WO2023122693A1

WO2023122693A1 - Deactivation resistant catalytic materials and method for making the same

Info

Publication number: WO2023122693A1
Application number: PCT/US2022/082181
Authority: WO
Inventors: Ekambaram Sambandan; Mia SHAHZAHAN; Bin Zhang; Shinya Kotake; Yoshie Satomi
Original assignee: Nitto Denko Corporation
Priority date: 2021-12-21
Filing date: 2022-12-21
Publication date: 2023-06-29

Abstract

The present disclosure relates to a deactivation resistant catalytic material for decomposing a volatile organic compound comprising a first catalytic element comprising a first noble metal supported on a conducting material, and a second catalytic element comprising a second noble metal supported on an n-type semiconducting oxide comprising at least one hydroxyl group on a surface of the n-type semiconducting oxide, and a method for making the same.

Description

DEACTIVATION RESISTANT CATALYTIC MATERIALS AND METHOD FOR MAKING THE SAME

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 63/292,384, filed December 21 , 2021 , which is incorporated by reference herein in its entirety.

BACKGROUND

Volatile organic compounds (VOCs) are environmental toxins that may accumulate and pollute food service, transportation, healthcare, and hospitality sectors. Photocatalysts are often utilized to provide decontamination and protection through the application of photocatalytic combustion which results in the removal of these environmental toxins from the air. VOCs are predominantly anthropogenic, organic compounds such as alcohols, aldehydes (e.g., formaldehyde), acetates, aromatics, esters, ketones, alkanes, alkenes, and other compounds comprising carbon, oxygen, hydrogen, and halogens.

Photocatalysts require incident irradiation in the UV or visible region of the spectrum to excite an electron from the valance band to the conduction band of a semiconductor. These photo-induced charge carriers then proceed to form reactive radicals, hydroxyl radicals and super oxide radicals that attack absorbed chemicals on the surface of the material. However, electromagnetic radiation in the form of visible light, UV sources, or even sunlight may not be available in dark areas, such as in ductless fume hoods, or where there is no power supply available for UV sources and, thus, limits the ability to decontaminate surfaces in these areas.

Current photocatalytic materials also have several other limitations. One such limitation is carbonization at the surface of a photocatalyst, which may be responsible for deactivation of the photocatalyst. Another limitation is the high temperature required for a photocatalyst’s efficiency and effectiveness to completely oxidize carbon molecules in VOCs. The dependence on higher temperatures makes catalytic combustion challenging for indoor or closed environments where the treated air exhausted from a photocatalytic combustor is returned at a higher temperature than the ambient and sub-ambient temperatures of the indoor environment. Moreover, photocatalysts ppm may require high concentrations of VOCs above 150 ppm which is not practical in environments where concentrations of VOCs are often much lower than 50.

Thus, there is a need for improved photocatalysts capable of overcoming the limitations of current photocatalysts.

SUMMARY

The catalytic material described herein may be used in the catalytic combustion of VOCs in low temperature and low light conditions. Importantly, the composition of the catalytic material of the present disclosure provides for less deactivation of the catalytic material.

In some embodiments, a deactivation resistant catalytic material for decomposing a VOC may comprise: a first catalytic element comprising a first noble metal loaded on a conducting material; and a second catalytic element comprising a second noble metal loaded on an n-type semiconducting oxide comprising at least one hydroxyl group (OH) on a surface of the n-type semiconducting oxide. In such an embodiment, when the second catalytic element is in proximity to the VOC, the second catalytic element induces the transfer of electron(s) from the VOC and then induces the transfer of the electron(s) from the second catalytic element to the first catalytic element.

In some embodiments, the n-type semiconducting oxide is an MO2 binary metal oxide, wherein MO2 may comprise oxides of Ti, Sn, Zr, Ce, Hf, Mn, Ge, Si, or combinations thereof.

In some embodiments, the n-type semiconducting oxide may comprise TiO2. In one embodiment, the n-type semiconducting oxide may consist of anatase phase TiC>2. In other embodiments, the n-type semiconducting oxide may comprise anatase TiC>2 phase and rutile phase TiC>2, wherein the ratio of the anatase phase to the rutile phase is at least 4:1 .

In various embodiments, the first noble metal comprises Pt, Ag, Pd, Ru, Ir, or a combination thereof, and the second noble metal comprises Pt, Ag, Pd, Ru, Au, Ir, or combinations thereof. In many embodiments, the first noble metal and the second noble metal are the same. In some examples, the first noble metal and the second noble metal are platinum.

In some embodiments, the conducting material comprises activated carbon, cuprous compounds, manganous compounds, stannous compounds, ferrous compounds, chromites, cobaltous compounds, or a combination thereof. In some embodiments, the conducting material is an oxide, wherein the reducible oxide comprises cuprous oxide, manganous oxide, stannous oxide, ferrous oxide, chromous oxide, chromite (ferrous oxide and chromous oxide), cobaltous oxide, or a combination thereof.

In many embodiments, the VOC is formaldehyde. In some embodiments, the concentration of formaldehyde is less than 20 ppm. In one representative embodiment, the catalytic material decomposes the VOC at a temperature less than about 40 -C and greater than about 10 -C. In another embodiment, the catalytic material decomposes the VOC in the absence of a source of light, wherein the intensity of the source of light is less than 0.5 lumens. In another embodiment, the catalytic material decomposes the VOC in the absence of ultraviolet irradiation, wherein the intensity of the ultraviolet irradiation is less than 0.1 mW/cm2.

