Patent GB-1248435-A (GB)
Title: Improvements relating to catalysts and the use thereof
IPC: B01J29/06
Filed: 1968-10-22
Abstract: 1,248,435. Hydrocracking catalysts. TEXACO DEVELOPMENT CORP. 22 Oct., 1968 [27 Oct., 1967], No. 49950/68. Heading B1E. [Also in Division C5] A hydrocracking catalyst comprises (1) a hydrogenating component which comprises at least one metal selected from Group VI and Group VIII and (2) a cracking component which consists essentially of a mixture of (a) amorphous inorganic oxide material selected from silica, alumina, zirconia, magnesia and mixtures thereof and (b) crystalline zeolite having an alkali metal content (calculated as the oxide) of not greater than 1.0 weight per cent, the zeolite constituting from 5 to 55 weight per cent of the cracking component and the rare earth metal content of the cracking component being less than 0.1 weight per cent. The metal selected from Group VI and Group VIII may be chromium, molybdenum, tungsten, cobalt, nickel or a metal of the palladium and platinum triads, for example palladium, and may be in the form of elemental metal, oxide, sulphide or a mixture thereof; the hydrogenating component may comprise a mixture of tungsten and nickel. The crystalline zeolite may be a natural zeolite, for example mordenite, analcite, chabazite or clinoptilolite, or a synthetic zeolite, for example zeolite X, zeolite Y, zeolite A or zeolite D. The inorganic oxide material, which advantageously has substantially the same chemical composition as the zeolite, may consist essentially of silica-alumina. The catalyst is characterized by its method of preparation which comprises subjecting crystalline zeolite to an initial ion exchange to reduce the alkali metal content thereof, subjecting the ion-exchanged zeolite to a first calcination, subjecting the calcined ion-exchanged zeolite to an additional ion-exchange to reduce the alkali metal content thereof (calculated as the oxide) to not greater than 1.0, preferably less than 0.5, weight per cent, mixing the resulting additional-ion-exchanged zeolite with amorphous inorganic oxide material, mixing the resulting mixture of zeolite and inorganic oxide material with a solution containing at least one compound of at least one metal selected from Group VI and Group VIII to provide a catalyst precursor, and subjecting the catalyst precursor to a final calcination at a temperature not greater than 1200‹F. Ion exchange may be effected by the use of acid or a compound capable of supplying ammonium ion, for example ammoniumchloride, ammonium sulphate, ammonium sulphide or a methylamine. The initial ion exchange preferably is such as to provide zeolite having an alkali metal content (calculated as the oxide) of less than 1.0 weight per cent. The zeolite may be subjected to an intermediate calcination, for example at a temperature between 750 and 1200‹F, after the additional ion exchange and before mixing with the inorganic oxide material. The catalyst may be sulphided, for example by contact with carbon disulphide or hydrogen sulphide at elevated temperature, after the final calcination. Examples relate to the preparation of catalysts comprising zeolite Y, silica-alumina (75-25 weight per cent mixture) and either 18 weight per cent tungsten and 6 weight per cent nickel (Examples I, II and III) or 0.75 weight per cent palladium (Example IV), the catalysts of Examples I, II and III optionally being in sulphide form.