Issue 11, 2010

Hydrogen release through catalyzed methanolysis of solid sodium borohydride

Abstract

Methanolysis of sodium borohydride (NaBH4) is a way of recovering the hydrogen stored in the hydride. Though the reaction is spontaneous, it can be accelerated by virtue of Co-TiO2 or Ru-TiO2 catalysts. Under our experimental conditions, Co-TiO2 shows high catalytic performances, higher than those of Ru-TiO2. Hydrogen generation rates of 144 to 644 L(H2) min−1 g−1(Co) were measured as the Co content was decreased. The kinetic parameters of the catalyzed reaction were determined. The Co-TiO2-catalyzed methanolysis follows a power law, i.e. r20 = k·[NaBH4]1.3·[CH3OH]0.9 with k = 1.8 × 10−2 s−1. The Langmuir–Hinshelwood bimolecular mechanism accounts for the kinetics. The apparent activation energy was found to be 20.4 kJ mol−1 whereas that of the catalyzed hydrolysis was 49.4 kJ mol−1. Indeed, the catalyzed methanolysis was compared to the catalyzed hydrolysis as well as the catalyzed ethanolysis. For instance, it was remarked that water in methanol has a detrimental effect on the H2 release kinetics. In parallel, the gravimetric hydrogen density of the system NaBH4-CH3OH has been optimized. Under our experimental conditions, it was found that the highest capacity that can be achieved is 3.4 wt%.

Graphical abstract: Hydrogen release through catalyzed methanolysis of solid sodium borohydride

Article information

Article type
Paper
Submitted
08 Apr 2010
Accepted
20 Jul 2010
First published
28 Sep 2010

Energy Environ. Sci., 2010,3, 1796-1803

Hydrogen release through catalyzed methanolysis of solid sodium borohydride

J. Hannauer, U. B. Demirci, G. Pastor, C. Geantet, J. M. Herrmann and P. Miele, Energy Environ. Sci., 2010, 3, 1796 DOI: 10.1039/C0EE00023J

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