HIGHLY ACIDIC COMPOSITIONS COMPRISING ZIRCONIUM AND SILICON OXIDES AND AN OXIDE OF AT LEAST ONE OTHER ELEMENT SELECTED FROM AMONG TITANIUM, ALUMINUM, TUNGSTEN, MOLYBDENUM, CERIUM, IRON, TIN, ZINC, AND MANGANESE

摘要

Compositions useful for treating the exhaust gases of diesel engines contain zirconium oxide, silicon oxide and at least one oxide of at least one element M selected from among titanium, aluminum, tungsten, molybdenum, cerium, iron, tin, zinc, and manganese, in the following mass proportions of these different elements: silicon oxide: 5%-30%; M-element oxide: 1%-20%; the balance being zirconium oxide; such compositions also have an acidity, as measured by the methylbutynol test, of at least 90% and are prepared by placing a zirconium compound, a silicon compound, at least one M-element compound and a basic compound in a liquid medium, thereby generating a precipitate, maturing the precipitate in a liquid medium and separating and calcining the precipitate.

主权项

1. A process for the catalytic treatment of exhaust gases, said process comprising employing a catalytic system comprising zirconium oxide, silicon oxide and at least one oxide of at least one element M selected from among titanium, aluminum, tungsten, molybdenum, cerium, iron, tin, zinc and manganese in the following proportions by weight of these various elements:
silicon oxide: 5%-30%; oxide of the element M: 1%-20%; the remainder of zirconium oxide; and having an acidity, measured by the methylbutynol test, of at least 90%, for the oxidation of CO and hydrocarbons present therein.