| 摘要 |
Crystalline metal silicate and metal borosilicate compositions show useful catalytic properties when the reaction mixture from which they have been prepared contains a metal whose oxide precipitates at a pH of above 7 with an amount of urea or another compound which, after hydrolysis, releases ammonia. The precipitated metal hydroxide is incorporated into the crystalline composition during the formation of the latter. These compositions show X-ray diagrams of a ZSM-5 zeolite and have an aluminium content of less than 100 parts by weight/million and a composition which, expressed as oxides, is as follows: <IMAGE> in which R is a tetramethylammonium cation, ammonium cation, hydrogen cation, an alkali metal cation, metal cation or mixtures thereof, n corresponds to the valency of R, M is a metal whose hydroxide precipitates at a pH of above 7, and m corresponds to the valency of this metal. These crystalline silicates and borosilicates are expediently employed as catalysts in the conversion of hydrocarbons. |
