Theoretical study of catalytic cracking of C5–C6 alkanes to olefins using zeolites

Abstract

The cracking mechanisms of n-pentane and n-hexane over the H-ZSM-5 and H-FER catalysts were investigated using the ONIOM(B3LYP/6-31+G(d,p):AM1) method with 52T and 64T cluster model, respectively. The computation results show that the cracking process of n-pentane and n-hexane over the H-ZSM-5 and H-FER catalysts consisting of two reaction paths. The first path is turnover path. The second path is poisoning path. The cracking processes of the n-pentane and n-hexane over either the H-ZSM-5 or H-FER catalyst afford the 1,2-pentene and 1,2-hexene as the major products and then provide 2-pentoxy and 2-hexoxy species as catalyst poisoning, respectively. Thermodynamic quantities, rate constants, equilibrium constants and reaction energies of cracking reaction of n-pentane and n-hexane over the H-ZSM-5 and H-FER catalysts are reported.