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.

Steam reforming, water separation, and hydrogen separation by membrane can be performed sequentially on a mixture of steam and a hydrocarbon. A hydrogen-rich permeate stream from the hydrogen membrane can be used as fuel for combustion heating, leaving a retentate mixture of a prescribed ratio of hydrogen to oxides of carbon. The retentate can be compressed and synthesized to methanol in a methanol synthesis reactor. The synthesized methanol can be separated into a methanol-rich stream and a tail gas stream containing the remaining outlet gas from the synthesis reactor. The methanol-rich stream can be refined. The tail gas stream can be divided into a methanol loop recycle stream, an SMR recycle stream, and a nitrogen purge stream. The methanol loop recycle stream is compressed and recycled to the methanol synthesis reactor. The SMR recycle stream is recycled as feedstock to the reformer. The nitrogen purge stream is combusted in a burner. Carbon dioxide may be separated from combustion products and sequestered.

Hydrogen purification devices and their components are disclosed. In some embodiments, the devices may include at least one foil-microscreen assembly disposed between and secured to first and second end frames. The at least one foil-microscreen assembly may include at least one hydrogen-selective membrane and at least one microscreen structure including a non-porous planar sheet having a plurality of apertures forming a plurality of fluid passages. The planar sheet may include generally opposed planar surfaces configured to provide support to the permeate side. The plurality of fluid passages may extend between the opposed surfaces. The at least one hydrogen-selective membrane may be metallurgically bonded to the at least one microscreen structure.

A reactive process for converting composite plastic waste into hydrogen gas and a reactor system for effecting such process.

It has been discovered that mixed-alcohol production can utilize the waste tail gas stream from the pressure-swing adsorption section of an industrial hydrogen plant. Some variations provide a process for producing mixed alcohols, comprising: obtaining a tail-gas stream from a methane-to-syngas unit (e.g., a steam methane reforming reactor); compressing the tail-gas stream; separating the tail-gas stream into at least a syngas stream, a CO.sub.2-rich stream, and a CH.sub.4-rich stream; introducing the syngas stream into a mixed-alcohol reactor operated at effective alcohol synthesis conditions in the presence of an alcohol-synthesis catalyst, thereby generated mixed alcohols; and purifying the mixed alcohols to generate a mixed-alcohol product. Other variations provide a process for producing clean syngas, comprising: obtaining a tail-gas stream from a methane-to-syngas unit; compressing the tail-gas stream; separating the tail-gas stream into at least a syngas stream, a CO.sub.2-rich stream, and a CH.sub.4-rich stream; and recovering a clean syngas product.

A method and to a device for producing a synthesis gas, which contains carbon monoxide and hydrogen, wherein natural gas having a first carbon dioxide partial pressure (CO.sub.2 pressure) is provided and is processed inter alia by means of a pressure increase to form a natural gas input for a thermochemical conversion, in which a synthesis raw gas having a second CO.sub.2 pressure greater than the first CO.sub.2 pressure is produced, from which synthesis raw gas at least carbon dioxide is subsequently separated in order to obtain the synthesis gas and carbon dioxide, at least some of which is returned and is used in the thermochemical conversion of the natural gas input. To separate carbon dioxide, the synthesis raw gas is conducted across the one membrane on the retentate side, which membrane is permeable to carbon dioxide and is flushed on the permeate side by the provided natural gas.

Synthesis gas containing nitrogen as the majority component is processed to increase the hydrogen to carbon dioxide ratio. Nitrogen, carbon dioxide, and other contaminants are subsequently removed by a purification unit to produce a purified hydrogen gas stream. A recycle stream within the purification unit helps achieve a hydrogen purity greater than 99.9 percent, and hydrogen recovery greater than 99 percent.

Bifunctional catalyst compositions, methods, and systems are provided for the use of CO.sub.2 as a soft oxidizing agent to effectively convert low-value small alkanes to high-value small olefins. The bifunctional catalyst comprises a metal oxide catalyst and a redox-active ceramic support.

Hydrogen-producing fuel processing systems and related methods. The systems include a hydrogen-producing region configured to produce a mixed gas stream from a feedstock stream, a hydrogen-separation membrane module having at least one hydrogen-selective membrane and configured to separate the mixed gas stream into a product hydrogen stream and a byproduct stream, and an oxidant delivery system configured to deliver an oxidant-containing stream to the hydrogen-separation membrane module in situ to increase hydrogen permeance of the hydrogen-selective membrane. The methods include operating a hydrogen-producing fuel processing system in a hydrogen-producing regime, and subsequently operating the hydrogen-producing fuel processing system in a restoration regime, in which an oxidant-containing stream is delivered to the hydrogen-separation membrane module in situ to expose the at least one hydrogen-selective membrane to the oxidant-containing stream to increase the hydrogen permeance of the at least one hydrogen-selective membrane.

Recovery of hydrogen from an ammonia cracking process in which the cracked gas is purified in a PSA device is improved by using a membrane separator on the PSA tail gas.