WO2026006015A1 - Oxygen carrier materials that include iron and silicon, and methods of making the same - Google Patents

Abstract

An oxygen carrier material may include a first composition. At least 95 wt.% of the first composition may consist of 1 part by mole iron, from 0.001 parts by mole to 0.15 parts by mole of one or more alkali metals, from 0.001 parts by mole to 0.08 parts by mole of tungsten, from 0.05 parts by mole to 10 parts by mole of silicon, and from 1.6 parts by mole to 22 parts by mole of oxygen.

Description

OXYGEN CARRIER MATERIALS THAT INCLUDE IRON AND SILICON, AND METHODS OF MAKING THE SAME

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application Serial No. 63/664,323 filed June 26, 2024, the contents of which are incorporated in their entirety herein.

TECHNICAL FIELD

[0002] Embodiments of the present disclosure generally relate to chemical processing and, in particular, to oxygen carrier materials utilized in chemical processing.

BACKGROUND

[0003] Some chemical processes that use oxygen as a reactant utilize oxygen carrier materials. Oxygen may be delivered or “carried” in a cycle via a reduction and subsequent oxidation of the oxygen carrier material. In such processes, the oxygen carried by the oxygen carrier material may be used as the source of oxygen. In particular, oxygen carrier materials may be utilized in cyclical chemical processes where oxygen may be added to and removed from the oxygen carrier material as it is used throughout the entire process. Such materials may be utilized in a wide variety of chemical processing methods.

SUMMARY

[0004] As such, there is a continued need for oxygen carrier materials that are suitable for use with chemical processes. Described herein are particular oxygen carrier materials that include at least iron, one or more alkali metals, tungsten, silicon, and oxygen, in particular amounts relative to one another. It has been found that the oxygen carrier materials described herein, according to one or more embodiments, may have relatively high selectivity for combusting hydrogen gas over combusting hydrocarbons. Such oxygen carrier materials may be utilized in processes that form olefinic compounds, among other contemplated uses, as described in detail herein.

[0005] According to one or more embodiments of the present disclosure, an oxygen carrier material may comprise a first composition. At least 95 wt.% of the first composition may consist of 1 part by mole iron, from 0.001 parts by mole to 0.15 parts by mole of one or more alkali metals, from 0.001 parts by mole to 0.08 parts by mole of tungsten, from 0.05 parts by mole to 10 parts by mole of silicon, and from 1.6 parts by mole to 22 parts by mole of oxygen.

[0006] Additional features and advantages of the present disclosure will be set forth in the detailed description, which follows, and in part will be apparent to those skilled in the art from that description or recognized by practicing the embodiments described herein, including the detailed description, which follows the claims, as well as the appended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The following detailed description of specific embodiments of the present disclosure can be best understood when read in conjunction with the following drawing, where like structure is indicated with like reference numerals and in which:

[0008] FIG. 1 is a schematic depiction of a reactor system suitable for use with an oxygen carrier material, according to one or more embodiments described herein.

[0009] Additional features and advantages of the present disclosure will be set forth in the detailed description, which follows, and in part will be apparent to those skilled in the art from that description or recognized by practicing the embodiments described herein, including the detailed description, which follows the claims, as well as the appended drawings.

[0010] It is to be understood that both the foregoing general description and the following detailed description describe various embodiments and are intended to provide an overview or framework for understanding the nature and character of the claimed subject matter. The accompanying drawings are included to provide a further understanding of the various embodiments and are incorporated into and constitute a part of this specification. The drawings illustrate the various embodiments described herein, and together with the description, explain the principles and operations of the claimed subject matter. DETAILED DESCRIPTION

[0011] Specific embodiments of the present application will now be described. The technical aspects of the present application may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth in this detailed description.

[0012] Generally, described in this disclosure are various embodiments of oxygen carrier materials. As described herein, the oxygen carrier materials may comprise a first composition and, optionally, one or more additional materials. In one or more embodiments, the first composition may comprise or consist of active materials, which are materials that, in general, contribute to the oxygen carrying functionality and/or the selectivity for hydrogen combustion of the oxygen carrier materials described herein. In general, in the embodiments described herein, at least 95 wt.% of the first composition may consist of iron (Fe), one or more alkali metals, tungsten (W), silicon (Si), and oxygen (O), in amounts defined by particular ratios between these various components.

[0013] In embodiments, the oxygen carrier material, in addition to the first composition, may further comprise one or more additional materials. In some embodiments, the one or more additional materials may function as binders in the oxygen carrier materials. In some embodiments, the binders may not substantially contribute to the oxygen carrying and/or catalytic functionality of the oxygen carrier materials. Binders may generally enhance the physical properties of the oxygen carrier material. According to embodiments, the one or more additional materials may be chosen from oxides of aluminum, calcium, magnesium, zirconium, boron, phosphorus, sulfur or combinations thereof. In general, the additional material or materials may not include elements that are present in the first composition, aside from oxygen. It is contemplated that mixtures of various oxides of an element may be included in the one or more additional materials. Without limitation, in one or more embodiments, additional materials may be chosen from those disclosed in "Progress in Chemical-Looping Combustion and Reforming technologies" Progress in Energy and Combustion Science 38 (2012) 215-282 and "Chemical Looping Systems for Fossil Energy Conversions", Liang-Shih Fan, published by WILEY 2010. For example, in certain embodiments, suitable additional materials that may act as binders include, without limitation, alumina (alpha, theta, or gamma crystal phases), CaAl_xO_y, MgAbC , zirconia, inorganic clays (e.g, kaolin, other alumina-silicates), and glass materials (such as glass fibers). [0014] According to one or more embodiments, the oxygen carrier material may comprise at least 75 wt.%, at least 80 wt.%, at least 85 wt.%, at least 90 wt.%, at least 95 wt.%, at least 99 wt.%, at least 99.5 wt.%, at least 99.9 wt.%, or may consist of the combination of the first composition and the one or more additional materials. For example, the oxygen carrier material may consist of the combination of the first composition and the one or more additional materials, where the one or more additional materials may act as binders and fill the balance of the oxygen carrier material that is not part of the first composition.

[0015] In one or more embodiments, the oxygen carrier material may comprise the first composition in an amount of from 1 wt.% to 5 wt.%, from 5 wt.% to 10 wt.%, from 10 wt.% to 15 wt.%, from 15 wt.% to 20 wt.%, from 20 wt.% to 25 wt.%, from 25 wt.% to 30 wt.%, from 30 wt.% to 35 wt.%, from 35 wt.% to 40 wt.%, from 40 wt.% to 45 wt.%, from 45 wt.% to 50 wt.%, from 50 wt.% to 55 wt.%, from 55 wt.% to 60 wt.%, from 60 wt.% to 65 wt.%, from 65 wt.% to 70 wt.%, from 70 wt.% to 75 wt.%, from 75 wt.% to 80 wt.%, from 80 wt.% to 85 wt.%, from 85 wt.% to 90 wt.%, from 90 wt.% to 95 wt.%, from 95 wt.% to 100 wt.%, or any combination of one or more of these ranges. For example, the oxygen carrier material may comprise the first composition in an amount greater than or equal to 95 wt.%. In some embodiments, the oxygen carrier material may comprise at least 5 wt.%, at least 10 wt.%, at least 15 wt.%, at least 20 wt.%, at least 25 wt.%, at least 30 wt.%, at least 35 wt.%, at least 40 wt.%, at least 45 wt.%, at least 50 wt.%, at least 55 wt.%, at least 60 wt.%, at least 65 wt.%, at least 70 wt.%, at least 75 wt.%, at least 80 wt.%, at least 85 wt.%, at least 90 wt.%, or even at least 95 wt.% of the first composition. In some embodiments, the oxygen carrier material may comprise the first composition in an amount of greater than or equal to 96 wt.%, greater than or equal to 97 wt.%, greater than or equal to 98 wt.%, greater than or equal to 99 wt.%, greater than or equal to 99.5 wt.%, or greater than or equal to 99.9 wt.%. In some embodiments, the oxygen carrier material may consist of the first composition.