In many embodiments, the ratio of the weight percent of the first noble metal to the second noble metal is at least 5:1 . In some embodiments, the noble metal wt.% is greater than 0.1 and less than 10.

Some embodiments include a catalytic material comprising a ceramic support material.

In many embodiments, the catalytic material has a deactivation lifetime of at least 900 minutes. In other embodiments, the catalytic material has a deactivation of less than 25% after 900 minutes. Other embodiments include a method for making a deactivation resistant catalytic material, comprising: providing a honeycombed ceramic substrate, and coating a first catalyst element comprising a first noble metal and a conductive substrate and coating a second catalyst element comprising a second noble metal and an n-type semiconducting oxide, wherein the catalytic coatings are in proximity to a volatile organic compound (VOC) and induce the transfer of electron(s) from the VOC. In many embodiments, the catalytic coating may comprise the catalytic material as described above

Some embodiments include a catalytic material made according to the method described above. These and other embodiments are described in greater detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustrating a proposed mechanism for an embodiment of a catalytic material described herein.

FIG. 2 is a graph depicting the zeta potential analysis of an embodiment of a catalytic material.

FIG. 3 is a graph depicting the zeta potential analysis of another embodiment of a catalytic material.

FIG. 4 is a schematic illustrating the preparation of a catalytic material.

DETAILED DESCRIPTION

The present disclosure is related to catalytic materials, and more particularly to deactivation resistant catalytic materials, for degrading environmental toxins under ambient conditions without the use of a light source.

As used herein, when a compound, element, or material is referred to as being “catalytic”, the said compound, element, or material may degrade an environmental pollutant with or without an exposure to a radiation source at ambient or sub-ambient temperatures.

The term “deactivation” as used herein means the loss of catalytic activity, and/or the ability to degrade an environmental pollutant, over time. The term “carbocation” as used herein means a carbon atom of a carbonyl group having an even number of electrons, in which a significant positive charge resides on the carbon atom.

The term “carbonyl group” as used herein means a functional group composed of a carbon atom double-bonded to an oxygen atom.

The term “hydroxyl group” as used herein means a functional group with the chemical formula OH which is composed of one oxygen (O) atom covalently bonded to one hydrogen (H) atom.

The term “bond” or “bonded” as used herein means a chemical bond between two atoms.

The term “volatile organic compound” or “VOC” as used herein means an environmental pollutant or toxin such as, but not limited to, organic compounds such as alcohols, aldehydes, acetates, aromatics, esters, ketones, alkanes, alkenes, and other compounds such as those comprising carbon, oxygen, hydrogen, and halogens.

Use of the term “may” or “may be” should be construed as shorthand for “is” or “is not” or, alternatively, “does” or “does not” or “will” or “will not,” etc. For example, the statement “the n-type semiconducting oxide may comprise TiC>2.” should be interpreted as, for example, “In some embodiments, the n-type semiconducting oxide comprises TiC>2,” or “In some embodiments, the n-type semiconducting oxide does not comprise TiC>2.”

The current disclosure includes a deactivation resistant catalytic material, comprising: a first catalytic element comprising a first noble metal loaded on a conducting material; and a second catalytic element comprising a second noble metal loaded on an n-type semiconducting oxide. The present disclosure also includes the use of the deactivation resistant catalytic material in the removal of VOCs, such as formaldehyde. In some embodiments, the deactivation resistant catalytic material may remove VOCs in a low temperature environment. In some embodiments, the deactivation resistant catalytic material may remove VOCs without light or UV radiation. In other embodiments, the deactivation resistant catalytic material may remove VOCs in a low temperature environment without light or UV radiation. The present disclosure includes a deactivation resistant catalytic material that permits the rapid exchange of electrons and improves the formation of reactive radical species, thereby facilitating the decomposition of VOCs.

In some embodiments, the second catalytic element comprises a second noble metal supported on an n-type semiconducting oxide. When the second catalytic element is in proximity with a VOC, e.g., formaldehyde, it initiates a reaction that results in the formation of reactive radical species. In a preferred embodiment, the n- type semiconducting oxide may comprise TiC>2. In some embodiments, hydroxyl groups may be present on the surface of TiC>2, which after treatment with basic solutions may be present as “-O’ . In some embodiments, the presence of negatively charged hydroxyl groups in proximity to formaldehyde may induce electron movement and transfer from formaldehyde to the second catalytic element. One example of the negative surface of the second catalytic element is illustrated by the negative zeta potential at neutral pH (see FIG. 2).

The electron movement induced by the second catalytic element, then induces the transfer of electron(s) from the second catalytic element to a first catalytic element comprising a first noble metal supported on a conducting material. The negative charge, or excess of electrons, is evidenced by the negative zeta potential at neutral pH as shown in FIG. 3. In some embodiments, the conducting material, such as activated carbon, is selected for its conductive functionality which promotes and/or facilitates the transfer of electrons from the second catalytic element to the first catalytic element. In some embodiments, electrons transfer from the second catalytic element to the first noble metal of the first catalytic element. In some embodiments, the electrons transfer from the second catalytic element to the conducting material of the first catalytic element and then transfer from the conducting material to the first noble metal of the first catalytic element.

