Photocatalytic airborne molecular decontamination system with improved passive adsorption

Abstract

The air filtration system includes a photocatalytic reactor and a first air filter upstream of the photocatalytic reactor. The photocatalytic reactor includes a photocatalytic composition and a lamp configured to irradiate the photocatalytic composition. The photocatalytic composition is configured to decompose one or more volatile organic compounds in the air. The first air filter is configured to filter one or more inactivated compounds from the air. A method of filtering air in an air filtration system includes passing air through a photocatalytic reactor and passing the air through the first filter and then through the photocatalytic reactor. Passing the air through the photocatalytic reactor includes a photocatalytic composition that decomposes one or more volatile organic compounds in the air.

Description

[Technical field]

[0001] FIELD OF THE DISCLOSURE The present disclosure relates to air filtration systems and, more particularly, to air filtration systems that produce filtered air for use in semiconductor manufacturing. [Background technology]

[0002] Air filtration systems can be employed in semiconductor manufacturing to provide filtered air to fabrication areas. The air filtration systems can provide clean air for use by and / or around semiconductor production tools. For example, clean air may be used as a clean purge gas in semiconductor wafer manufacturing. Also, for example, clean air may be used in clean rooms in which semiconductor wafers are manufactured. Air filtration systems may be configured to filter the air to remove various contaminants that may adversely affect the quality of the semiconductors being produced. For example, such contaminants may include particulates and / or volatile organics that may contaminate the wafer material and reduce the quality of the produced semiconductors. Summary of the Invention

[0003] In one embodiment, an air filtration system includes a photocatalytic reactor, a first air filter disposed upstream of the photocatalytic reactor, and a second air filter disposed downstream of the photocatalytic reactor. The photocatalytic reactor includes a photocatalytic composition and a lamp configured to irradiate the photocatalytic composition. The photocatalytic composition is configured to decompose one or more volatile organic compounds in air passing through the photocatalytic reactor. The first air filter is configured to filter the one or more compounds from the air. The second air filter is configured to filter at least one of the one or more products from air passing through the second air filter.

[0004] In one embodiment, an air filtration system includes a photocatalytic reactor and an air filter disposed upstream of the photocatalytic reactor. The photocatalytic reactor includes an agitated bed of a photocatalytic composition and a lamp configured to irradiate the photocatalytic composition. The photocatalytic composition is configured to decompose one or more volatile organic compounds in air passing through the photocatalytic reactor. The air filter is configured to filter the one or more compounds from the air.

[0005] A method of filtering air in an air filtration system includes passing air through a photocatalytic reactor comprising a photocatalytic composition and a lamp, and passing the air through a first filter and then passing the air through the photocatalytic reactor. Passing the air through the photocatalytic reactor includes irradiating the photocatalytic composition with the lamp and using the photocatalytic composition to decompose one or more volatile organic compounds in the air into one or more products. Passing the air through the first filter includes filtering one or more compounds from the air. The method includes passing the air through a second air filter, including filtering at least one of the one or more products from the air, and / or passing the air through the photocatalytic reactor includes passing the air through a stirred bed of the photocatalytic composition. [Brief description of the drawings]

[0006] [Figure 1] FIG. 1 is a schematic diagram of one embodiment of an air filtration system 1. [Diagram 2] FIG. 1 is a schematic diagram of one embodiment of an air filtration system 1. [Diagram 3] FIG. 2 is a block flow diagram of one embodiment of a method for filtering air.