[0016] In additional embodiments, the oxygen carrier material may comprise the one or more additional materials. In some embodiments, the one or more additional materials may function as binders. According to some embodiments, the oxygen carrier material may comprise less than or equal to 5 wt.% of the one or more additional materials. For example, the one or more additional materials may be present in the oxygen carrier material in an amount of less than or equal to 4.5 wt.%, less than or equal to 4 wt.%, less than or equal to 3.5 wt.%, less than or equal to 3 wt.%, less than or equal to 2.5 wt.%, less than or equal to 2 wt.%, less than or equal to 1.5 wt.%, less than or equal to 1 wt.%, or even less than or equal to 0.5 wt.%. In some embodiments, the one or more additional materials may be present in the oxygen carrier material in an amount of from 1 wt.% to 5 wt.%, from 1 wt.% to 4 wt.%, from 1 wt.% to 3 wt.%, from 1 wt.% to 2 wt.%, from 2 wt.% to 5 wt.%, from 3 wt.% to 5 wt.%, from 4 wt.% to 5 wt.%, or any combinations of these ranges. Without being bound by any particular theory, it is believed that the presence of the one or more additional materials may increase the physical strength and attrition of the oxygen carrier material.

[0017] As described herein, the relative amounts of the materials of the first composition are described in terms of relative amounts of atoms of each element that are included in the first composition. Also, as described herein, the components of the oxygen carrier material may be described in amounts relative to other components. For example, described herein are components represented in amounts described as “parts by mole.” Parts by mole, as used herein, describes the molar ratio of one component with another, and does not restrict the total number or moles of a particular substituent. For example, iron may be present in an amount of 1 part by mole, and oxygen may be present in an amount of from 1.6 parts by mole to 22 parts by mole, which means all compositions that meet this ratio of iron atoms to oxygen atoms fall within embodiments described herein regardless of the raw amount of these constituents. In general, and unless stated otherwise, where multiple elements or other materials are listed together as being in a specific amount, this refers to the total of the combination of all of these elements or other materials, even when not explicitly stating that the “sums” of these elements or the “combination” of these elements is in the amount specified. For example, when “one or more alkali metals” are listed in an amount, the amount refers to the combination of all alkali metals.

[0018] Now turning to the first composition of the oxygen carrier material, in one or more embodiments, 95 wt.% of the first composition may consist of iron; one or more alkali metals; tungsten; silicon; and oxygen. For example, at least 96 wt.%, at least 97 wt.%, at least 98 wt.%, at least 99 wt.%, at least 99.5 wt.%, or at least 99.9 wt.% of the first composition may consist of iron; one or more alkali metals; tungsten; silicon; and oxygen. In some embodiments, the first composition may consist of iron; one or more alkali metals; tungsten; silicon; and oxygen. [0019] In one or more embodiments, iron may be present in the first composition, where iron is present in the first composition in a relative amount of 1 part by mole. The amounts of the other constituents are generally compared to the 1 part by mole of iron. Without being bound by any particular theory, it is believed that iron may work as the major constituent that binds and unbinds from oxygen in redox reactions by changing its oxidation state.

[0020] In one or more embodiments, one or more alkali metals may be present in the first composition, where the one or more alkali metals may be present in the first composition in a relative amount of from 0.001 parts by mole to 0.15 parts by mole. Without being bound by any particular theory, it is believed that the presence of this amount of alkali metals may improve selectivity to hydrogen combustion over combustion of hydrocarbons. Further, it is believed that oxygen carrier materials with a relatively low amount of alkali metals (i.e., less than 0.15 parts by mole), as compared to conventional oxygen carrier materials, may be advantageous in the processes and systems described herein, and particularly advantageous in processes utilizing circulating fluidized beds. It is believed that an alkali metal content of less than 0.15 parts by mole may reduce the risk associated with agglomeration of particles and alkali migration in the presence of alkali compounds with low melting points.

[0021] According to embodiments, the one or more alkali metals may be chosen from lithium, sodium, and potassium, where the combination of lithium, sodium, and potassium is in a relative amount of from 0.001 parts by mole to 0.15 parts by mole. In some embodiments, lithium is present in the first composition but sodium and potassium are not. In additional embodiments, sodium is present in the first composition but lithium and potassium are not. In additional embodiments, potassium is present in the first composition but sodium and lithium are not. In some yet additional embodiments, lithium and sodium are present in the first composition and potassium is not, sodium and potassium are present in the first composition at lithium is not, or potassium and lithium are present in the first composition and sodium is not. In some embodiments, lithium, sodium, and potassium are present in the first composition.

[0022] In some embodiments, the one or more alkali metals may be present in the first composition in a relative amount of less than or equal to 0.15 parts by mole and at least 0.01 parts by mole, at least 0.01 parts by mole, at least 0.02 parts by mole, at least 0.03 parts by mole, at least 0.04 parts by mole, at least 0.05 parts by mole, at least 0.06 parts by mole, at least 0.07 parts by mole, at least O.O8 parts by mole, at least 0.09 parts by mole, at least 0.1 parts by mole, at least 0.11 parts by mole, at least 0.12 parts by mole, at least 0.13 parts by mole, or at least 0.14 parts by mole.

[0023] In additional embodiments, the one or more alkali metals may be present in the first composition in a relative amount of at least 0.001 parts by mole and less than or equal to 0.14 parts by mole, less than or equal to 0.13 parts by mole, less than or equal to 0.12 parts by mole, less than or equal to 0.11 parts by mole, less than or equal to 0.1 parts by mole, less than or equal to 0.09 parts by mole, less than or equal to 0.08 parts by mole, less than or equal to 0.07 parts by mole, less than or equal to 0.06 parts by mole, less than or equal to 0.05 parts by mole, less than or equal to 0.04 parts by mole, less than or equal to 0.03 parts by mole, less than or equal to 0.02 parts by mole, or less than or equal to 0.01 parts by mole.

