Natural Flavonoids as Efficient Catalyst for Fast H2 Production from Nabh4 Methanolysis in Cold Climates

Abstract

Natural flavonoids such as quercetin, rutin, baicalein and puerarin were applied to the methanolysis of NaBH4 as efficient catalysts for the first time. Quercetin exhibits the optimal catalytic performance for the methanolysis of NaBH4, and the HGR value is 26374 mL H2·gcat-1·min-1 for 0.2 g NaBH4 catalyze by 50 mg quercetin. The catalytic activity of quercetin is unparalleled for methanolysis of NaBH4 particularly at low-temperature, and the HGR value is as high as 1948 mL/gcat.·min even at -25 °C. Furthermore, the activation energy is calculated to be 17.2 kJ·mol-1 for the NaBH4 methanolysis catalysis by quercetin at low temperature range of -25 ~ 25 °C. The investigates of re-usability and re-generation of catalyst show that over 74% catalytic activity are retained after fifth consecutive reuse, and the catalytic activity can be completely recovered through simple acid treatment. In addition, the kinetic reaction orders of NaBH4 methanolysis catalyzed by quercetin were identified to obey first-order kinetics with respect to all of NaBH4 concentration, catalyst dosage, and methanol content. This study lays the foundation for the practical application of NaBH4 for hydrogen production in cold climate conditions, such as those found in Polar Regions or during severe winters in northern latitudes.

Keywords: NaBH4, flavonoids, Quercetin, methanolysis, kinetics