[0007] Like numbers refer to like features. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] FIG. 1 is a schematic diagram of one embodiment of an air filtration system 1. The air flow of the air filtration is indicated by dotted arrows in FIG. 1. The air filtration system 1 includes an inlet 5 and an outlet 10. Air to be filtered enters the air filtration system 1 through the inlet 5, flows through the air filtration system 1, and then is discharged from the air filtration system 1 through the air outlet 10 as filtered air. As the air passes through the air filtration system 1 from the inlet 5 to the outlet 10, it is filtered by the air filtration system 1. The filtered air discharged from the air filtration system 1 is then directed to one or more of a clean room 15A and / or a semiconductor manufacturing tool 15B. For example, the filtered air may be used as a clean purge gas in semiconductor manufacturing. For example, the filtered air may be discharged to a clean room 15A used for semiconductor manufacturing. In another embodiment, the air filtration system 1 may be used to provide highly clean air in other clean environments other than semiconductor manufacturing (e.g., hospitals, other types of manufacturing, etc.).

[0009] Figure 2 is a schematic diagram of one embodiment of an air filtration system 100. In one embodiment, the air filtration system 100 may be the air filtration of Figure 1. Dotted arrows are provided to indicate the flow of air through the air filtration system 100 of Figure 1.

[0010] 2, air filtration system 100 includes an inlet 102, an outlet 104, and an air flow path 106 that extends from inlet 102 to outlet 104. Air enters air filtration system 100 through inlet 102, flows through air flow path 106 from inlet 102 to outlet 104, and then the air (e.g., filtered air) is exhausted through outlet 104. The air is filtered as it flows through air flow path 106 of air filtration system 100.

[0011] The air filtration system 100 includes a photocatalytic reactor 120 and one or more filters 110, 130, 140, 150. Air is filtered by the air filtration system 100 by passing through the photocatalytic reactor 120 and the filters 110, 130, 140, 150. In the illustrated embodiment, the air filtration system 100 includes a first filter 110, a photocatalytic reactor 120, a second filter 130, a third filter 140, and a fourth filter 150. Air flows through the first filter 110, the photocatalytic reactor 120, the second filter 130, the third filter 140, and the fourth filter 150 in sequence. In one embodiment, the air filtration system 100 may also include an air displacement device 160, such as a blower or fan, for generating flow through the air filtration system 100 (e.g., air flowing through the air flow path 106 of the air filtration pathway 100).

[0012] The inlet air f1 (e.g., air to be filtered) entering the inlet 102 of the air filtration system 100 can be one or a mixture of ambient air (e.g., air from outside the building), air inside the building, clean room return air, etc. The first filter 100 is located upstream of the photocatalytic reactor 120. It should be understood that the "upstream" and "downstream" described are relative to the direction of air flow through the air filtration system 100 from the inlet 102 to the outlet 104 (e.g., position in the air flow path 106 relative to the air flow from the inlet 102 to the outlet 104). For example, being located upstream of the photocatalytic reactor 120 refers to the first filter 100 being near the inlet 102 such that air passes through the first filter 100 before entering the photocatalytic reactor 120 (e.g., air flowing through the photocatalytic reactor 120 has passed through the first filter 110).

[0013] The inlet air f1 includes one or more contaminants. The contaminants include one or more volatile organic compounds. For example, the volatile organic compounds may include, but are not limited to, isopropyl alcohol (IPA), toluene, acetic acid, acetone, propylene glycol methyl ether acetate, trimethylsilanol, acetaldehyde, benzene, ethanol, ethylbenzene, and the like. The photocatalytic reactor 120 is used to remove / reduce the amount of volatile organic compounds from the air. In one embodiment, the photocatalytic reactor 120 can be used to reduce the content of IPA in the air.

[0014] The photocatalytic reactor 120 comprises a photocatalytic composition 122 and a lamp 124. The lamp 124 produces light 126 that is directed onto the photocatalytic composition 122. The lamp 124 may be in the form of an LED or other suitable light source. The photocatalytic composition 122 and the lamp 124 may be located within the air filtration system 100 with or without a separate housing / unit.

