Silver-based sorbents

Abstract

Disclosed are sorbent compositions that include a porous titanium dioxide support impregnated with a silver material. The sorbent compositions may be utilized in systems and methods for removing sulfur compounds from hydrocarbon streams such as jet fuel.

1 . A sorbent composition comprising porous titanium dioxide particles impregnated with a silver material, wherein the impregnated particles comprise about 80-99.9% titanium dioxide (w/w) and about 0.1-20% silver material (w/w). 
     
     
         2 . The sorbent composition of  claim 1 , comprising about 95-99% titanium dioxide (w/w) and about 1-5% silver material (w/w). 
     
     
         3 . The sorbent composition of  claim 1 , wherein the silver material is selected from a group consisting of silver metal, silver oxide, silver salt, and mixtures thereof. 
     
     
         4 . The sorbent composition of  claim 1 , wherein the silver material is silver metal, silver oxide, or a mixture thereof. 
     
     
         5 . The sorbent composition of  claim 1 , wherein the silver material is in a nanocrystallite form. 
     
     
         6 . The sorbent composition of  claim 1 , wherein the particles have a pore volume of about 0.1-3.0 cc/g. 
     
     
         7 . The sorbent composition of  claim 1 , wherein the particles have a surface area of about 100-1000 m 2 /g. 
     
     
         8 . The sorbent composition of  claim 1 , wherein the particles have an average diameter of about 30-6000 microns. 
     
     
         9 . The sorbent composition of  claim 1 , wherein the particles have an average diameter of about 20-250 microns. 
     
     
         10 . The sorbent composition of  claim 1 , wherein the particles have an average pore diameter of about 1-20 nm. 
     
     
         11 . The sorbent composition of  claim 1 , wherein the particles are in the form of powder, grains, pellets, extrudates, or combinations thereof. 
     
     
         12 . The sorbent composition of  claim 1  dispersed on a support material selected from a group consisting of silicon dioxide, aluminum oxide, and activated carbon. 
     
     
         13 . The sorbent composition of  claim 1 , wherein the silver material comprises a dopant selected from a Group VIII metal or an oxide thereof and the ratio of silver material to dopant in the sorbent composition is about (7-3): 1. 
     
     
         14 . A filter material comprising the sorbent composition of  claim 1  entrapped in a matrix of fibers. 
     
     
         15 . The filter material of  claim 14 , wherein the fibers have an average diameter of about 2-20 microns and the particles have an average diameter of about 20-250 microns. 
     
     
         16 . The filter material of  claim 14 , wherein the sorbent composition is bonded to the matrix of fibers. 
     
     
         17 . The filter material of  claim 16 , wherein the fibers are ceramic fibers. 
     
     
         18 . A method for preparing the sorbent composition of  claim 1 , the method comprising:
 (a) impregnating porous titanium dioxide particles with a volume of silver precursor solution to provide wet impregnated particles, wherein the volume of silver precursor solution is no more than the pore volume of the titanium dioxide particles;   (b) drying and calcining the impregnated particles.   
     
     
         19 . The method of  claim 18 , wherein step (b) comprises heating the wet impregnated particles to a temperature of about 100-400° C. for at least about 2 hours. 
     
     
         20 . The method of  claim 18 , wherein the silver precursor solution is a silver salt solution. 
     
     
         21 . The method of  claim 18 , wherein the step of impregnating is performed by incipient wetness impregnating, spray impregnating, or a combination of both. 
     
     
         22 . The method of  claim 18 , wherein the step of drying is performed by a step selected from a group consisting of:
 drying at a temperature range of about 22-250° C.;   drying in sub-atmospheric pressures of about 0.001-759 torr;   drying in the presence of flowing gas stream; and   a combination thereof.   
     
     
         23 . The method of  claim 22 , wherein the flowing gas stream comprises a gas selected a group consisting of air, nitrogen, oxygen, argon, helium, and a combination thereof. 
     
     
         24 . The method of  claim 22 , wherein calcining is performed by heating the dried particles to a temperature in a range of about 100-800° C. for at least about 1 hour 
     
     
         25 . The method of  claim 24 , wherein the oxidizing agent is selected from a group consisting of air, pure oxygen, ozone, hydrogen peroxide, and a combination thereof. 
     
     
         26 . A process for removing sulfur compounds from a hydrocarbon stream, the process comprising passing the hydrocarbon stream through an effective amount of the sorbent composition of  claim 1  for a sufficient period of time to reduce sulfur compounds in the hydrocarbon stream to a level of no more than about 1 ppmw. 
     
     
         27 . The process of  claim 26 , wherein the sorbent composition is contained within a cartridge having a bottom and a top and the hydrocarbon stream passes from the bottom of the cartridge to the top of the cartridge. 
     
     
         28 . The process of  claim 27 , further comprising removing sulfur compounds adsorbed to the sorbent composition and any retained hydrocarbons. 
     
     
         29 . The process of  claim 28 , wherein the step of removing sulfur compounds adsorbed to the sorbent composition and any retained hydrocarbons is performed by heating the sorbent composition to a temperature between about 100-900° C. and passing an oxidizing agent over the sorbent composition. 
     
     
         30 . The process of  claim 27 , further comprising removing sulfur compounds adsorbed to the sorbent composition and any retained hydrocarbons by heating the sorbent composition to a temperature between about 100-900° C. and passing air over the sorbent composition in a direction from the top of the cartridge to the bottom of the cartridge. 
     
     
         31 . The process of  claim 28 , further comprising recovering the removed sulfur compounds and any retained hydrocarbons through condensation. 
     
     
         32 . A filtering system comprising:
 (a) a first sorbent composition according to  claim 1 , wherein the first sorbent composition preferentially adsorbs a first sulfur compound; and   (b) a second sorbent composition according to  claim 1 , wherein the second sorbent composition preferentially adsorbs a second sulfur compound.   
     
     
         33 . The filtering system of  claim 32  contained in a cartridge. 
     
     
         34 . A fuel filter assembly comprising the filtering system of  claim 32 .