Supported perovskite-type oxides and methods for preparation thereof

Abstract

Supported perovskite-type oxides are described. The perovskite-type oxides have the general formula of A x A′ x′ B y B′ y′ O 3- δ , wherein A is an ion of a metal of Group IIIa or IIIb of the periodic table of elements or mixtures thereof; A′ is an ion of a metal of Groups Ia or IIa of the periodic table or mixtures thereof; B and B′ are ions of a d-block transition metal of the periodic table or mixtures thereof; x, x′, y and y′ vary from 0 to 1; 0.95<x+x′<1.05; 0.95<y+y′<1.05; δ is the deviation from ideal oxygen stoichiometry. This invention also provides for the selection of support materials and the shapes of supported perovskite-type oxides as well as the methods for making them.

Having thus described the invention, what we claim is:  
     
         1 . A composition comprising a supported perovskite-type oxide having a general formula A x A′ x′ B y B′ y′ O 3-     δ   , wherein: 
 A is an ion of a metal of Group IIIa or IIIb of the periodic table of elements or mixtures of these;  
 A′ is an ion of a metal of Groups Ia or IIa of the periodic table of elements or mixtures of these;  
 B and B′ are ions of a d-block transition metal of the periodic table of elements or mixtures of these;  
 x, x′, y and y′ range from 0 to 1.05;  
 0.95<x+x′<1.05;  
 0.95<y+y′<1.05; and  
 δ is the deviation from ideal oxygen stoichiometry:  
 
     
     
         2 . The composition as claimed in  claim 1  wherein A is an La ion, A′ is an Sr ion; and B and B′ are selected from the group consisting of Ni, Co and Fe ions.  
     
     
         3 . The composition as claimed in  claim 1  wherein said supported perovskite-type oxide has the formula La x Sr x′ Ni y Co y′  Fe y″ O 3-     δ   , wherein x, x′, y, y′ and y″ are all smaller than 1.05 but greater than 0.  
     
     
         4 . The composition as claimed in  claim 3  wherein 0.5<x<1, 0.1<x′<0.5, 0.2<y<0.8, 0.2<y′<0.6 and 0.1<y″<0.5.  
     
     
         5 . The composition as claimed in  claim 1  wherein said perovskite-type oxide has particle sizes in the range of about 0.01 to 100 microns.  
     
     
         6 . The composition as claimed in  claim 1  wherein said perovskite-type oxide has particle sizes in the range of about 0.1 to 50 microns.  
     
     
         7 . The composition as claimed in  claim 1  wherein said support is selected from the group consisting of porous inorganic materials, which are stable at temperatures in the range of 600-1200° C.  
     
     
         8 . The composition as claimed in  claim 1  wherein said support is selected from the group consisting of: (1) metal oxides; (2) aluminates; (3) metal aluminum silicates, and (4) metals.  
     
     
         9 . The composition as claimed in  claim 8  wherein said metal oxides are selected from the group consisting of alpha-Al 2 O 3 , gamma-Al 2 O 3 , eta-Al 2 O 3 , ZrO 2 , TiO 2 , MgO, CeO 2 , CaO and SiO 2 .  
     
     
         10 . The composition as claimed in  claim 8  wherein said aluminate is selected from the group consisting of MgAl 2 O 4  and CaAl 2 O 4 .  
     
     
         11 . The composition as claimed in  claim 8  wherein said metal aluminum silicate is a cordierite.  
     
     
         12 . The composition as claimed in  claim 8  wherein said metal is a porous high nickel containing alloy.  
     
     
         13 . The composition as claimed in  claim 1  wherein said support is selected from the group consisting of alpha-Al 2 O 3 , gamma-Al 2 O 3  and eta-Al 2 O 3  or mixtures of these.  
     
     
         14 . The composition as claimed in  claim 1  wherein said support is selected from the group of cordierites consisting of Mg 2 Al 3  [AlSi 5 O 18 ] and Fe 2 Al 3  [AlSi 5 O 18 ].  
     
     
         15 . The composition as claimed in  claim 1  wherein said support is MgAl 2 O 4 .  
     
     
         16 . The composition as claimed in  claim 1  wherein said support has particle sizes in the range of about 1 to 10,000 microns.  
     
     
         17 . The composition as claimed in  claim 16  wherein said support has particle sizes in the range of about 10 to 1,000 microns.  
     
     
         18 . The composition as claimed in  claim 1  which is prepared by dispersing perovskite-type oxides onto the selected support with or without the aid of a liquid solvent; and treating the mixture of perovskite-type oxide and support at a temperature of 600-1,500° C.  
     
     
         19 . The composition as claimed in  claim 1  wherein said supported perovskite-type oxide has the shape selected from the group consisting of beads, rings, extrudates with any cross sectional shapes with or without holes, honey-comb with uniform channels and monolith with random porosity and foam structure.  
     
     
         20 . The composition as claimed in  claim 19  wherein the shape is selected from the group consisting of monolith or extrudates with cylindrical shape.  
     
     
         21 . The composition as claimed in  claim 1  further comprising additives useful in the forming process and useful to control the pore structure.  
     
     
         22 . The composition as claimed in  claim 21  wherein said additives are selected from the group consisting of water, organic solvents, cellulose, polymers, synthetic and naturally formed fibers, starch and metal oxides.  
     
     
         23 . The composition as claimed in  claim 22  wherein said additives are selected from the group consisting of water, cellulose, about 0.1 to 1 wt % MgO and about 0.1 to 0.5 wt % TiO 2 .  
     
     
         24 . The composition as claimed in  claim 1  having pore sizes in the range of about 0.001 to 10 microns, and surface area in the range of 1 to 200 m 2 /g.  
     
     
         25 . The composition as claimed in  claim 1  can be coated on one or more support materials to achieve an increase in performance, and enhancement of thermal and mechanical properties.  
     
     
         26 . The composition as claimed in  claim 1  be further coated or impregnated with metals selected from transition and noble metals selected from the group consisting of Rh, Pt, and Ag.  
     
     
         27 . The composition as claimed in  claim 24  having pore size in the range of 0.01-1 microns and surface area in the range of 1 to 50 m2/g.  
     
     
         28 . The composition as claimed in  claim 1 , which is formed by extrusion.  
     
     
         29 . The composition as claimed in  claim 28  wherein said extrusion is performed using screw extrusion methods.  
     
     
         30 . The composition as claimed in  claim 1 , which is formed by pressing procedures.  
     
     
         31 . A method of separating a gas component from a mixture of gases by either of pressure swing adsorption or thermal swing adsorption comprising passing said gas mixture through the composition as claimed in  claim 1 .  
     
     
         32 . A method for converting hydrocarbons into hydrogen and carbon monoxide by contacting said hydrocarbons with a composition as claimed in  claim 1 .  
     
     
         33 . The method as claimed in  claim 32  wherein reactions of partial oxidation, steam reforming, or auto-thermal reforming, take place in either continuous or cyclic operations.