Carrier for olefin oxide catalyst

Abstract

A carrier for a catalyst useful for the epoxidation of an olefin which comprises an inert, refractory solid carrier is provided. The carrier has no or little absolute volume from small pores, of less than 1 micrometer, and large pores, of above 5 micrometer. By “no or little absolute volume from small pores of less than 1 micron” it is meant that the pore volume of such pores is less than 0.20 ml/g. By “no or little absolute volume from large pores of above 5 micron” it is meant that the pore volume of such pores is less than 0.20 ml/g. The invention further provides a catalyst useful for the epoxidation of an olefin supported on such a carrier and a process for the oxidation of an olefin, especially ethylene, to an olefin oxide, especially ethylene oxide.

1 . A carrier for a catalyst useful for the epoxidation of an olefin, said carrier having a pore volume from pores with less than 1 micron in diameter of less than 0.20 ml/g, a pore volume from pores with greater than 5 micron in diameter of less than 0.20 ml/g, and a pore volume from pores between 1 micron in diameter and 5 microns in diameter comprising at least 40 percent of a total pore volume. 
   
   
       2 . The carrier of  claim 1  wherein the carrier comprises aluminum oxide, charcoal, pumice, magnesia, zirconia, titania, kieselguhr, fuller's earth, silicon carbide, silica, silicon dioxide, magnesia, clays, artificial zeolites, natural zeolites, ceramics or combinations thereof. 
   
   
       3 . The carrier of  claim 1  wherein the carrier has a surface area from about 0.3 m 2 /g to about 3 m 2 /g and a water pore volume from about 0.10 cc/g to about 0.8 cc/g. 
   
   
       4 . The carrier of  claim 1  wherein the carrier comprises alpha alumina. 
   
   
       5 . The carrier of  claim 1  wherein said pore volume from said pores with said diameter greater than 5 micron is less than 0.1 ml/g and said pores with said diameter less than 1 micron is less than 0.16 ml/g. 
   
   
       6 . The carrier of  claim 1  wherein said pore volume from said pores with said diameter greater than 5 micron is less than 0.05 ml/g and said pores with said diameter less than 1 micron is less than 0.12 ml/g. 
   
   
       7 . The carrier of  claim 1  wherein the carrier has a total pore volume from about 0.2 ml/g to about 0.6 ml/g. 
   
   
       8 . An alpha alumina carrier with a total pore volume from 0.2 ml/g to 0.6 ml/g and having a surface area from about 0.3 to about 3.0 m 2 /g, at least 40% of pore volume from pores with diameters between 1 and 5 micrometers, and a median pore diameter between 1 and 5 micrometers, and wherein the pore volume from pores with a diameter of greater than 5 micrometers is less than 0.20 ml/g and the pore volume from pores with a diameter of less than 1 micrometer is less than 0.20 ml/g. 
   
   
       9 . A catalyst useful for the epoxidation of an olefin which comprises a carrier and a catalytically effective amount of silver thereon, said carrier having a pore volume from pores with less than 1 micron in diameter of less than 0.20 ml/g, a pore volume from pores with greater than 5 micron in diameter of less than 0.20 ml/g and a pore volume from pores between 1 micron in diameter and 5 microns in diameter comprising at least 40 percent of a total pore volume. 
   
   
       10 . The catalyst of  claim 9  further comprising a promoting amount of a promoter thereon, the promoter comprising one or more of an alkali metal containing compounds, one or more transition metal containing compounds, one or more sulfur components, one or more fluorine containing components, or combinations thereof. 
   
   
       11 . The catalyst of  claim 10  wherein the promoter is one of more transition metal containing compounds comprises an element selected from Groups 5b, 6b, 7b and 8 of the Periodic Table of the Elements, and combinations thereof. 
   
   
       12 . The catalyst of  claim 11  wherein the one or more transition metal containing compounds comprises rhenium, molybdenum, tungsten or combinations thereof. 
   
   
       13 . The catalyst of  claim 10  wherein the promoter is an alkali metal containing compound comprises lithium, sodium, potassium, rubidium, cesium or combinations thereof. 
   
   
       14 . A catalyst useful for the epoxidation of an olefin which comprises a carrier and a catalytically effective amount of silver thereon, said carrier having a total pore volume from 0.2 ml/g to 0.6 ml/g, a surface area from about 0.3 to about 3.0 m 2 /g, at least 40% of pore volume from pores with diameters between 1 and 5 micrometers, and a median pore diameter between 1 and 5 micrometers, and wherein the pore volume from pores with a diameter of greater than 5 micrometers is less than 0.20 ml/g and the pore volume from pores with a diameter of less than 1 micrometer is less than 0.20 ml/g. 
   
   
       15 . The catalyst of  claim 14  further comprising a promoting amount of a promoter thereon, the promoter comprising one or more of an alkali metal containing compounds, one or more transition metal containing compounds, one or more sulfur components, one or more fluorine containing components, or combinations thereof. 
   
   
       16 . The catalyst of  claim 15  wherein the promoter is one of more transition metal containing compounds comprises an element selected from Groups 5b, 6b, 7b and 8 of the Periodic Table of the Elements, and combinations thereof. 
   
   
       17 . The catalyst of  claim 16  wherein the one or more transition metal containing compounds comprises rhenium, molybdenum, tungsten or combinations thereof. 
   
   
       18 . The catalyst of  claim 15  wherein the promoter is an alkali metal containing compound comprises lithium, sodium, potassium, rubidium, cesium or combinations thereof. 
   
   
       19 . A process for the oxidation of ethylene to ethylene oxide which comprises the vapor phase oxidation of ethylene with molecular oxygen in a fixed bed, tubular reactor, in the presence of the catalyst of  claim 9 . 
   
   
       20 . A process for the oxidation of ethylene to ethylene oxide which comprises the vapor phase oxidation of ethylene with molecular oxygen in a fixed bed, tubular reactor, in the presence of the catalyst of  claim 14 .