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AssigneeExxon Research & Engineering Co.
InventorsJohn P. DeLuca, Gary B. McVicker, Lawrence L. Murrell
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The instant invention relates to high surface area multilayered oxide supports coated with ruthenium of the type Ru-MgO-MgAl.sub.2 O.sub.4 -MgAl.sub.2 O.sub.4 +Mg.sub.2 SiO.sub.4 -Core. The system comprises ruthenium on a critical amount of free MgO, i.e., at least 2 wt. % minimum, on pre-reacted Al.sub.2 O.sub.3 which itself is on a monolithic ceramic substrate. This combination demonstrates the desirable, and previously unachievable characteristic of resistance to ruthenium volatilization and agglomeration, coupled with high catalytic activity. The high surface area oxides (MgO+Al.sub.2 O.sub.3) are strongly bonded to and reacted with the monolithic core substructure so as to possess physical strength. Ruthenium catalyst systems prepared utilizing the supported support (multilayered mixed oxides) method disclosed by the instant invention are useful for the treatment of waste gases, particularly exhaust gases from internal combustion engines and stationary sources and the removal of oxides of nitrogen therefrom.
A catalyst, resistant to ruthenium volatilization and resistant to agglomeration to 850.degree. C in air, comprising ruthenium deposited on and bonded to a layer of free MgO, the MgO being deposited on and reacted with a 10-200 m.sup.2 /g surface area alumina washcoated cordierite monolith core to the extent necessary to yield a MgAl.sub.2 O.sub.4 spinel and Mg.sub.2 SiO.sub.4 forsterite layer supporting the reactive layer of free MgO, the high surface area alumina being initially washcoated on the cordierite monolith core and calcined so as to react with said core giving a stable foundation.
A method for preparing multilayer supported support ruthenium catalysts resistant to ruthenium volatilization and resistant to ruthenium agglomeration to a temperature of 850.degree. C comprising the steps of impregnating an alumina washcoated monolithic core with magnesium nitrate, drying the magnesium nitrate coated structure, calcining the magnesium nitrate coated structure to produce at least 2 wt. % free MgO, contacting the free MgO coated core with a solution of ruthenium salt, reducing the ruthenium salt to elemental ruthenium.
Dependencies are inferred from the claim text.