InInvestigating the influence of porosity and reactant diffusion on alkane isomerisation

The isomerisation of n-butane is the main route to isobutane, a market valued at $20 billion, due to isobutanes use as a fuel additive, propellant and precursor for tert-butyl hydroperoxide. Zeolite catalysts are suited to this reaction because their micropores offer a confined space to control the reaction pathway and prevent bulky side products forming. However it is important that diffusion through the porous framework is not hindered, as this will lower the reaction conversion. Therefore we propose to contrast the diffusion of n-butane in three different zeotype frameworks with different porosities, but identical active sites. Thus allowing us to focus purely on the diffusion characteristics of the framework, to explain the significant differences in catalytic activity. We will investigate the diffusion of n-butane through the internal pores of CoAlPO-5, CoAlPO-11 and CoAlPO-18.