RUTHENIUM PNP-PINCER COMPLEX-CATALYZED AMINE-FREE REVERSIBLE HYDROGEN STORAGE IN FORMATE SALTS WITHOUT pH CONTROL OR SOLVENT CHANGE

摘要

Hydrogen, the clean energy fuel, can be produced by electrochemical water splitting using renewable energy sources. Unfortunately, its low volumetric energy density and high flammability renders its handling and storage very difficult. Thus, there is a need to store hydrogen safely and efficiently. One of the proposed ways is to react it with CO2, an abundant, cheap, non-toxic C1 raw material, which can be captured from a variety of sources. Hydrogenation of CO2 produces many valuable chemicals; for example, CO2 can be reduced to formic acid (FA) or formate salts, formate esters, methane or methanol. Among the CO2 hydrogenation products, formic acid and HCOONa/H2O can generate 4.4 wt. % and 2.3 wt. % H2, respectively. Formic acid and its salts are nonflammable and non-toxic systems, making them safe and convenient H2 storage media. In the presence of an appropriate catalyst, formic acid and formates, can be selectively decomposed to hydrogen and CO2 and a carbon neutral cycle can be envisioned by recycling the CO2 back to formic acid and its salts.