A stable flow hydrogen production of sodium borohydride hydrolysis using millimeter-scale Ru/Al2O3 spheres as catalyst

Abstract

In this study, we investigated the performance of continuous flow hydrogen production from NaBH4 hydrolysis by loading Ru onto millimeter-scale Al2O3 spheres (0.5–1 mm in diameter) (Ru/m-Al2O3) using a simple impregnation method. The results from transmission electron microscopy (TEM) and N2 adsorption and desorption revealed that Ru particles, with an average size of 2.73 nm, were evenly distributed on the Al2O3 spheres, and the catalysts exhibited a typical mesoporous structure. The study investigated the impact of Ru loading, catalyst quantity, catalyst reduction temperature, hydrogen production temperature, feeding rate, and concentrations of NaBH4 and NaOH on the rate of hydrogen production (HPR). The evaluation of hydrogen production revealed that the top-performing Ru/m-Al2O3 catalyst achieved a HPR of 22.44 L min–1 gRu–1 at 30 °C, with an apparent activation energy (Ea) of 33.98 kJ mol–1. The catalyst could continuously produce hydrogen for 1700 min with a 20 % decrease in activity. The characterization results before and after hydrogen production revealed that Ru/m-Al2O3 exhibited excellent structural stability after a prolonged period of hydrogen production, with no apparent changes in its morphology, crystal structure, Ru particle size, and pore structure. In addition, the X-ray diffraction (XRD), inductively coupled plasma optical emission spectrometry (ICP-OES), and hydrogen production performance results showed that the flow system could effectively prevent the aggregation of NaBO2 on the catalyst's surface, thereby significantly improving the hydrogen production activity.