[0015] The light 126 activates the photocatalytic composition 122, which then oxidizes volatile organic compounds in the air. More specifically, the photocatalytic composition 122 decomposes the volatile organic compounds into one or more products. A photocatalytic reaction begins when a photocatalyst in the photocatalytic composition 122 absorbs a photon from the light 126 with an energy equal to or greater than the band gap energy of the photocatalyst, resulting in the formation of electron-hole pairs (e - / h + The electron-hole pairs formed react with oxygen (O2) and water / moisture (H2O) in the air to form active radicals (O2· -and OH·), which then react with the volatile organic compounds to decompose the volatile organic compounds. Volatile organic pollutants / compounds are generally decomposed into carbon dioxide (CO2) and water (H2O) as the primary products. References to compounds and / or species that react with or are decomposed by the photocatalytic composition 122 should be understood to refer to reaction with the active radicals generated by the photocatalytic composition 122, unless otherwise specified. The product or products are then exhausted from the photocatalytic reactor 120 with the air. Some organic species may also form other species / compounds (i.e., other than carbon dioxide and water) during decomposition (e.g., may form intermediates that may only be partially decomposed, may not decompose further, etc.). These other species / compounds may also be referred to as by-products.

[0016] The photocatalytic composition 122 is one or more photocatalysts capable of decomposing volatile organic compounds that may pollute the air when irradiated. The irradiated photocatalyst generates free radicals in the air that react with and decompose the volatile organic compounds, as discussed above. In one embodiment, the photocatalytic composition 122 may be in the form of a metal oxide semiconductor and / or a doped metal oxide semiconductor. Examples of photocatalysts include, but are not limited to, one or more of TiO2, ZnO, Fe-TiO2, Ce-TiO2, and the like.

[0017] The photocatalytic composition 122 may be provided on a support. In one embodiment, the photocatalytic composition 122 may be a coating provided on a solid substrate (e.g., a TiO2 coating provided on an aluminum substrate). In one embodiment, the photocatalytic composition 122 may be provided on a porous material such that air flows across the photocatalytic composition 122 as air passes through the porous material (e.g., a filter material, a porous fibrous structure, etc.). In one embodiment, the photocatalytic composition 122 may be provided in the form of a packed bed.

[0018] In one embodiment, the photocatalytic composition 122 may be provided in the photocatalytic reactor 120 in the form of a stirred bed. For example, the photocatalytic composition 122 may be provided as a coating on substrate beads / particles in a stirred bed. In such an embodiment, the photocatalytic reactor 120 comprises a stirred bed of the photocatalytic composition 122. In one embodiment, the stirred bed may be a fluidized bed that is agitated by air flowing through the photocatalytic reactor 120. In one embodiment, the stirred bed may be a fixed bed, and the photocatalytic reactor 120 comprises a mechanical means for agitating the fixed bed of the photocatalytic composition. For example, the mechanical means 128 may be one or more of a stirrer that agitates the beads in the fixed bed, a rotator that rotates the entire fixed bed to agitate the beads in the fixed bed, a rotator that rotates one or more portions of the fixed bed (e.g., rotating the sides of the fixed bed) to agitate the beads in the fixed bed, and the like.

[0019] The inlet air f1 may contain one or more other compounds different from volatile organic compounds. These other compounds are gaseous contaminants in the air. These other compounds may inactivate the photocatalyst and / or react with the photocatalyst to produce other undesirable contaminants. The compounds thus produced are different from the main products (i.e., not H2O and / or CO2) and may be referred to as by-products. For example, some of the other compounds may be compounds that are oxidized by the photocatalyst to form one or more oxidation products that are not H2O and / or CO2. The first type of by-products remains and blocks the active sites of the photocatalyst, reducing the activity of the photocatalyst. This may be referred to as inactivating the photocatalyst. The second type of by-products is exhausted from the photocatalyst composition 122 together with the air, which becomes a contaminant / pollutant in the air. Some by-products may inactivate the photocatalytic composition 122 and be discharged from the photocatalytic composition 122 along with the air (e.g., from the photocatalytic composition 122 / photocatalytic reactor 120 as airborne contaminants).