[0024] In additional embodiments, the one or more alkali metals may be present in the first composition in a relative amount of from 0.001 parts by mole to 0.005 parts by mole, from 0.005 parts by mole to 0.01 parts by mole, from 0.01 parts by mole to 0.02 parts by mole, from 0.02 parts by mole to 0.03 parts by mole, from 0.03 parts by mole to 0.04 parts by mole, from 0.04 parts by mole to 0.05 parts by mole, from 0.05 parts by mole to 0.06 parts by mole, from 0.06 parts by mole to 0.07 parts by mole, from 0.07 parts by mole to 0.08 parts by mole, from 0.08 parts by mole to 0.09 parts by mole, from 0.09 parts by mole to 0.1 parts by mole, from 0.1 parts by mole to 0.11 parts by mole, from 0.11 parts by mole to 0.12 parts by mole, from 0.12 parts by mole to 0.13 parts by mole, from 0.13 parts by mole to 0.14 parts by mole, from 0.14 parts by mole to 0.15 parts by mole, or any combination of one or more of these ranges.

[0025] In one or more embodiments, tungsten may be present in the first composition, where the tungsten may be present in the first composition in a relative amount of 0.001 parts by mole to 0.08 parts by mole. In some embodiments, tungsten may be present in the first composition in a relative amount of 0.007 parts by mole to 0.08 parts by mole. Without being bound by theory, it is believed that the presence of tungsten in this amount may regulated the oxygen release from iron, which may suppress the oxidation of hydrocarbons.

[0026] In some embodiments, tungsten may be present in the first composition in a relative amount of less than or equal to 0.08 parts by mole and at least 0.005 parts by mole, at least 0.01 parts by mole, at least 0.015 parts by mole, at least 0.02 parts by mole, at least 0.025 parts by mole, at least O.O3 parts by mole, at least 0.035 parts by mole, at least 0.04 parts by mole, at least 0.045 parts by mole, at least 0.05 parts by mole, at least 0.055 parts by mole, at least 0.06 parts by mole, at least 0.065 parts by mole, at least 0.07 parts by mole, or at least 0.075 parts by mole.

[0027] In additional embodiments, tungsten may be present in the first composition in a relative amount of at least 0.001 parts by mole and less than or equal to 0.075 parts by mole, less than or equal to 0.07 parts by mole, less than or equal to 0.065 parts by mole, less than or equal to 0.06 parts by mole, less than or equal to 0.055 parts by mole, less than or equal to 0.05 parts by mole, less than or equal to 0.045 parts by mole, less than or equal to 0.04 parts by mole, less than or equal to 0.035 parts by mole, less than or equal to 0.03 parts by mole, less than or equal to 0.025 parts by mole, less than or equal to 0.02 parts by mole, less than or equal to 0.015 parts by mole, less than or equal to 0.01 parts by mole, or less than or equal to 0.005 parts by mole.

[0028] In additional embodiments, tungsten may be present in the first composition in a relative amount of from 0.001 parts by mole to 0.005 parts by mole, from 0.005 parts by mole to 0.01 parts by mole, from 0.01 parts by mole to 0.015 parts by mole, from 0.015 parts by mole to

0.02 parts by mole, from 0.02 parts by mole to 0.025 parts by mole, from 0.025 parts by mole to

0.03 parts by mole, from 0.03 parts by mole to 0.035 parts by mole, from 0.035 parts by mole to

0.04 parts by mole, from 0.04 parts by mole to 0.045 parts by mole, from 0.045 parts by mole to

0.05 parts by mole, from 0.05 parts by mole to 0.055 parts by mole, from 0.055 parts by mole to

0.06 parts by mole, from 0.06 parts by mole to 0.065 parts by mole, from 0.065 parts by mole to

0.07 parts by mole, from 0.07 parts by mole to 0.075 parts by mole, from 0.075 parts by mole to

0.08 parts by mole, or any combination of one or more of these ranges.

[0029] In one or more embodiments, silicon may be present in the first composition, where the silicon may be present in the first composition in a relative amount of 0.05 parts by mole to 10 parts by mole. In some embodiments, silicon may be present in the oxygen carrier material as an active component that affects catalytic functionality (z. e. , not as a binder). Without being bound by any particular theory, it is believed that the presence of silicon in amounts as described herein may improve fuel combustion activity of the oxygen carrier material. Moreover, the presence of silicon may help to homogenously distribute iron particles with a particle size of less than 1 pm, which may be observed by scanning electron microscopy. Amounts below 0.05 parts by mole and above 10 parts by mole may decrease performance of the oxygen carrier material. [0030] In some embodiments, silicon may be present in the first composition in a relative amount of less than or equal to 10 parts by mole and at least 0.5 parts by mole, at least 1 part by mole, at least 1.5 parts by mole, at least 2 parts by mole, at least 2.5 parts by mole, at least 3 parts by mole, at least 3.5 parts by mole, at least 4 parts by mole, at least 4.5 parts by mole, at least 5 parts by mole, at least 5.5 parts by mole, at least 6 parts by mole, at least 6.5 parts by mole, at least 7 parts by mole, at least 7.5 parts by mole, at least 8 parts by mole, at least 8.5 parts by mole, at least 9 parts by mole, or at least 9.5 parts by mole.

[0031] In additional embodiments, silicon may be present in the first composition in a relative amount of at least 0.05 parts by mole and less than or equal to 9.5 parts by mole, less than or equal to 9 parts by mole, less than or equal to 8.5 parts by mole, less than or equal to 8 parts by mole, less than or equal to 7.5 parts by mole, less than or equal to 7 parts by mole, less than or equal to 6.5 parts by mole, less than or equal to 6 parts by mole, less than or equal to 5.5 parts by mole, less than or equal to 5 parts by mole, less than or equal to 4.5 parts by mole, less than or equal to 4 parts by mole, less than or equal to 3.5 parts by mole, less than or equal to 3 parts by mole, less than or equal to 2.5 parts by mole, less than or equal to 2 parts by mole, less than or equal to 1.5 parts by mole, less than or equal to 1 parts by mole, or less than or equal to 0.5 parts by mole.

[0032] In additional embodiments, silicon may be present in the first composition in a relative amount of from 0.05 parts by mole to 0.5 parts by mole, from 0.5 parts by mole to 1 part by mole, from 1 part by mole to 1.5 parts by mole, from 1.5 parts by mole to 2 parts by mole, from 2 parts by mole to 2.5 parts by mole, from 2.5 parts by mole to 3 parts by mole, from 3 parts by mole to 3.5 parts by mole, from 3.5 parts by mole to 4 parts by mole, from 4 parts by mole to 4.5 parts by mole, from 4.5 parts by mole to 5 parts by mole, from 5 parts by mole to 5.5 parts by mole, from 5.5 parts by mole to 6 parts by mole, from 6 parts by mole to 6.5 parts by mole, from 6.5 parts by mole to 7 parts by mole, from 7 parts by mole to 7.5 parts by mole, from 7.5 parts by mole to 8 parts by mole, from 8 parts by mole to 8.5 parts by mole, from 8.5 parts by mole to 9 parts by mole, from 9 parts by mole to 9.5 parts by mole, from 9.5 parts by mole to 10 parts by mole, or any combination of one or more of these ranges.

[0033] In one or more embodiments, oxygen may be present in the first composition in a relative amount of from 1.6 parts by mole to 22 parts by mole. The amount of oxygen may depend on the oxidation state of the oxygen carrier material, where more oxygen may be present in embodiments when the oxygen carrier material is storing oxygen atoms and less oxygen may be present once such oxygen has been provided for reaction and prior to regeneration. In general, the amount of oxygen may vary at different points in processing to form olefinic compounds, as is described herein.

