The mechanism of alkane activation over zeolite Brّnsted acid sites. A density-functional study

Semi-empirical and density-functional molecular orbital methods are used to investigate the mechanism of monomolecular cracking of n-butane over Brønsted acid sites. Both techniques show the reaction proceeds via protolytic attack at the centre of CC bonds and not at the carbon atoms themselves, as has been previously suggested. The carbonium ion is also shown to collapse to an alkane/alkene and not an alkane/alkoxide as has been recently proposed.