A highly efficient heterogeneous catalyst of Ru/MMT: Preparation, characterization, and evaluation of catalytic effect

作者：Peng, Shuge; Fan, Xinjie; Zhang, Jun; Wang, Fayuan^*

来源：Applied Catalysis B: Environmental , 2013, 140: 115-124.

DOI：10.1016/j.apcatb.2013.03.029

• Hydrogen generation
• Ruthenium nanoparticles
• Montmorillonite
• Sodium borohydride

This study focuses on the evaluation of the catalyst activity and reutilization in the catalyzed hydrolysis of sodium borohydride (NaBH4). To date, few studies on reutilization are available in literature. In the present study, a facile method was used to obtain a highly efficient catalyst, Ru nanoparticles deposited on external surface of montmorillonite (Ru/MMT). Catalytic activity and reutilization were evaluated by analyzing the H-2 generation rate from an alkaline NaBH4 solution. The catalytic activity of the as-prepared Ru/MMT was determined as a function of the catalyst amount, NaBH4 concentration, and temperature. By using the as-prepared Ru/MMT catalyst with a concentration of 1 wt% NaBH4, an average hydrogen generation rate as high as 28,500 +/- 500 mL min(-1) g(Ru)(-1) is achieved at 25 degrees C. The kinetic study demonstrates that the hydrolysis reaction is first-order in terms of the catalyst concentration and zero-order in terms of the substrate concentration. The apparent activation energy of NaBH4 hydrolysis is 54.7 +/- 1 kJ/mol, which is lower than most Ru-based catalysts reported in literatures. However, the catalytic activity of the reused catalyst dramatically decreased, with only 49% of the initial H-2 generation rate remaining after 10 runs. The degradation mechanism of the Ru/MMT catalyst during cycling was investigated and discussed in detail. Before and after 10 reutilizations, the textural properties of the catalysts were characterized based on the nitrogen adsorption-desorption isotherms (obtained using Brunauer-Emmett-Teller analysis), the surface morphology (obtained using field-emission scanning electron microscopy, and transmission electron microscopy), and on the surface composition (obtained using energy-dispersive X-ray spectroscopy, elemental analysis, and X-ray photoelectron spectroscopy). The deterioration of the reused catalyst seemed to be caused by the aggregation and partial fall-off of the Ru nanoparticles deposited on the MMT external surface.

• 出版日期2013-9
• 单位河南大学