An investigation of light alkane conversion reactions on zeolites with a cluster approach

Light alkane catalytic conversion reactions on zeolites, including methane, ethane, propane, and iso-butane, were studied using density functional theory methods. The effect of zeolite acidity on the light alkane conversion reactions was studied. The calculated activation energies had good agreement with the available experimental data and the absolute errors were within a few kcal/mole. The activation barriers were the largest for dehydrogenation reactions, second highest for cracking reactions, and lowest for hydrogen exchange reactions, indicating the hydrogen exchange reactions were most energetically favorable. The zeolite acidity effect was mimicked by changing the terminating Si-H bond lengths of the zeolite cluster. Linear relationships were found between the activation energies and the deprotonation energies. Applying the correlations, activation energies could be predicted for different zeolite catalysts as long as their deprotonation energies are first acquired. This is an abstract of a paper presented at the AIChE Annual Meeting and Fall Showcase (Cincinnati, OH 1/04/2005).