In some embodiments, the first noble metal may include platinum. In some examples, the platinum of the first catalytic element generates a reactive radical species, such as a super oxide radical, by donating an electron to molecular oxygen (O2). The super oxide radicals facilitate the decomposition and oxidation of formaldehyde by attacking the carbon atom of the carbonyl group of formaldehyde. Water vapor (H2O) and carbon dioxide (CO2) are the harmless byproducts of the degradation and oxidation of formaldehyde and other VOCs. In some embodiments, the electrons responsible for decomposing formaldehyde may be transferred back to the second catalytic element, then to the first catalytic element, and ultimately to the first noble metal (e.g., platinum) of the first catalytic element, thus completing the catalytic cycle. One example of the catalytic activity principle of the decomposition resistant catalytic material as described herein is illustrated in FIG 1 . As shown in FIG. 1 , the first catalytic element comprises activated carbon as the conducting material, the first noble metal comprises platinum, the second catalytic element comprises MO2 (e.g. TiO2) as the n-type semiconducting oxide, and the second noble metal comprises platinum. In some embodiments, the excess electron in the decomposing formaldehyde molecule is transferred back to the first catalytic element, then to the second catalytic element, and ultimately to the second noble metal (e.g., platinum) of the second catalytic material, thus completing the catalytic cycle. In some embodiments, any of the potential electron transfers between the first catalytic element comprising the first noble metal and the conducting material, second catalytic element comprising the second noble metal and the n-type semiconducting oxide, the oxygen molecule, and the VOC, are each mechanisms which may contribute to the decomposition of VOCs using the deactivation resistant catalytic materials described herein.

In various embodiments, the first noble metal is independently selected from Pt, Ag, Pd, Ru, Ir, their oxides and/or hydroxides or combinations thereof, and the second noble metal is independently selected from Pt, Ag, Pd, Ru, Au, Ir, their oxides and/or hydroxides, or combinations thereof. In some embodiments, the first noble metal and second noble metal may be a transition metal, or a transition metal oxide and/or a transition metal hydroxide. In a preferred embodiment, the first noble metal and second noble metal may be platinum (Pt) or its oxides and/or hydroxides. In some embodiments, the first noble metal and second noble metal may be chosen from different groups of elements including a transition metal and a noble metal or their respective oxides and hydroxides. In a preferred embodiment, the first noble metal and the second noble metal are the same.

In some embodiments, the ratio of the weight percent of the first noble metal to the second noble metal is at least about 5:1 . In another embodiment, the weight ratio of the first noble metal may be about 80 wt.% to about 100 wt.%, about 80-85 wt.%, about 85-90 wt.%, about 90-95 wt.%, about 95-100 wt.%, about 80-90 wt.%, or about any wt.% in a range bounded by any of these values. In some embodiments, the second noble metal may be about 0 wt.% to about 20 wt.%, about 0-5 wt.%, about 5- 10 wt.%, about 10-15 wt.%, about 15-20 wt.%, about 10-20 wt.%, or about any wt.% in a range bounded by any of these values. In some embodiments, the first noble metal of the catalytic material is greater than 0.1 wt.% and less than 10 wt.%.

In some embodiments, the catalytic material may comprise a first catalytic element comprising a first noble metal supported on a conducting material. The conducting material preferably has a combination of relatively high surface area, electric conductivity, tensile strength, and chemical stability. In a preferred embodiment, the conducting material comprises activated carbon. As an embodiment of particular interest, the activated carbon works through a mechanism of adsorption and has a higher catalytic efficiency and improved removal efficiency. In another embodiment, the conducting metal may be a carbon-based material. In some embodiments, the conducting material may comprise activated carbon, Cu¹⁺ (cuprous) compounds, Mn²⁺ (manganous) compounds, Sn²⁺ (stannous) compounds, Fe²⁺ (ferrous) compounds, Cr³⁺ (chromous) compounds, Cr³⁺/Fe²⁺ (chromite) compounds, Co²⁺ (cobaltous) compounds, or a combination thereof. A non-limiting example of a suitable conducting metal may include, but is not limited to, Pt loaded carbon sold by Sigma-Aldrich (St. Louis, MO, USA) or carbon sold under the name Vulcan sold by Fuel Cell Inc. (Danbury, CT, USA). In some embodiments, the conducting material is an oxide that may react as an electron donating (or reducing) agent, wherein the oxide comprises cuprous oxide (CU2O), manganous oxide (MnO), stannous oxide (SnO), ferrous oxide (FeO), chromous oxide (Cr20s), chromite (Cr20s + FeO = FeCr2O4), cobaltous (Co²⁺) compounds, or a combination thereof. These oxides are characterized by their ability to donate electrons, facilitating changes to their oxidation state.

In some embodiments, the catalytic material may comprise a second catalytic element comprising a second noble metal supported on an n-type semiconducting oxide. In some embodiments, the n-type semiconducting oxide is an MO2 binary metal oxide, wherein M comprises Ti, Sn, Zr, Ce, Hf, Mn, Ge, or Si. In some embodiments, the n-type semiconducting oxide is a mixture of MO2 binary metal oxides comprising a combination of Ti, Sn, Zr, Ce, Hf, Mn, Ge, and/or Si oxides. In some embodiments, the n-type semiconducting oxide may be TiC>2, and may comprise an anatase X-ray diffraction (XRD) phase. In some embodiments, the n-type semiconducting oxide may be TiC>2, and may comprise both an anatase XRD phase and a rutile XRD phase. In some embodiments, the anatase phase may be about 2.5% to about 97.5%, about