[0034] In some embodiments, oxygen may be present in the first composition in a relative amount of less than or equal 22 parts by mole and at least 2 parts by mole, at least 3 parts by mole, at least 4 parts by mole, at least 5 parts by mole, at least 6 parts by mole, at least 7 parts by mole, at least 8 parts by mole, at least 9 parts by mole, at least 10 parts by mole, at least 11 parts by mole, at least 12 parts by mole, at least 13 parts by mole, at least 14 parts by mole, at least 15 parts by mole, at least 16 parts by mole, at least 17 parts by mole, at least 18 parts by mole, at least 19 parts by mole, at least 20 parts by mole, or at least 21 parts by mole.

[0035] In additional embodiments, oxygen may be present in the first composition in a relative amount of at least 1.6 part by mole and less than or equal to 21 parts by mole, less than or equal to 20 parts by mole, less than or equal to 19 parts by mole, less than or equal to 18 parts by mole, less than or equal to 17 parts by mole, less than or equal to 16 parts by mole, less than or equal to 15 parts by mole, less than or equal to 14 parts by mole, less than or equal to 13 parts by mole, less than or equal to 12 parts by mole, less than or equal to 11 parts by mole, less than or equal to 10 parts by mole, less than or equal to 9 parts by mole, less than or equal to 8 parts by mole, less than or equal to 7 parts by mole, less than or equal to 6 parts by mole, less than or equal to 5 parts by mole, less than or equal to 4 parts by mole, less than or equal to 3 parts by mole, or less than or equal to 2 parts by mole.

[0036] In additional embodiments, oxygen may be present in the first composition in a relative amount of from 1.6 parts by mole to 2 parts by mole, from 2 parts by mole to 4 parts by mole, from 4 parts by mole to 6 parts by mole, from 6 parts by mole to 8 parts by mole, from 8 parts by mole to 10 parts by mole, from 10 parts by mole to 12 parts by mole, from 12 parts by mole to 14 parts by mole, from 14 parts by mole to 16 parts by mole, from 16 parts by mole to 18 parts by mole, from 18 parts by mole to 20 parts by mole, from 20 parts by mole to 22 parts by mole, or any combination of one or more of these ranges. [0037] In one or more embodiments, the oxygen carrier material may be capable of fluidization. In some embodiments, the oxygen carrier material may have a median particle size (D50) of from 20 pm to 1000 pm, such as from 20 pm to 800 pm, from 20 pm to 600 pm, from 20 pm to 400 pm, from 20 pm to 200 pm, from 20 pm to 100 pm, from 100 pm to 1000 pm, from 100 pm to 800 pm, from 100 pm to 600 pm, from 100 pm to 400 pm, from 100 pm to 200 pm, from 400 pm to 1000 pm, from 400 pm to 800 pm, from 400 pm to 600 pm, from 600 pm to 1000 pm, from 600 pm to 800 pm, from 800 pm to 1000 pm, or any combination of one or more of these ranges.

[0038] In some embodiments, the oxygen carrier material may exhibit properties known in the industry as “Geldart A”, “Geldart B”, or “Geldart D” properties. Particles may be classified as “Group A”, “Group B”, or “Group D” according to D. Geldart, Gas Fluidization Technology, John Wiley & Sons (New York, 1986), 34-38; and D. Geldart, “Types of Gas Fluidization,” Powder Technol. 7 (1973) 285-292, which are incorporated herein by reference in their entireties.

[0039] Group A is understood by those skilled in the art as representing an aeratable powder, having a bubble-free range of fluidization; a high bed expansion; a slow and linear deaeration rate; bubble properties that may include a predominance of splitting/recoalescing bubbles, with a maximum bubble size and large wake; high levels of solids mixing and gas backmixing, assuming equal U-Umf (U is the velocity of the carrier gas, and Umf is the minimum fluidization velocity, typically though not necessarily measured in meters per second, m/s, i.e. , there is excess gas velocity); axisymmetric slug properties; and no spouting, except in very shallow beds. The properties listed tend to improve as the mean particle size decreases, assuming equal cfp; or as the < 45 micrometers (pm) proportion is increased; or as pressure, temperature, viscosity, and density of the gas increase. In general, the particles may exhibit a small mean particle size and/or low particle density (<1.4 grams per cubic centimeter, g/cm³), fluidize easily, with smooth fluidization at low gas velocities, and may exhibit controlled bubbling with small bubbles at higher gas velocities.

[0040] Group B is understood by those skilled in the art as representing a “sand-like” powder that starts bubbling at Umf; that exhibits moderate bed expansion; a fast deaeration rate; no limits on bubble size; moderate levels of solids mixing and gas backmixing, assuming equal U-Umf; both axisymmetric and asymmetric slugs; and spouting in only shallow beds. These properties tend to improve as mean particle size decreases, but particle size distribution and, with some uncertainty, pressure, temperature, viscosity, or density of gas seem to do little to improve them. In general, most of the particles having a particle size (cfp) of 40 pm <cfp <500 pm when the density (pp) is 1.4 <pp <4 g/cm³, and preferably 60 pm <cfp <500 pm when the density (pp) is 4 g/cm³ and 250 pm <cfp <100 pm when the density (pp) is 1 g/cm³.

[0041] Group D is understood by those skilled in the art as representing coarse solids that exhibit low bed expansion; fast deaeration rate; no known upper limits on bubble size and a small wake; low levels of solids mixing and gas backmixing, assuming equal U-Umf; horizontal voids, solids slugs, and wall slugs; and spouting even in deep beds. It is not generally known whether these properties are affected depending on the mean particle size, however, particle size distribution tends to increase segregation and there is some uncertainty that these properties increase pressure, temperature, viscosity, or density of gas. In general, Group D particles are confined to large and or very dense particles.

[0042] In one or more embodiments, the oxygen carrier materials described herein may be prepared by a variety of synthetic techniques including solid-state synthesis, or wet or dry impregnation followed by drying and high-temperature calcination, as known to those skilled in the art. In general, various components in the first composition can be added as solid powders in their oxide form, then well-mixed or homogenized, followed by calcination in air at high temperatures. Alternatively, some components in the first composition can be incorporated by completely (wet or dry impregnation) or partially (slurry impregnation) dissolving their precursors in water, and then combining them with solid powders of remaining components, followed by drying and high-temperature calcination in air. Optionally, small amount of the additional materials described herein can be added during the synthesis of the oxygen carrier to provide physical strength and stability.

[0043] In some embodiments, as described hereinabove, the oxygen carrier material can be prepared by impregnation. The impregnation may utilize wet impregnation or dry impregnation (sometimes referred to as incipient wetness impregnation). The impregnation may utilize an aqueous solution that includes some components of the first composition. For example, in various embodiments, the aqueous solution may comprise precursors of one or more alkali metals, such as potassium, and/or tungsten. In one or more embodiments, the aqueous solution may have a pH of greater than 7. For example, the aqueous solution may have a pH of greater than 7.5, greater than 8, greater than 8.5, greater than 9, greater than 9.5, greater than 10, greater than 10.5, greater than 11, or even greater than 11.5. In some embodiments, multiple impregnation steps may occur to impregnate different materials.