[0020] These other compounds in the inlet air f1 can include one or more inorganic compounds that deactivate the photocatalytic composition 122 and / or silicon compounds that deactivate the photocatalytic composition 122. One or more contaminating by-products may also result from the photooxidation process. For example, inorganic compounds (e.g., SO2, H2S, NH3, etc.) may be oxidized by the photocatalyst to produce by-products (e.g., SO4 2- , H2SO4, NO2, HNOx, etc.), which may be exhausted from the photocatalytic composition 122 into the air as a polluting by-product and / or may remain and block the active sites of the photocatalyst (i.e., photocatalytic composition 122). For example, silicon compounds that deactivate the photocatalyst composition 122 may react with the photocatalyst to produce by-products (e.g., SiO2, SiO3 2- ) and then block the active sites of the photocatalyst.

[0021] The first filter 110 is disposed upstream of the photocatalytic reactor 120. Air f1 flows from the inlet 102 to the first filter 110 and is filtered by the first filter 110 before passing through the photocatalytic reactor 120. The first filter 110 is an air filter configured to filter at least one of one or more compounds from the air f1. The first filter 100 includes a material that adsorbs one or more compounds from the air f1. For example, the first filter 110 in one embodiment may include one or more of carbon (e.g., treated carbon, untreated carbon), zeolite, ion exchange resin, etc., configured to adsorb one or more compounds from the air f1.

[0022] The second filter 130 is disposed downstream of the photocatalytic reactor 120. The second filter 130 receives the air discharged from the photocatalytic reactor 120. The second filter 130 is a particulate air filter that removes particulates from the air discharged from the photocatalytic reactor 120. Examples of particulate filters can include, but are not limited to, HEPA air filters and ULPA air filters. In one embodiment, the second filter 130 is configured to filter particulates discharged from the photocatalytic reactor 120. The second filter 130 can filter particulates of the photocatalytic composition 122 discharged from the fluidized bed of the photocatalytic reactor 120. The second filter 130 is configured to filter particulates of the fluidized bed of the photocatalytic composition 122 in the air flowing from the photocatalytic reactor 120.

[0023] The third air filter 140 is disposed downstream of the photocatalytic reactor 120. In the illustrated embodiment, the third air filter 140 is disposed downstream of the photocatalytic reactor 120 and the second filter 130. The third air filter 140 is an air filter configured to filter the air after passing through the photocatalytic reactor 120. The third filter 140 is configured to filter one or more products produced by the photocatalytic reactor 120 from the air f1. In one embodiment, the third filter 140 may be configured to filter one or more by-products produced in the photocatalytic composition 122 from the air f1. The third filter 140 adsorbs the products from the air f1. For example, the first filter 110 in one embodiment may include one or more of carbon (e.g., treated carbon, untreated carbon), zeolite, ion exchange resin, etc., configured to adsorb one or more deactivating compounds from the air f1. In one embodiment, the third filter 140 may be the same type of air filter as the first filter 110 (e.g., the first filter 110 and the third filter 140 are made of the same type of material). In another embodiment, the third filter 140 and the first filter 110 may be different types of filters (e.g., made of different materials).

[0024] The fourth filter 150 is disposed downstream of the third filter 140. The fourth filter 150 is an air filter configured to filter the air f1 after passing through the third filter 140. The fourth filter 150 is a particulate filter configured to filter particulates from the air f1. Specifically, the fourth filter 150 is configured to filter particulates discharged from the third filter 140 into the air. Examples of particulate filters may include, but are not limited to, HEPA air filters and ULPA air filters. The fourth filter 150 may be the same or different type of particulate filter as the second filter 130.

