Methods of making and using a selective hydrogenation catalyst

Abstract

In an embodiment, a method of hydrogenating a highly unsaturated hydrocarbon to an unsaturated hydrocarbon includes contacting the highly unsaturated hydrocarbon with a catalyst in the presence of hydrogen. The catalyst comprises palladium and an inorganic support having a surface area of from about 4.5 to about 20 m 2 /g, or alternatively 5 to 14.5 m 2 /g. The inorganic support may comprise α-alumina treated with a fluoride source. The palladium may be primarily disposed near the surface of the support. In addition, the catalyst may comprise silver distributed throughout the support. In another embodiment, a method of making the foregoing selective hydrogenation catalyst includes contacting a fluorine-containing compound with an inorganic support, heating the support, and adding palladium to the inorganic support. After adding palladium to the support, the support can then be heated again, followed by adding silver to and then heating the support once again.

1 . A method of hydrogenating a highly unsaturated hydrocarbon to an unsaturated hydrocarbon, comprising contacting the highly unsaturated hydrocarbon with a catalyst in the presence of hydrogen at conditions effective to selectively hydrogenate the highly unsaturated hydrocarbon to the unsaturated hydrocarbon, wherein the catalyst comprises palladium and an inorganic support having a surface area of from about 4.5 to about 20 m 2 /g.  
   
   
       2 . The method of  claim 1 , wherein the surface area of the inorganic support is from about 5 to about 14.5 m 2 /g.  
   
   
       3 . The method of  claim 1 , wherein the inorganic support comprises alumina, silica, titania, zirconia, aluminosilicates, spinels such as zinc aluminate, zinc titanate, and magnesium aluminate, or combinations thereof.  
   
   
       4 . The method of  claim 1 , wherein the inorganic support comprises α-alumina.  
   
   
       5 . The method of  claim 1 , wherein the inorganic support comprises α-alumina treated with a fluoride source.  
   
   
       6 . The method of  claim 5 , further comprising washing the α-alumina treated with a fluoride source to remove any residual material from the fluorine source prior to calcining the support.  
   
   
       7 . The method of  claim 1 , wherein the catalyst further comprises silver distributed throughout the inorganic support.  
   
   
       8 . The method of  claim 7 , wherein a weight ratio of the silver to the palladium in the catalyst ranges from about 2 to about 10.  
   
   
       9 . The method of  claim 1 , wherein the palladium is primarily disposed near the periphery of the inorganic support.  
   
   
       10 . The method of  claim 1 , wherein the palladium is primarily disposed within 400 microns of the periphery of the inorganic support.  
   
   
       11 . The method of  claim 8 , wherein the catalyst further comprises fluorine.  
   
   
       12 . The method of  claim 11 , wherein the fluorine is provided from alkali metal fluoride, alkali metal bifluoride, hydrogen fluoride, ammonium fluoride, tetraalkylammonium fluoride, ammonium bifluoride, or combinations thereof.  
   
   
       13 . The method of  claim 11 , wherein the fluorine is provided from potassium fluoride.  
   
   
       14 . The method of  claim 11 , wherein an amount of the fluorine in the catalyst is in a range of from about 10 to about 10,000 parts per million by weight.  
   
   
       15 . The method of  claim 11 , wherein an amount of the fluorine in the catalyst is in a range of from about 10 to about 8,000 parts per million by weight.  
   
   
       16 . The method of  claim 11 , wherein an amount of the fluorine in the catalyst is in a range of from about 10 to about 5,000 parts per million by weight.  
   
   
       17 . The method of  claim 1 , wherein the highly unsaturated hydrocarbon comprises acetylene and the unsaturated hydrocarbon comprises ethylene.  
   
   
       18 . The method of  claim 17 , wherein the hydrogenation of the acetylene to the ethylene occurs in the presence of less than about 0.0015 mol % carbon monoxide based on the total moles of feed.  
   
   
       19 . The method of  claim 1 , further comprising regenerating the catalyst.  
   
   
       20 . The method of  claim 19 , wherein said regenerating comprises heating the catalyst in the presence of air at a temperature of less than or equal to about 500° C.  
   
   
       21 . The method of  claim 17 , wherein a mole ratio of the hydrogen to the acetylene is in a range of from about 0.1 to about 10.  
   
   
       22 . The method of  claim 17 , wherein an amount of carbon monoxide in contact with the acetylene is less than about 0.0015 mol %.  
   
   
       23 . The method of  claim 17 , wherein the catalyst further comprises iodide on the inorganic support.