Abstract: An alkaline water electrolyzer (AWE) incorporates a cation-exchange membrane (CEM) instead of a conventional porous diaphragm or an anion-exchange membrane used in the conventional AWE. The corresponding change in the nature of the charge carrier from the hydroxyl anion (OH?) in the conventional AWE to an alkali cation (A+) has a substantial effect on the electrochemistry and performance of the resulting CEM-alkaline water electrolyzer (CEM-AWE). The water electrolysis device combines advantages of: 1) non-PGM (precious group metal) catalysts involved in L-AWE (liquid alkaline water electrolyzer) and in AEM-AWE (anion exchange membrane-AWE), and 2) higher efficiency, differential pressure operation, responsiveness, and long-life of PEM-WE (proton-exchange membrane water electrolyzer). The novel water electrolyzer combines advantages of the two in the CEM-AWE involving non-PGM catalysts, graphite/SS PTLs and bipolar plates.

Abstract: A direct impure water electrolysis (DIWE) approach generates green hydrogen in a modified proton-exchange membrane pure water electrolyzer (PEM-PWE), that avoids fouling, corrosion, deactivation, and side reactions normally caused by the ions in impure or saline waters. Conventional electrolyzers require ultrapure deionized (DI) water as feed because: 1) the proton-exchange membrane (PEM) and electrocatalysts are readily poisoned by the anions, e.g., chloride, and cations, e.g., sodium, calcium, and magnesium that are present in seawater or brackish water; and 2) the chloride anions readily form chlorine at the PEM-electrolyzer anode, which is toxic and corrosive. This adds substantially to the cost and complexity of the electrolyzer plant due to the water treatment plant needed for producing ultrapure DI water. The tolerance of impure water as described herein avoids reverse osmosis and deionization requirements steps which is beneficial for use in semi-arid regions with a paucity of fresh water.

Abstract: In an embodiment, a method comprises adding a methanol feed stream from a source methanol reservoir to a loop; wherein the loop comprises an electrolyzer, a base methanol reservoir, an electrolyzer inlet stream that directs a methanol mixture from the base methanol reservoir to the electrolyzer, and a methanol carbon dioxide stream that directs an unreacted methanol from the electrolyzer to the base methanol reservoir; and maintaining a methanol concentration in the base methanol reservoir through the opening and closing of a purge valve that allows a purge stream to flow from the base methanol reservoir to the source methanol reservoir and through the opening and closing of a feed valve that allows the methanol feed stream to flow from the source methanol reservoir into the loop. A product hydrogen stream can be recovered for use in an engine.

Abstract: In an embodiment, a method comprises adding a methanol feed stream from a source methanol reservoir to a loop; wherein the loop comprises an electrolyzer, a base methanol reservoir, an electrolyzer inlet stream that directs a methanol mixture from the base methanol reservoir to the electrolyzer, and a methanol carbon dioxide stream that directs an unreacted methanol from the electrolyzer to the base methanol reservoir; and maintaining a methanol concentration in the base methanol reservoir through the opening and closing of a purge valve that allows a purge stream to flow from the base methanol reservoir to the source methanol reservoir and through the opening and closing of a feed valve that allows the methanol feed stream to flow from the source methanol reservoir into the loop. A product hydrogen stream can be recovered for use in an engine.