Doped zirconium hydroxides

At MEL Chemicals we have a range of differnt dopants we can add to our zirconium hydroxide products to make materials suitable for a wide range of applications.

PRODUCTS IN GENERAL

At MEL Chemicals we have developed a range of proprietary processes for producing zirconia doped with a wide range of materials, the most common being Ce, La, Y, Nd, Pr, Ti, Al, Si, S and W hydroxides and oxides, however we do have experience doping with other hydroxides and oxides of Fe, Cu, Mg, Mn, Gd, Cs, Na, K, B, Nb, Li and Sn for specific customer projects.

Examples of some of our more common standard development grade materials are listed in the tables below.  Typical impurity levels for these catalyst grades are SO₃ <0.05%, Na <200ppm and Cl <200pm.

By use of proprietary techniques MEL Chemicals can lower the value of various impurities in our zirconium hydroxides. Typically it is possible to reduce the content of Na, Cl, SO₃, SiO₂, TiO₂, but other impurities can also be lowered.

Any of the products listed below can also be calcined at a range of temperatures or to a specific surface area target in addition to the products shown in our doped zirconium oxide pages.

As with many of our other products the specific grade of choice will depend on the chemical and physical properties required for specific application. Please contact us with your specific requirements or for further information.

Please see descriptions below for idea of some of our products, and example conditions for lab testing.

 

SILICA DOPED PRODUCTS 

Silica is used for surface area stability, the material is also weakly acidic. Products are amorphous hydroxides that will crystallise as zirconium oxide at calcination temperatures in excess of 450°C (static air).

 

SULPHATE DOPED PRODUCTS

Used commonly as solid acid catalyst. Sulphated zirconium hydroxide is amorphous. Needs activating by calcining at 500-600°C (preferably in static air) immediately before use. The optimum temperature will depend upon the acidity requirements of the reaction being catalysed. Preferably, cool in a P₂O₅ desiccator, or dry at 300°C immediately before use. Note calcinations temperatures above ~700°C may result in loss of SO₃.

 

TUNGSTEN DOPED PRODUCTS

As with sulphated zirconia, these are used as solid acid catalysts. Tungstated zirconium hydroxide needs activating by calcining at 700-800°C (preferably in static air) immediately before use. The optimum temperature will depend upon the acidity requirements of the reaction being catalysed. Preferably, cool in a P₂O₅ desiccator, or dry at 300°C  immediately before use. Note calcination temperature above 850°C may result on loss of WO₃.

 

LANTHANUM DOPED PRODUCTS

High thermal stability giving it large surface area after calcination. Products are amorphous hydroxides that will crystallise as zirconium oxide after calcination, maintaining tetragonal phase >1000°C.

 

CERIUM DOPED PRODUCTS

Useful because of their high thermal stability and redox properites (oxygen storage ability) Products are amorphous hydroxides that will crystallise as zirconium oxide after calcination, maintaining tetragonal phase >1000°C.