[0044] In some embodiments, the precursor may be a single source of potassium and tungsten, such as K2WO4 salt, or, in other embodiments, the precursors may come from separate sources, such as a precursor comprising potassium and a precursor comprising tungsten. In some embodiments, the precursor comprising potassium may be chosen from a group comprising potassium carbonate (K2CO3), potassium sulfate (K2SO4), potassium nitrate (KNO3), potassium phosphate (K3PO4) potassium acetate (CH3COOK), and potassium containing ores, such as potash feldspar and similar compounds. In some embodiments, the precursor comprising tungsten may be chosen from a group comprising tungsten oxide (WO3), ammonium para tungstate (NH4)io(H2Wi2042).4H20, ammonium meta tungstate (NH4)eH2Wi2O4xH2O, tungstic acid (H2WO4), and tungsten containing ores such as wolframite and similar compounds. Use of separate sources for potassium and tungsten may allow for tuning of the ratio of potassium to tungsten in the final oxygen carrier material while use of a single source precursor may keep such stoichiometry at a fixed ratio.

[0045] The impregnated material may then be dried after impregnation. In some embodiments, the impregnated material may be dried under air. In one or more embodiments, the impregnated material may be dried at a temperature of less than 200 °C, such as less than 175 °C, less than 150 °C, less than 125 °C, less than 100 °C, less than 75 °C, or even less than 50 °C. In certain embodiments, impregnation can be done more than once with the aqueous solution, and the impregnated material may be dried between each impregnation.

[0046] The dried impregnated material may then be calcined to produce the oxygen carrier material. In one or more embodiments, the calcination may be at a temperature of greater than 600 °C, such as greater than 700 °C, greater than 800 °C, greater than 900 °C, greater than 1000 °C, greater than 1100 °C, or even greater than 1200 °C. In one or more embodiments, the dried impregnated material may be calcined under air. In embodiments where multiple impregnation steps are utilized, the impregnated material may be calcined between each impregnation. In some embodiments, the dried impregnated material may be calcined in air for more than 1 hour. For example, the dried impregnated material may be calcined in air for more than 2 hours, more than 4 hours, more than 10 hours, or even more than 20 hours.

[0047] In some embodiments, the oxygen carrier material may be prepared by a single- step or “one-pot” approach, where precursors for iron, one or more alkali materials (such as potassium), tungsten, and silicon are mixed together in appropriate amounts as dry solids or with some amount of water to homogenize the mixture. The homogenized mixture or paste may be calcined in air at temperatures and for durations as described herein, such as at temperatures greater than 800 °C for at least 1 hour.

[0048] In embodiments where the oxygen carrier material is prepared by a single step approach, the particle size for the precursors may be less than 20 pm, less than 15 pm, less than 10 pm, or even less than 5 pm. It is believed that particle size for the precursors in this range allow for better homogenization of solids and particle-to-particle contact for dehydrogenation. Precursors that may be used in single-step or one -pot approach may include iron oxides (Fe2O3, FeO, FC3O4), iron tungstate (FeWC ), potassium carbonate (K2CO3), potassium sulfate (K2SO4), potassium nitrate (KNO3), potassium acetate (CH3COOK), tungsten oxide (WO3), ammonium para tungstate (NH4)io(H2Wi2042).4H20, ammonium meta tungstate (NH^eFhW^C o xFhO, fumed silica (Cabosil M5, Aerosil 200, Aerosil 380, Aerosil 0X50), colloidal silica (LUDOX AS- 30, LUDOX AS-40), mesoporous silica (SBA-15) and/or alkali silicate solution (Zacsil 30).

[0049] In some embodiments, the oxygen-carrier materials may be utilized in processes comprising fluidized beds or moving beds or circulating fluidized bed (CFB). In such embodiments, it may be desirable to have oxygen carries as engineered particles with “Geldart A” or “Geldart B” properties. Without being limited by theory, in one or more embodiments, it is believed that the choice in methods of making engineered particles of oxygen carrier materials such as manufacturing techniques like spray drying, high-shear granulation, and fluidized bed granulation can be utilized followed by drying and high temperature calcination to achieve fluidizable particles.

[0050] According to one or more embodiments of the present disclosure, a method for producing olefinic compounds is provided that utilizes the oxygen carrier materials described herein. As used herein, the term “olefinic compounds” refers to hydrocarbons having one or more carbon-carbon double bonds apart from the formal double bonds in aromatic compounds. For example, ethylene and styrene are olefinic compounds, but ethylbenzene would not be an olefinic compound as the only double bonds present in ethylbenzene are formal double bonds present as part of the aromatic structure.

[0051] Now referring to FIG. 1, a reactor system 100 that may be used with the methods of the present disclosure is shown, but other reactor systems that would be suitable for the presently disclosed methods are contemplated as suitable. FIG. 1 is a simplified system, and other systems are contemplated. Additionally, in FIG. 1, a wide variety of reactor types are contemplated as potentially suitable for the methods described herein. For example, the oxygen carrier materials of the present disclosure may be utilized in the systems and methods that are disclosed in at least PCT International Application No. PCT/US23/73963, entitled “Methods For Dehydrogenating Hydrocarbons By Thermal Dehydrogenation” and International Patent Publication WO 2020/046978, entitled “Methods for Dehydrogenating Hydrocarbons,” the teachings of each of which are incorporated by reference in their entirety herein. The technical aspects of these disclosures may further describe the methods and systems described herein with respect to FIG. 1. Additionally, it is noted that the steps indicated by FIG. 1 are not to be interpreted as essential steps, particularly in view of the methods of the appended claims.

[0052] Referring still to FIG. 1, the reactor system 100 may include a reactor 110 and a regeneration unit 120. In one or more embodiments, the reactor 110 may be a fluidized bed reactor. Generally, a feed stream 101 may be passed into the reactor 110 and be processed in the reactor 110 to form a product stream 102 that includes one or more olefinic compounds. As described in detail herein, according to one or more embodiments, the oxygen carrier material may be cycled between the reactor 110 and the regeneration unit 120, where the oxygen carrier material enters the reactor 110 in an oxygen-rich state, provides oxygen in the reactor 110, leaves the reactor 110 in an oxygen-diminished state, and may be regenerated to an oxygen-rich state in the regeneration unit 120.

[0053] In one or more embodiments, the feed stream 101 may comprise one or more hydrocarbons. As described herein, the feed stream 101 may be passed into the reactor 110. In one or more embodiments, the one or more hydrocarbons may comprise one or more of ethane, propane, butane, or ethylbenzene. According to one or more embodiments, the one or more hydrocarbons may comprise at least 50 wt. %, at least 60 wt. %, at least 70 wt. %, at least 80 wt. %, at least 90 wt. %, at least 95 wt. % or even at least 99 wt. % of any of ethane. In additional embodiments, the one or more hydrocarbons may comprise at least 50 wt. %, at least 60 wt. %, at least 70 wt. %, at least 80 wt. %, at least 90 wt. %, at least 95 wt. % or even at least 99 wt. % of propane. In additional embodiments, the one or more hydrocarbons may comprise at least 50 wt. %, at least 60 wt. %, at least 70 wt. %, at least 80 wt. %, at least 90 wt. %, at least 95 wt. % or even at least 99 wt. % of butane. In additional embodiments, the one or more hydrocarbons may comprise at least 50 wt. %, at least 60 wt. %, at least 70 wt. %, at least 80 wt. %, at least 90 wt. %, at least 95 wt. % or even at least 99 wt. % of ethylbenzene. In additional embodiments, the one or more hydrocarbons may comprise at least 50 wt. %, at least 60 wt. %, at least 70 wt. %, at least 80 wt. %, at least 90 wt. %, at least 95 wt. % or even at least 99 wt. % of the sum of ethane, propane, butane, and ethylbenzene.

