| 摘要 |
1,231,276. Catalyst compositions. UNIVERSAL OIL PRODUCTS CO. 10 June, 1968, No. 27413/68. Heading B1E. A catalyst composite is prepared by a method which comprises impregnating a porous alumina carrier with a solution containing an amount of an alkaline earth metal component which imparts to the final composite from 1 to 20 per cent by weight of alkaline earth metal (the alkaline earth metal being calcium or strontium or barium) and with a separate solution containing an amount of a catalytically active metallic component which imparts to the final composite from 0.01 to 10 per cent by weight of catalytically active metal, the impregnation with the solution containing the catalytically active metallic component being effected in the presence of from 0.1 to 1.5 per cent by weight (based upon the weight of alumina carrier) of a dibasic organic acid having the formula: a hydrogen atom or a hydroxyl or alkyl group, R' is a hydrogen atom or an alkyl or carboxyl group and n is an integer from 0 to 6, thereby to form a composite which thereafter is dried. The impregnations with the two solutions may be effected in either order. The solution containing the catalytically active metallic component also may contain the dibasic organic acid; alternatively, the organic acid may be added to the alumina carrier prior to the addition thereto of the solution containing the catalytically active metallic component. The composite may be dried, for example at a temperature of about 210‹F, and thereafter may be reduced, for example at a temperature of from 200‹F to 1800‹F and preferably in an atmosphere of hydrogen; the composite may be calcined but it is preferred that the composite is not subjected to high temperature oxidation treatment such as calcination. The alkaline earth metal component may be a formate or nitrate but preferably is a hydroxide. The metal or metals of the catalytically active metallic component may be a transition metal selected from Groups I, V, VI and VIII of the Periodic Table, for example copper, silver, gold, vanadium, chromium, molybdenum, tungsten, iron, cobalt, nickel, ruthenium, rhodium, palladium, iridium or platinum, or a mixture thereof, specified mixtures being Pd-Fe, Pd-Co, Pd-Ni, Pt-Fe, Pt-Co, Pt-Ni, Pd-Pt, Pd-Pt-Co, Pd-Cu-Co and Pt-Cu-Co-Ni; specified catalytically active metallic components are carbonates, nitrates, sulphates, chlorates and chlorides which, after impregnation of the alumina carrier therewith, may be converted to the corresponding metal oxide or oxides by heating. The preferred metal is platinum in which case the catalytically active metallic component may be chloroplatinous acid, chloroplatinic acid, platinous chloride or platinic chloride. The dibasic organic acid may be oxalic, malonic, succinic, glutaric, adipic, pinelic, suberic, malic, tartaric, citric, 2- methyl succinic, 2, 3-diethyl succinic or 2, 2- dimethyl succinic acid; a mixture of two or more of these acids may be used. The organic acid may be used in admixture with a non- alkaline diluent, for example water, alcohol or acetone. The catalyst composite additionally may contain halogen which either may be composited with the alumina carrier during the manufacture thereof, for example from an aluminium chloride hydrosol, or may be added to the composite at any stage during the manufacture thereof, for example by the use of an acid, for example hydrogen fluoride and/or hydrogen chloride, or a volatile salt, for example ammonium fluoride and/or ammonium chloride. The alumina carrier may be in the form of spheres, pills, extrudates, granules, cakes, briquettes or rings, for example Raschig rings. A preferred catalyst composite is in the form of spherical particles, each particle having a diameter of for example from 1/16 to 3/16 inch and comprising an alkaline earth metal in an amount of from 1 to 20 per cent by weight based on the weight of the alumina carrier, the alkaline earth metal being distributed uniformly throughout the particle and being present preferably as alkaline earth metal oxide, and platinum in an amount of from 0.01 to 1.0 per cent by weight based on the weight of the alumina carrier, the platinum being embedded as a layer a finite distance below the surface of the particle and a finite distance from the centre of the particle. The catalyst composite may be used in the treatment of combustible waste products, for example unsaturated hydrocarbons, alcohols, ketones, aldehydes, acids, carbon monoxide and oxides of nitrogen and sulphur; in particular, the composite may be used in the conversion of exhaust gases, for example vehicle exhaust gases, by a process which comprises contacting the gases with an oxygen-containing gas in the presence of the composite. |