[0025] It should be understood that filters 110, 130, 140, 150 are referred to as first, second, third, and fourth to provide a clearer description, but should not be construed as limiting the location / configuration of any particular filter. For example, the total number and / or particular arrangement of filters in air filtration system 100 may differ in other embodiments. In one embodiment, air filtration system 100 may include first filter 110 and photocatalytic reactor 120. In another embodiment, air filtration system 100 may include first filter 110, photocatalytic reactor 120, and one or more of second filter 130, third filter 140, and fourth filter 150. In one embodiment, air filtration system 100 may include first filter 110, photocatalytic reactor 120, and third filter 140.

[0026] In one embodiment, the air filtration system 100 may be in the form of a single housing 108. For example, the housing 108 may be in the form of a cabinet or unit that filters air. The housing 108 includes an inlet 102 and an outlet 104. The photocatalytic reactor 120 and one or more filters 110, 130, 140, 150 are disposed within the housing 108. In one embodiment, the air filtration system 100 may include multiple photocatalytic reactors 120 in parallel. For example, air from a first filter 110 is split into multiple flows that each pass through a corresponding one of the multiple photocatalytic reactors 120. The air discharged from each of the multiple photocatalytic reactors 120 may then be directed to a next air filter (e.g., the second air filter 130).

[0027] Air filtration system 100 can be configured to filter at least 100 cubic feet per minute ("CFM") of air. Air filtration system 100 can be configured to filter at least 100 cubic feet per minute ("CFM") of air. In one embodiment, air filtration system 100 can be configured to filter at least 200 CFM of air. In one embodiment, air filtration system 100 can be configured to filter at least 200-500 CFM of air.

[0028] For example, conventional air filtration systems for providing filtered air to semiconductor manufacturing tools utilize carbon filters to remove volatile organic compounds from the air that are replaced periodically (e.g., more than monthly, monthly or approximately monthly, bimonthly or approximately bimonthly, semi-annually or approximately semi-annually, etc.) (e.g., carbon filters used to remove IPA are replaced no more than once a month). As an example, carbon filters used to remove IPA are typically replaced at least monthly. For example, the removal efficiency of such carbon filters fell below 60% removal efficiency after filtering 6,000 ppb-hrs of IPA from the air. Air filtration system 100 can advantageously provide filtration of volatile organic compounds over extended periods of time without maintenance (e.g., in the illustrated embodiment, without replacing one or more of its filters, filters 110, 130, 140, 150).

[0029] Figure 3 is a block flow diagram of a method 1000 for filtering air. For example, method 100 may be employed by air filtration system 1 of Figure 1 and / or air filtration system 100 of Figure 2. Method 1000 begins at 1010.

[0030] At 1010, air is passed through a first filter (e.g., first air filter 110). Passing the air through the first filter at 1010 includes filtering one or more deactivating compounds from the air. Method 1000 then proceeds to 1020.

[0031] At 1020, air is passed through a photocatalytic reactor (e.g., photocatalytic reactor 120). The air passes through a first filter at 1010 in an air filtration system before passing through the photocatalytic reactor at 1020. Passing the air through the photocatalytic reactor at 1020 includes irradiating a photocatalytic composition (e.g., photocatalytic composition 122) with a lamp (e.g., lamp 124) and using the photocatalytic composition to decompose one or more volatile organic compounds in the air into one or more products. In one embodiment, the photocatalytic reactor includes a fluidized bed of the photocatalytic composition, and passing the air through the photocatalytic reactor at 1020 includes passing the air through the fluidized bed of the photocatalytic composition. In one embodiment, method 1000 may continue to 1030.

[0032] At 1030, the air is passed through a second filter (e.g., second air filter 130). Passing the air through the second filter at 1030 may include filtering particulates from the air. In one embodiment, filtering particulates from the air may include filtering particulates of the fluidized bed photocatalytic composition from the air with the second filter. In one embodiment, method 1000 may continue to 1040.

[0033] At 1040, the air is passed through a third filter (e.g., third air filter 140). Passing the air through the third filter at 1040 may include filtering at least one of the one or more products produced at 1020 from the air with the third filter. In one embodiment, method 1000 may continue to 1050.

