| 摘要 |
A hydrocarbon conversion catalyst comprises a crystalline zeolite molecular sieve which has a pore diameter between 5 and 15 </>rA and incorporates elemental selenium or tellurium. The zeolite, preferably having the X-type of crystalline structure and containing predominantly alkali metal cations may be mixed with solid selinium or tellurium and the mixture heated to 1200-1300 DEG F. in a helium atmosphere to disperse the metal and drive off excess. Alternatively, the metal vapour may be passed through a bed of zeolite or a gaseous compound of the metal used and subsequently decomposed to the metal by e.g. reduction. Zeolites of the X-type containing 5% or less of Se or Te are active cracking catalysts for e.g. the conversion of hexane to C1 to C5 hydrocarbons. For aromatization, a Se or Te content of more than 5%, preferably at least 8% is required. The catalyst may be used to convert low-octane components of petroleum naphthas to aromatics, to reform petroleum naphthas to gasoline, in the aromatization of naphthenes, cyclization of paraffins, dehydrogenation of paraffins to olefins and in hydrogenation. A hydrocarbon mixture of higher boiling point than gasoline may be contacted first at 1100 DEG F. with a catalyst containing less than 5% Se or Te to form a gasoline fraction which is subsequently contacted with a catalyst containing more than 8% Se or Te to produce a high anti-knock gasoline. At conversion temperatures Se or Te tends to migrate from the zeolite, and may be trapped in a second bed of zeolite, containing less Se or Te. The flow of reactants is periodically reversed. Alternatively the Se or Te may be trapped in a bed of activated carbon, silica gel or low pore size zeolitic sieves, and carried back periodically by reverse flushing.ALSO:A hydrocarbon conversion catalyst comprises a crystalline zeolite molecular sieve which has a pore diameter between 5 and 15 </>rA and incorporates elemental selenium or tellurium. The zeolite, preferably having the X type of crystalline structure and containing predominantly alkali metal cations, may be mixed with solid selenium or tellurium and the mixture heated to 1200-1300 DEG F. in a helium atmosphere to disperse the metal and drive off excess. Alternatively, the metal vapour may be passed through a bed of zeolite, or a gaseous compound of the metal used and subsequently decomposed to the metal by e.g. reduction. Zeolites of the X-type containing 5% or less of Se or Te are active cracking catalysts for e.g. the conversion of hexane to C1 to C5 hydrocarbons. For aromatization, a Se or Te content of more than 5%, preferably at least 8% is required. The catalyst may be used to convert low octane components of petroleum naphthas to aromatics, to reform petroleum naphthas to gasoline, in the aromatization of naphthenes, cyclization of paraffins, dehydrogenation of paraffins to olefins and in hydrogenation. A hydrocarbon mixture of higher boiling point than gasoline may be contacted first at 1100 DEG F. with a catalyst containing less than 5% Se or Te to form a gasoline fraction which is subsequently contacted with a catalyst containing more than 8% Se or Te to produce a high anti-knock gasoline. At conversion temperatures Se or Te tends to migrate from the zeolite, and may be trapped in a second bed of zeolite, containing less Se or Te. The flow of reactants is periodically reversed. Alternatively the Se or Te may be trapped in a bed of activated carbon, silica gel or low pore size zeolitic sieves, and carried back periodically by reverse flushing.ALSO:A hydrocarbon conversion catalyst comprises a crystalline zeolite molecular sieve which has a pore diameter between 5 and 15 and incorporates elemental selenium or tellurium. The zeolite, preferably having the X-type of crystalline structure and containing predominantly alkali metal cations may be mixed with solid selenium or tellurim and the mixture heated to 1200-1300 DEG F. in a helium atmosphere to disperse the metal and drive off excess. Alternatively, the metal vapour may be passed through a bed of zeolite, or a gaseous compound of the metal used and subsequently decomposed to the metal by e.g. reduction. Zeolites of the X-type containing 5% or less of Se or Te are active cracking catalysts for e.g. the conversion of hexane to C, to C5 hydrocarbons. For aromatisation, a Se or Te content of more than 5%, preferably at least 8% is required. The catalyst may be used to convert low octane components of petroleum naphthas to aromatics, to reform petroleum naphthas to gasoline, in the aromatisation of naphthenes, cyclisation of paraffins, dehydrogenation of paraffins to olefins and in hydrogenation. A hydrocarbon mixture of higher boiling point than gasoline may be contacted first at 1100 DEG F. with a catalyst containing less than 5% Se or Te to form a gasoline fraction which is subsequently contacted with a catalyst containing more than 8% Se or Te to produce a high anti-knock gasoline. At conversion temperatures Se or Te tends to migrate from the zeolite, and may be trapped in a second bed of zeolite, containing less Se or Te. The flow of reactants is periodically reversed. Alternatively the Se or Te may be trapped in a bed of activated carbon, silica gel or low pore size zeolitic sieves, and carried back periodically by reverse flushing. |
