| http://www.w3.org/ns/prov#value | - ther metal oxides, including metal oxides which exist in multiple oxidation states (e.g. TiO2, Fe2O3, etc.) Preferably, the mass ratio of silica (SiO2) to alumina (Al2O3) is greater than about 1 in the aluminosilicate materials used in certain embodiments of the present invention.
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