[0054] According to embodiments, the oxygen carrier material may be passed to the reactor 110 in an oxygen-rich state. In the reactor 110, the one or more hydrocarbons of the feed stream 101 may be dehydrogenated to form hydrogen (i.e., gas phase H2) and one or more olefinic compounds. According to embodiments, a portion or an entirety of the hydrogen may be reacted with oxygen from the oxygen carrier material to form water. Reacting the hydrogen with oxygen from the oxygen carrier material may reduce the oxygen carrier material and convert it to an oxygen-diminished state. As described herein, the oxygen-rich state of the oxygen carrier material has a greater amount of oxygen than the oxygen-diminished state of the oxygen carrier material. However, it should be understood that some oxygen may still be contained in the oxygendiminished state oxygen carrier material.

[0055] According to some embodiments, the dehydrogenation reaction in the reactor 110 may be thermally driven (z. e. , non-catalytic) wherein, in such embodiments, a dehydrogenation catalyst is not utilized in the reactor 110. While the temperature of the reactor 110 may vary, in some embodiments, the reactor 110 may operate at a temperature of from 500 °C to 850 °C, which may be appropriate to promote thermal dehydrogenation. For example, the reactor 110 may operate at a temperature of from 525 °C to 850 °C, from 550 °C to 850 °C, from 575 °C to 850 °C, from 600 °C to 850 °C, from 625 °C to 850 °C, from 650 °C to 850 °C, from 675 °C to 850

°C, from 700 °C to 850 °C, from 725 °C to 850 °C, from 750 °C to 850 °C, from 775 °C to 850

°C, from 800 °C to 850 °C, from 500 °C to 825 °C, from 500 °C to 800 °C, from 500 °C to 775

°C, from 500 °C to 750 °C, from 500 °C to 725 °C, from 500 °C to 700 °C, from 500 °C to 675 °C, from 500 °C to 650 °C, from 500 °C to 625 °C, from 500 °C to 600 °C, from 500 °C to 575 °C, from 500 °C to 550 °C, or any combinations of these ranges.

[0056] In additional embodiments, a dehydrogenation catalyst may be utilized to promote dehydrogenation in the reactor 110. The dehydrogenation catalyst may be passed along with the oxygen carrier material and cycled between the reactor 110 and the regeneration unit 120. In embodiments where a dehydrogenation catalyst is utilized, temperatures of from 500 °C to 850 °C may also be utilized, including the subranges described hereinabove. As is described herein, the combustion of hydrogen may form steam, which may be in direct contact with the dehydrogenation catalyst. It is contemplated that not all dehydrogenation catalysts are equally effective in steam environments. As such, suitable dehydrogenation catalysts may be steam- tolerant, such that the dehydrogenation catalyst exhibits suitable stability when in the presence of steam. Suitable dehydrogenation catalysts include, without limitation, those including platinum, platinum and gallium, platinum and tin, chromium, or platinum and zinc. For example, suitable catalysts are described in Chem. Rev. 2014, 114, 20, 10613-10653, which is incorporated herein by reference in its entirety and U.S. Pat. No. 8,669,406 and U.S. Pat. No. 11,724,974, which are incorporated herein by reference in their entireties.

[0057] The one or more olefinic compounds produced in the reactor 110, as well as unconverted hydrocarbons, water, and unconverted hydrogen may exit the reactor 110 via product stream 102. In one or more embodiments, the olefinic compounds may comprise one or more of ethylene, propylene, butylene, or styrene. The term butylene includes any isomers of butylene, such as a-butylene, cis-P-butylene, trans-P-butylene, and isobutylene. In some embodiments, the one or more olefinic compounds may comprise at least 20 wt. %, at least 30 wt. %, at least 40 wt. %, at least 50 wt. %, or even at least 60 wt. % of ethylene. In additional embodiments, the one or more olefinic compounds may comprise at least 20 wt. %, at least 30 wt. %, at least 40 wt. %, at least 50 wt. %, or even at least 60 wt. % of propylene. In additional embodiments, the one or more olefinic compounds may comprise at least 20 wt. %, at least 30 wt. %, at least 40 wt. %, at least 50 wt. %, or even at least 60 wt. % of butylene. In additional embodiments, the one or more olefinic compounds may comprise at least 20 wt. %, at least 30 wt. %, at least 40 wt. %, at least 50 wt. %, or even at least 60 wt. % of styrene. In additional embodiments, the one or more olefinic compounds may comprise at least 20 wt. %, at least 30 wt. %, at least 40 wt. %, at least 50 wt. %, or even at least 60 wt. % of the sum of one or more of ethylene, propylene, butylene, and styrene. The product stream 102 may further comprise unreacted components of the feed stream 101, as well as other reaction products that are not considered olefinic compounds. The olefinic compounds may be separated from unreacted components in subsequent separation steps.

[0058] As described herein, in the reactor 110, the one or more hydrocarbons, such as ethane, may be dehydrogenated to produce hydrogen, and that hydrogen may be reacted with oxygen via a combustion reaction to form water. The oxygen is supplied by the oxygen carrier material, and the reaction of the hydrogen into water pushes the dehydrogenation reaction equilibrium towards the products, such as ethylene. In such embodiments, it is advantageous that the oxygen carrier material promotes the combustion of hydrogen over reactions with hydrocarbons present in the reactor 110. Such hydrocarbons may include the feed hydrocarbons, such as ethane, as well as product olefinic compounds, such as ethylene. Reaction of these hydrocarbons with the oxygen from the oxygen carrier material may undesirably form carbon monoxide and/or carbon dioxide. Carbon dioxide and carbon monoxide in the product stream 102 may cause several issues, such as difficulty in separating such components from other compounds in the product stream 102 as well as the potential emission of carbon dioxide into the environment or need to sequester such carbon dioxide. For example, carbon monoxide may be an undesirable inhibitor in certain downstream unit operations like acetylene hydrogenation reactors. With this in mind, it has been found that the presently disclosed oxygen carrier materials may have relatively high selectivity for promoting hydrogen combustion to form water as compared with selectivity for promoting the undesirable combustion of hydrocarbons with feed alkanes, such as ethane, and/or product olefinic compounds, such as ethylene.