[0034] At 1050, the air passes through a fourth filter (e.g., the fourth air filter 150). Passing the air through a filter at 1040 may include filtering particulates from the air (e.g., particulates from the third filter 140 that were exhausted into the air).

[0035] It should be understood that the method 1000 in one embodiment may be modified to include features described with respect to the air filtration system 1 of FIG. 1 and / or the air filtration system 100 of FIG.

[0036] Aspects: Any of the embodiments 1 to 8 may be combined with any of the embodiments 9 to 20, and any of the embodiments 9 to 16 may be combined with any of the embodiments 17 to 20.

[0037] Aspect 1. An air filtration system comprising: a photocatalytic reactor comprising a photocatalytic composition and a lamp configured to irradiate the photocatalytic composition, the photocatalytic composition configured to decompose one or more volatile organic compounds in air passing through the photocatalytic reactor into one or more products; a first air filter positioned upstream of the photocatalytic reactor to filter air before the photocatalytic reactor, the first air filter configured to filter the one or more compounds from the air; and a second air filter positioned downstream of the photocatalytic reactor, the second air filter configured to filter at least one of the one or more products from the air passing through the second air filter.

[0038] Embodiment 2. The air filtration system of embodiment 1, further comprising an inlet and an outlet, wherein air flows sequentially from the inlet to the outlet through the first air filter, the photocatalytic reactor, and the second air filter.

[0039] Embodiment 3. The air filtration system of any one of embodiments 1-2, wherein the one or more compounds filtered by the first air filter include one or more of an inorganic compound that inactivates the photocatalytic composition, and a silicon compound that inactivates the photocatalyst.

[0040] Aspect 4. The air filtration system of any one of aspects 1-3, further comprising a third air filter positioned to filter air flowing from the photocatalytic reactor, the third air filter being a particulate filter configured to filter solid particulates from the air.

[0041] Aspect 5. The air filtration system of aspect 4, further comprising a fourth air filter positioned to filter air flowing from the second air filter, the fourth air filter being a particulate filter configured to filter solid particulates discharged from the second air filter, and a third air filter positioned to filter air flowing from the photocatalytic reactor to the second air filter and configured to filter solid particulates of the photocatalytic composition discharged from the photocatalytic reactor.

[0042] Embodiment 6. The air filtration system of any one of embodiments 1-5, further comprising a housing that houses the first air filter, the photocatalytic reactor, and the second air filter, the housing forming a flow path that directs air sequentially through the first air filter, the fluidized bed of the photocatalytic reactor, and the second air filter.

[0043] Embodiment 7. The air filtration system of any one of embodiments 1-6, wherein the one or more volatile compounds include isopropyl alcohol and the photocatalytic composition is configured to decompose isopropyl alcohol.

[0044] Embodiment 8. The air filtration system of any one of embodiments 1-7, wherein the photocatalytic reactor comprises a stirred bed of the photocatalytic composition.

[0045] Embodiment 9. An air filtration system comprising: a photocatalytic reactor comprising an agitated bed of a photocatalytic composition and a lamp configured to irradiate the photocatalytic composition and configured to agitate the agitated bed of the photocatalytic composition, wherein the photocatalytic composition is configured to decompose one or more volatile organic compounds in air passing through the photocatalytic reactor into one or more products; and a first air filter positioned upstream of the photocatalytic reactor to filter the air before passing it through the photocatalytic reactor, the first air filter configured to filter the one or more compounds from the air.

[0046] Embodiment 10. The air filtration system of embodiment 9, wherein the agitated bed is a fluidized bed or the agitated bed is a fixed bed and the photocatalytic reactor comprises a means for mechanically agitating the fixed bed of the photocatalytic composition.

[0047] Embodiment 11. The air filtration system of any one of embodiments 9-10, further comprising a second air filter disposed downstream of the photocatalytic reactor, the second air filter being a particulate air filter configured to filter particles of the photocatalytic composition discharged from the stirred bed from the air.

