GB1343736A - Zeolite-promoted hydrocarbon conversion catalyst - Google Patents

Abstract

1343736 Faujasite-promoted hydrocarbon cracking catalysts W R GRACE & CO 19 April 1971 [26 March 1970] 25425/71 Heading B1E A catalytic composition comprising faujasite, clay and silica-alumina is prepared by a process which comprises (a) providing a mixture which has been obtained in the synthesis of faujasite from alkali metal, silica and alumina values and which comprises faujasite having a SiO 2 :Al 2 O 3 molar ratio of from 3:1 to 6:1 and residual silicate-containing mother liquor, (b) separating the faujasite from the mother liquor, (c) adding clay to the mother liquor, (d) gelling silicate in the resulting reaction medium by addition thereto of carbon dioxide or mineral acid, for example sulphuric acid or hydrochloric acid, (e) ageing the gel-containing reaction medium, (f) adding an aluminium salt to the reaction medium, (g) precipitating alumina from the reaotion medium, for example by addition thereto of ammonia, and (h) recovering solids from the reaction medium, there being added to the reaction medium, at any time after silicate gellation and before solids recovery, faujasite. The clay, which may constitute 20-50 weight per cent of the composition, may be naturally occurring or thermally modified, for example calcined; specified clays, are kaolin, metakaolin, kaolinite, halloysite, montmorillonite, anauxite, dickite and nacrite. Additional silicate may be added either to the mother liquor prior to addition thereto of clay or to the reaction medium prior to silicate gellation; sodium aluminate may be added to the gel-containing reaction medium prior to ageing. The recovered solids may be spray-dried at a temperature of 250-350‹F to provide microspheres having an average diameter of 50-70 microns and/or may be subjected to ion exchange with rare earth metal chloride solution so that rare earth metal constitutes 2.0-4.0 weight per cent (expressed as oxide) of the composition which may contain 10-20 weight per cent faujasite and, correspondingly, 90-80 weight per cent amorphous matrix consisting of 25-50 weight per cent clay and, correspondingly 75-50 weight per cent silica-alumina having an alumina content of 25-40 weight per cent. According to a first example, a composition containing 3.27 weight per cent rare earth metal (expressed as oxide) and consisting of 15.7 weight per cent faujasite, 41.8 weight per cent clay and 42.5 weight per cent silicaalumina having an alumina content of 40 weight per cent is prepared by a procedure which comprises synthesising faujasite by a technique involving seeding, separating faujasite from the synthesis mixture by filtration, adding kaolin to the resulting mother liquor adding carbon dioxide thereby to gel silicate, adding sodium aluminate solution, ageing, adding aluminium sulhpate solution, adding aqueous ammonia thereby to precipitate alumina, adding faujasite separated from the synthesis mixture, filtering, slurrying the resulting filter cake, spray-drying the resulting slurry, subjecting the spray-dried product to ion exchange with ammonium sulphate solution, slurrying the ammonium-exchanged material, adding sulphuric acid, subjecting the resulting material to ion exchange with rare earth metal chloride solution and drying the rare earth metal-exchanged material. According to a second example, a composition containing 3.02 weight per cent rare earth metal (expressed as oxide) and consisting of 15.7 weight per cent faujasite, 24.3 weight per cent clay and 60.0 weight per cent silica-alumina having an alumina content of 25 weight per cent is prepared by a similar procedure modified in that sodium silicate solution is added to the mother liquor prior to addition of kaolin thereto, the addition of sodium aluminate prior to ageing is omitted and the rare earth metal-exchanged material is filtered and washed with water prior to drying.