2.5-5%, about 5-10%, about 10-15%, about 15-20%, about 20-30%, about 30-40%, about 40-50%, about 50-60%, about 60-70%, about 70-80%, about 80-90%, about 90- 95%, about 5-95%, about 10-90%, about 15-85%, about 20-80%, or about 83%, or about a percentage in a range bounded by any of these values. In some embodiments, the rutile phase may be about 2.5% to about 97.5%, about 2.5-5%, about 5-10%, about 10-15%, about 15-20%, about 20-30%, about 30-40%, about 40- 50%, about 50-60%, about 60-70%, about 70-80%, about 80-90%, about 90-95%, about 5-95%, about 10-90%, about 15-85%, about 20-80%, or about 17%, or about a percentage in a range bounded by any of these values. In some embodiments, the n- type semiconducting titanium oxide is about 80% to about 90% anatase phase and about 20% to about 10% rutile phase. In a preferred embodiment, the ratio of the anatase phase to the rutile phase is at least 4:1 . A non-limiting example of a suitable n-type semiconducting oxide may include, but is not limited to, a TiC>2 phase mixture sold under the brand name P25 (83% Anatase TiC>2 + 17% Rutile TiC ) sold by Evonik (Parsippany, NJ, USA).

In some embodiments, the n-type semiconducting oxide of the catalytic material may be doped. In other embodiments, the n-type semiconducting oxide comprises Zn doped MO2 oxides, Nb⁵⁺ doped MO2 oxides, or Ta⁵⁺ doped MO2 oxides. In some embodiments, the dopant concentration may be about 0.0001 wt%, about 0.0001 -0.01 wt%, about 0.01 -0.05, about 0.05-0.10 wt% about 0.1 -1 wt%, about 1 -2.5 wt%, about

2.5-5 wt%, about 5-7.5 wt%, about 7.5-10 wt%, about 10-12.5 wt%, about 12.5-15 wt%, about 15-17.5 wt%, about 17.5-20 wt%, or about 0.01 wt%, about 0.5 wt%, about 0.1 wt%, about 10 wt%, about 12.5 wt%, about 15.0 wt%, about 17.5 wt%, about 20.0 wt% ratio, or about a wt% in a range bounded by any of these values.

Some embodiments include a decomposition resistant catalytic material wherein the second catalytic element is in proximity to the volatile organic compound (VOC) and results in inducing the transfer of at least one electron from a VOC and transfer of the at least one electron from the second catalytic element to the first catalytic element. In some embodiments, the catalytic material in proximity to the VOC results in the transfer of at least one electron from the VOC and transfer of the at least one electron from the second catalytic element to the first catalytic element. In some embodiments, the second catalytic element is in proximity to the VOC when the second catalytic element is less than about 0.1 inches, about 0.1 -0.5 inches, about 0.5-1 inch, about 1 -3 inches, about 3-6 inches, or less than 12 inches from the VOC, or any distance in a range bounded by any of these values. In some embodiments, the second catalytic element is in proximity to the VOC when they are within the same environment, e.g., a room or a building. In another embodiment, the second catalytic element is in proximity to the VOC once the decomposition resistant catalytic material is activated by the VOC .

In some embodiments, the VOC comprises any of alcohols, aldehydes, acetates, aromatics, esters, ketones, alkanes, alkenes, and other compounds comprising carbon, oxygen, hydrogen, halogens, or a combination thereof, or any combination of the foregoing compounds.

In many embodiments, the VOC comprises formaldehyde. The presence of formaldehyde generally occurs within a closed environment. Formaldehyde is often found in gas stoves and open fireplaces and is used in the manufacturing of many household items, such as furniture, glues, paints, and cosmetics. It may be desirable to remove formaldehyde from air based on its inherent toxicity toward human health. For example, when formaldehyde is present in the air at levels exceeding 0.1 ppm, some individuals may experience adverse effects such as burning sensations, watery eyes, coughing, and skin irritation. In some embodiments, the decomposition resistant catalytic material described herein may decompose or oxidize concentrations of formaldehyde of less than 20 ppm.

Any suitable method may be used to evaluate the catalytic activity of the embodiments of the present disclosure and the oxidation of formaldehyde. One example of determining whether a catalytic material may decompose concentrations of formaldehyde over time is by measuring the decrease or percentage loss of formaldehyde concentration (e.g., the difference in the concentration of formaldehyde present relative to the initial formaldehyde concentration) over time. In one embodiment, degradation of formaldehyde is analyzed by injecting a mixture of formaldehyde and methanol gases into a single pass chamber reactor and measuring the concentration of formaldehyde. The injection exposes the formaldehyde to the catalytic material and the oxidation reaction occurs. At 15-minute intervals, gas is collected from the outlet of the chamber reactor for analysis of formaldehyde ppm and methanol ppm. Analysis of the concentration of formaldehyde may be performed by a large-volume injection system, e.g., a gas chromatograph/barrier discharge ionization detector (GC-BID). As evidenced by the results in Table 3 below, the concentration of formaldehyde decreased over time.

Because air being circulated indoors is generally used for respiration, it is desirable to have the temperature of the indoor air to remain relatively consistent, or even constant. Thus, an advantage of the present disclosure may include the ability of the catalytic material to decompose VOCs at or near ambient temperatures (e.g., room temperature). Significant advantages may also be realized by the present disclosure where the costs associated with operating such a catalytic system are reduced because the atmosphere would not need to be heated. In some embodiments, the decomposition resistant catalytic materials described herein may decompose the VOCs at temperatures less than about 40 -C and greater than about 10 -C. In some embodiments, the decomposition resistant catalytic materials described herein decompose the VOCs at about 10-15 -C, about 15-20 -C, about 20- 25 -C, about 25-30 -C, about 30-35 -C, about 20-35 -C, or any temperature in a range bounded by any of these values.

