Hydrocracking of aromatic hydrocarbons over USY-zeolite

Hydrocracking of 1-butylbenzene, tetralin, diphenylmethane, naphthalene, l-methylnaphthalene, 9,10-dihydroanthracene, anthracene, and phenanthrene was investigated at 400, 500, and 600 degrees C under 5 MPa of hydrogen pressure. With metal-free ultrastable Y-zeolite catalyst and at a severe cracking temperature of 600 degrees C, accumulated yields of benzene, toluene, and xylene (BTX) and C-1-C-3 hydrocarbon gases were nearly 100%. The formation of tar and coke was almost negligible. On the basis of the product distribution pattern, the reaction pathways leading to BTX and light gases were postulated. The reaction for diphenylmethane, n-butylbenzene, and tetralin was initiated by the hydrocracking of a C-C single bond, whereas for other compounds the hydrogenation of the aromatic ring was the initial step followed by the hydrocracking reaction. Even in the case of l-methylnaphthalene, the hydrogenation of the aromatic ring preceded the hydrocracking of the methyl group. The hydrocracking of anthracene and phenanthrene was likely to proceed via the cracking at the outer ring.