[0048] Aspect 12. The air filtration system of aspect 11, further comprising a third air filter positioned to filter air flowing from the second air filter, the third air filter configured to filter at least one of the one or more products from the air passing through the third air filter.

[0049] Embodiment 13. An air filtration system according to any one of embodiments 9 to 12, further comprising an inlet and an outlet, wherein air flows from the inlet to the outlet through the first air filter and the photocatalytic reactor in sequence.

[0050] Embodiment 14. The air filtration system of any one of embodiments 9-12, wherein the one or more compounds filtered by the first air filter include one or more of an inorganic compound that inactivates the photocatalytic composition, and a silicon compound that inactivates the photocatalyst.

[0051] Embodiment 15. The air filtration system of any one of embodiments 9-14, further comprising a housing that contains the photocatalytic reactor and the first air filter, the housing forming a flow path that directs air through the first air filter and, in turn, through the stirred bed of the photocatalytic reactor.

[0052] Embodiment 16. An air filtration system according to any one of embodiments 9 to 15, wherein the one or more volatile compounds include isopropyl alcohol and the photocatalytic composition is configured to decompose isopropyl alcohol.

[0053] Embodiment 17. A method of filtering air in an air filtration system, comprising one or more of: passing air through a photocatalytic reactor comprising a photocatalytic composition and a lamp, the method comprising: irradiating the photocatalytic composition with the lamp and using the photocatalytic composition to decompose one or more volatile organic compounds in the air into one or more products; and passing the air through a first filter and then passing the air to the photocatalytic reactor, the method comprising: passing the air through a second air filter, the method comprising filtering at least one of the one or more products from the air; and passing the air to the photocatalytic reactor, the method comprising: passing the air through a stirred bed of the photocatalytic composition.

[0054] Embodiment 18. The method of embodiment 17, comprising passing the air through a second air filter.

[0055] Embodiment 19. The method of embodiment 18, wherein passing the air through the photocatalytic reactor comprises passing the air through an agitated bed of the photocatalytic composition.

[0056] Aspect 20. The method of aspect 19, further comprising passing the air through a particulate filter to filter solid particulates of the photocatalytic composition discharged from the fluidized, agitated bed of the photocatalytic composition.

[0057] The examples disclosed in this application are to be considered in all respects as illustrative and not restrictive. The scope of the disclosure is indicated by the appended claims, rather than the foregoing description, and all changes that come within the meaning and range of equivalency of the claims are intended to be embraced therein.

Claims

1. a photocatalytic reactor comprising a photocatalytic composition and a lamp configured to irradiate the photocatalytic composition, the photocatalytic composition configured to decompose one or more volatile organic compounds in air passing through the photocatalytic reactor into one or more products; a first air filter positioned upstream of the photocatalytic reactor to filter air before the photocatalytic reactor, the first air filter configured to filter one or more compounds from the air; a second air filter disposed downstream of the photocatalytic reactor, the second air filter configured to filter at least one of the one or more products from air passing through the second air filter; An air filtration system comprising:

2. an inlet and an outlet, wherein air flows from the inlet to the outlet through the first air filter, the photocatalytic reactor, and the second air filter, in that order; 10. The air filtration system of claim 1.

3. The one or more compounds filtered by the first air filter are an inorganic compound that inactivates the photocatalytic composition; and 3. The air filtration system of claim 1 or 2, comprising one or more silicon compounds that deactivate the photocatalytic composition.

4. a third air filter positioned to filter air flowing from the photocatalytic reactor, the third air filter being a particulate filter configured to filter solid particulates from the air; The air filtration system of any one of claims 1 to 3, further comprising:

5. a fourth air filter positioned to filter air flowing from the second air filter, the fourth air filter being a particulate filter configured to filter solid particulates exhausted from the second air filter; The third air filter is disposed to filter air flowing from the photocatalytic reactor to the second air filter, and is configured to filter solid particles of the photocatalytic composition discharged from the photocatalytic reactor.

