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AssigneeHoechst Aktiengesellschaft
InventorsFriedrich Wunder, Therese Quadflieg, Gunter Roscher, Gunther Heck
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The carriers contain common active components, namely noble metals of the 8th sub-group or compounds thereof, and as activators alkali metal compounds, alkaline earth metal compounds or cadmium compounds. The carriers, too, consist of common materials, such as silicic acid. A novel feature is to be seen in the shape of the carrier particles which are designed as rod sections having a star-shaped cross section (FIGS. 1 to 7) or as ribbed rods (FIG. 8). In relation to the apparent density and thus in relation to the amount of noble metal employed, a considerably higher space-time yield is reached than with carrier particles of a conventional shape.
In a process for the preparation of vinyl acetate in the gaseous phase by reacting ethylene with acetic acid and oxygen or oxygen-containing gases in the presence of a catalyst containing a noble metal of sub-group VIII of the periodic table, or a compound thereof, and as an activator an alkali metal compound, an alkaline earth metal compound or a cadmium compound, or any combination thereof, the improvement which comprises applying said noble metal and said activator onto a carrier consisting essentially of particles of silicic acid having a star-shaped cross section with a core portion and at least 3 star points with a core diameter in the range of 2 mm to 4 mm, an average radius of 1.5 mm to 7.5 mm as measured by the distance from the center of the core portion to the apex of a star point and an average indentation in the range of 0.5 mm to 6.5 mm as measured by the distance from the outer surface of the core portion to the apex of a star point.
In a process for the preparation of vinyl acetate in the gaseous phase by reacting ethylene with acetic acid and oxygen or oxygen-containing gases in the presence of a catalyst containing a noble metal of sub-group VIII of the periodic table, or a compound thereof, and as an activator an alkali metal compound, an alkaline earth metal compound or a cadmium compound, or any combination thereof, the improvement which comprises applying palladium, cadmium acetate and potassium acetate onto a carrier consisting essentially of particles of silicon dioxide having a star-shaped cross section with a core portion and 5 star points with an average radius of 2 mm to 3.5 mm as measured from the center of said core portion to the apex of a star point and an average indentation in the range of 1 mm to 2.5 mm as measured by the distance from the outer surface of the core portion to the apex of a star point.
Dependencies are inferred from the claim text.