Process for preparing a catalyst, the catalyst and a use of the catalyst

Abstract

A process for preparing a catalyst which process comprises the steps of: (a) introducing a Group 8 metal compound onto a carrier, (b) converting a first portion of the Group 8 metal compound on the carrier into metallic species in a liquid phase reaction, and (c) subsequently converting a further portion of the Group 8 metal compound on the carrier into metallic species in a gas phase reaction; a catalyst which is obtainable by this process; and a process for preparing an alkenyl carboxylate comprising reacting a mixture comprising an olefin, a carboxylic acid and oxygen in the presence of the catalyst.

1 . A process for preparing an alkenyl carboxylate comprising reacting a mixture comprising an olefin, a carboxylic acid and oxygen in the presence of a catalyst prepared by a process comprising the steps of: 
 (a) introducing a Group 8 metal compound onto a carrier,    (b) converting a first portion of the Group 8 metal compound on the carrier into metallic species in a liquid phase reaction, and    (c) subsequently converting a further portion of the Group 8 metal compound on the carrier into metallic species in a gas phase reaction.    
   
   
       2 . The process as claimed in  claim 1 , wherein the carboxylic acid comprises a monocarboxylic acid.  
   
   
       3 . The process as claimed in  claim 1 , wherein the carboxylic acid comprises acetic acid.  
   
   
       4 . The process as claimed in  claim 1 , wherein the olefin comprises a monoolefin.  
   
   
       5 . The process as claimed in  claim 1 , wherein the olefin comprises ethylene.  
   
   
       6 . The process as claimed in  claim 1 , wherein the carboxylic acid is selected from the group consisting of butyric acid, propionic acid, acetic acid, and mixtures of two or more thereof.  
   
   
       7 . The process as claimed in  claim 1 , wherein the olefin is selected from the group consisting of 1-butene, 2-butene, isobutene, propylene, ethylene, and mixtures of two or more thereof.  
   
   
       8 . The process as claimed in  claim 1 , wherein the quantity of carboxylic acid is in the range of from 1 to 20%-mole, relative to the number of moles of the feed.  
   
   
       9 . The process as claimed in  claim 1 , wherein the quantity of carboxylic acid is in the range of from 5 to 15%-mole, relative to the number of moles of the feed.  
   
   
       10 . The process as claimed in  claim 1 , wherein the quantity of olefin is in the range of from 10 to 80 %-mole, relative to the number of moles of the feed.  
   
   
       11 . The process as claimed in  claim 1 , wherein the quantity of olefin is in the range of from 30 to 60 %-mole, relative to the number of moles of the feed.  
   
   
       12 . The process as claimed in  claim 1 , wherein the quantity of oxygen is in the range of from 1 to 15%-mole, relative to the number of moles of the feed.  
   
   
       13 . The process as claimed in  claim 1 , wherein the catalyst is based on palladium as the Group 8 metal, and in addition on a Group 1b metal comprising gold.  
   
   
       14 . The process as claimed in  claim 1 , wherein the process for preparing the catalyst additionally comprises precipitating the Group 8 metal and optionally in addition a Group 1b metal onto the carrier by pore impregnating the carrier with one or more aqueous solutions comprising a Group 8 metal compound precursor and optionally a Group 1b metal compound precursor and then precipitating a Group 8 metal compound and optionally a Group 1b metal compound onto the carrier from such solutions, by using a precipitating agent.  
   
   
       15 . The process as claimed in  claim 1 , wherein the liquid phase reaction comprises converting at least 50%-mole of the total of the Group 8 metal and an optional Group 1b metal, if any, present on the carrier, into metallic species.  
   
   
       16 . The process as claimed in  claim 15 , wherein the liquid phase reaction comprises converting 70 to 90%-mole of the total of the Group 8 metal and the optional Group 1b metal, if any, present on the carrier, into metallic species.  
   
   
       17 . The process as claimed in  claim 1 , wherein the liquid phase reaction comprises converting the Group 8 metal compound on the carrier into metallic species by reaction with a non-gaseous reducing agent comprising hydrazine.  
   
   
       18 . The process as claimed in  claim 17 , wherein the non-gaseous reducing agent is hydrazine.  
   
   
       19 . The process as claimed in  claim 1 , wherein the gas phase reaction comprises converting the remaining portion of the Group 8 metal compound on the carrier into metallic species.  
   
   
       20 . The process as claimed in  claim 1 , wherein the gas phase reaction comprises converting the Group 8 metal compound on the carrier into metallic species by reaction with a gaseous reducing agent comprising hydrogen.  
   
   
       21 . The process as claimed in  claim 20 , wherein the gaseous reducing agent is hydrogen.  
   
   
       22 . The process as claimed in  claim 13 , wherein the process for preparing the catalyst additionally comprises a step of impregnating the carrier with a source of an alkali metal.  
   
   
       23 . The process as claimed in  claim 1 , wherein the carrier is a silica-containing carrier.  
   
   
       24 . The process as claimed in  claim 22 , wherein the quantity of palladium as the Group 8 metal is in the range of from 10 to 500 mmoles/kg catalyst, and in addition the quantity of gold as the Group 1b metal is in the range of from 1 to 200 mmoles/kg catalyst, and the quantity of alkali metal is in the range of from 0.1 to 5 mole/kg catalyst.