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|Title:||First principles study of the effect of carbon and boron on the activity of a Ni catalyst|
|Citation:||Xu, J., Saeys, M. (2009-03-12). First principles study of the effect of carbon and boron on the activity of a Ni catalyst. Journal of Physical Chemistry C 113 (10) : 4099-4106. ScholarBank@NUS Repository. https://doi.org/10.1021/jp805579d|
|Abstract:||Ni catalysts are commonly used for hydrocarbon processes such as steam reforming. First principles calculations indicate that carbon atoms are relatively unstable on the terraces of a Ni catalyst, and diffusion to subsurface octahedral sites and to step sites is thermodynamically favorable. The presence of subsurface carbon significantly increases the barrier for methane activation from 91 to 143 kJ/mol and is hence expected to reduce catalyst activity. The presence of carbon atoms at the step sites also increase methane activation barriers, from 57 to 93 kJ/mol. On the basis of first principles simulations, boron has been proposed to enhance the stability of Ni catalysts by selectively blocking both the subsurface and the step sites. Boron has a strong preference for the subsurface octahedral sites, and subsurface boron causes a reconstruction of the Ni(111) surface. This reconstruction lowers methane activation barriers to 64 kJ/mol, and hence subsurface boron atoms do not reduce catalyst activity. Boron adsorption at the step sites increases the methane activation barrier from 57 to 70 kJ/mol. The activity variations are well described by the d-band model.|
|Source Title:||Journal of Physical Chemistry C|
|Appears in Collections:||Staff Publications|
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