Abstract:
A process for producing ethylene oxide by gas-phase oxidation of ethylene, comprising: directing a feed comprising gaseous ethylene and gaseous oxygen through a packing of individual shaped catalyst bodies, under conditions conducive to obtain a reaction mixture containing at least 2.7 vol.-% of ethylene oxide, wherein each shaped catalyst body comprises silver deposited on a refractory support and is characterized by a content of at least 20 wt.-% of silver, relative to the total weight of the shaped catalyst body; a BET surface area in the range of 1.6 to 3.0 m2/g; a first face side surface, a second face side surface and a circumferential surface with a plurality of passageways extending from the first face side surface to the second face side surface; and a uniform multilobed cross-section; and a longest direct diffusion pathway d, with 2d being in the range of 0.7 to 2.4 mm, wherein the longest diffusion pathway d is defined as the shortest distance from the geometric surface of the shaped catalyst body to a point inside the structure of the shaped catalyst body for which point the shortest distance is the largest among all points. The process allows for increased activity and/or stability of the catalyst while maintaining or increasing selectivity at high productivity.
Abstract:
What is described is a catalyst for preparation of an α,β-unsaturated carboxylic acid by gas phase oxidation of an α,β-unsaturated aldehyde, comprising a shaped support body with an active composition applied thereto, wherein the active composition coverage q q = Q ( 100 - Q ) S m is at most 0.3 mg/mm2, where Q is the active composition content of the catalyst in % by weight and Sm is the specific geometric surface area of the shaped support body in mm2/mg. Also described are a process for preparing the catalyst and a process for preparing an α,β-unsaturated carboxylic acid by gas phase oxidation of an α,β-unsaturated aldehyde over a fixed catalyst bed comprising a bed of the catalyst. The catalyst, with constantly high conversion of acrolein, reduces overoxidation to COx and increases the selectivity of acrylic acid formation.
Abstract:
A process for preparing (meth)acrylic acid by heterogeneously catalyzed gas phase partial oxidation of (meth)acrolein over a multimetal oxide composition which comprises the elements Mo, V and W and is obtained by a hydrothermal preparation route, and the multimetal oxide composition obtainable by this preparation route.
Abstract:
A catalyst for the gas phase oxidation of organic hydrocarbons comprises a multielement oxide which comprises at least one transition meal such as vanadium, wherein the catalyst has a charge transport activation energy Ec at a temperature of 375 to 425° C. of less than 0 kJ/mol. The catalyst serves for preparation of maleic anhydride.
Abstract:
A catalyst for the gas phase oxidation of organic hydrocarbons comprises a multielement oxide which comprises at least one transition meal such as vanadium, wherein the catalyst has a charge transport activation energy Ec at a temperature of 375 to 425° C. of less than 0 kJ/mol. The catalyst serves for preparation of maleic anhydride.
Abstract:
A process for preparing (meth)acrylic acid by heterogeneously catalyzed gas phase partial oxidation of (meth)acrolein over a multimetal oxide composition which comprises the elements Mo, V and W and is obtained by a hydrothermal preparation route, and the multimetal oxide composition obtainable by this preparation route.
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 multilobe structure; a plurality of passageways extending from the first face side surface to the second face side surface, outer passageways being arranged around a central passageway with one outer passageway being assigned to each lobe, wherein neighboring outer passageways are arranged essentially equidistantly to each other and the outer passageways are arranged essentially equidistantly to the central passageway; a minimum wall thickness A between two neighboring passageways in the range of 0.6 to 1.3 mm; a minimum wall thickness B between each outer passageway and the circumferential surface in the range of 1.1 to 1.8 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 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 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.
Abstract:
What is described is a catalyst for preparation of an α,β-unsaturated carboxylic acid by gas phase oxidation of an α,β-unsaturated aldehyde, comprising a shaped support body with an active composition applied thereto, wherein the active composition coverage q q = Q ( 100 - Q ) S m is at most 0.3 mg/mm2, where Q is the active composition content of the catalyst in % by weight and Sm is the specific geometric surface area of the shaped support body in mm2/mg. Also described are a process for preparing the catalyst and a process for preparing an α,β-unsaturated carboxylic acid by gas phase oxidation of an α,β-unsaturated aldehyde over a fixed catalyst bed comprising a bed of the catalyst. The catalyst, with constantly high conversion of acrolein, reduces overoxidation to COx and increases the selectivity of acrylic acid formation.