GB685079A - Improvements in or relating to the dealkylation of aromatic compounds - Google Patents

Abstract

Simultaneous dealkylation of an alkylated aromatic compound and dehydrogenation of an alicyclic hydrocarbon are effected by contacting the compounds, in the vapour phase, at 250-650 DEG , especially 500-600 DEG C., in the presence of a cracking catalyst, preferably activated carbon. Hydrogen from the alicyclic hydrocarbon combines with the alkyl group to form a paraffin. The products should be removed as formed. The alicyclic hydrocarbons generally have 5 or more alicyclic carbons and are more saturated than the compounds being dealkylated. Examples are cyclopentane, cyclotetralin, hydrindene, and compounds having unsaturation in the ring or side chain. Naphthenes give aromatics or cyclo-olefins. The alkylated aromatic compounds may be benzenoid p or polycyclic hydrocarbons, e.g. diphenyl naphthalene, anthracene or phenanthrene derivatives. The carbon used as catalyst may be from vegetable, petroleum or like sources or from pure organic compounds, and activated with steam or other inert gas. Metallic oxides or salts may be present. A molar ratio of naphthalene to aromatic compound of about 1 : 1-3 is employed. The partial pressure of hydrogen should be less than about 150 p.s.i. Total feed rates are normally 0.1-10 liquid vols./vol./hour. Fixed or moving catalyst bed or fluidized operation may be employed. Examples relate to the reaction of cyclohexane, cyclopentane, their methyl derivatives, or naphthenic naphthas, with toluene, ethyl benzene, methyl naphthalene, xylenes, C9 aromatic fraction, aromatic kerosene extracts or m, p-cresols, with activated bituminous or coconut charcoal or iron oxide-pumice as catalyst.