Air filtration media comprising metal-doped silicon-based gel materials
The present invention relates generally to an environmental control unit for use in air handling systems that provides highly effective filtration of noxious gases (such as ammonia). Such a filtration system utilizes novel metal-doped silica-based gels to trap and remove such undesirable gases from an enclosed environment. Such gels exhibit specific porosity requirements and density measurements. Furthermore, in order for proper metal doping to take effect, such gels must be treated while in a wet state. The combination of these particular properties and metal dopant permits highly effective noxious gas filtration such that uptake and breakthrough results are attained, particularly in comparison with prior silica gel filtration products. Methods of using and specific filter apparatuses are also encompassed within this invention.
1 . A filter medium comprising multivalent metal-doped silicon-based gel materials, wherein said materials exhibit a BET surface area of between than 100 and 300 m 2 /g; a pore volume of between about 0.18 cc/g to about 0.7 cc/g as measured by nitrogen porosimetry; a cumulative surface area measured for all pores having a size between 20 and 40 Å of between 50 and 150 m 2 /g; and wherein the multivalent metal doped on and within said silicon-based gel materials is present in an amount of from 5 to 25% by weight of the total amount of the silicon-based gel materials.
2 . The filter medium of claim 1 wherein said BET surface area is between 150 m 2 /g and 250 m 2 /g; a pore volume of between about 0.25 to about 0.5 cc/g; a cumulative surface area measured for all pores having a size between 20 and 40 Å of between 80 and 120 m 2 /g; wherein said multivalent metal is present in an amount of from about 8 to about 20%.
3 . The filter medium of claim 1 wherein said multivalent metal is selected from the group consisting of cobalt, iron, manganese, zinc, aluminum, chromium, copper, tin, antimony, tungsten, indium, silver, gold, platinum, mercury, palladium, cadmium, nickel, and any combinations thereof.
4 . The filter medium of claim 3 wherein said multivalent metal is copper.
5 . The filter medium of claim 2 wherein the metal within said metal-doped silicon-based gel materials is selected from the group consisting of cobalt, iron, manganese, zinc, aluminum, chromium, copper, tin, antimony, indium, tungsten, silver, gold, platinum, mercury, palladium, cadmium, nickel, and any combinations thereof.
6 . The filter medium of claim 5 wherein said multivalent metal is copper.
7 . A filter system comprising the filter medium as defined in claim 1 .
8 . A filter system comprising the filter medium as defined in claim 2 .
9 . A filter system comprising the filter medium as defined in claim 3 .
10 . A filter system comprising the filter medium as defined in claim 4 .
11 . A filter system comprising the filter medium as defined in claim 5 .
12 . A filter system comprising the filter medium as defined in claim 6.