Ethylene glycol enabled high-rate nominally catalyst-free hydrogen generation from potassium borohydride

Abstract

In this study, the nominally catalyst-free solvolysis of potassium borohydride (KBH4) in ethylene glycol (EG)based media was systematically investigated as a controllable hydrogen-generation strategy. The effects of solvent composition, solvent volume, temperature, and KBH4 dosage on hydrogen production kinetics were examined. Hydrogen generation rates were evaluated using the T1/2 method. Pure ethylene glycol exhibited the highest hydrogen generation rate, reaching 1560 mL min- 1 at 45 degrees C. Arrhenius analysis yielded an apparent activation energy of 34.74 kJ mol-1, indicating a relatively low kinetic barrier under the investigated conditions. Compared with representative literature reports on nominally catalyst-free borohydride systems, the KBH4/ ethylene glycol system exhibited relatively rapid hydrogen generation under mild conditions. Kinetic and thermodynamic analyses further suggested the possible involvement of a more ordered solvent-assisted transition state during hydrogen evolution. The results suggest that solvent-solute interactions may contribute to the observed behavior, highlighting solvent engineering as a promising approach for nominally catalyst-free hydrogen production.