5. The air filtration system of claim 4.

6. a housing containing the first air filter, the photocatalytic reactor, and the second air filter, the housing defining a flow path that directs air through the first air filter, the fluidized bed of the photocatalytic reactor, and the second air filter, in that order; The air filtration system of any one of claims 1 to 5, further comprising:

7. 7. The air filtration system of claim 1, wherein the one or more volatile compounds include isopropyl alcohol, and the photocatalytic composition is configured to decompose the isopropyl alcohol.

8. 8. The air filtration system of claim 1, wherein the photocatalytic reactor comprises a stirred bed of the photocatalytic composition.

9. a photocatalytic reactor comprising an agitated bed of a photocatalytic composition and a lamp configured to irradiate the photocatalytic composition and configured to agitate the agitated bed of the photocatalytic composition, the photocatalytic composition configured to decompose one or more volatile organic compounds in air passing through the photocatalytic reactor into one or more products; a first air filter disposed upstream of the photocatalytic reactor to filter air before passing the air through the photocatalytic reactor, the first air filter configured to filter one or more compounds from the air; An air filtration system comprising:

10. the stirred bed is a fluidized bed, or the stirred bed is a fixed bed and the photocatalytic reactor comprises a means for mechanically stirring the fixed bed of the photocatalytic composition; 10. The air filtration system of claim 9.

11. a second air filter disposed downstream of the photocatalytic reactor, the second air filter being a particulate air filter configured to filter particles of the photocatalytic composition discharged from the stirred bed from the air; 11. The air filtration system of claim 9 or 10, further comprising:

12. a third air filter positioned to filter air flowing from the second air filter, the third air filter configured to filter at least one of the one or more products from air passing through the third air filter.

12. The air filtration system of claim 11, further comprising:

13. an inlet and an outlet, wherein air flows from the inlet to the outlet through the first air filter and the photocatalytic reactor, in that order; 13. The air filtration system of claim 12.

14. The one or more compounds filtered by the first air filter are an inorganic compound that inactivates the photocatalytic composition; and 14. The air filtration system of any one of claims 9 to 13, comprising one or more silicon compounds that deactivate the photocatalytic composition.

15. a housing that contains the photocatalytic reactor and the first air filter, the housing defining a flow path that directs air through the first air filter and, in that order, through the stirred bed of the photocatalytic reactor; The air filtration system of any one of claims 9 to 14, further comprising:

16. 16. The air filtration system of any one of claims 9 to 15, wherein the one or more volatile compounds include isopropyl alcohol, and the photocatalytic composition is configured to decompose the isopropyl alcohol.

17. 1. A method of filtering air in an air filtration system, comprising: Passing air through a photocatalytic reactor comprising a photocatalytic composition and a lamp, irradiating the photocatalytic composition with the lamp; and passing air through a photocatalytic reactor, the photocatalytic reactor comprising decomposing one or more volatile organic compounds in the air into one or more products using the photocatalytic composition; passing the air through a first filter and then through the photocatalytic reactor, wherein passing the air through the first filter comprises filtering one or more deactivating compounds from the air that deactivate the photocatalytic composition; the method including passing the air through a second air filter, the second air filter including filtering at least one of the one or more products from the air; and passing air through the photocatalytic reactor comprises passing air through an agitated bed of the photocatalytic composition; The method of claim 1,

18. Passing the air through the second air filter.

20. The method of claim 17, comprising:

19. 19. The method of claim 17 or 18, wherein passing air through the photocatalytic reactor comprises passing air through the agitated bed of the photocatalytic composition.

20. Passing the air through a particulate filter to filter solid particulates of the photocatalytic composition discharged from the stirred bed, which is a fluidized bed of the photocatalytic composition.

20. The method of claim 19, further comprising:

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