Zeolite compositions and preparation and use thereof
AssigneeTotal Raffinage Marketing
InventorsWalter Vermeiren, Jean-Pierre Dath, Valérie Buono
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Abstract
This invention relates to novel compositions of zeolites or microporous metallosilicates characterized by a continuous spatial distribution of the metal and silicon in the crystals and characterized by a crystal surface enriched in silicon relative to the internal part of the same crystals. This invention also relates to a synthesis method of producing these metallosilicates with spatial distribution of the constituting elements. These novel zeolitic compositions can be used in various hydrocarbon conversion reactions. The crystalline metallosilicates can be selected from the group consisting of aluminosilicates, gallosilicates, ferrosilicates, titanosilicates and borosilicates.
Claims34
A process for producing a crystalline metallosilicate composition, the method comprising the steps of:
- a. providing an aqueous liquid phase comprising at least one silicon-containing compound and at least one metal-containing compound;
- and
- b. crystallising the crystalline metallosilicate composition from the aqueous liquid phase, the crystallising step having a first stage followed by a second stage and wherein the concentration of the at least one silicon-containing compound in the aqueous liquid phase is increased in the second stage.
A process for producing a crystalline metallosilicate composition, the method comprising the steps of:
- (a) providing an aqueous liquid comprising at least one silicon-containing compound dissolved or dispersed therein and at least one metal-containing compound dissolved or dispersed therein;
- (b) crystallising the crystalline metallosilicate composition from the aqueous liquid medium in a vessel under autogenous conditions, wherein in at least an end phase of the crystallising step a portion of the water is removed from the vessel;
- and
- (c) isolating the crystallised product.
A crystalline metallosilicate composition comprising crystallites having a crystal outer surface layer having a depth of about 10 nm below the outer surface, and an inner part extending inwardly from a depth of about 50 nm below the outer surface, wherein the atomic ratio of silicon to metal in the metallosilicate composition is at least 1.75 times higher in the crystal outer surface layer as compared to that in the inner part;
- and wherein the metallosilicate composition has a continuous spatial distribution of silicon to metal, and an atomic ratio of silicon to metal that decreases continuously from the outer surface to the inner part of each crystallite.
Dependencies are inferred from the claim text.