Titania oxidation catalyst support

Abstract

A method of a preparing a strong metal-support interaction catalyst comprising contacting a titania support material with a transition metal under conditions suitable for the formation of a titania supported transition metal; and calcining the titania supported transition metal to form the strong metal-support interaction catalyst. A method of a preparing a strong metal-support interaction catalyst comprising contacting a titania support material with a transition metal salt under conditions suitable for the formation of a titania supported transition metal; and calcining the titania supported transition metal to form the strong metal-support interaction catalyst.

Description

TITANIA OXIDATION CATALYST SUPPORTCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims benefit of U.S. provisional patent application Serial No 63 / 655,447 filed June 03, 2024 and entitled “TITANIA OXIDATION CATALYST SUPPORT,” which is hereby incorporated herein by reference in its entirety for all purposes.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0002] Not applicable.TECHNICAL FIELD

[0003] The present disclosure relates generally to oxidation catalysts. More particularly, the present disclosure relates to support materials for heterogeneous oxidation catalysts and the corresponding heterogeneous oxidation catalysts.BACKGROUND

[0004] Catalysts are essential to modem society in many fields, such as energy conversion, chemical manufacturing, and environmental remediation. It is estimated that -85% of industrial chemical processes rely on catalysts. Compared to homogeneous catalysts, heterogeneous catalysts are environmentally friendly and sustainable due to the simplicity and versatility of process engineering, easy recovery and reuse, less reactor and plant corrosion problems, and environmentally safe disposal.

[0005] In particular, oxidation catalysis not only play a crucial role in the current chemical industry for the production of key intermediates such as alcohols, epoxides, aldehydes, ketones and organic acids, but also will contribute to the establishment of novel green and sustainable chemical processes. Some well-known highly challenging chemical reactions involve selective oxidation reactions and the aerobic oxidation of alcohols in the liquid phase which have attracted much attention in recent years because of their high significance in green or energy chemistry.

[0006] In heterogeneous catalysis, a support material in addition to providing structural advantages may facilitate the catalytic activity. For example, the catalytic performance can be influenced by properties of the support material surface active sites. For example, a supported transition metal catalyst of the type disclosed herein may displayenhanced catalytic activity through the formation of oxygen vacancies on the support surface. Oxygen vacancies are generally considered defect states that are easily excited, creating more catalytic active sites and enhancing catalytic activity. Strong metal-support interaction (SMSI) can greatly affect the catalytic performance in various reactions. The porosity and the surface area of the support are factors that also influence performance of the catalyst and will determine to some extent the amount of catalytic material employed on the support. Consequently, an ongoing need exists for novel compositions and methods for the preparation of support materials.BRIEF SUMMARY OF THE DISCLOSURE

[0007] Disclosed herein is a method of a preparing a strong metal-support interaction catalyst comprising contacting a titania support material with a transition metal under conditions suitable for the formation of a titania supported transition metal; and calcining the titania supported transition metal to form the strong metal-support interaction catalyst.

[0008] Also disclosed herein is a method of a preparing a strong metal-support interaction catalyst comprising contacting a titania support material with a transition metal salt under conditions suitable for the formation of a titania supported transition metal; and calcining the titania supported transition metal to form the strong metalsupport interaction catalyst. Aspects described herein comprise a combination of features and characteristics intended to address various shortcomings associated with certain prior devices, systems, and methods. The foregoing has outlined rather broadly the features and technical characteristics of the disclosed aspects in order that the detailed description that follows may be better understood. The various characteristics and features described above, as well as others, will be readily apparent to those skilled in the art upon reading the following detailed description, and by referring to the accompanying drawings. It should be appreciated that the conception and the specific aspects disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes as the disclosed aspects. It should also be realized that such equivalent constructions do not depart from the spirit and scope of the principles disclosed herein.DETAILED DESCRIPTION

[0009] The following discussion is directed to various exemplary aspects. However, one of ordinary skill in the art will understand that the examples disclosed herein havebroad application, and that the discussion of any aspect is meant only to be exemplary of that aspect, and not intended to suggest that the scope of the disclosure, including the claims, is limited to that aspect.

[0010] In the following discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to... .” As used herein, the terms “approximately,” “about,” “substantially,” and the like mean within 10% (i.e., plus or minus 10%) of the recited value. Thus, for example, a recited angle of “about 80 degrees” refers to an angle ranging from 72 degrees to 88 degrees.

