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.
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.
摘要:
Compositions based on zirconium oxide, including 1 to 20% yttrium oxide, 1 to 30% tungsten oxide and the balance zirconium oxide, have a specific surface area of at least 40 m2/g after calcination at 700° C. for 4 hours and an acidity measured by the methylbutynol test of at least 90%, and are useful as catalyst or catalyst supports, especially for the treatment of motor vehicle exhaust gases.
摘要:
Compositions useful for treating exhaust gases contain zirconium, titanium and tungsten oxides, and optionally the oxide of an element M selected from among silicon, aluminum, iron, molybdenum, manganese, zinc, tin, and rare earths in the following mass proportions of these different elements: titanium oxide: 20%-50%; tungsten oxide: 1%-20%, M-element oxide: 1%-20%; the balance being zirconium oxide; such compositions are prepared by placing in a liquid medium a zirconium compound, a titanium compound, optionally an M-element compound and a basic compound, adding a tungsten compound to the precipitate suspension thus obtained and having a pH value ranging from 1 to 7, maturing the suspension resulting from the preceding step, and optionally separating the precipitate and calcining same.
摘要:
A method and system for blending assessment scores for expressing the blended score as a single score while taking into account the non-compensatory nature of each assessment is disclosed. The method includes executing a test of a cognitive characteristic and a separate test of a non-cognitive characteristic. A cognitive test score and a non-cognitive test score are obtained from executing the test. The cognitive score and the non-cognitive score are blended using a non-compensatory blending scheme for outputting a blended score.