Nano-Structured Composite Materials for Chemical Air Pollutant and Odor Removal from Air

Abstract

Described is related to nano-structured composite materials for removing harmful chemical air pollutants and odors from the air to prevent people from breathing in disease-causing chemicals and provide them with clean indoor air. The nano-structured composite materials comprise nano-catalysts embedded in the pores of nano-structured substrate materials selected from the group consisting of nano-porous carbon, nano-porous rare earth oxide, nano-porous zeolite, nano-porous alumina and nano-porous silica. The nano-scale synergy of nano-catalysts and nano-structured substrate materials provides effective air filtration materials for the complete trapping and elimination of the full spectrum of chemical air pollutants including both organic and inorganic compounds and odors for indoor spaces, which HEPA or activated carbon filters cannot achieve.

Claims

1. Nano-structured composite materials for removing chemical air pollutants and odors from air at room temperature comprise nano-catalysts supported on nano-structured substrate materials in the form of “Nano-in-Nano” configuration wherein nano-sized catalysts distributed and anchored inside the nano-pores of the substrate materials which include at least one of nano-porous carbon, nano-porous rare earth oxide, nano-porous zeolite, nano-porous alumina, nano-porous silica, or combinations thereof.

2. The nano-structured composite materials according to claim 1, wherein said chemical air pollutants include carbon monoxide, nitric oxide, nitrogen dioxide, sulfur dioxide, hydrogen sulfide, ammonia, chlorine, ozone, formaldehyde, acetaldehyde, butadiene, propene, butane, acetone, benzene, phenol, toluene, xylene, methylene chloride, tetrachloroethylene, mercaptans and polycyclic aromatic hydrocarbons.

3. The nano-structured composite materials according to claim 1, wherein said odors include cigarette smoke, wildfire smoke, alcoholic beverages, body odors, perfumes, bathroom and toilet smells, dirty laundry smells, mold smells, locker room odors, sewer odors, garlic and onion odors, rotten and burned food, diesel and gasoline fumes, paint odors, moth balls, pet, fish and poultry odors.

4. The nano-structured composite materials according to claim 1, wherein said nano-catalysts are selected from a group consisting of iron, cobalt, nickel, copper, zinc, manganese, magnesium, sodium, potassium, calcium, barium, titanium, platinum, palladium, rhodium, ruthenium, silver, cerium, their corresponding oxides, and combinations thereof.

5. The nano-structured composite materials according to claim 1, wherein said nano-porous carbon is derived from raw carbon materials selected from a group consisting of coal charcoal, bamboo charcoal, coconut shell charcoal, willow bark charcoal, wood dust charcoal and liquid carbon precursors.

6. The nano-structured composite materials according to claim 5, wherein said liquid carbon precursors are selected from epoxy resin, phenolic resin and Furan resin.

7. The nano-structured composite materials according to claim 1, wherein said rare earth oxide is selected from a group consisting of yttrium oxide, lanthanum oxide, cerium oxide, praseodymium oxide, samarium oxide, and rare earth doped oxides including yttria-zirconia and ceria-zirconia, and combinations thereof.

8. The nano-structured composite materials according to claim 1, wherein said zeolite is selected from a group consisting of 3A zeolite, 4A zeolite, 5A zeolite, 13X zeolite, Beta zeolite, Pentasil zeolite and Mordenite zeolite, and combinations thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0008] This invention is related to nano-structured composite materials for removing harmful chemical air pollutants and odors from air, consisting of nano-catalysts supported on nano-porous substrate materials. The nano-porous substrate materials include at least one of nano-porous carbon, nano-porous zeolite, nano-porous rare earth oxide, nano-porous silica and nano-porous alumina, with nano-sized catalysts distributed and anchored on the surface of internal nano-pores of those nano-porous substrate materials.

[0009] The above nano-structured composite materials are made by mixing nano-catalysts with at least one substrate materials selected from raw carbon materials, rare earth oxide, silica, alumina and zeolite, as well as ceramic fillers, pore formers, organic binder and solvents together into a slurry or paste, followed by spraying or extrusion or tape-casting or molding to form various shapes, or by coating on existing substrate of various forms, then followed by drying, calcination and activation at high temperatures to create highly porous and active filter materials. The final physical formats of nano-structured composite materials made by this approach include fine powders, small grains, pellets, laminated sheets in cylindrical configuration or corrugated/pleated configuration, honeycomb monoliths, molded pieces in the form of ball, cylinder, cube, and hexagonal prism with interconnected internal porous structure.

