Hydrophilic isopropanol/acetone‐substituted polymers for safe hydrogen storage

Abstract

The development of hydrogen carriers that are free from safety risks such as explosivity, volatility and toxicity is essential for safe hydrogen storage. In this study, we synthesize a safe and hydrophilic isopropanol/acetone‐substituted polymeric hydrogen carrier by a facile synthetic procedure that is conducted in water and only requires dialysis with water for purification. A simple nucleophilic substitution of poly(allylamine) and 2‐bromoacetone produces a hydrophilic acetone‐substituted poly(allylamine) derivative, facilitating control over the hydrophilicity of the polymer according to the degree of substitution. The polymer is readily hydrogenated using NaBH4 to obtain a hydrophilic isopropanol‐substituted poly(allylamine). The high density of the repeating units and high hydrophilicity of the amine groups enable the maximization of the mass hydrogen storage density of the redox polymer to ca 1.5 wt%. Reversible hydrogen gas fixation/release from the polymeric hydrogels via chemical bond formation/disconnection is realized with complete conversion, with dehydrogenation occurring at 65–95 °C in the presence of an iridium complex catalyst. © 2021 Society of Industrial Chemistry.

A Bird’s-Eye View on Polymer-Based Hydrogen Carriers for Mobile Applications

“…Despite the lower hydrogen storage mass, acetone-substituted poly(allylamine) could provide a non-explosive fuel system that could be hydrogenated through a safe procedure. However, the complete dehydrogenation with 100% yield occurred only after 8 h at 95 °C, which is slower than other carrier groups [ 48 ]. This study, as well as similar studies that have used the same method, is extremely useful for future research, due to the mild conditions of hydrogenation and dehydrogenation ( T < 150 °C and p < 3 bar) as well as the high reversibility.…”

Polymers for Reversible Hydrogen Storage Inspired by Electrode-active Materials in Organic Batteries

“…18 Recently, organic polymers capable of facile and reversible hydrogen storage have been reported by our group. [19][20][21][22][23][24][25][26][27] The hydrogen carrier polymers are characterized by (1) the bistability of both of the hydrogenated and the dehydrogenated states giving rise to the excellent robustness, (2) the moderate mass storage density of H 2 comparable to other carrier materials, (3) the highly safe and convenient H 2 storage/production process to allow easy handling use, and (4) the variety in chemical structures by virtue of susceptibility of organic materials to molecular design. The reversible H 2 storage with organic molecules under mild conditions were first found for fluorenone/fluorenol, 19 which has been extended to various families such as tetrahydroquinoxaline/ quinoxaline derivatives, 22,24 2-propanol/acetone, 25,26 and 1,4-butanediol/γ-butyrolactone derivatives.…”

“…[19][20][21][22][23][24][25][26][27] The hydrogen carrier polymers are characterized by (1) the bistability of both of the hydrogenated and the dehydrogenated states giving rise to the excellent robustness, (2) the moderate mass storage density of H 2 comparable to other carrier materials, (3) the highly safe and convenient H 2 storage/production process to allow easy handling use, and (4) the variety in chemical structures by virtue of susceptibility of organic materials to molecular design. The reversible H 2 storage with organic molecules under mild conditions were first found for fluorenone/fluorenol, 19 which has been extended to various families such as tetrahydroquinoxaline/ quinoxaline derivatives, 22,24 2-propanol/acetone, 25,26 and 1,4-butanediol/γ-butyrolactone derivatives. The rational design of the polymers, not only for the reactive sites to undergo the H 2 storage but also for the main chains to populate the functional group per repeating unit, allowed the tuning of the hydrogenation/ dehydrogenation conditions such as the temperature and the H 2 pressure, mass storage densities, and kinetic properties.…”

Accelerating the dehydrogenation reaction of alcohols by introducing them into poly(allylamine)

“…This value is smaller than 62 kJ mol −1 , which is the difference in the standard enthalpy of formation between 1,4-butanediol and γ-butyrolactone. 40 Similar to the conventional 9-fluorenol- 18 and 2-propanol-substituted polymers, 41 the catalytic cycle peculiar to the Ir catalyst dramatically lowers the activation energy of the cyclization reaction (dehydrogenation reaction) of the 1,4-butanediol-substituted polymer.…”