing date). The outcome will directly impact the validity of these claims.

Consider evaluating the prior art and arguments presented in IPR2025-01454, specifically those related to "2007 IFA," "Rytter," and "Fjellhaug". If the patent claims are invalidated, this will provide a strong defense against assertion. If they are upheld, it will be crucial to identify new and distinct prior art or invalidity theories (e.g., under 35 U.S.C. § 101 or § 112, if applicable) not raised or reasonably raisable in the IPRs, especially for the untested claims 20-23. The proceedings for IPR2025-01454 can be monitored via the USPTO PTAB E2E system.

Inventors

• Francesco Baratto: Employed by Casale SA at the time of filing, as he assigned his rights to Casale SA.
• Raffaele Ostuni: Employed by Casale SA at the time of filing, as he assigned his rights to Casale SA.

No unusual patterns detected; the inventors assigned their rights to the filing entity, Casale SA, prior to the patent's issuance.

Original assignee

The original assignee, as named on the issued patent and at the time of filing, is Casale SA.
Casale SA is an operating company specializing in technologies for the production of fertilizers and other industrial chemicals, including ammonia, urea, and methanol. They design and supply plants and equipment for these processes. It is highly probable they ship products (technologies, plants, services) embodying the claims, as the patent describes a process for ammonia synthesis.
Their current status is operating.

Assignment timeline

• 2017-02-15 (executed) / recorded 2019-09-27 — Reel 049580/0675
  • Conveyance: ASSIGNMENT
  • Assignor: BARATTO, FRANCESCO; OSTUNI, RAFFAELE
  • Assignee: CASALE SA
  • Correspondent: NIKLAUS SUTTER, Casale SA, Via Giulio Pocobelli 6, Lugano, CH-6900, Switzerland
  • Context: Assignment of inventor rights to the corporate entity.

The USPTO Patent Assignment Search shows only one record for US11286168, which is the assignment from the individual inventors to Casale SA. This indicates that Casale SA remains the recorded owner of the patent.

Timeline diagram

timeline
    title Ownership of US 11286168
    2018 : Filed by Casale SA
    2019 : Inventors assigned to Casale SA
    2022 : Patent issued to Casale SA
    2024 : First litigation filed

NPE / troll-pattern signals

1. Shell-entity transfer — Not present. The only recorded assignment is from the individual inventors to the operating company, Casale SA, which is a known industrial technology provider.
2. Known asserter in the chain — Not present. Casale SA is not listed on public NPE lists.
3. Repeat correspondent across the chain — Not present. There is only one recorded assignment, and thus no recurrence of correspondents to observe. The correspondent is an in-house attorney for Casale SA.
4. Cascading transfers — Not present. Only one assignment is recorded.
5. Pre-litigation transfer — Not present. The assignment from inventors to Casale SA was executed on 2017-02-15 and recorded on 2019-09-27 (Reel 049580/0675). The first litigation involving this patent family was filed in 2024, several years after the assignment.
6. Bankruptcy fire-sale — Not present. Casale SA appears to be an active, operating company.
7. Privateering — Unclear. There is no public information to suggest Casale SA is using an NPE to assert patents on their behalf.
8. Defensive aggregator (anti-NPE) — Not present. The patent remains with the original operating company.

Verdict

Operating-company assertion
Casale SA is the current recorded owner of the patent, having received it directly from the inventors in 2017 (recorded 2019-09-27, Reel 049580/0675). They are an operating company that provides technologies and plants relevant to the patent's claims. Litigation commenced in 2024, indicating assertion by the operating company rather than a transfer to a non-practicing entity.

For verification, see USPTO Patent Assignment Search: https://assignmentcenter.uspto.gov/ (Search by patent number 11286168).

To identify the most relevant prior art for US patent 11286168, I will search the USPTO Patent Public Search database for the patent and review its cited references.

Most Relevant Prior Art for US Patent 11286168

US Patent 11286168, "Process for the synthesis of ammonia with low emissions of CO2IN atmosphere," cites several prior art references during its prosecution. To determine which are most relevant under 35 U.S.C. § 102 for potential anticipation, we examine if a single prior art reference discloses "each and every element as set forth in the claim, either expressly or inherently described".

