Process for Preparing a Layered Molecular Sieve Composition

Abstract

A process for preparing a layered composition has been developed. The composition comprises an inner core and an outer layer comprising a molecular sieve. The process involves providing a slurry comprising inner core particles and sources of the framework elements of the molecular sieve. To this slurry there are added nutrient(s), i.e. framework element sources thereby forming crystals of the molecular sieve which agglomerate onto the inner core. The process is carried out for a time sufficient to form a layer of desired thickness.

1 . A layered composition comprising an alpha alumina inner core and an outer layer comprising a molecular sieve having a three dimensional microporous framework structure and a framework composition represented by an empirical formula of:  
         (El w Al x P y Si z )O 2    (1)  
       where El, Al, P and Si are framework elements present as tetrahedral oxide units, “w” is the mole fraction of El and has a value from 0 to about 0.5, “x” is the mole fraction of Al and has a value from 0 to about 0.5, “y” is the mole fraction of P and has a value from 0 to about 0.5, and “z” is the mole fraction of Si and has a value from 0 to about 1, w+x+y+z=1 and “y” and “z” are not simultaneously zero, wherein the molecular sieve layer is bonded to the inner core by the agglomeration of molecular sieve crystals.  
     
     
         2 . The composition of  claim 1  where “w” and “y” are zero and the molecular sieve has the structure of zeolite Y.  
     
     
         3 . The composition of  claim 1  further comprising at least one additional layer where the layer comprises a composition selected from the group consisting of a molecular sieve having the empirical formula of equation (1) but having a structure or a composition different from the layer immediately underneath it, aluminas, silica, silica-alumina, zirconia, alumina-phosphates, zinc oxides, tin oxides, iron oxides, ruthenium oxides, and mixtures thereof.  
     
     
         4 . A hydrocarbon conversion process comprising contacting a hydrocarbon with a catalytic composite at hydrocarbon conversion conditions to give a converted product, the catalytic composite comprising a layered composition comprising an inner core and an outer layer, the outer layer comprising a molecular sieve having a three dimensional microporous framework structure and a framework composition represented by an empirical formula of:  
         (El w Al x P y Si z )O 02    (1)  
       where El, Al, P and Si are framework elements present as tetrahedral oxide units, “w” is the mole fraction of El and has a value from 0 to about 0.5, “x” is the mole fraction of Al and has a value from 0 to about 0.5, “y” is the mole fraction of P and has a value from 0 to about 0.5, and “z” is the mole fraction of Si and has a value from 0 to about 1, w+x+y+z=1 and “y” and “z” are not simultaneously zero.