[0059] According to one or more embodiments, and as is described herein, the hydrogen formed by the dehydrogenation reaction is gaseous H2, which reacts with oxygen from the oxygen carrier material. This is in contrast to some other reaction mechanisms, such as oxidative dehydrogenation, where hydrogen is not formed. Rather, in such oxidative dehydrogenation reactions, alkanes are processed to form olefins in a single reaction step where hydrogen (H2) is not formed as an intermediary. This concept is described in detail in, for example, “Oxidative Dehydrogenation of Ethane: Common Principles and Mechanistic Aspects,” Gartner et al. ChemCatChem 2013, 5, 3196-3217. [0060] As described herein, the oxygen carrier material may be passed into the reactor 110 and subsequently out of the reactor 110. Referring again to FIG. 1, in some embodiments, the oxygen carrier material may be cycled between the reactor 110 and a regeneration unit 120. The oxygen carrier material may pass from the reactor 110 to the regeneration unit 120 via stream 103 and be passed from the regeneration unit 120 back to the reactor 110 via stream 104, and be continuously looped. In general, the oxygen carrier material may enter the reactor 110 in an oxygen-rich state, lose some or all oxygen atoms in the reactor 110 (to combust with hydrogen gas), and exit the reactor 110 in an oxygen-diminished state via stream 103. The oxygen carrier material in the oxygen-diminished state may be passed to the regeneration unit 120 where it is exposed to oxygen and regenerated into its oxygen-rich state. This oxygen carrier material in the oxygen-rich state may be passed from the regeneration unit 120 via stream 104 back to the reactor 110.

[0061] According to one or more embodiments, in the regeneration unit 120, the oxygen carrier material may be exposed to oxygen, such as by exposure to air, oxygen enriched air, or even pure oxygen. This exposure allows the oxygen carrier material to be replenished with oxygen. Additionally, in the regeneration unit 120, a fuel gas may be combusted in order to heat the oxygen carrier material. This heat may be the main source of heat to maintain temperatures in the reactor 110, which is using heat by the dehydrogenation reaction. The fuel gas may comprise a variety of combustible compounds, such as hydrogen, methane, ethane, propane, etc. In some embodiments, methane may be the primary constituent of the fuel gas. In embodiments, the regeneration unit 120 may operate at elevated temperatures, such as from 600 °C to 900 °C, or temperatures that would be sufficient to heat the oxygen carrier materials to a temperature such that their heat can be utilized in the reactor 110 to drive the dehydrogenation reaction.

[0062] As described herein, a fuel gas, such as one comprising methane, may be combusted in the regeneration unit 120. In some embodiments, the fuel gas may comprise hydrogen, methane, or combinations thereof. In some embodiments, the fuel gas may comprise methane, ethane, propane, or combinations thereof. It has been discovered that the composition of the oxygen carrier material may affect the fuel gas combustion rate, according to some embodiments. As such, it is undesirable to utilize an oxygen carrier material that has a composition that will slow the combustion of hydrocarbons in the presence of molecular oxygen. This is particularly a problem, since the oxygen carrier materials may be chosen such that they promote combustion of hydrogen but not alkanes and/or alkenes in the reactor 110. However, it has been observed that the presently disclosed oxygen carrier materials, according to one or more embodiments, may have acceptable levels of promotion of alkane combustion, such as methane combustion, in the regeneration unit 120 while having good selectivity for hydrogen combustion over ethane combustion in the reactor 110.

[0063] In some embodiments, the oxygen-rich state of the oxygen carrier material may be partially reduced before being passed to the reactor 110. This may include exposing the oxygen carrier material in stream 104 to a reducing gas such as H2 and/or methane. Such treatment may allow for removal of some oxygen from the lattice of the oxygen carrier material. However, the amount of remaining oxygen is still suitable for supplying oxygen to the reactor 110 for combustion of hydrogen, as disclosed herein.

[0064] The present disclosure includes numerous aspects, including aspects 1-15 described herein.

[0065] Aspect 1. An oxygen carrier material comprising a first composition, wherein at least 95 wt.% of the first composition consists of: 1 part by mole iron; from 0.001 parts by mole to 0.15 parts by mole of one or more alkali metals; from 0.001 parts by mole to 0.08 parts by mole of tungsten; from 0.05 parts by mole to 10 parts by mole of silicon; and from 1.6 parts by mole to 22 parts by mole of oxygen.

[0066] Aspect 2. The oxygen carrier material of aspect 1, further comprising one or more additional materials chosen from oxides of aluminum, calcium, magnesium, zirconium, boron, phosphorus, sulfur or combinations thereof.

[0067] Aspect 3. The oxygen carrier material of aspect 2, wherein the one or more additional materials function as binders.

[0068] Aspect 4. The oxygen carrier material of aspect 2, wherein at least 99 wt.% of the oxygen carrier material is the first composition and the one or more additional materials.

[0069] Aspect 5. The oxygen carrier material of aspect 2, wherein the oxygen carrier material comprises less than or equal to 5 wt.% of the one or more additional materials. [0070] Aspect 6. The oxygen carrier material of aspect 5, wherein the oxygen carrier material comprises greater than or equal to 95 wt.% of the first composition.

[0071] Aspect 7. The oxygen carrier material of any previous aspect, wherein the one or more alkali metals are chosen from lithium, sodium, and potassium.

[0072] Aspect 8. The oxygen carrier material of any previous aspect, wherein the one or more alkali metals comprise potassium.

[0073] Aspect 9. The oxygen carrier material of any previous aspect, wherein at least 99 wt.% of the first composition consists of: 1 part by mole iron; from 0.001 parts by mole to 0.15 parts by mole of one or more alkali metals; from 0.001 parts by mole to 0.08 parts by mole of tungsten; from 0.05 parts by mole to 10 parts by mole of silicon; and from 1.6 parts by mole to 22 parts by mole of oxygen.

[0074] Aspect 10. The oxygen carrier material of any previous aspect, wherein the first composition consists of: 1 part by mole iron; from 0.001 parts by mole to 0.15 parts by mole of one or more alkali metals; from 0.001 parts by mole to 0.08 parts by mole of tungsten; from 0.05 parts by mole to 10 parts by mole of silicon; and from 1.6 parts by mole to 22 parts by mole of oxygen.

[0075] Aspect 11. The oxygen carrier material of any previous aspect, wherein the first composition comprises from 0.007 parts by mole to 0.08 parts by mole of tungsten.

[0076] Aspect 12. The oxygen carrier material of any previous aspect, wherein the oxygen carrier material has a median particle size of from 20 pm to 1000 pm.

[0077] Aspect 13. A method for making the oxygen carrier material of any previous aspect.

[0078] Aspect 14. The method of aspect 13, wherein the method comprises wet or dry impregnation.

[0079] Aspect 15. The method of aspect 13, wherein the method comprise solid state synthesis. EXAMPLES

[0080] The various embodiments of the present disclosure will be further clarified by the following examples. The examples are illustrative in nature and should not be understood to limit the subject matter of the present disclosure.

[0081] Example 1 - Sample Preparation

[0082] Comparative Samples X and Y: Quartz chips were sourced commercially from Pyromatics and sieved to 100-200 mesh before use.

[0083] Comparative Sample A: A stoichiometric amount of Fe2O3, TiCh (Noah Technologies Corporation, anatase), and WO3 (Sigma- Aldrich, < 25 pm) was weighed in a mortar. The dry powders were first ground with a pestle for 5 minutes (min). The powders were then shaken for 1 minute in a separate container and replaced back into the mortar. The grinding and shaking were repeated two times (for a total of 10 min of grinding and 2 min of shaking). Separately, a stoichiometric amount of K2CO3 powders were dissolved in ~ 10 mL of deionized H2O. The mixed metal oxide powders were ground and pasted for 5 minutes after introducing the alkali solution. The paste was then transferred to an alumina crucible and dried for at least 2 hours at 120 °C in air. The dried mixture was calcined in air at 950 °C for 6 hours.

