Process intensification for generating and decomposing formic acid, a liquid hydrogen carrier

Abstract

We preview two processes that facilitate using formic acid (HCOOH) as a liquid hydrogen carrier to store renewably‐generated electrical energy and then release it to generate electrical power cleanly for backup or emergency applications. First, we show that simultaneously oxidizing an organic solute (typically a waste stream) can assist the electrochemical synthesis of formic acid by lowering the cell potential. The electrolyser comprises a hybrid 3‐chamber PEM stack that reduces CO₂ via a gas‐diffusion cathode boosted by the oxidation of aqueous methanol. However, the extent of the boosting needs to be optimized across the whole operation of the cell. Next, we present results from an intensified reactor for decomposing formic acid back into H₂ and CO₂ at elevated pressure so that the H₂ can be used in a fuel cell. The reactor combines three operations: Vaporization of the formic acid, its decomposition, and separation of the product stream. Their close coupling affords energy savings and a compact design that could be mounted on a mobile skid. We briefly discuss the electrode catalyst that facilitates the first process and two thermally activated catalysts (Ir supported on covalent triazine framework and Pd supported on carbon) that enable the second process.

Cyclic Amide-Anchored NHC-Based Cp*Ir Catalysts for Bidirectional Hydrogenation–Dehydrogenation with CO2/HCO2H Couple

“…remained as critical bottlenecks of several past approaches, including high pressure and cryogenic techniques, metal hydrides, metal organic frameworks, , and so on, for hydrogen storage/transportation. On the contrary, the use of easy-to-handle/store/transport liquid hydrogen carriers (LHCs) is advocated as a safe, practical, and viable approach for indirectly consuming the H 2 fuel on demand via catalytic dehydrogenative extraction (discharging) of stored H 2 from H 2 -rich LHCs, followed by a hydrogenative recharging of H 2 -lean LHCs with fresh (green) H 2 gas in a cyclic manner (Figure A). − This type of “energy storage and use” system is equivalent to a (rechargeable) battery, and hence, it is called (rechargeable) chemical hydrogen battery . Catalytically efficient bidirectional hydrogenation–dehydrogenation (BHD) is one of the important keys to devise such systems.…”

Techno-Economic Assessment of Green H2 Carrier Supply Chains

“…A significant amount of effort in recent years has been applied to evaluate the feasibility of these carriers. − Another potential hydrogen carrier which has begun to receive more attention is formic acid. Recent literature has considered the use of formic acid to deliver hydrogen due to its relatively high volumetric hydrogen capacity (53 g H2 L –1 ). − Much of this attention has been focused upon formic acid dehydrogenation strategies, − but less attention has been applied to considering if this carrier makes economic sense across a green hydrogen supply chain relative to other popular carriers. This motivates a comparative techno-economic assessment to evaluate the economic viability of the use of formic acid as a hydrogen carrier.…”

“…Previously reported values were used to estimate these costs (Supporting Discussion 4). ,, Since the liberation of hydrogen from methanol and formic acid resulted in CO 2 emissions, carbon capture was deployed in the model (Supporting Discussion 4). Key assumptions that were used to construct the supply chain used in this model have been tabulated (Table ).…”