Catalysts for water dealkylation of aromatic hydrocarbons
AssigneeElf Union
InventorsMichel Grand, Daniel Duprez
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Abstract
A water dealkylation catalyst of aromatic hydrocarbons containing at least one metal of Group VIII and eventually, one metal of group VII.sub.b deposited on a gamma alumina of special properties containing at least 1000 ppm of sulfate ions having undergone a pre-treatment in aqueous medium at a pH between 1 and 10 at a temperature below 100.degree. C. The catalysts contain rhodium on pre-treated gamma alumina and the bimetallic catalysts contain 2 metals of the group VIII or one metal of the group VII and one metal of the group VII.sub.b on pre-treated gamma alumina.
Claims14
A water dealkylation catalyst for an aromatic hydrocarbon consisting essentially of from 0.1 to 5% by weight of (A) one or two metals selected from the group consisting of rhodium, platinum, palladium and iridium or (B) Rh with at least one metal selected from the group consisting of Pt, Pd, Ir and Mn deposited on a gamma alumina carrier, said catalyst having improved properties of activity, selectivity and stability wherein said catalyst is prepared by:
- (a) pretreating said gamma alumina carrier in an aqueous medium for 15 minutes to 78 hours, at a pH from 1 to 10, at a temperature of 0.degree. to 100.degree. C.;
- (b) impregnating the pretreated gamma alumina carrier with an aqueous or acid solution of a salt of the metal, to a total concentration of metal in the carrier of from 0.1 to 5% by weight;
- (c) drying said impregnated carrier;
- (d) calcining said dried impregnated carrier in air;
- (e) reducing the calcined impregnated carrier in a hydrogen current at 400.degree.-500.degree. C.;
- (f) treating the reduced impregnated carrier with a water vapor current at 400.degree. to 600.degree. C. for a period of 5 minutes to 15 hours whereby the catalyst is formed.
Dependencies are inferred from the claim text.