US 11673805

US Patent 11673805, titled "Process and plant for preparation of hydrogen and separation of carbon dioxide," was assigned to L'Air Liquide SA pour l'Etude et l'Exploitation des Procedes Georges Claude. The inventors are Sophia SCHMIDT and Teja Schmid McGuinness. The application was filed on August 11, 2021, and the patent was issued on June 13, 2023.

Abstract:
The patent describes a process for producing hydrogen by steam reforming hydrocarbons and separating carbon dioxide. It uniquely combines endothermic and autothermal reforming steps to generate a synthesis gas stream, utilizing heat from the autothermal step for heating the endothermic step. The process further involves converting the synthesis gas to enrich it with hydrogen, separating hydrogen via pressure swing adsorption (PSA), and then separating carbon dioxide cryogenically from the residual gas left after PSA. The reforming units for the endothermic and autothermal steps can be arranged either in parallel or in series.

Plain-Language Overview of Independent Claims:

• Claim 1 (Process): This claim outlines a method for producing hydrogen and separating carbon dioxide, comprising the following key steps:

  1. Feed Gas Provision: A feed gas containing at least methane as a hydrocarbon and steam is provided.
  2. Endothermic Reforming: At least a portion of this feed gas is reacted endothermically (requiring heat) over a catalyst to produce a first synthesis gas (SG1), which contains hydrogen, carbon monoxide, carbon dioxide, and unreacted methane.
  3. Autothermal Reforming & Combination: This step presents two possible arrangements for the reforming units:
     • Parallel Arrangement: A separate portion of the feed gas is reformed in an autothermal process (exothermic partial oxidation followed by endothermic steam reforming) to produce a second synthesis gas (SG2). SG1 and SG2 are then combined to form a third synthesis gas (SG3).
     • Series Arrangement: The first synthesis gas (SG1) itself is reformed in an autothermal process to produce the third synthesis gas (SG3).
       In both arrangements, a crucial aspect is that the heat generated by the autothermal reforming step is used to provide heat for the endothermic reforming step. Both SG2 and SG3 contain hydrogen, carbon monoxide, carbon dioxide, and unreacted methane.
  4. Carbon Monoxide Conversion: The carbon monoxide in the third synthesis gas (SG3) is reacted with steam to produce more hydrogen and carbon dioxide, resulting in a fourth synthesis gas (SG4).
  5. Hydrogen Separation (PSA): Hydrogen is separated from the fourth synthesis gas (SG4) using pressure swing adsorption (PSA), yielding a hydrogen-rich stream (HG1) and a first residual gas stream (RG1). The residual gas contains carbon dioxide, unreacted carbon monoxide, hydrogen not captured by PSA, and unreacted methane.
  6. Cryogenic Carbon Dioxide Separation: Carbon dioxide is separated from the first residual gas stream (RG1) using a cryogenic process, producing a carbon dioxide-rich stream (CG1) and a second residual gas stream (RG2). RG2 still contains unreacted carbon monoxide, hydrogen not captured by PSA, carbon dioxide not captured cryogenically, and unreacted methane.

• Claim 12 (Plant): This claim describes a physical plant designed to perform the process detailed in Claim 1. It specifies that the plant includes the necessary components (means for providing feed gas, a first reforming unit for endothermic reforming, a second reforming unit for autothermal reforming, a converter unit, a pressure swing adsorption unit, and a separation unit for cryogenic carbon dioxide separation) configured and connected in fluid communication to carry out the steps of the process, including the specific heat integration between the autothermal and endothermic reforming units.

Legal Status and Litigation:
The patent US11673805B2 is currently active and is set to expire on August 12, 2041.

As of April 26, 2026, the patent family has experienced litigation. Specifically, there are two PTAB (Patent Trial and Appeal Board) cases recorded:

• IPR2025-01173: This Inter Partes Review (IPR) was filed by TOPSOE, INC. and is currently pending and instituted.
• IPR2025-01174: This IPR was filed but was not instituted due to procedural reasons.

No specific CAFC (Court of Appeals for the Federal Circuit) dockets for 2026 related to US11673805 are explicitly mentioned within the provided patent text.