Propane cracking over different types of zeolites was investigated using the realistic nanocluster of 120T performed at the M06L/6-31G(d,p)//14T ONIOM(M06L/6-31G(d,p):UFF) level of theory. The adsorption energies of propane were predicted to be -7.6 and -9.9 kcal/mol for H-FAU and H-MOR, respectively. Using the experimental adsorption energies as the benchmark, our combined ONIOM scheme is found to represent the interaction of propane with zeolites. After adsorption, the zeolite's proton was inserted into a C-C bond of a propane molecule and yielded a methane and ethoxide intermediate. The intermediate was then deprotonated to form the ethylene product. The first step was found to be rate-determining with actual activation energies of 43.7 and 41.3 kcal/mol  for H-FAU and H-MOR, respectively. The activation energies for the second step were 24.7 and 18.5 kcal/mol for H-FAU and H-MOR, respectively. Our findings suggested that the propane cracking was insensitive to the zeolite structure.

Propane cracking reaction over different types of nanostructured zeolites: A newly developed DFT approach

239th National Meeting (2010)

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