Abstract: Two classes of hybrid/thermochemical water splitting processes for the production of hydrogen and oxygen have been proposed based on (1) metal sulfate-ammonia cycles (2) metal pyrosulfate-ammonia cycles. Methods and systems for a metal sulfate MSO4—NH3 cycle for producing H2 and O2 from a closed system including feeding an aqueous (NH3)4SO3 solution into a photoctalytic reactor to oxidize the aqueous (NH3)4SO3 into aqueous (NH3)2SO4 and reduce water to hydrogen, mixing the resulting aqueous (NH3)2SO4 with metal oxide (e.g.

Abstract: A system for hydrogen sulfide removal from a sour gas mixture including hydrogen sulfide. The sour gas mixture is reacted with a transition metal compound in a scrubber. Sulfide from the hydrogen sulfide is oxidized to form elemental sulfur and the transition metal is reduced to form a reduced state transition metal compound. An electrochemical redox reaction is performed including the reduced state transition metal compound to regenerate the transition metal compound in an electrolyzer including a power source. During the electrochemical redox reaction a voltage from the power source applied to the electrolyzer is controlled to regenerate the transition metal compound at a rate sufficient to match a flow rate of hydrogen sulfide into the scrubber or maintain a predetermined maximum hydrogen sulfide level out from the scrubber. The transition metal compound regenerated is returned to the scrubber for the reacting.

Abstract: A system for hydrogen sulfide removal from a sour gas mixture including hydrogen sulfide. The sour gas mixture is reacted with a transition metal compound in a scrubber. Sulfide from the hydrogen sulfide is oxidized to form elemental sulfur and the transition metal is reduced to form a reduced state transition metal compound. An electrochemical redox reaction is performed including the reduced state transition metal compound to regenerate the transition metal compound in an electrolyzer including a power source. During the electrochemical redox reaction a voltage from the power source applied to the electrolyzer is controlled to regenerate the transition metal compound at a rate sufficient to match a flow rate of hydrogen sulfide into the scrubber or maintain a predetermined maximum hydrogen sulfide level out from the scrubber. The transition metal compound regenerated is returned to the scrubber for the reacting.

Abstract: A method and system for hydrogen sulfide removal from a sour gas mixture including hydrogen sulfide includes providing an aqueous solution comprising a transition metal oxide, sulfide or carbonate compound, wherein a transition metal of the transition metal oxide is at a first valence and has at least one reduction state from the first valence. The sour gas mixture is reacted with the transition metal compound and the aqueous solution in a reactor, wherein sulfide from the hydrogen sulfide is oxidized to form elemental sulfur and the transition metal is reduced to form a reduced state transition metal compound. An electrochemical redox reaction is performed including the reduced state transition metal compound to regenerate the transition metal compound in an electrolyzer comprising an anode, a cathode, and an electrolyte membrane between the anode and cathode, wherein an oxygen including gas is added to the cathode during the electrochemical redox reaction.

Abstract: Processes, methods, systems and devices for zero emission liquid hydrogen production directly from a variety of methane sources, such as natural gas and landfill gas, are disclosed. Five embodiments of plant designs for liquid hydrogen production are presented. The embodiments combine hydrogen production and liquefaction into a single process to produce liquid hydrogen directly via methane containing gases; thus, eliminating the conventional technology of pressure swing adsorption process for gas mixture separation. The innovative process can be applied to produce high purity liquid hydrogen with no carbon dioxide emission to the atmosphere; and can also co-produce highly pure solid carbon and liquid carbon dioxide as by-products for industrial application.