| abstract |
A shaped catalyst body for producing ethylene oxide by gas-phase oxidation of ethylene, comprising silver deposited on a porous refractory support, the shaped catalyst body having a first face side surface, a second face side surface and a circumferential surface, characterized by a content of at least 20 wt.-% of silver, relative to the total weight of the shaped catalyst body; a cylinder structure with n void spaces running in the cylinder periphery along the cylinder height to form an n-lobed structure, wherein n is 2, 3, 4, 5 or 6; n passageways extending from the first face side surface to the second face side surface, each passageway being assigned to one lobe, wherein neighboring passageways are arranged essentially equidistantly to each other; an n-fold rotational symmetry; a shortest distance A between two neighboring passageways in the range of 1.0 to 2.0 mm; a shortest distance B between each passageway and the circumferential surface in the range of 1.1 to 2.0 mm; and a BET surface area in the range of 1.6 to 3.0 m2/g. The shaped catalyst bodies allow for a favorable balance between mechanical stability, pressure drop and selectivity. The invention further relates to a reactor tube packed with a plurality of shaped catalyst bodies as defined above, wherein the ratio of the diameter of the circumscribed circle dcc of the shaped catalyst bodies to the inner diameter of the reactor tube is in the range of 0.15 to 0.35. The invention also relates to a process for producing ethylene oxide by gas-phase oxidation of ethylene, comprising reacting ethylene and oxygen in the presence of a shaped catalyst body as defined above. The invention further relates to a process for preparing a shaped catalyst body as defined above, comprising i) impregnating a refractory support having a BET surface area in the range of 1.4 to 2.5 m2/g with a silver impregnation solution; and ii) subjecting the impregnated refractory support to a calcination process; wherein steps i) and ii) are optionally repeated. |