[0011] Disclosed herein are novel oxidation catalysts comprising (i) a titania support material and (ii) a transition metal. In one or more aspects, the support material comprises titania. Titanium dioxide, also known as titanium(IV) oxide or titania having the chemical formula TiO2. In all three of its main dioxides, titanium exhibits octahedral geometry, being bonded to six oxide anions. The oxides in turn are bonded to three Ti centers. The overall crystal structures of rutile and anatase are tetragonal in symmetry whereas brookite is orthorhombic. The oxygen substructures are all slight distortions of close packing: in rutile, the oxide anions are arranged in distorted hexagonal closepacking, whereas they are close to cubic close-packing in anatase and to "double hexagonal close-packing" for brookite. In one or more aspects, the SMSI-Ti comprises TiC>2. In another aspect, the SMSI-Ti comprises amorphous titania. Herein for simplicity the titanium support is referred to as “titania” and may comprise a titanium- containing compound where the material has a crystal structure of the type disclosed herein.

[0012] In one or more aspects, the SMSI-Ti comprises one or more transition metals. For example, the one or more transition metals are a Group 8 transition metal, a Group 10 transition metal, a Group 11 transition metal or combinations thereof

[0013] In an aspect, the SMSI-Ti comprises one or more transition metals; alternatively 2 or more transition metals. In some aspects, the transition metal is a Group 10 metal. In some aspects, the transition metal is a Group 11 metal. In other aspects, the transition metal is a Group 8 metal. In one or more aspects, the transition metal comprises gold (Au), palladium (Pd), platinum (Pt), iron (Fe) or combinations thereof. Generally, the transition metal can have any positive oxidation state available to the metal atom. In an aspect, the transition metal has an oxidation state of from +2 to +6; additionally or alternatively, from +2 to +4; additionally or alternatively, from +2 to +3additionally or alternatively +2, +3, +4, +5, or +6. In one or more aspects, the transition metal is gold which can assume oxidation states ranging from -3 to +5.

[0014] In a non-limiting aspect, the transition metal is a salt. In one or more aspects, the transition metal salt comprises halides, carboxylates, p-diketonates, or combinations thereof. For example, the transition metal salt may comprise palladium halides, palladium carboxylates, palladium p-diketonates, platinum halides, platinum carboxylates, platinum p-diketonates, iron halides, iron carboxylates, iron p- diketonates, gold halides, gold carboxylates, and gold p-diketonates,

[0015] In or more aspects, the SMSI-Ti has one or more transition metals present in an amount ranging from about 0.1 weight percent (wt.%) to about 20 wt.% based on the total weight of the SMSI-Ti; additionally or alternatively from about 0.5 wt.% to about 15 wt.%; additionally or alternatively from about 1 wt.% to about 10 wt.%; additionally or alternatively from about 1 wt.% to about 5 wt.%; additionally or alternatively About 0.1 wt.%, about 0.25 wt.%, about 0.5 wt.%, about 0.75 wt.%, about 1 wt.%, about 1 .25 wt.%, about 1 .5 wt.%, about 1 .75 wt.%, about 2 wt.%, about 2.25 wt.%, about 2.5 wt.%, about 2.75 wt.%, about 3 wt.%, about 3.25 wt.%, about 3.5 wt.%, about 3.75 wt.%, about 4 wt.%, about 4.25 wt.%, about 4.5 wt.%, about 4.75 wt.%, about 5 wt.%, about 5.25 wt.%, about 5.5 wt.%, about 5.75 wt.%, about 6 wt.%, about 6.25 wt.%, about 6.5 wt.%, about 6.75 wt.%, about 7 wt.%, about 7.25 wt.%, about 7.5 wt.%, about 7.75 wt.%, about 8 wt.%, about 8.25 wt.%, about 8.5 wt.%, about 8.75 wt.%, about 9 wt.%, about 9.25 wt.%, about 9.5 wt.%, about 9.75 wt.%, about 10 wt.%, about 10.25 wt.%, about 10.5 wt.%, about 10.75 wt.%, about 11 wt.%, about 11.25 wt.%, about 11.5 wt.%, about 11.75 wt.%, about 12 wt.%, about 12.25 wt.%, about 12.5 wt.%, about 12.75 wt.%, about 13 wt.%, about 13.25 wt.%, about 13.5 wt.%, about 13.75 wt.%, about 14 wt.%, about 14.25 wt.%, about 14.5 wt.%, about 14.75 wt.%, about 15 wt.%, about 15.25 wt.%, about 15.5 wt.%, about 15.75 wt.%, about 16 wt.%, about 16.25 wt.%, about 16.5 wt.%, about 16.75 wt.%, about 17 wt.%, about 17.25 wt.%, about 17.5 wt.%, about 17.75 wt.%, about 18 wt.%, about 18.25 wt.%, about 18.5 wt.%, about 18.75 wt.%, about 19 wt.%, about 19.25 wt.%, about 19.5 wt.%, about 19.75 wt.%, or about 20 wt.%.