In some embodiment, the catalytic process, or the decomposition of VOCs described herein, may not be limited by environmental factors such as radiation in the electromagnetic spectrum, including ultraviolet light, visible light, and near-infrared light to activate the catalytic material. For example, in some embodiments, the catalytic material may decompose the VOC in the absence of a source of light, wherein the amount of the source of light is less than or equal to about 0.5 lumens, less than or equal to about 0.1 lumens, or about 0 lumens. In another embodiment, the catalytic material decomposes the VOC in the absence of ultraviolet irradiation, wherein the intensity of the ultraviolet irradiation is less than or equal to about 0.5 mW/cm², less than or equal to about 0.1 mW/cm², or less than or equal to about 0 mW/cm².

Any suitable method may be used to evaluate the ability of a catalytic material to withstand deactivation. In some embodiments, the ability of a catalytic material to resist deactivation is measuring the decomposition of VOCs by monitoring the formation of byproducts in real-time with a proton-transfer-reaction mass spectrometer (PTR-MS). In another embodiment, determining formaldehyde degradation by measuring the formation of carbon dioxide (CO2), or percentage increase of the concentration of CO2 (the byproduct of the degradation and oxidation of formaldehyde) is a potential way to determine the catalytic material’s properties with respect to deactivation of the VOC. In some examples, the formation of CO2 (based on the difference in the amount of carbon dioxide formed to initial formaldehyde concentration over time) may be about 0% to about 100%, about 0-10%, about 10-20%, about 20- 30%, about 30-40%, about 40-50%, about 50-60%, about 60-70%, about 70-80%, about 80-90%, about 90-100%, or at least about 65%, at least about 70%, at least about 75%, at least about 80%, or about 83%, or about 84%, or about 85%. A catalytic material may be characterized with respect to its performance in a deactivation test, such as the deactivation of formaldehyde. During the measurements, a mixture of 1 ppm formaldehyde is injected into an single pass chamber reactor with a total flow of 600mL/min. At 15-minute intervals, gas is collected from the outlet of the chamber reactor for measurement of the amount of carbon dioxide. Analysis of the concentration of CO2 may be performed by a large-volume injection system, e.g., a gas chromatograph/barrier discharge ionization detector (GC-BID). The time measurements of the deactivation of formaldehyde and/or formation of CO2, may be from about 1 minute to about 20 hours, about 1 -5 min, about 5-15 min, about 15-30 min, about 30-60 min, about 60-120 min, about 120-240 min, about 2-5 h, about 4-6 h, about 5-10 h, about 10-20 h, or any time period in a range bounded by any of these values. In many embodiments, the catalytic material has a deactivation lifetime of at least about 900 min, at least about 900-1000 min, at least about 1000-1100 min, at least about 1 100-1200 min, or greater than 1200 min. In other embodiments, the catalytic material has a deactivation after 900 min of less than or equal to about 25%, less than or equal to about 20%, less than or equal to about 15%, less than or equal to about 10%, less than or equal to about 5%, or less than or equal to about 1%. The deactivation performance of the catalytic materials described herein, and the formation of CC from formaldehyde, are summarized in Table 3.

Some embodiments may include a ceramic support material, wherein the ceramic support material may include the aforementioned catalytic material.

Many embodiments include a method for making a deactivation resistant catalytic material, the method comprising: providing a honeycombed ceramic substrate, and creating at least one catalytic coating upon the honeycombed ceramic substrate, wherein the catalytic coating in proximity to a VOC results in inducing the transfer of at least one electron from the VOC. In many embodiments, the catalytic coating may comprise any of the catalytic materials described in the present disclosure.

Some embodiments may include a catalytic material made according to the method described above.

Unless otherwise indicated, all numbers expressing quantities of ingredients, properties, such as, molecular weight, reaction conditions, and so forth used in the specifications and embodiments are to be understood as being modified in all instances by the term “about”. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the specification and attached embodiments are approximations that may vary depending upon the desired properties sought to be obtained. At the very least, and not as an attempt to limit the application of the doctrine of equivalents, to the scope of the embodiments, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying conventional and ordinary rounding techniques.

For the processes and/or methods disclosed, the functions performed in the process and methods may be implemented in differing order, as may be indicated by context. Furthermore, the outlined steps and operations are only provided as examples and some of the steps and operations may be optional, combined into fewer steps and operations, or expanded into additional steps and operations. This disclosure may sometimes illustrate different components contained within, or connected with, other different components. Such depicted architectures are merely examples, and many other architectures may be implemented to achieve the same or similar functionality.

The terms used in this disclosure and in the appended embodiment, (e.g., bodies of the appended embodiments) are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including, but not limited to,” the term “having” should be interpreted to “having at least”, the term “includes” should be interpreted as “includes, but not limited to,” etc. in addition, if a specific number of elements is introduced, this may be interpreted to mean at least the recited number, as may be indicated by context (e.g., the bare recitation of “two recitations”, without other modifiers, means at least two recitations or two or more recitations). As used in this disclosure, any disjunctive word and/or phrase presenting two or more alternative terms should be understood to contemplate the possibilities of including one of those terms, either of the terms, or both terms. For example, the phrase “A or B” will be understood to include the possibilities of “A” or “B” or “A and B”. Similarly, the phrase “A and/or B” will be understood to include the possibilities of “A” or “B” or “A and B”.

