Titanosilicate molecular sieve supported metallic nanodots and methods of use to adsorb noble gases

Abstract

A metal nanodot material is formed by ion-exchange with an ETS zeolite, followed by activation to form metallic nanodots. The nanodot may be formed from silver, nickel, copper, gold or a platinum group metal.

1 . A method of forming surface accessible metal nanodots, comprising the steps of:
 (a) performing ion-exchange with a solution of the metal ions and an ETS zeolite; and   (b) activating the ion-exchanged ETS zeolite.   
     
     
         2 . The method of  claim 1  wherein the ETS zeolite comprises ETS-4 or ETS-10. 
     
     
         3 . The method of  claim 1  wherein the metal comprises silver, copper, nickel, gold or a member of the platinum group. 
     
     
         4 . The method of  claim 3  wherein the metal comprises silver. 
     
     
         5 . The method of  claim 1  wherein the activation step comprises drying or annealing the material. 
     
     
         6 . The method of  claim 5  wherein the activation step is performed under reducing conditions. 
     
     
         7 . The method of  claim 5  wherein the activation step is performed under oxidizing conditions. 
     
     
         8 . The method of  claim 5  wherein the activation step is performed at a temperature greater than about 75° C. and less than about 500° C. 
     
     
         9 . The method of  claim 8  wherein the activating step is performed at a temperature between about 75° C. and 400° C. 
     
     
         10 . The method of  claim 1  wherein the ion-exchange occurs with an excess of metallic ions. 
     
     
         11 . An ETS supported metal nanoparticulate material, comprising surface-accessible metal nanodots having a particle size less than about 100 nm. 
     
     
         12 . The material of  claim 11  wherein the nanodots have a particle size less than about 50 nm. 
     
     
         13 . The material of  claim 12  wherein the nanodots have a particle size less than about 15 nm and greater than about 5 nm. 
     
     
         14 . The material of  claim 11  wherein the metal comprises silver, copper, nickel, gold or a member of the platinum group, or mixtures thereof 
     
     
         15 . The material of  claim 14  wherein the metal comprises silver. 
     
     
         16 . The material of  claim 11  wherein the ETS material comprises ETS-10. 
     
     
         17 . A method of selectively adsorbing a noble gas from a gas stream containing the noble gas, using an adsorbent comprising metal nanodots formed from the process of  claim 1 , or comprising the material comprising metal nanodots of  claim 11 , the method comprising the step of passing the gas stream over the surface accessible metal nanodot ETS. 
     
     
         18 . The method of  claim 17  wherein the noble gas comprises xenon. 
     
     
         19 . The method of  claim 18  which occurs at a temperature between 20° C. and 150° C. 
     
     
         20 . The method of  claim 18  further comprising the step of releasing the xenon from the adsorbent by heating the adsorbent under a reduced pressure. 
     
     
         21 . The method of  claim 20  wherein the xenon is released from the adsorbent by heating to about 150° C. under a full or partial vacuum. 
     
     
         22 . The method of  claim 17  wherein the noble gas comprises argon. 
     
     
         23 . The method of  claim 22  wherein the method comprises a method of producing substantially pure oxygen from a gas stream comprising oxygen and argon. 
     
     
         24 . A method of preventing or treating an infection in a body part by contacting the body part with metal nanodots formed from the process of  claim 1 , or the material comprising metal nanodots of  claim 11 .