[0016] A titania support material suitable for use in the present disclosure may have a surface area of from about 100 m2 / g to about 1000 m2 / g, additionally or alternatively from about 200 m2 / g to about 900 m2 / g; additionally or alternatively from about 250 m2 / g to about 500 m2 / g; additionally or alternatively about 100 m2 / g, about 125 m2 / g,about 150 m2 / g, about 175 m2 / g, about 200 m2 / g, about 225 m2 / g, about 250 m2 / g, about 275 m2 / g, about 300 m2 / g, about 325 m2 / g, about 350 m2 / g, about 375 m2 / g, about 400 m2 / g g, about 425 m2 / g, about 450 m2 / g, about 475 m2 / g, about 500 m2 / g, about 525 m2 / g, about 550 m2 / g, about 575 m2 / g, about 600 m2 / g, about 625 m2 / g, about 650 m2 / g, about 675 m2 / g, about 700 m2 / g, about 725 m2 / g, about 750 m2 / g, about 775 m2 / g, about 800 m2 / g, about 825 m2 / g, about 850 m2 / g, about 875 m2 / g, about 900 m2 / g, about 925 m2 / g, about 950 m2 / g, about 975 m2 / g, or about 1000 m2 / g.

[0017] In one or more aspects, the titania support material is characterized by a pore volume of from about 0.10 cc / g to about 0.4 cc / g; additionally or alternatively from about 0.10 g / cc to about 0.3 g / cc; additionally or alternatively from about 0.1 g / cc to about 0.25 g / cc; additionally or alternatively about 0.1 g / cc, about 0.12 g / cc, about 0.14 g / cc, about 0.16 g / cc, about 0.18 g / cc, about 0.2 g / cc, about 0.22 g / cc, about 0.24 g / cc, about 0.26 g / cc, about 0.28 g / cc, about 0.3 g / cc, about 0.32 g / cc, about 0.34 g / cc, about 0.36 g / cc, about 0.38 or about 0.4 g / cc.

[0018] In one or more aspects, the titania support material is characterized by a pore size of from about 0.5 nm to about 5 nm; additionally from about 1 nm to about 5 nm; additionally or alternatively from about 2.5 nm to about 5 nm; additionally or alternatively about 0.5 nm, about 0.6 nm, about 0.8 nm, about 1 nm, about 1.2 nm, about 1 .4 nm, about 1 .6 nm, about 1.8 nm, about 2 nm, about 2.2 nm, about 2.4 nm, about 2.6 nm, about 2.8 nm, about 3 nm, about 3.2 nm, about 3.4 nm, about 3.6 nm, about 3.8 nm, about 4 nm, about 4.2 nm, about 4.4 nm, about 4.6 nm, about 4.8 nm, or about 5 nm.

[0019] In one or more aspects, the titanium is mesoporous. Mesoporous TiC>2 can be classified into disordered and ordered structures according to the arrangement of pores in space. For disordered mesoporous TiCh, the pores formed by the accumulation between particles and particles are irregular and not interconnected, and the pore size distribution is wide; whereas, for ordered mesoporous materials, the pores are regularly arranged in space and the pore size distribution is narrow.

[0020] In one or more aspects, a process for the preparation of a SMSI-Ti comprises calcination of the titania support material prior to contacting the support material with the transition metal. In such aspects, the titania support material may be calcined at temperatures ranging from about 200 °F to about 1500 ° F, additionally or alternatively from about 300 ° F to about 10000F; additionally or alternatively from about 500 ° Fto about 700 ° F for a time period of from about 1 hour to about 72 hours, alternatively from about 3 hours to about 24 hours or from about 5 hours to about 12 hours to produce a calcined titania support material. Any calcination disclosed herein may be carried out by exposing materials to the temperatures disclosed herein for the time periods also disclosed herein.

