When a product gas producing operation is stopped, a purge operation is executed in which steam purge processing and product gas purge processing are sequentially performed. The steam purge is supplying, instead of a source gas, a product gas from a product gas tank to a reformer using a compressor, and supplying a reformed gas from a reforming processing unit to a plurality of adsorption towers, which perform a pressure swing adsorption operation, while the reformer is heated by a heating burner and steam is supplied to the reformer. The product gas purge is supplying the product gas from the product gas tank to the reformer using the compressor, and supplying the product gas from the reforming processing unit to the plurality of adsorption towers, which perform the pressure swing adsorption operation, while the supply of the steam is stopped and the heating of the reformer is maintained.

Improved processes and systems are disclosed for producing renewable hydrogen suitable for reducing metal ores, as well as for producing activated carbon. Some variations provide a process comprising: pyrolyzing biomass to generate a biogenic reagent comprising carbon and a pyrolysis off-gas; converting the pyrolysis off-gas to additional reducing gas and/or heat; reacting at least some of the biogenic reagent with a reactant to generate a reducing gas; and chemically reducing a metal oxide in the presence of the reducing gas. Some variations provide a process for producing renewable hydrogen by biomass pyrolysis to generate a biogenic reagent, conversion of the biogenic reagent to a reducing gas, and separation and recovery of hydrogen from the reducing gas. A reducing-gas composition for reducing a metal oxide is provided, comprising renewable hydrogen according to a hydrogen-isotope analysis. Reacted biogenic reagent may also be recovered as an activated carbon product. Many variations are disclosed.

Embodiments of the invention are directed to methods, processes, and systems for safely and reliably purifying hydrogen from a gas mixture containing hydrogen and oxygen.

The present invention relates to a process for producing hydrogen and for separating carbon dioxide from synthesis gas using a physical absorption medium. The process comprises the steps where the synthesis gas and the absorption medium are cooled; carbon dioxide is removed from the cooled synthesis gas via the cooled absorption medium in a physical absorption step at elevated pressure; laden absorption medium is treated in a plurality of flash stages, wherein co-absorbed carbon monoxide, hydrogen and carbon dioxide are separately removed from the laden absorption medium; hydrogen is separated from synthesis gas freed of carbon dioxide in a physical separation step, wherein hydrogen as product gas and an offgas comprising hydrogen, carbon monoxide and carbon dioxide are obtained; product gas hydrogen and carbon dioxide are discharged from the process. The invention further relates to a plant for performing the process.

A process for manufacturing a dihydrogen-containing outlet gas, including injecting a hydrocarbon inlet gas into a reactor, an operation of cracking the inlet gas with a three-phase plasma torch, and then delivering the outlet gas. The manufacture is carried out from injecting the inlet gas into the reactor to delivering the outlet gas, without either the inlet gas or the outlet gas undergoing expansion.

A processing facility is provided. The processing facility includes an asphaltenes and metals (AM) removal system configured to process a feed stream to produce a power generation stream, a hydroprocessing feed stream, and an asphaltenes stream. A power generation system is fed by the power generation feed stream. A hydroprocessing system is configured to process the hydroprocessing feed stream to form a gas stream and a liquid stream. A hydrogen production system is configured to produce hydrogen, carbon monoxide and carbon dioxide from the gas feed stream. A carbon dioxide conversion system is configured to produce synthetic hydrocarbons from the carbon dioxide, and a cracking system is configured to process the liquid feed stream.

Process and plant for producing hydrocarbon products from a feedstock originating from a renewable source, where a hydrogen-rich stream and on off-gas stream comprising hydrocarbons is formed. A portion of the hydrogen-rich stream is used as a recycle gas stream in a hydroprocessing stage for the production of said hydrocarbon products, and another portion may be used for hydrogen production, while the off-gas stream is treated to remove its H.sub.2S content and used as a recycle gas stream in the hydrogen producing unit, from which the hydrogen produced i.e. make-up hydrogen, is used in the hydroprocessing stage. The invention enables minimizing natural gas consumption in the hydrogen producing unit as well as steam reformer size.

In an aspect a method of recovering hydrogen, the method comprises reacting a hydrocarbon to form a carbon compound and hydrogen in the presence of a catalyst, wherein the carbon compound comprises at least one of carbon dioxide or carbon monoxide; separating the carbon compound from the hydrogen; directing the carbon compound to a cathode side of an electrochemical cell and directing water to an anode side of the electrochemical cell; electrolyzing the water on the anode side to form oxygen and protons; applying a voltage to a membrane and electrode assembly in the electrochemical cell to cause the protons to traverse through a proton exchange membrane from an anode to a cathode on the cathode side; and reacting the protons with the carbon compound to form an organic product.

A hydrogen feed stream comprising one or more impurities selected from the group consisting of nitrogen, argon, methane, carbon monoxide, carbon dioxide, oxygen, and water, is contacted with liquid hydrogen in a cryogenic wash column (CWC) process that produces pure hydrogen with high overall recovery. The waste liquid stream leaving the CWC may be used to improve the performance of upstream hydrogen processing steps.

A hydrogen feed stream comprising oxygen and one or more impurities selected from the group consisting of nitrogen, argon, methane, carbon monoxide, carbon dioxide, and water, is purified using a cryogenic temperature swing adsorption (CTSA) process with high overall recovery of hydrogen. The CTSA is regenerated using an inert gas to prevent an explosive mixture of hydrogen and oxygen from occurring.