| Abstract
| - A single-event kinetic model is applied to the hydrocracking of cycloalkane model componentson two bifunctional Pt/US-Y zeolites over a wide range of experimental conditions (T = 493−573 K, P = 10−50 bar, molar H2-to-hydrocarbon ratio = 50−300). Values for the standardactivation entropies of the elementary steps were obtained from transition state theory, whileindependently determined Henry coefficients were used to describe the physisorption. Valuesfor the composite activation energies, i.e., the sums of the protonation enthalpies of the alkeneintermediates and the activation energies of the elementary carbenium ion transformations,were obtained from a regression of the experimental data. The composite activation energiesfor intra-ring alkyl shifts vary from 21 to 25 kJ/mol, which is higher than those for thecorresponding acyclic alkyl shifts, which vary from 10 to 16 kJ/mol. The composite activationenergies for cyclic protonated cyclopropane branching reactions range between 27 and 40 kJ/mol and are comparable to those of the corresponding acyclic reactions. The same holds for exo-and acyclic β-scission, with values from 22 to 76 kJ/mol. Endocyclic β-scissions, in general, havelower composite activation energies, varying from 31 to 56 kJ/mol, than acyclic β-scissions.However, because of a much lower preexponential factor, they proceed at a lower rate thanacyclic β-scissions.
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