Tableted alpha-alumina catalyst 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 m 2 /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., more preferably at least 1400° C., in particular at least 1450° C., to obtain the tableted alpha-alumina catalyst support. The invention moreover relates to a compacted body obtained by tableting a free-flowing feed mixture which comprises, 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, as determined, and a median pore diameter of at least 15 nm. The invention moreover relates to a shaped catalyst body for producing ethylene oxide by gas-phase oxidation of ethylene, comprising at least 15 wt.-% of silver, relative to the total weight of the catalyst, deposited on the tableted alpha-alumina catalyst support. The invention moreover relates to a process for producing ethylene oxide by gas-phase oxidation of ethylene, comprising reacting ethylene and oxygen in the presence of the shaped catalyst body.

1 .- 19 . (canceled) 
     
     
         20 . 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 m 2 /g. 
     
     
         21 . The catalyst support according to  claim 20 , wherein the pore volume contained in pores with a diameter of less than 0.1 μm constitutes less than 5% of the total pore volume, as determined by mercury porosimetry. 
     
     
         22 . The catalyst support according to any  claim 20 , wherein at least one passageway extends from the first face side surface to the second face side surface. 
     
     
         23 . The catalyst support according to  claim 20 , wherein at least one of the first face side surface and the second face side surface is curved. 
     
     
         24 . A plurality of catalyst supports according to  claim 20 , wherein the supports have a height with no more than a 5% sample standard deviation s from the mean height. 
     
     
         25 . A plurality of catalyst supports according to  claim 20 , wherein the supports have an outer diameter with no more than a 1% sample standard deviation s from the mean outer diameter. 
     
     
         26 . 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, wherein the free-flowing feed mixture further comprises a pore-forming material;   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. to obtain the tableted alpha-alumina catalyst support.   
     
     
         27 . The process according to  claim 26 , wherein the transition alumina has 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. 
     
     
         28 . The process according to  claim 26 , wherein the compacted body is dried prior to heat treating. 
     
     
         29 . The process according to  claim 26 , wherein the transition alumina comprises a phase selected from gamma-alumina, delta-alumina and theta-alumina. 
     
     
         30 . The process according to  claim 26 , wherein the free-flowing feed mixture comprises, based on inorganic solids content, an alumina hydrate in an amount of at most 40 wt.-%. 
     
     
         31 . The process according to  claim 30 , wherein the alumina hydrate comprises gibbsite, bayerite, boehmite and/or pseudoboehmite. 
     
     
         32 . The process according to  claim 26 , wherein the pore-forming material is selected from the group consisting of thermally decomposable materials, burnout materials and organic polymers. 
     
     
         33 . The process according to  claim 32 , wherein the pore-forming material is selected from water-soluble pore formers. 
     
     
         34 . The process according to  claim 26 , wherein the free-flowing feed mixture further comprises a lubricant. 
     
     
         35 . A compacted body obtained by tableting a free-flowing feed mixture which comprises, 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, as determined, and a median pore diameter of at least 15 nm. 
     
     
         36 . A shaped catalyst body for producing ethylene oxide by gas-phase oxidation of ethylene, comprising at least 15 wt.-% of silver, relative to the total weight of the catalyst, deposited on a tableted alpha-alumina catalyst support according to  claim 20 . 
     
     
         37 . The shaped catalyst body of  claim 36 , wherein the shaped catalyst body comprises 400 to 2000 ppm of rhenium relative to the total weight of the shaped catalyst body. 
     
     
         38 . 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 according to  claim 36 .