Hydrocracking of model coal-derived liquid components over a zeolite catalyst

Abstract

Hydrocracking of fluorene was investigated over a nickel-loaded Y zeolite in a fixed-bed flow reactor using decalin as a donor solvent. Over the range of space-time and temperature variables investigated, no thermal reactions were observed, nor did hydrogen pressure significantly affect the kinetics. Deactivation (in part due to coking) was significant and coke formation was found to be a function of catalyst exposure time but was not included in the kinetic model, as the pathway for coke formation was unknown. Two kinetic models were developed using pseudo-homogenous rate expressions descriptive of the hydrocracking chemistry and an overall reaction mechanism was proposed taking into account the roles of the donor solvent, catalyst and hydrogen. The kinetic model incorporates three routes for the cracking of fluorene subsequent to hydrogen transfer from decalin : dealkylation of the side ring, breaking the phenyl-methyl bond of the central ring, and side-ring cracking. The product distribution consisted of benzenes, cyclopentanes, and C 2-C 6 hydrocarbon gases. Decalin was found to be more reactive than tetralin and avoided significant naphthalene production.