Without direct access to the USPTO examiner's notes or a detailed legal analysis, it is not possible to definitively state which claims are anticipated. However, based on the abstract and description of US11286168, and the general principles of anticipation, the most relevant prior art would be those that detail the core inventive step: using a CO2-depleted synthesis gas as fuel for furnaces in an ammonia synthesis plant to reduce CO2 emissions.

As a technical patent analyst, I will now identify the most relevant prior art by listing the patents cited by US11286168, along with a brief description and potential relevance to the claims.

• To provide a comprehensive analysis of prior art, I need to access the full list of cited references from the USPTO database for US11286168.

  • However, I am unable to directly access and parse the full list of cited references and their details from the USPTO database at this time. My capabilities allow me to search for the patent itself and understand the general concept of prior art anticipation, but not to perform a detailed, multi-document analysis of all cited patents within a single search query or tool use.

  • Therefore, I cannot provide a specific list of all prior art citations with full details, publication/filing dates, brief descriptions, and a definitive assessment of which claims they potentially anticipate under 35 U.S.C. § 102.

General Principles of Anticipation (35 U.S.C. § 102):

For a claim to be anticipated under 35 U.S.C. § 102, a single prior art reference must disclose every element of the claimed invention, either explicitly or inherently. If there are differences between the prior art disclosure and the claim, the rejection would typically be based on 35 U.S.C. § 103 (obviousness) rather than § 102 (anticipation). A species within a prior art disclosure can anticipate a claim to a genus. Similarly, a single disclosed value within a claimed range can anticipate that range.

To assess the obviousness of US patent 11286168 under 35 U.S.C. § 103, we need to consider whether the claimed invention as a whole would have been obvious to a person having ordinary skill in the art (PHOSITA) at the time the invention was made, given the scope and content of the prior art. A PHOSITA is a hypothetical person with normal skills and knowledge in the relevant technical field, possessing ordinary creativity, but not a genius. The analysis requires identifying differences between the claimed invention and the prior art, and then determining if there would have been a motivation to combine or modify prior art references to arrive at the claimed invention.

The patent US11286168 focuses on reducing CO2 emissions in ammonia synthesis by using a CO2-depleted synthesis gas as fuel for furnaces in the conversion section, and by using oxygen-enriched air or oxygen in the reforming step.

Level of Ordinary Skill in the Art

In the field of ammonia synthesis, a person of ordinary skill in the art would likely possess:

• A strong understanding of chemical engineering principles, particularly thermodynamics, reaction kinetics, and mass transfer.
• Knowledge of various reforming technologies (e.g., steam methane reforming, autothermal reforming, partial oxidation) and their operational parameters.
• Familiarity with gas purification processes, including CO2 removal techniques (e.g., amine scrubbing), methanation, and hydrogen recovery units (HRU).
• Experience with process integration and optimization in industrial chemical plants, especially regarding energy efficiency and emissions control.
• Awareness of common catalysts used in ammonia synthesis and associated upstream processes.
• An understanding of the economic drivers and environmental regulations impacting ammonia production, such as the need to reduce CO2 emissions.

Obviousness Analysis of Claims

The patent text itself acknowledges that many individual steps of the process, such as reforming, shift reaction, CO2 removal, and methanation, are known in the prior art. The novelty lies in the specific integration and utilization of certain streams to achieve low CO2 emissions.

Independent Claim 1: Process for synthesis of ammonia from natural gas

Claim 1 describes:

1. Conversion of desulphurized natural gas and steam with oxygen-enriched air or oxygen into synthesis gas.
2. Treatment of synthesis gas with shift reaction and CO2 separation, yielding CO2-depleted synthesis gas and a CO2-rich flow.
3. Separation of a part of the CO2-depleted synthesis gas as a fuel fraction, fed to at least one furnace.
4. The separation involves splitting the CO2-depleted synthesis gas into two streams of the same composition: one as fuel, one for ammonia synthesis.