[0021] In one or more aspects, the calcination is carried out in stages. For example, a catalyst of the type disclosed herein may be calcined at 600 °F by exposing the catalyst to a first stage characterized by a first temperature t1. Calcination may continue to second stage characterized by a temperature ramp of 50 °F over a 10 minute period to achieve a second temperature t2, followed by holding the material at t2 for some period of time. A third stage in the calcination may be characterized by another temperature ramp to a third temperature, t3. These stages may be carried out any number of times as needed to reach one or more user and / or process goals.

[0022] In an aspect, a method of forming an SMSI-Ti comprises contacting the calcined titania support material with a transition metal. Contacting of the calcined titania support material with the transition metal may be made using any suitable methodology. Nonlimiting examples of methods for contacting the transition metal and calcined titania support material may include incipient wetness impregnation, chemical vapor deposition, deposition precipitation (DP), reductive deposition, strong electrostatic adsorption (SEA), charge-enhanced dry impregnation (CEDI), and liquidphase reduction. Contacting of the transition metal and calcined titania support results in the formation of a titania supported transition metal.

[0023] In one or more aspects, the titania supported transition metal is subjected to one or more processing techniques to form a precursor SMSI-Ti. For example, the titania supported transition metal may be washed with a fluid to remove undesirable material from the titania supported transition metal. Further examples of processing techniques include thermal treatments to remove any fluid that is contacted with the titania supported transition metal. For example, the titania supported transition metal may be washed one or more times and subsequently thermally treated to remove residual fluid. Herein washing may comprise contacting the titania supported transition metal with sufficient fluid (e.g., aqueous fluid) to fill it material’s pores. In one or more aspects, the titania supported transition metal having been further processed is termed a precursor SMSI-Ti.

[0024] A method of the present disclosure further comprises calcining the precursor SMSI-Ti to form an SMSI-Ti. Calcining as the final step in catalyst preparation can provide numerous benefits. For example, calcining the precursor SMSI-Ti may cure or “set” the actual catalyst material, typically a transition metal, onto the support; ensuring that the catalyst and support are well bonded and also hardens the catalyst to improve its structural integrity. In addition, calcination may also assist in (i) removing impurities that could otherwise poison the catalyst; (ii) aiding in control of surface density; (iii) finalizing the surface area of the support structure; (iv) locking in pore structure; (v) securing crystallization phase; and (vi) activating wetting and spreading.

[0025] In one or more aspects, an SMSI-Ti of the type disclosed herein is used to catalyze the oxidation of a sugar (e.g., glucose) to form one or more sugar oxidation products. In one or more aspects, the SMSI-Ti catalyzes the oxidation of glucose, or subsequent glucose oxidation products. For example, the SMSI-Ti may catalyze the oxidation glucodialdose, 2-keto-D-glucose. In another aspect, a SMSI-Ti catalyzes the oxidation of an alcohol. In alternative aspects, the SMSI-Ti catalyzes the oxidation of an amino alcohol, for example the oxidation of ethanolamine to glycine. In one or more aspects, an SMSI-Ti is utilized in a method for the production of higher value chemicals. For example, glucose may be enzymatically oxidized in the presence of oxygen to form an oxidized glucose product such as D-glucono-5-1 ,5-lactone, glucodialdose or 2-keto-D-glucose. The oxidized glucose product may then be reacted with a catalyst of the type disclosed herein under conditions suitable for the formation of a high value product such as through further oxidation, the introduction of a nitrogensource, amination of the oxidized glucose product, and / or the introduction of a reducing agent and hydrogenation of the oxidized glucose product.ADDITIONAL DISCLOSURE

[0026] The following are additional nonlimiting exemplary aspects of the presently disclosed subject matter.

[0027] A first aspect which is a method of a preparing a strong metal-support interaction catalyst comprising contacting a titania support material with a transition metal under conditions suitable for the formation of a titania supported transition metal and calcining the titania supported transition metal to form the strong metal-support interaction catalyst.

