Continuous reactors of formate-bicarbonate cycle for hydrogen storage and release

An apparatus for continuous production of hydrogen by dehydrogenation of aqueous formate solution, comprising:

• a first storage tank, in which an aqueous formate solution is held, connected by a feed line to a dehydrogenation reactor, with a heat exchanger optionally positioned along said feed line;
• a catalyst feeder to supply dry granular or powdered material to the dehydrogenation reactor, e.g., a screw conveyor hooper;
• the dehydrogenation reactor, having a first outlet equipped with a gas discharge line to withdraw hydrogen gas evolving in the reactor and deliver the hydrogen to pressure cylinder or a fuel cell, and a second outlet equipped with a liquid discharge line to direct flowable effluent from the dehydrogenation reactor to a product tank;
• the product tank, which is partitioned by sieve into to a lower section and an upper section, with the liquid discharge line from the dehydrogenation reactor entering the lower section of said product tank,
• a separation and washing unit, which is supplied alternately by appropriate arrangement of valves either from the product tank, wherein the upper section of the product tank is connected by a discharge line to the separation and washing unit, or from a washing solution feed line, such that the separation and washing unit alternates between a separation mode, during which it is supplied by an effluent pumped through the discharge line from the product tank, and a washing mode, during which it is supplied by the washing solution;
• wherein the separation and washing unit is provided with a return line to direct liquid phase consisting of formate solution collected during separation to the dehydrogenation reactor, and with a catalyst recycle line connected to a drying and oxidation unit, to supply refreshed catalyst the catalyst feeder or to spent catalyst to a storage tank.

An apparatus for continuous storage of hydrogen by reacting aqueous bicarbonate slurry with hydrogen to form formate, comprising:

• a first storage tank, in which bicarbonate slurry is held, connected by a feed line to a mixing unit;
• a catalyst feeder to supply dry granular or powdered material to the mixing unit, e.g., a screw conveyor hooper;
• a mixing unit, provided with an agitator to produce an aqueous slurry of bicarbonate and catalyst particles and with a discharge line to supply said suspension to a first hydrogenation reaction;
• a first hydrogenation reactor and optionally a second hydrogenation reactor, arranged in series, wherein the discharge line of the mixing unit is connected to an inlet of the first hydrogenation reactor and wherein each hydrogenation reactor has a gas inlet connected to hydrogen feed line to introduce hydrogen gas to each hydrogenation reactor;
• and wherein the first hydrogenation reactor or the second hydrogenation reactor, as appropriate, discharges to a solid/liquid separation unit, wherein the first hydrogenation reactor has a sieve mounted in proximity to the reactor outlet to prevent bicarbonate particles from leaving the reactor;
• A product tank, connected to the solid/liquid separation unit, to receive liquid stream therefrom consisting of aqueous formate;
• A washing tank, connected to the solid/liquid separation unit, to receive the solid catalyst particles collected in the solid/liquid separation unit;
• wherein the washing tank is connected by a catalyst recycle line to a drying and oxidation unit, to supply refreshed catalyst the catalyst feeder or a spent catalyst to a recycle tank.