The terms “a”, “an”, “the”, and similar referents used in the context of describing the present disclosure (especially in the context of the following embodiments) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The use of any and all examples, or representative language (e.g., “such as” or “for example”) provided herein is intended merely to better illustrate the present disclosure and does not pose a limitation on the scope of any embodiments. No language in this specification herein shall be construed as indicating any non-embodied element essential to the practice of the present disclosure.

Groupings of alternative elements or embodiments disclosed herein are not to be construed as limitations. Each group member may be referred to and embodied individually or in any combination with other members of the group or other elements found herein. It is anticipated that one or more members of a group may be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is deemed to contain the group as modified, thus fulfilling the written description of all Markush groups used in the appended embodiments.

Certain embodiments are disclosed herein, including the best mode known to the inventors for carrying out the present disclosure. Of course, variations on these described embodiments, will become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventor expects skilled artisans to employ such variations as appropriate, and the inventors intend for the present disclosure to be practiced otherwise than specifically described herein. Accordingly, the embodiments are permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is contemplated unless otherwise indicated herein or otherwise clearly contradicted by context. In closing, it is to be understood that the embodiments disclosed herein are illustrative of the principles of the embodiments. Therefore, by way of example, but not of limitation, alternative embodiments may be utilized in accordance with the teachings herein. Henceforth, the embodiments are not limited to the embodiments precisely as shown and described herein.

Examples of non-limiting embodiments are disclosed below.

EMBODIMENTS:

Embodiment 1. A deactivation resistant catalytic material for decomposing a volatile organic compound comprising: a first catalytic element comprising a first noble metal supported on a conducting material; and a second catalytic element comprising a second noble metal supported on an n-type semiconducting oxide, the n-type semiconducting oxide comprising at least one hydroxyl group on a surface of the n-type semiconducting oxide, wherein the second catalytic element in proximity to the volatile organic compound results in inducement of at least one electron from the volatile organic compound and transfer of the at least one electron from the second catalytic element to the first catalytic element.

Embodiment 2. The catalytic material of embodiment 1 , wherein the n-type semiconducting oxide is a MO2 binary metal oxide.

Embodiment 3. The catalytic material of embodiment 2, wherein M is independently selected from Ti, Sn, Zr, Ce, Hf, Mn, Ge, Si, or combinations thereof.

Embodiment 4. The catalytic material of embodiment 1 , wherein the n-type semiconducting oxide consists of a anatase XRD phase.

Embodiment 5. The catalytic material of embodiment 1 , wherein the n-type semiconducting oxide comprises a anatase XRD phase and a rutile XRD phase, wherein the ratio of the anatase to the rutile is at least 4:1 .

Embodiment 6. The catalytic material of embodiment 1 , wherein the first noble metal is independently selected from Pt, Ag, Pd, Ru, Ir, or combinations thereof, and wherein the second noble metal is independently selected from Pt, Ag, Pd, Ru, Au, Ir, or combinations thereof.

Embodiment 7. The catalytic material of embodiment 6, wherein the first noble metal and the second noble metal are the same.

Embodiment 8. The catalytic material of embodiment 1 , wherein the conducting material is independently selected from carbon, cuprous, manganous, stannous, ferrous, chromites, cobaltous, or combinations thereof.

Embodiment 9. The catalytic material of embodiment 1 , wherein the volatile organic compound comprises formaldehyde. Embodiment 10. The catalytic material of embodiment 9, wherein the concentration of formaldehyde is less than 20 ppm.

Embodiment 11. The catalytic material of embodiment 1 , wherein the catalytic material decomposes the volatile organic compound at a temperature less than 40 ^QC and greater than 10 ^QC.

Embodiment 12. The catalytic material of embodiment 1 , wherein the catalytic material decomposes the volatile organic compound in the absence of a source of light, wherein the amount of the source of light is less than 0.5 lumens.

Embodiment 13. The catalytic material of embodiment 1 , wherein the catalytic material decomposes the volatile organic compound in the absence of ultraviolet irradiation, wherein the intensity of the ultraviolet irradiation is less than 0.1 mW/cm².

Embodiment 14. The catalytic material of embodiment 1 , wherein the ratio of the weight percent of the first noble metal to the second noble metal is at least 5:1 .

Embodiment 15. The catalytic material of embodiment 1 , wherein the noble metal wt.% is greater than 0.1 and less than 10.

Embodiment 16. The catalytic material of embodiment 1 , further comprising a ceramic support material.

Embodiment 17. The catalytic material of embodiment 1 , wherein the n-type semiconducting oxide comprises a Nb⁵⁺ doped MO2 oxide or Ta⁵⁺ doped MO2 oxide.

Embodiment 18. The catalytic material of embodiment 1 , wherein the catalytic material has a deactivation of less than 25% after 900 minutes.

Embodiment 19. A method of making a deactivation resistant catalytic material comprising: providing a honeycombed ceramic substrate; and creating at least one catalytic coating upon the ceramic substrate, wherein the catalytic coating in proximity to a volatile organic compound results in inducement of at least one electron from the volatile organic compound.