[0028] A second aspect which is the method of the first aspect wherein the titania support comprises titania oxide, amorphous titania, mesoporous titania or combinations thereof.

[0029] A third aspect which is the method of any of the first through second aspects wherein the titania support has a surface area of from about 100 m2 / g to about 1000 m2 / g,

[0030] A fourth aspect which is the method of any of the first through third aspects wherein the titania support has a pore volume of from about 0.10 cc / g to about 0.4 cc / g.

[0031] A fifth aspect which is the method of any of the first through fourth aspects wherein the titania support has a pore volume of from about 0.50 cc / g to about 0.4 cc / g.

[0032] A sixth aspect which is the method of any of the first through fifth aspects wherein the titania support has a pore size of from about 0.5 nm to about 5 nm.

[0033] A seventh aspect which is the method of any of the first through sixth aspects wherein the titania support has a pore size of from about 1 nm to about 5 nm.

[0034] An eighth aspect which is the method of any of the first through seventh aspects wherein the transition metal comprises a Group 10 metal, a Group 11 metal or combinations thereof.

[0035] A ninth aspect which is the method of any of the first through eighth aspects wherein the transition metal comprises gold (Au), palladium (Pd), platinum (Pt), iron (Fe) or combinations thereof.

[0036] A tenth aspect which is the method of any of the first through ninth aspects wherein the transition metal has an oxidation state of from +2 to +6.

[0037] An eleventh aspect which is the method of any of the first through tenth aspects wherein the transition metal comprises a salt comprising halides, carboxylates, 0- diketonates, or combinations thereof.

[0038] A twelfth aspect which is a method of any of the first through eleventh aspects wherein the transition metal comprises palladium halides, palladium carboxylates, palladium 0-diketonates, platinum halides, platinum carboxylates, platinum 0- diketonates, gold halides, gold carboxylates, gold 0-diketonates; iron halides, iron carboxylates, iron 0-diketonate, or combinations thereof.

[0039] A thirteenth aspect which is the method of any of the first through twelfth aspects wherein contacting comprises wetness impregnation, chemical vapordeposition, deposition precipitation (DP), reductive deposition, strong electrostatic adsorption (SEA), charge-enhanced dry impregnation (CEDI), liquid-phase reduction or combinations thereof.

[0040] A fourteenth aspect which is the method of any of the first through thirteenth aspects wherein the one or more transition metals are present in an amount ranging from about 0.1 wt.% to about 20 wt.% based on the total weight of the strong metalsupport interaction catalyst.

[0041] A fifteenth aspect which is a method of a preparing a strong metal-support interaction catalyst comprising contacting a titania support material with a transition metal salt under conditions suitable for the formation of a titania supported transition metal; and calcining the titania supported transition metal to form the strong metalsupport interaction catalyst.

[0042] A sixteenth aspect which is the method of the fifteenth aspect wherein the titania support has a surface area of from about 100 m2 / g to about 1000 m2 / g,

[0043] A seventeenth aspect which is the method of any of the fifteenth through sixteenth aspects wherein the titania support has a pore volume of from about 0.10 cc / g to about 0.4 cc / g.

[0044] An eighteenth aspect which is the method of any of the fifteenth through seventeenth aspects wherein the titania support has a pore size of from about 0.5 nm to about 5 nm.

[0045] A nineteenth aspect which is the method of any of the fifteenth through eighteenth aspects wherein the transition metal comprises gold (Au), palladium (Pd), platinum (Pt), iron (Fe) or combinations thereof.

[0046] A twentieth aspect which is the method of any of the fifteenth through nineteenth aspects wherein contacting comprises wetness impregnation, chemical vapor deposition, deposition precipitation (DP), reductive deposition, strong electrostatic adsorption (SEA), charge-enhanced dry impregnation (CEDI), liquid-phase reduction or combinations thereof.

[0047] The subject matter having been shown and described, modifications thereof can be made by one skilled in the art without departing from the spirit and teachings of the subject matter. The aspects described herein are exemplary only and are not intended to be limiting. Many variations and modifications of the subject matter disclosed herein are possible and are within the scope of the disclosed subject matter. Where numerical ranges or limitations are expressly stated, such express ranges orlimitations should be understood to include iterative ranges or limitations of like magnitude falling within the expressly stated ranges or limitations (e.g., from about 1 to about 10 includes, 2, 3, 4, etc.; greater than 0.10 includes 0.11 , 0.12, 0.13, etc.). Use of the term "optionally" with respect to any element of a claim is intended to mean that the subject element is required, or alternatively, is not required. Both alternatives are intended to be within the scope of the claim. Use of broader terms such as comprises, includes, having, etc. should be understood to provide support for narrower terms such as consisting of, consisting essentially of, comprised substantially of, etc.

