Supported nanoparticle catalyst

Abstract

A supported catalyst is provided comprising catalyst metal nanoparticles having an average particle size of 3.0 nm or less, or more typically 2.0 nm or less, and typically having a standard deviation of particle size of 0.5 nm or less, which are supported on support particles at a loading of 30% or more. Typical catalyst metals are selected from platinum, palladium, ruthenium, rhodium, iridium, osmium, molybdenum, tungsten, iron, nickel and tin. Typical support particles are carbon. A method of making a supported catalyst is provided comprising the steps of: a) providing a solution of metal chlorides of one or more catalyst metals in solvent system containing at least one polyalcohol, typically ethylene glycol containing less than 2% water; b) forming a colloidal suspension of unprotected catalyst metal nanoparticles by raising the pH of the solution, typically to a pH of 10 or higher, and heating said solution, typically to 125 ° C. or higher; c) adding support particles to the colloidal suspension; and d) depositing the unprotected catalyst metal nanoparticles on the support particles by lowering the pH of said suspension, typically to a pH of 6.5 or lower.

1 . A supported catalyst comprising catalyst metal nanoparticles having an average particle size of 3.0 nm or less supported on support particles, wherein the weight of catalyst metal nanoparticles in the supported catalyst is 30% or more of the weight of the supported catalyst.  
     
     
         2 . The supported catalyst according to  claim 1  wherein said catalyst metal nanoparticles have an average particle size of 2.5 nm or less.  
     
     
         3 . The supported catalyst according to  claim 1  wherein said catalyst metal nanoparticles have an average particle size of 2.0 nm or less.  
     
     
         4 . The supported catalyst according to  claim 1  wherein said catalyst metal nanoparticles have an average particle size of 1.8 nm or less.  
     
     
         5 . The supported catalyst according to  claim 1  wherein said catalyst metal nanoparticles have a standard deviation of particle size of 0.5 nm or less.  
     
     
         6 . The supported catalyst according to  claim 4  wherein said catalyst metal nanoparticles have a standard deviation of particle size of 0.5 nm or less.  
     
     
         7 . The supported catalyst according to  claim 1  wherein the weight of catalyst metal nanoparticles in the supported catalyst is 40% or more of the weight of the supported catalyst.  
     
     
         8 . The supported catalyst according to  claim 1  wherein the weight of catalyst metal nanoparticles in the supported catalyst is 50% or more of the weight of the supported catalyst.  
     
     
         9 . The supported catalyst according to  claim 1  wherein said support particles comprise carbon.  
     
     
         10 . The supported catalyst according to  claim 1  wherein said support particles consist essentially of carbon.  
     
     
         11 . The supported catalyst according to  claim 4  wherein said support particles comprise carbon.  
     
     
         12 . The supported catalyst according to  claim 4  wherein said support particles consist essentially of carbon.  
     
     
         13 . The supported catalyst according to  claim 1  wherein said catalyst metal nanoparticles comprise platinum.  
     
     
         14 . The supported catalyst according to  claim 13  wherein said catalyst metal nanoparticles consist essentially of platinum.  
     
     
         15 . The supported catalyst according to  claim 13  wherein said catalyst metal nanoparticles consist essentially of platinum and ruthenium.  
     
     
         16 . The supported catalyst according to  claim 13  wherein said support particles consist essentially of carbon.  
     
     
         17 . The supported catalyst according to  claim 4  wherein said catalyst metal nanoparticles comprise platinum.  
     
     
         18 . The supported catalyst according to  claim 17  wherein said catalyst metal nanoparticles consist essentially of platinum.  
     
     
         19 . The supported catalyst according to  claim 17  wherein said catalyst metal nanoparticles consist essentially of platinum and ruthenium.  
     
     
         20 . The supported catalyst according to  claim 17  wherein said support particles consist essentially of carbon.  
     
     
         21 . A fuel cell membrane electrode assembly comprising the supported catalyst according to  claim 1.