Alumina support for silver catalyst, preparation and use thereof

A process for preparing an alpha-alumina support, comprising the following steps:

• I) preparing a mixture of:
• component (a) of a trihydrate alpha-alumina at 5-90% by weight, based on the total weight of solids in the mixture;
• component (b) of a pseudo-boehmite at 5-90% by weight, based on the total weight of solids in the mixture;
• component (c) of a fluoride mineralizing agent at 0.01-3.0% by weight, based on the total weight of solids in the mixture;
• component (d) of a potassium compound at 0.01-3.0% by weight, based on the total weight of solids in the mixture;
• component (e) of a heavy alkaline-earth metal compound at 0-2.0% by weight, based on the total weight of solids in the mixture;
• component (f) of a binder that is different from components (c) to (e) at 10-45% by weight, based on the total weight of components (a) to (e);
• and
• component (g) an appropriate amount of water;
• wherein the total weight of the solids in the mixture means the total weight of components (a) through (e);
• and wherein the total amount of all solid components in the mixture is 100% by weight;
• II) kneading the mixture of step (I) homogenously and extruding into shape to give shaped bodies;
• III) drying at least one of the shaped bodies from step (II), and then calcining it to form an alpha-alumina support;
• and
• IV) optionally, water-washing the alpha-alumina support of step (III).

A silver catalyst for producing ethylene oxide by oxidation of ethylene, comprising:

• an alpha-alumina support of claim 1, silver deposited on the alpha-alumina support, an optional alkali metal promoter, an optional alkaline-earth metal promoter, an optional rhenium promoter and optionally its co-promoter,
• wherein silver is present in the silver catalyst in an amount selected from the group consisting of 1-40% and 5-25%, calculated based on silver atom and the total weight of the silver catalyst,
• wherein the optional alkali metal promoter is present in the silver catalyst in an amount selected from the group consisting of 0-2000 ppm, 5-2000 ppm, and 5-1500 ppm, calculated based on alkali metal atom and the total weight of the silver catalyst,
• wherein the optional rhenium promoter is present in the silver catalyst in an amount selected from the group consisting of 0-2000 ppm, 10-2000 ppm, and 100-1000 ppm, calculated based on rhenium atom and the total weight of the silver catalyst,
• wherein the optional alkaline-earth metal promoter is present in the silver catalyst in an amount selected from the group consisting of 0-10000 ppm and 0-8000 ppm, calculated based on alkaline-earth metal atom and the total weight of the silver catalyst.