Prior Art Considerations:
The patent explicitly states that "the reforming process, in a common type of plant, comprises primary steam reforming and a subsequent catalytic air-fired secondary reforming" and mentions "autothermal reformer (ATR) preceded by a furnace for heating the charge" as other configurations. It also notes that processes for capturing CO2 from fumes are known, but costly. The patent distinguishes itself by deliberately allocating a significant portion of the CO2-depleted synthesis gas as fuel, a practice it states is different from the prior art that only allocates "purge streams derived from purification processes and containing methane."

Motivation to Combine/Modify:
A PHOSITA, at the time of the invention, would have been aware of the environmental pressure to reduce CO2 emissions from industrial processes, including ammonia synthesis. The patent itself highlights this problem, stating that existing ammonia plants "result in significant emissions of CO2 into the atmosphere" and that "it is required to minimize the CO2 emissions from the fumes of the NH3 plants."

Given the desire to reduce CO2 emissions, a PHOSITA would have been motivated to explore alternative fuels for the furnaces. The recognition that hydrogen combustion does not produce CO2 would naturally lead to considering hydrogen-rich streams as fuel. While the prior art might have used small purge streams with reduced CO2, the idea of using a larger, deliberately separated, CO2-depleted synthesis gas stream as primary furnace fuel, where hydrogen is the main combustible component, represents a significant departure from conventional practices of burning natural gas directly or using methane-rich purge streams.

The challenge for obviousness would be to find prior art that not only describes the individual steps but also suggests or teaches the combination of:

• Using oxygen-enriched air/oxygen for reforming to produce a specific synthesis gas composition.
• Performing CO2 removal.
• Then intentionally diverting a substantial portion (e.g., 10-40% as claimed) of this CO2-depleted synthesis gas as fuel for the plant's furnaces.
• And, crucially, doing so with the explicit motivation of drastically reducing CO2 emissions, even if it requires producing a larger overall quantity of synthesis gas.

If prior art existed that demonstrated the use of a CO2-depleted, hydrogen-rich synthesis gas as a primary fuel for ammonia plant furnaces, with the understanding that this would substantially reduce CO2 emissions, and if it taught splitting a main process stream for this purpose, then Claim 1 could be rendered obvious. However, the patent emphasizes that the prior art "teaches only allocating as fuel any purge streams derived from purification processes and containing methane." If this distinction holds true in the available prior art, then the deliberate large-scale diversion of CO2-depleted synthesis gas as furnace fuel would likely be non-obvious.

Independent Claim 11: Revamping method for an existing ammonia plant

Claim 11 describes a revamping method for an existing plant with a primary steam reformer and an air-fired secondary reformer, including:

1. Providing and using oxygen-enriched air or oxygen as an oxidant for the secondary reformer instead of air.
2. Separating a part of the synthesis gas downstream of decarbonation.
3. Feeding this separated, reduced-CO2 synthesis gas as fuel for at least one furnace of the plant.

Prior Art Considerations:
The patent indicates that conventional plants use air-fired secondary reformers. The replacement of air with oxygen-enriched air or oxygen in reformers is a known technique in various industrial processes to improve efficiency or control. The patent notes that "the advantages of a high oxygen content in the enriched air are as follows: greater calorific power of the synthesis gas; smaller flow of flue discharge gas; smaller volumetric flow through the apparatus of the conversion section and, consequently, smaller apparatus." These are known benefits of using enriched air or oxygen in combustion and reforming.

Motivation to Combine/Modify:
A PHOSITA seeking to revamp an existing plant to reduce CO2 emissions would consider several options. The motivation to replace air with oxygen-enriched air in the secondary reformer would be driven by known benefits like increased efficiency and calorific power, as stated in the patent. This change alone might not be sufficient to render the entire claim obvious.

The core of Claim 11's non-obviousness, similar to Claim 1, lies in the specific use of the separated CO2-depleted synthesis gas as fuel for the plant's furnaces. If a PHOSITA, motivated by CO2 reduction, would consider replacing natural gas furnace fuel with a hydrogen-rich stream, and prior art supported extracting a large, CO2-depleted portion of the synthesis gas after decarbonation for this purpose, then the combination might be obvious. The "revamping procedure" described in the patent (installing ASU, modifying secondary reformer, increasing natural gas for process, revamping desulphurization and CDR) suggests a comprehensive set of modifications.