[0010] The above nano-structured composite materials can also be made by mixing liquid catalyst precursors with at least one substrate materials selected from liquid carbon precursor, rare earth oxide, silica, alumina and zeolite, as well as ceramic fillers, pore formers, organic binder and solvents together into a slurry or paste, followed by spraying or extrusion or tape-casting or molding to form various shapes, or by coating on existing substrate of various forms, then followed by drying, calcination and activation at high temperatures to create highly porous and active filter materials. The final physical formats of nano-structured composite materials made by this approach include fine powders, small grains, pellets, laminated sheets in cylindrical configuration or corrugated/pleated configuration, honeycomb monoliths, molded pieces in the form of ball, cylinder, cube, and hexagonal prism with interconnected internal porous structure.

[0011] The raw carbon materials are selected from the group consisting of coal charcoal, bamboo charcoal, coconut shell charcoal, willow bark charcoal and wood dust charcoal. The liquid carbon precursor is selected from epoxy resin, phenolic resin and Furan resin. The rare earth oxide is selected from the group consisting of yttrium oxide, lanthanum oxide, cerium oxide, praseodymium oxide, samarium oxide, and rare earth doped oxides, including yttria-zirconia and ceria-zirconia, and combinations. The nano catalysts are selected from the group consisting of iron, cobalt, nickel, copper, zinc, manganese, magnesium, potassium, sodium, calcium, barium, titanium, platinum, palladium, rhodium, ruthenium, silver, cerium, and their corresponding oxides and combinations. The liquid catalyst precursors are selected from the corresponding salt solution group consisting of iron, cobalt, nickel, copper, zinc, manganese, magnesium, potassium, sodium, calcium, titanium, platinum, palladium, rhodium, ruthenium, silver, cerium, and combinations. The ceramic fillers are selected from silica, alumina, rare earth doped silica, rare earth doped alumina, aluminosilicate, silicon carbide, cordierite, mullite, or combinations. The zeolite is selected from the group consisting of 3A zeolite, 4A zeolite, 5A zeolite, 13X zeolite, Beta zeolite, Pentasil zeolite and Mordenite zeolite. The pore formers are selected from cellulose powder, polyethylene powder, polypropylene powder, corn starch and potato starch. The organic binder is selected from methyl cellulose and polyethylene glycol.

[0012] The chemical air pollutants that can be removed by the nano-structured composite materials of this invention include, but are not limited to, carbon monoxide, nitric oxide, nitrogen dioxide, sulfur dioxide, hydrogen sulfide, ammonia, chlorine, ozone, formaldehyde, benzene, acetaldehyde, butadiene, propene, acetone, toluene, xylene, mercaptans and polycyclic aromatic hydrocarbons. The odors that can be removed by the nano-structured composite materials of this invention include, but are not limited to, cigarette smoke, wildfire smoke, alcoholic beverages, body odors, perfumes, bathroom and toilet smells, dirty laundry smells, sewer odors, mold smells, garlic and onion odors, rotten and burned food, diesel and gasoline fumes, paint odors, moth balls, pet, fish and poultry odors, etc.

[0013] In one embodiment, raw carbon material powder, rare earth oxide powder, zeolite powder, nano-sized catalysts, ceramic filler powders, pore former and organic binder are mixed together with water into a paste and is extruded into pellets with size from 1 mm to 5 mm. The pellets are then dried at 50° C. to 160° C., calcined at 400° C. to 900° C., and activated at 500° C. to 900° C. by agents chosen from water vapor, carbon dioxide, sodium hydroxide, potassium hydroxide, magnesium hydroxide, calcium hydroxide, sodium carbonate, potassium carbonate, magnesium carbonate and calcium carbonate.

[0014] In another embodiment, the liquid carbon precursor, the liquid catalyst precursors, rare earth oxide powder, zeolite powder, ceramic filler powders, pore former and organic binder are mixed together with water into a paste and is extruded into pellets with size from 1 mm to 5 mm. The pellets are then dried at 50° C. to 160° C., calcined at 400° C. to 900° C., and activated at 500° C. to 900° C. by agents chosen from water vapor, carbon dioxide, sodium hydroxide, potassium hydroxide, magnesium hydroxide, calcium hydroxide, sodium carbonate, potassium carbonate, magnesium carbonate and calcium carbonate.

[0015] In another embodiment, the raw carbon material powder, alumina powder, the liquid catalyst precursors, ceramic filler powders, pore former and organic binder are mixed together with isopropanol into a slurry and is spray dried into powders or small grains with size ranging from 18 mesh to 200 mesh. The powders or grains are then calcined at 400° C. to 900° C., and activated at 500° C. to 900° C. by agents chosen from water vapor, carbon dioxide, sodium hydroxide, potassium hydroxide, magnesium hydroxide, calcium hydroxide, sodium carbonate, potassium carbonate, magnesium carbonate and calcium carbonate. The resulting powders or grains are further coated onto a synthetic non-woven fiber sheet, which is then laminated with another non-coated fiber sheet to form a sandwiched structure with nano-structured composite powders held in-between. The laminated sheet can be used as it is in flat format or can be stacked onto each other with corrugated sheet in between to form air channels, or can be made into pleated form, as chemical and odor air filter.