Crystalline microporous and mesoporous metal silicates and use thereof

Abstract

Microporous and mesoporous metal silicates are prepared by the hydrothermal reaction of a silicon and metal source in the presence of a template. The choice of raw materials influences the purity and hence the catalytic activity of the products. A pyrogenic mixed oxide is used as the silicon and metal source. Prepared products have the composition (SiO 2 ) 1−x (A m O n ) x , where A is Ti, Al, B, V or Zr and x is 0.005 to 0.1. Shaped objects of the microporous and mesoporous metal silicates are obtained directly by using a shaped object of the pyrogenic mixed oxide. The products obtained are used as oxidation catalysts.

We claim:  
     
         1 . A binder-free shaped objected selected from the group consisting of microporous and mesoporous metal silicates, obtained by the hydrothermal reaction of a silicon and metal source in the presence of a template, wherein a pyrogenic metal-silicon mixed oxide is the silicon and metal source.  
     
     
         2 . The binder-free shaped object according to    claim 1    wherein the crystalline microporous and mesoporous metal silicates are represented by the composition  
       (SiO 2 ) 1−x (A m O n ) x    (Ia), (SiO 2 ) 1−x ((A m O n ) 1-y (A′ m ,O n ,) y ) x    (Ib)  or    (SiO 2 ) 1−x (M r A m O n ,) x    (II)    in which    x is a number from 0.0001 to 0.25;    y is a number greater than 0 and less than 1;    A and A′ are a metal of valency p selected from the group consisting of B, Al, Ga, In, Ge, Sn, Pb, and subgroups 3 to 8 of the Periodic Table of Elements;    M is a cation of valency q selected from the group consisting of alkali metals, alkaline earth metals, H + , NH 4   + and N(alkyl) 4   +      m, m′, n, n′, n″ and r are the number of atoms, where: 
 m·p=2n and m′·p=2n′ and  
 m·p+r·q=2n″,  
 wherein a pyrogenic mixed oxide of composition (Ia) or (Ib) is used and the cation M of formula (II) is incorporated via the template or via alkali metal or alkaline earth metal hydroxide present in the hydrothermal reaction.  
   
     
     
         3 . The binder-free shaped object according to    claim 1    wherein said pyrogenic metal-silicon mixed oxide is prepared by flame hydrolysis.  
     
     
         4 . The binder-free shaped object according to    claim 1    wherein said pyrogenic mixed oxide is selected from the group consisting of 
 (SiO 2 ) 1−x (TiO 2 ) x , (SiO 2 ) 1−x (Al 2 O 3 ) x , (SiO 2 ) 1−x (B 2 O 3 ) x , (SiO 2 ) 1−x (V 2 O 5 ) x  and (SiO 2 ) 1−x  (ZrO 2 ) x .  
 
     
     
         5 . The binder-free shaped object according to    claim 4    which is  
       (SiO 2 ) 1−x (TiO 2 ) x    
       .  
     
     
         6 . The binder-shaped object according to    claim 1    wherein said template is an amine having one or more amino groups, an amino alcohol or a tetrasubstituted ammonium compound.  
     
     
         7 . The binder-free shaped object according to    claim 1    wherein said template is used in an amount of 0.05 to 2.0 mol per mol of SiO 2  in the mixed oxide.  
     
     
         8 . The binder-free shaped object according to    claim 1    further comprising carrying out the hydrothermal reaction for the preparation of microporous metal silicates at a temperature from 100 to 220°C.  
     
     
         9 . The binder-free shaped object according to    claim 1    further comprising carrying out the hydrothermal reaction for preparation of microporous metal silicates at a temperature from 150 to 190°C.  
     
     
         10 . The binder-free shaped object according to    claim 1    wherein the preparation of mesoporous metal silicates is carried out at a temperature from 50 to 175°C. under at least autogenous pressure.  
     
     
         11 . A process for catalytic oxidation reactions, wherein a catalyst is present corresponding to an Al-free metal silicalite defined in    claim 1   .  
     
     
         12 . The process according to    claim 11    wherein the catalyst is (SiO 2 ) 1−x (TiO 2 ) x .  
     
     
         13 . A process for the oxidation of an olefin wherein a catalyst is present, said catalyst being the binder-free shaped object of    claim 1   .  
     
     
         14 . The process according to    claim 13    wherein the catalyst is (SiO 2 ) 1−x (TiO 2 ) x .  
     
     
         15 . The process according to    claim 11    wherein propene is oxidized with hydrogen peroxide to give the corresponding epoxide.  
     
     
         16 . The process according to    claim 12    wherein propene is oxidized with hydrogen peroxide to give the corresponding expoxide.  
     
     
         17 . A process for preparing a hydroxy aromatic compound comprising reacting an aromatic compound with hydrogen peroxide or an organic hydroperoxide in the presence of a binder-free shaped object according to    claim 1   .  
     
     
         18 . A process for producing an alcohol or ketone comprising reacting an aliphatic hydrocarbon with hydrogen peroxide or an organic hydroperoxide in the presence of a binder-free shaped object according to    claim 1   .  
     
     
         19 . The process according to    claim 18   , wherein a ketone is converted to an oxime by reacting with hydrogen peroxide and ammonia.  
     
     
         20 . A process for the catalytic epoxidation of an olefin with hydrogen peroxide as the oxidant comprising carrying out the epoxidation in the presence of a catalyst which is a crystalline microporous titanium silicate of the composition (SiO 2 ) 1−x (TiO 2 ) x  in which x is a number from 0.001 to 0.2 wherein a pyrogenic silicon-titanium mixed oxide is reacted with tetraalkylammonium hydroxide template in a hydrothermal reaction at a temperature from 100 to 220°C., and wherein the pyrogenic silicon-titanium mixed oxide is shaped to microgranules by a spray drying process prior to the hydrothermal reaction and a crystalline microporous titanium silicate in the form at microgranules is formed.  
     
     
         21 . The process of    claim 20   , wherein the olefin is propene.