Abstract: A porous shaped catalyst support body comprising at least 85% by weight of alpha-alumina, wherein the support has a total pore volume in the range from 0.5 to 2.0 mL/g as determined by mercury porosimetry, and a pore structure characterized by a geometric tortuosity ? in the range from 1.0 to 2.0; and an effective diffusion parameter ? in the range from 0.060 to 1.0; wherein geometric tortuosity ? and effective diffusion parameter ? are determined by image analysis algorithms from computer-assisted 3D reconstructions of focused ion beam scanning electron microscope analyses. The structure of the support has a high total pore volume, such that impregnation with a large amount of silver is possible, while the surface area is kept sufficiently high in order to assure optimal dispersion of the catalytically active species, especially metal species. The support has a pore structure that leads to a maximum rate of mass transfer within the support.

Abstract: A porous alpha-alumina catalyst support is prepared by (i) preparing a precursor material comprising a boehmitic-derived alumina having a pore volume of at least 0.6 mL/g, wherein the boehmitic-derived alumina is obtained by thermal decomposition of a boehmitic starting material and the boehmitic starting material consists predominantly of block-shaped crystals, and optionally an inorganic bond material; (ii) forming the precursor material into shaped bodies; (iii) calcining the shaped bodies to obtain the porous alpha-alumina catalyst support. The support structure has a high overall pore volume, while keeping its surface area sufficiently large so as to provide optimal dispersion of catalytically active species, in particular metal species. The support is useful for a catalyst for producing ethylene oxide by gas-phase oxidation of ethylene.

Abstract: A process for producing a porous alpha-alumina catalyst support, comprising i) preparing a precursor material comprising, based on inorganic solids content, at least 50 wt.-% of a transition alumina having a loose bulk density of at most 600 g/L, a pore volume of at least 0.6 mL/g and a median pore diameter of at least 15 nm; and at most 30 wt.-% of an alumina hydrate; ii) forming the precursor material into shaped bodies; and iii) calcining the shaped bodies to obtain the porous alpha-alumina catalyst support. The catalyst support has a high overall pore volume, thus allowing for impregnation with a high amount of silver, while keeping its surface area sufficiently large so as to provide optimal dispersion of catalytically active species, in particular metal species. The invention further relates to a shaped catalyst body for producing ethylene oxide by gas-phase oxidation of ethylene, comprising at least 15 wt.

Abstract: A shaped catalyst body for producing ethylene oxide by gas-phase oxidation of ethylene, having a BET surface area in the range of 2 to 20 m2/g and comprising silver and a rhenium promotor deposited on a porous alpha-alumina catalyst support, characterized in that the support has a calcination history of at least 1460° C. The catalyst support has a high surface area and little ethylene oxide isomerization and/or decomposition activity. The invention further relates to a porous alpha-alumina catalyst support having a BET surface area of 1.7 to 10 m2/g, the porous alpha-alumina catalyst support being obtainable by a) preparing a precursor material comprising a transition alumina and/or an alumina hydrate; b) forming the precursor material into shaped bodies; and c) calcining the shaped bodies at a temperature of 1460° C. to 1700° C. to obtain the porous alpha-alumina support.

Abstract: A tableted catalyst support, characterized by an alpha-alumina content of at least 85 wt.-%, a pore volume of at least 0.40 mL/g, as determined by mercury porosimetry, and a BET surface area of 0.5 to 5.0 m2/g. The tableted catalyst support is an alpha-alumina catalyst support obtained with high geometrical precision and displaying a high overall pore volume, thus allowing for impregnation with a high amount of silver, while exhibiting a surface area sufficiently large so as to provide optimal dispersion of catalytically active species, in particular metal species. The invention further provides a process for producing a tableted alpha-alumina catalyst support, which comprises i) forming a free-flowing feed mixture comprising, based on inorganic solids content, at least 50 wt.-% of a transition alumina; ii) tableting the free-flowing feed mixture to obtain a compacted body; and iii) heat treating the compacted body at a temperature of at least 1100° C., preferably at least 1300° C.

Abstract: A process for producing a silver-based epoxidation catalyst, comprising i) impregnating a particulate porous refractory support with a first aqueous silver impregnation solution comprising silver ions and an aminic complexing agent selected from amines, alkanolamines and amino acids; ii) converting at least part of the silver ions impregnated on the refractory support to metallic silver by heating while directing a stream of a first gas over the impregnated refractory support to obtain an intermediate catalyst, wherein the first gas comprises at least 5 vol.

Abstract: The present invention is directed to a shaped catalyst body for preparing ethylene oxide, which comprises at least silver, cesium and rhenium applied to an alumina support, wherein the alumina support comprises Si, Ca, and Mg in a defined amount. Furthermore, the present invention is directed to a process for preparing the catalyst according to the present invention and process for preparing ethylene oxide by gas-phase oxidation of ethylene by means of oxygen in the presence of a shaped catalyst body according to the present invention.

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.

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.

Abstract: A catalyst bed contains one or more segments of monolithic catalyst, wherein the monolithic catalyst includes a mono-lithic honeycomb structure and a layer of catalyst coating the honeycomb structure; the honeycomb structure contains a plurality of channels aligned side by side; and each channel includes an inlet positioned at a first terminus of the channel, an outlet positioned at a second terminus of the channel, and openings positioned along the channel in the direction of fluid flow through the channel for transverse fluid flow in and/or out of the channel.

