Agglomerates of precipitated silica, method for their preparation and their use as filter medium for gas filtration

Abstract

A micro-porous material having agglomerates of precipitated silica, according to the formula MeO x .HiSiO 2 , The agglomerates are composed of porous particles, and the agglomerates exhibit a size in the range 0.5-500 μm. A gas filter having the micro-porous material, and a method of filtering air through the micro-porous material.

1 . A micro-porous material, comprising agglomerates of precipitated silica, according to the formula
   MeO 2 .HiSiO 2      wherein   Me denotes any two or more metals selected among Ca, Mg, Cu, Zn, Mn, Cd, Pb, Ni, Fe, Cr, Ag, Al, Ti, V, Co, Mo, Sn, Sb, Sr, Ba and W, and wherein x denotes the molar ratio of oxygen to metallic constituents, and wherein m denotes the molar ratio of Si/Me, and wherein   the agglomerates are composed of porous particles, said agglomerates exhibiting a size in the range 0.5-500 μm.   
     
     
         2 . The micro-porous material as claimed in  claim 1 , wherein the molar ratio, m=Si/Me, is in the range 1-4. 
     
     
         3 . The micro-porous material, as claimed in  claim 1  wherein the porosity of the material is 0.5-1.2 cm 3 /g; and the BET surface is 300-800 m 2 /g. 
     
     
         4 . The micro-porous material, as claimed in  claim 1 , exhibiting a dry matter content of >97%. 
     
     
         5 . The micro-porous material, as claimed in  claim 1 , wherein the level of impregnation agents is 0-20%. 
     
     
         6 . The micro-porous material, as claimed in  claim 1 , which when exposed to saturated water vapor as well as liquid water does not disintegrate or dissolve. 
     
     
         7 . A gas filter apparatus comprising a material as claimed in  claim 1 . 
     
     
         8 . A method of filtering air comprising passing contaminated air through a gas filter apparatus as claimed in  claim 7 .