Embodiment 20. The method of embodiment 19, wherein the at least one catalytic coating comprises the catalytic material as in embodiments 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 , 12, 13, 14, 15, 16, 17, or 18.

Embodiment 21. A deactivation resistant catalytic material made according to embodiments 19 or 20. EXAMPLES

It has been discovered that embodiments of the catalytic material described herein have improved performance as compared to other compositions of catalytic material for decomposing a VOC. These benefits are further demonstrated by the following examples, which are intended to be illustrative of the disclosure but are not intended to limit the scope or underlying principles in any way.

The following examples are synthesis procedures of some embodiments of the catalytic material as described herein:

Synthesis Procedure

Example 1. Synthesis of 2.7%Pt loaded on 1-3wt.% Zn doped TiO2: About 0.224g Pt(NH₃)4(NO₃)2 was dissolved in 80g of type 1 filtered water (e.g., water filtered by a Mill iQ® water purification system). About 4.19g of 1 -3wt.% Zn doped TiC>2 powder was added to a 60mL plastic container. To the plastic container, 80g aqueous solution of Pt(NH₃)4(NO₃)2 was added to the Zn doped TiC>2 powder and was mixed homogeneously in a mixer, such as a Thinky™ Mixer, for 5min at 2000 RPM. Then, the slurry was transferred to a 250mL round bottom flask (two necks) and was stirred at 700 RPM at room temperature for 30 minutes. In a separate 20mL glass vial, 2g of basic solution of NaBH4 was dissolved in 10g of type 1 water. The aqueous basic solution of NaBH4 was added drop by drop for about 5 minutes to the slurry in the round bottom flask. Then, it was stirred for another 30min at 700 RPM to complete the loading of Pt on the surface of the Zn doped TiC>2. Then, it was transferred to centrifuge tubes and was centrifuged at 4000 RPM for about 5min to separate the solid. The solid was dried at 120 -C overnight to provide 2.7% Pt loaded on 1 -3wt % Zn doped TiC>2.

Table 1 summarizes various supports used for loading Pt wt. % ratio. The examples of Table 1 are simply to provide illustrations of some embodiments of the present disclosure and are in no-way limiting.

Table 1

Example 2: 2.7%Pt/P25 Benchmark Comparative Example Step 1 : Synthesis of reduced-P25:

4.0 g of P25(TiC>2) was dispersed in 100 mL of MilliQ® water using ultrasonic bath sonication for 1 min and stirring for 30 min. In this dispersion, a mixture of 0.208g of NaBH4 in 5 mL water and 0.22g of NaOH in 5 mL was added dropwise. The reaction was carried out for 30 min. After NaBH4 treatment, the reduced-P25 was washed with MilliQ® water 2 times to remove access NaBH4 and the product was collected using centrifugation.

Step 2: Synthesis of 2.65%Pt/reduced-P25:

The reduced-P25 was redispersed in 100 mL of water and the dispersion was transferred to a 250 mL beaker. After 30 mins vigorous stirring, 2.65 wt% Pt ions were added to the solution. The stirring was continued for another 60 mins to impregnate the Pt on reduced TiO2 surface. The surface Pt-ions were reduced using 10 mL (0.1 mole/L) NaBH4 and 10 mL (0.5 mole/L) NaOH mixture. After 1 h, the solid Pt-Na, B/ Anatase TiO2 were separated using centrifugation and washed with water to remove the unreacted Pt ions and NaBH4. The inorganic powder sample was dried at 105 -C for 2 h.

Step 3: Preparation of (2.65%Pt/reduced-P25+ST01 ,80:20) composite and filter:

120.0 mg of 2.65%Pt/reduced-P25 was redispersed in MilliQ® water using probe sonication at 50% intensity for 10 min and mixed with 30.0 mg of ST01 (TiO2) to prepare a slurry solution of 3-5 wt% in MilliQ® water. The slurry was used to coat a 1cmx1 cm ceramic filter. The total solid content on the ceramic filter was 5.5±0.5 mg. The filter was used in the chamber reactor for formaldehyde decomposition.

Example 3. Making aqueous slurry of physical mixture of 3%Pt/activated carbon and 2.7%Pt,xNa/MO2:

General Procedure:

i Add about 8.5g water to the physical

t 2000rpm

Example 4. Making aqueous slurry of catalyst for dip coating process: About 0.225g of 2.7%Pt,xNa/MO2 was weighed in 20mL glass vial. To this, about 1.275g of 3%Pt/activated carbon was added. The physical mixture of these two components were mixed by acoustic mixer. The input values are 40% amplitude for 5 minutes. The output value was 46% GS. To this physical mixture of two components about 8.5g of type 1 water filtered by a Mill iQ® water purification system was added. Then, homogeneous slurry of the physical mixture was made by Thinky™ Mixer followed by probe sonication. Conditions for Thinky™ Mixer were 2000rpm for about 5 minutes. The conditions for probe sonication were 55% amplitude for 30min and output result was about 20000 joules. Then, the homogeneous slurry of physical mixture was ready for dip coating process.

Table 2 is a summary of some example homogenous aqueous physical mixtures made for dip coating process. The examples of Table 2 are simply to provide illustrations of some embodiments of the present disclosure and are in no-way limiting.

Table 2

Filter making process by dip coating method: Aqueous slurry made was used for coating the powder on 1 *1 cm honeycomb ceramic filter. After every dip coating the filter was dried at 150 -C for about 30min. This process was repeated for loading of about 5mg of powder coated on 1 *1 cm honeycomb ceramic filter. FIG. 4 outlines one example of a process of dip coating of a filter making for evaluation study.