Abstract: The present invention is directed to a shaped catalyst body for preparing ethylene oxide, which comprises at least silver, cesium and rhenium applied to an alumina support, wherein the alumina support comprises Si, Ca, and Mg in a defined amount. Furthermore, the present invention is directed to a process for preparing the catalyst according to the present invention and process for preparing ethylene oxide by gas-phase oxidation of ethylene by means of oxygen in the presence of a shaped catalyst body according to the present invention.

Abstract: The present invention provides a catalyst effective in the oxidative conversion of ethylene to ethylene oxide, comprising an alumina support and 20 to 45%by weight of the catalyst, of silver applied to the support, the catalyst meeting the following limitations (i) to (v): (i) an amount of cesium c(Cs) in mmol per Kg of catalyst of at least 2; (ii) an amount of rhenium c(Re) in mmol per Kg of catalyst of at least 3.0; (iii) an amount of tungsten c(W) in mmol per Kg of catalyst of at least 1.6; (iv) a silicon to alkaline earth metal molar ratio x of not higher than 1.80; (v) c(Cs)?c(Re)?c(W)?4·x?0.5.

Abstract: A method for preparing a silver impregnation solution comprises (a) charging a neutralization reactor R1 with an aqueous organic amine; (b) adding oxalic acid powder through a first feeding conduit to the neutralization reactor R1 to obtain an aqueous oxalic acid-organic amine solution; (c) directing the aqueous oxalic acid-organic amine solution from the neutralization reactor to a complexation reactor R2; (d) adding particulate silver oxide through a second feeding conduit to the complexation reactor R2 to obtain a silver impregnation solution; and, optionally, (e) subjecting the silver impregnation solution to filtration. The silver impregnation solution is used for producing a catalyst effective in the oxidative conversion of ethylene to ethylene oxide. The method allows for the preparation of a silver impregnation solution in an efficient and occupationally and environmentally safe way.

Abstract: The present disclosure provides a three-way conversion (TWC) catalyst composition, and a catalyst article comprising such a catalyst composition suitable for at least partial conversion of gaseous hydrocarbons (HCs), carbon monoxide (CO), and nitrogen oxides (NOx). Generally, the catalyst article includes a catalyst substrate having a plurality of channels adapted for gas flow, each channel having a wall surface and a catalytic coating on the surfaces or inside the pores of the wall. The catalytic coating generally includes a first washcoat with a platinum group metal (PGM) component and a first refractory metal oxide support and a second washcoat having a plurality of palladium-rhodium nanoparticles and a second refractory metal oxide support.

Abstract: Catalytic materials for exhaust gas purifying catalyst composites comprise platinum group metal (PGM)-containing catalysts whose PGM component(s) are provided as nanoparticles and are affixed to a refractory metal oxide, which may be provided as a precursor. Upon calcination of the catalysts, the PGM is thermally affixed to and well-dispersed throughout the support. Excellent conversion of hydrocarbons and nitrogen oxides can advantageously be achieved using such catalysts.

Abstract: Catalytic materials, and in particular, rhodium-containing catalytic materials for exhaust gas purifying catalyst composites are provided herein. Such materials comprise multimetallic Rh-containing nanoparticles, which are present primarily inside aggregated particles of a support (such as alumina). Such catalytic materials can exhibit excellent conversion of hydrocarbons and nitrogen oxides.

Abstract: Catalysts that improve carbon monoxide (CO), hydrocarbon (HC), Catalyst outlet temperature and speed traces of and nitrogen oxides (NOx) light-off performance are provided. A catalyst composite for combustion engines, as provided herein, comprises a carrier and a first layer comprising a catalytic material on the carrier, the catalytic material comprising a palladium component supported on both a ceria-praseodymia-based oxygen storage component and a ceria-zirconia-based oxygen storage component, wherein the first layer is essentially free of alumina. The catalytic material is effective to substantially simultaneously oxidize carbon monoxide and hydrocarbons and reduce nitrogen oxides.

Abstract: Catalytic materials for exhaust gas purifying catalyst composites comprise platinum group metal (PGM)-containing catalysts whose PGM component(s) are provided as nanoparticles and are affixed to a refractory metal oxide, which may be provided as a precursor. Upon calcination of the catalysts, the PGM is thermally affixed to and well-dispersed throughout the support. Excellent conversion of hydrocarbons and nitrogen oxides can advantageously be achieved using such catalysts.

Abstract: Catalytic materials, and in particular, rhodium-containing catalytic materials for exhaust gas purifying catalyst composites are provided herein. Such materials comprise multimetallic Rh-containing nanoparticles, which are present primarily inside aggregated particles of a support (such as alumina). Such catalytic materials can exhibit excellent conversion of hydrocarbons and nitrogen oxides.

Abstract: The present invention relates to a composite oxide comprising ceria, praseodymia and alumina, wherein the cerium:praseodymium molar ratio of the composite oxide is 84:16 or less, as well as to a method of preparing the composite oxide and to its use, in particular in a method of treating an exhaust gas stream.