Development of a polyfunctional catalyst for benzene production from pyrolysis gasoline

The concurrence of hydrodealkylation, hydrocracking, and hydrodesulfurization reactions necessitates a polyfunctional catalyst in the production of pure benzene from pyrolysis gasoline or other industrial mixtures containing various alkylaromatic and nonaromatic hydrocarbons. A chromium catalyst was developed in this study with comparable performance to the commercial catalyst Pyrotol H-9430 (Houdry, USA). The new catalyst contained 15 wt.% Cr and was doped with KF. When tested utilizing a hydrocleaned BTX fraction of pyrolysis gasoline, it preserved its benzene selectivity and hydrocracking activity for 3000 h, but lost about 10% of its hydrodealkylation activity. The deactivated catalyst completely recovered its original surface properties and hence activity when subjected to oxidative regeneration. The developed catalyst maintained its Cr and KF content in regeneration as it did in drying, calcination, and reaction. The characteristics of the catalyst were examined by BET, XRD, DTA, TGA and electron microscope. (C) 2002 Elsevier Science B.V. All rights reserved.