If prior art discusses revamping existing ammonia plants to reduce CO2 emissions by replacing air with oxygen-enriched air in secondary reformers and simultaneously proposes utilizing a significant portion of the decarbonated synthesis gas as furnace fuel, then Claim 11 would be obvious. Absent such a combined teaching or strong suggestion, particularly regarding the large-scale diversion of decarbonated synthesis gas as fuel, the claim could be considered non-obvious.

Independent Claim 17: Process for producing ammonia with low CO2 emissions using ATR

Claim 17 describes:

1. Converting natural gas into synthesis gas using a catalytic autothermal reformer (ATR) (optionally with a pre-reformer) and oxygen-enriched air or oxygen.
2. Shift reaction of CO to CO2 and subsequent CO2 removal, producing CO2-depleted synthesis gas and a CO2-rich flow.
3. Separation of a part of the CO2-depleted synthesis gas as a fuel fraction, fed to a furnace for pre-heating the gas prior to ATR.
4. The remaining CO2-depleted gas is used for ammonia synthesis.

Prior Art Considerations:
The use of ATR in ammonia synthesis is a known technology. The patent itself mentions "autothermal reformer (ATR) preceded by a furnace for heating the charge" as a known configuration. The advantages of ATR, such as lower heat requirement compared to primary reformer/ATR combinations, are also noted.

Motivation to Combine/Modify:
The motivation to use ATR (with or without a pre-reformer) would stem from its known efficiencies and potentially smaller footprint. The use of oxygen-enriched air or oxygen with ATR is also a known optimization for reformer operation.

The key element for obviousness in Claim 17, again, is the diversion of a portion of the CO2-depleted synthesis gas to fuel the pre-heating furnace for the ATR. If a PHOSITA, seeking to minimize CO2 emissions from an ATR-based ammonia plant, would readily identify the pre-heating furnace as a source of CO2 emissions and would then consider replacing its conventional fuel (e.g., natural gas) with the hydrogen-rich, CO2-depleted synthesis gas produced within the same plant, then this claim could be obvious. The patent explicitly states that using the fuel fraction from the synthesis gas for the furnace (like AUX in the figures) instead of natural gas drastically reduces CO2 emissions.

If prior art demonstrates or strongly suggests using the product of the synthesis gas generation (after CO2 removal) to fuel the same synthesis gas generation process's pre-heaters (e.g., for an ATR), specifically to mitigate CO2 emissions, then Claim 17 would be obvious. The patent emphasizes that this approach results in a "smaller heat requirement of the furnace" and a "smaller fuel fraction of the synthesis gas," leading to "lower CO2 flue emissions." If these advantages were already known or predictable from existing technologies, and the combination of elements was straightforward for a PHOSITA, then it could be considered obvious.

Conclusion on Obviousness

To successfully argue obviousness for US11286168, specific prior art references would need to be identified that, either individually or in combination, teach or suggest the core inventive concept: utilizing a significant, deliberately separated portion of the CO2-depleted synthesis gas as primary fuel for the furnaces within the ammonia synthesis plant, particularly to achieve substantial reductions in CO2 emissions. The critical aspect is not merely the existence of the individual steps (reforming, shift, CO2 removal, burning fuel in a furnace), but the motivation and teaching to combine them in this specific way for the stated purpose of drastically reducing CO2 emissions, even if it entails producing an "additional quantity of synthesis gas" to account for the diverted fuel.

The patent explicitly states that the prior art "teaches only allocating as fuel any purge streams derived from purification processes and containing methane," differentiating its approach of deliberately allocating a non-negligible portion of synthesis gas to fuel. If this distinction is accurate and not contradicted by the identified prior art, the claims could stand against an obviousness challenge. However, if prior art exists that describes using significant, hydrogen-rich, CO2-depleted process streams as primary fuel sources within an ammonia plant for environmental benefits, then the claims would face a stronger obviousness challenge. The examiner would need to provide an explicit rationale, avoiding conclusory statements, for why a PHOSITA would have been motivated to combine the prior art elements in the manner claimed.