Single pass evaluation method: Evaluation of catalysts were carried out using an in-house built single pass evaluation chamber reactor with total flow of 600mL/min with about mixture of 1 ppm formaldehyde and 33 ppm methanol gases. Every 15 minutes, gas is collected from the outlet of the evaluation chamber reactor for automatic injection to GO-BID for analysis of formaldehyde ppm and CO2 ppm and methanol ppm. Table 3 below summarizes the results using the formulae used for decomposition of formaldehyde ppm and formation of CO2 ppm in presence of methanol ppm. The results of Table 3 are examples and are in no-way limiting. % Performance

Initial HCHO ppm - HCHO ppm in 900min *100

Initial HCHO ppm

% Deactivation

CO2 ppm in 120min-CO2ppm 900min *100

Initial HCHO ppm

Evaluation Results

Table 3

Claims

CLAIMS What is claimed is:

1 . A deactivation resistant catalytic material for decomposing a volatile organic compound (VOC) comprising: a first catalytic element comprising a first noble metal loaded on a conducting material; and a second catalytic element comprising a second noble metal loaded on an n- type semiconducting oxide, wherein the n-type semiconducting oxide comprises at least one hydroxyl group on a surface of the n-type semiconducting oxide; wherein the second catalytic element is in proximity to the VOC and induces transfer of at least one electron from the VOC to the second catalytic element, and wherein the second catalytic element induces transfer of at least one electron from the second catalytic element to the first catalytic element.

2. The deactivation resistant catalytic material of claim 1 , wherein the n-type semiconducting oxide is a binary metal oxide.

3. The deactivation resistant catalytic material of claim 2, wherein the binary metal oxide comprises Ti, Sn, Zr, Ce, Hf, Mn, Ge, Si, or a combination thereof.

4. The deactivation resistant catalytic material of claim 1 , 2, or 3, wherein the n- type semiconducting oxide comprises anatase phase TiC>2.

5. The deactivation resistant catalytic material of claim 1 , 2, or 3, wherein the n- type semiconducting oxide comprises anatase phase TiC and rutile phase TiC , and wherein the ratio of the anatase phase to the rutile phase is at least 4:1 .

6. The deactivation resistant catalytic material of claim 1 , wherein the first noble metal comprises Pt, Ag, Pd, Ru, Ir, or a combination thereof, and wherein the second noble metal comprises Pt, Ag, Pd, Ru, Au, Ir, or a combination thereof.

7. The deactivation resistant catalytic material of claim 6, wherein the first noble metal and the second noble metal are the same.

8. The deactivation resistant catalytic material of claim 7, wherein the first noble metal and the second noble metal are platinum.

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9. The deactivation resistant catalytic material of claim 1 , wherein the conducting material of the first catalytic element comprises activated carbon, Cu¹⁺ (cuprous) compounds, Mn²⁺ (manganous) compounds, Sn²⁺ (stannous) compounds, Fe²⁺ (ferrous) compounds, Cr³⁺ (chromous) compounds, Cr³⁺/Fe²⁺ (chromite) compounds, Co²⁺ (cobaltous) compounds, or a combination thereof.

10. The deactivation resistant catalytic material of claim 9, wherein the conducting material of the first catalytic element comprises activated carbon.

11 . The deactivation resistant catalytic material of claim 1 , wherein the VOC is formaldehyde.

12. The deactivation resistant catalytic material of claim 11 , wherein the concentration of formaldehyde is less than about 20 ppm.

13. The deactivation resistant catalytic material of claim 1 , wherein the catalytic material decomposes the VOC at a temperature between about 10 -C and about 40 C.

14. The deactivation resistant catalytic material of claim 1 , wherein the catalytic material decomposes the VOC in the absence of a source of light, wherein the intensity of the source of light is less than about 0.5 lumens.

15. The deactivation resistant catalytic material of claim 1 , wherein the catalytic material decomposes the VOC in the absence of ultraviolet irradiation, wherein the intensity of the ultraviolet irradiation is less than about 0.1 mW/cm².

16. The deactivation resistant catalytic material of claim 1 , wherein the ratio of the weight percent of the first noble metal to the second noble metal is at least about 5:1 .

17. The deactivation resistant catalytic material of claim 1 , wherein the noble metal wt.% is greater than about 0.1 and less than about 10.

18. The deactivation resistant catalytic material of claim 1 , wherein the noble metal wt.% is about 2.7 wt.%.

19. The deactivation resistant catalytic material of claim 1 , further comprising a ceramic support material.

20. The deactivation resistant catalytic material of claim 1 , wherein the deactivation resistant catalytic material has a deactivation of less than about 25% after 900 minutes.

21 . A method of making a deactivation resistant catalytic material comprising: providing a honeycombed ceramic substrate; coating upon the ceramic substrate: a first catalytic element comprising a first noble metal and a conducting material; and a second catalytic element comprising a second noble metal and an n-type semiconducting oxide, wherein the first catalytic element and the second catalytic element are in proximity to a volatile organic compound (VOC) and result in inducing at least one electron from the VOC.

22. The method of claim 21 , wherein the first catalytic element and the second catalytic element comprise the deactivation resistant catalytic material of claim 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 , 12, 13, 14, 15, 16, 17, 18, or 19.