Alcohol-Substituted Vinyl Polymers for Stockpiling Hydrogen

Abstract

Hydrogen has a high energy density and produces only water during combustion; consequently, it has attracted considerable attention as a next-generation sustainable energy source. To be used on a daily basis, hydrogen-storage materials need to stockpile hydrogen safely and to release it using only small amounts of energy. Chemically bonded hydrogen stored in a polymer is highly safe, enabling hydrogen to be stored under ambient conditions in a non-volatile, non-toxic, and non-flammable manner. Herein, we report the dehydrogenation reactions of alcohol-substituted vinyl polymers at mild temperatures. Poly(allyl alcohol) was dehydrogenated at 65–95 °C in the presence of an iridium complex catalyst to produce poly(acrylic acid) due to the extremely low activation energy (10 kJ/mol) associated with the catalyst-specific cycle. Poly(allyl alcohol) exhibits a hydrogen-storage density of 6.8 wt% by releasing two equivalents of hydrogen gas, which demonstrates that alcohol-substituted vinyl polymers can be used to stockpile hydrogen and release it under mild conditions.