Natural flavonoids as highly efficient catalyst for rapid H2 generation from NaBH4 methanolysis in cold climates

Natural flavonoids, including quercetin, rutin, baicalein and puerarin have been employed for the first time as efficient catalysts in the alcoholysis of NaBH 4 . Among them, quercetin demonstrates optimal catalytic performance for this reaction, achieving an HGR value of 26374 mL H 2 g cat −1 min −1 when 0.2 g NaBH 4 is catalyzed by 50 mg quercetin. The catalytic activity of quercetin is unparalleled for methanolysis of NaBH 4 , particularly at low-temperature; notably, a high HGR value of 1948 mL H 2 g cat −1 min −1 is observed even at −25 °C. Furthermore, the activation energy for the NaBH 4 methanolysis catalyzed by quercetin within a low temperature range of −25 to 25 °C has been calculated to be 17.2 kJ mol −1 . Investigates into the reusability and regeneration of quercetin reveal that over 74 % of its catalytic activity is retained after five consecutive uses; additionally, complete recovery of catalytic activity can be achieved through simple acid treatment. Moreover, kinetic studies indicate that the reaction orders of NaBH 4 methanolysis catalyzed by quercetin obey to first-order kinetics concerning all concentrations: NaBH 4 concentration, catalyst dosage, and methanol content. This study establishes a foundation for practical application involving NaBH 4 in hydrogen production under cold climate conditions typical in Polar Regions or during severe winters at northern latitudes.