[0048] Accordingly, the scope of protection is not limited by the description set out above but is only limited by the claims which follow, that scope including all equivalents of the subject matter of the claims. Each and every claim is incorporated into the specification as an aspect of the present disclosure. Thus, the claims are a further description and are an addition to the aspects of the present invention. The discussion of a reference herein is not an admission that it is prior art to the presently disclosed subject matter, especially any reference that may have a publication date after the priority date of this application. The disclosures of all patents, patent applications, and publications cited herein are hereby incorporated by reference, to the extent that they provide exemplary, procedural or other details supplementary to those set forth herein.

Claims

CLAIMSWhat is claimed is:1 . A method of a preparing a strong metal-support interaction catalyst comprising: contacting a titania support material with a transition metal under conditions suitable for the formation of a titania supported transition metal; and calcining the titania supported transition metal to form the strong metal-support interaction catalyst.

2. The method of claim 1 , wherein the titania support comprises titania oxide, amorphous titania, mesoporous titania or combinations thereof.

3. The method of claim 1 , wherein the titania support has a surface area of from about 100 m2 / g to about 1000 m2 / g.

4. The method of claim 1 , wherein the titania support has a pore volume of from about 0.10 cc / g to about 0.4 cc / g.

5. The method of claim 1 , wherein the titania support has a pore volume of from about 0.50 cc / g to about 0.4 cc / g.

6. The method of claim 1 , wherein the titania support has a pore size of from about 0.5 nm to about 5 nm .

7. The method of claim 1 , wherein the titania support has a pore size of from about 1 nm to about 5 nm.

8. The method of claim 1 , wherein the transition metal comprises a Group 10 metal, a Group 11 metal or combinations thereof.

9. The method of claim 1 , wherein the transition metal comprises gold (Au), palladium (Pd), platinum (Pt), iron (Fe) or combinations thereof.

10. The method of claim 1 , wherein the transition metal has an oxidation state of from +2 to +6.11 . The method of claim 1 , wherein the transition metal comprises a salt comprising halides, carboxylates, p-diketonates, or combinations thereof.

12. The method of claim 1 , wherein the transition metal comprises palladium halides, palladium carboxylates, palladium p-diketonates, platinum halides, platinum carboxylates, platinum p-diketonates, gold halides, gold carboxylates, gold p- diketonates; iron halides, iron carboxylates, iron p-diketonate or combinations thereof.

13. The method of claim 1 , wherein contacting comprises wetness impregnation, chemical vapor deposition, deposition precipitation (DP), reductive deposition, strong electrostatic adsorption (SEA), charge-enhanced dry impregnation (CEDI), liquidphase reduction or combinations thereof.

14. The method of claim 1 , wherein the one or more transition metals are present in an amount ranging from about 0.1 wt.% to about 20 wt.% based on the total weight of the strong metal-support interaction catalyst.

15. A method of a preparing a strong metal-support interaction catalyst comprising: contacting a titania support material with a transition metal salt under conditions suitable for the formation of a titania supported transition metal; and calcining the titania supported transition metal to form the strong metal-support interaction catalyst.

16. The method of claim 15, wherein the titania support has a surface area of from about 100 m2 / g to about 1000 m2 / g.

17. The method of claim 15, wherein the titania support has a pore volume of from about 0.10 cc / g to about 0.4 cc / g.

18. The method of claim 15, wherein the titania support has a pore size of from about 0.5 nm to about 5 nm.

19. The method of claim 15, wherein the transition metal comprises gold (Au), palladium (Pd), platinum (Pt), iron (Fe) or combinations thereof.

20. The method of claim 15, wherein contacting comprises wetness impregnation, chemical vapor deposition, deposition precipitation (DP), reductive deposition, strong electrostatic adsorption (SEA), charge-enhanced dry impregnation (CEDI), liquidphase reduction or combinations thereof.