Catalytic hydrolysis of ammonia borane: Intrinsic parameter estimation and validation
✍ Scribed by S. Basu; Y. Zheng; A. Varma; W.N. Delgass; J.P. Gore
- Publisher
- Elsevier Science
- Year
- 2010
- Tongue
- English
- Weight
- 572 KB
- Volume
- 195
- Category
- Article
- ISSN
- 0378-7753
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✦ Synopsis
Ammonia borane (AB) hydrolysis is a potential process for on-board hydrogen generation. This paper presents isothermal hydrogen release rate measurements of dilute AB (1 wt%) hydrolysis in the presence of carbon supported ruthenium catalyst (Ru/C). The ranges of investigated catalyst particle sizes and temperature were 20-181 m and 26-56 • C, respectively. The obtained rate data included both kinetic and diffusion-controlled regimes, where the latter was evaluated using the catalyst effectiveness approach. A Langmuir-Hinshelwood kinetic model was adopted to interpret the data, with intrinsic kinetic and diffusion parameters determined by a nonlinear fitting algorithm. The AB hydrolysis was found to have an activation energy 60.4 kJ mol -1 , pre-exponential factor 1.36 × 10 10 mol (kg-cat) -1 s -1 , adsorption energy -32.5 kJ mol -1 , and effective mass diffusion coefficient 2 × 10 -10 m 2 s -1 . These parameters, obtained under dilute AB conditions, were validated by comparing measurements with simulations of AB consumption rates during the hydrolysis of concentrated AB solutions (5-20 wt%), and also with the axial temperature distribution in a 0.5 kW continuous-flow packed-bed reactor.