[0084] Comparative Sample B: A stoichiometric amount of potassium tungstate (K2WO4, Thermofisher) was weighed. The potassium tungstate was then wettened in 2-3 mL deionized water. The slurry was added to a stoichiometric amount of iron oxide (Fe2O3, Noach Chemicals) to make a paste. The paste was ground in a mortar and pestle to homogenize and calcined at 950 °C for 6 hours.

[0085] Comparative Sample C: A stoichiometric amount of hydrophilic fumed silica (Aerosil 200) was weighed and then dispersed in water to make a paste. The paste was then added to a stoichiometric amount of iron oxide (Fe2O3, Noah chemical) in a mortar and pestle and mixed until a homogeneous colored paste formed. Tungsten oxide (WO3, Sigma Aldrich) powder was added to the iron oxide and silica paste and mixed again until homogenized. The paste was calcined at 950 °C for 6 hours.

[0086] Comparative Sample D: A stoichiometric amount of hydrophilic fumed silica (Aerosil 200) was weighed and then dispersed in water to make a paste. The paste was then added to a stoichiometric amount of iron oxide (Fe2O3, Noah chemical) in a mortar and pestle and mixed until a homogeneous colored paste formed. In a separate vial, a stoichiometric amount of potassium carbonate (K2CO3, Fisher Scientific) was dissolved in water. The aqueous solution of potassium carbonate was added to the paste and calcined at 950 °C for 6 hours.

[0087] Comparative Sample E: A stoichiometric amount of Fe2O3 (Noah Technologies Corporation) was ground and pasted for 5 min after introducing 5 - 10 mE of deionized H2O. The paste was transferred to an alumina crucible and dried for at least 2 hours at 120 °C in air. The dried mixture was calcined in air at 950 °C for 6 hours.

[0088] Comparative Sample F: A stoichiometric amount of Fe2O3 was ground and pasted for 5 min after introducing a stoichiometric amount of EUDOX AS-40. The paste was transferred to an alumina crucible and dried for at least 2 hours at 120 °C in air. The dried mixture was calcined in air at 950 °C for 6 hours.

[0089] Comparative Sample G: A stoichiometric amount of Fe2O3 and WO3 (Sigma- Aldrich, < 25 pm) was weighed into a mortar. The dry powders were grinded with a pestle for 5 min. The powders were then shaken for 1 min in a separate container and replaced back into the mortar. The mixing and shaking were repeated for two times (in total 10 min grinding + 2 min shaking). Subsequently, the powders were grinded and pasted for 5 min after introducing a stoichiometric amount of EUDOX AS-40. The paste was transferred to an alumina crucible and dried for at least 2 hours at 120 °C in air. The dried mixture was calcined in air at 950 °C for 6 hours.

[0090] Comparative Sample H: A stoichiometric amount of M113O4 (Elkem MicroMax EU) and K2WO4 (Alfa Aesar) was weighed into a mortar. The dry powders were first grinded with a pestle for 5 min. The powders were then shaken for 1 min in a separate container and replaced back into the mortar. The mixing and shaking were repeated for two times (in total 10 min grinding + 2 min shaking). Subsequently, the powders were grinded and pasted for 5 min after introducing a stoichiometric amount of EUDOX AS-40. The paste was transferred to an alumina crucible and dried for at least 2 hours at 120 °C in air. The dried mixture was calcined in air at 950 °C for 6 hours.

[0091] Comparative Sample I and J: A stoichiometric amount of K2WO4 (Alfa Aesar) was thoroughly dry mixed with ilmenite (Alfa Aesar) powder, then small amount of deionized water was added to form paste. The paste was grinded by mortar and pestle and transferred to alumina crucible for 950 °C calcination in air for 6 hours. [0092] Comparative Sample K: A stoichiometric amount of Fe20s and TiCh (Evonik, AEROXIDE P25) was weighed into a mortar. The dry powders were first grinded with a pestle for 5 min. The powders were then shaken for 1 min in a separate container and replaced back into the mortar. The mixing and shaking were repeated for two times (in total 10 min grinding + 2 min shaking). Separately, a stoichiometric amount of K2WO4 powders were dissolved in ~ 10 mE of deionized H2O. The mixed metal oxide powders were grinded and pasted for 5 min after introducing the alkali solution. The paste was transferred to an alumina crucible and dried for at least 2 hours at 120 °C in air. The dried mixture was calcined in air at 950 °C for 24 hours.

[0093] Samples 1-3: A stoichiometric amount of Fe2O3, K2CO3 (Armand Products Company), and WO3 were weighed into a mortar. The dry powders were grinded with a pestle for 5 min. The powders were then shaken for 1 minute in a separate container and replaced back into the mortar. The mixing and shaking were repeated two times (in total 10 min grinding + 2 min shaking). Subsequently, the powders were grinded and pasted for 5 min after introducing a stoichiometric amount of EUDOX AS-40. The paste was transferred to an alumina crucible and dried for at least 2 hours at 120 °C in air. The dried mixture was calcined in air at 950 °C for 6 hours.

[0094] Samples 4 and 5 : A stoichiometric amount of hydrophilic fumed silica (Aerosil 200) was weighed and then dispersed in water to make a paste. The paste was added to a stoichiometric amount of iron oxide (Fe2O3, Noah Chemical) in a mortar and pestle and mixed until a homogeneous colored paste formed. Tungsten oxide (WO3, Sigma Aldrich) powder was added to the iron oxide and silica paste and mixed again until homogenized. In a separate vial, a stoichiometric amount of potassium carbonate (K2CO3, Fisher Scientific) was dissolved in water. The aqueous solution of potassium carbonate was added to the paste and calcined at 950 °C for 6 hours.

[0095] Samples 6-8: A stoichiometric amount of hydrophilic fumed silica (Cabosil M5) was weighed and then dispersed in water to make a paste. The paste was added to a stoichiometric amount of iron oxide (Fe2O3, Noah Chemical) in a mortar and pestle and mixed until a homogeneous colored paste formed. Tungsten oxide (WO3, Sigma Aldrich) powder was added to the iron oxide and silica paste and mixed again until homogenized. In a separate vial, a stoichiometric amount of potassium carbonate (K2CO3, Fisher Scientific) was dissolved in water. The aqueous solution of potassium carbonate was added to the paste and calcined at 950 °C for 6 hours.

[0096] Samples 9-11 : A stoichiometric amount of hydrophilic fumed silica (Aerosil 200 for Sample 10, Aerosil 380 for Sample 11, and Aerosil 0X50 for Sample 12) was weighed and then dispersed in water to make a paste. The paste was added to a stoichiometric amount of iron oxide (Fe2O3, Noah Chemical) in a mortar and pestle and mixed until a homogeneous colored paste formed. Tungsten oxide (WO3, Sigma Aldrich) powder was added to the iron oxide and silica paste and mixed again until homogenized. In a separate vial, a stoichiometric amount of potassium carbonate (K2CO3, Fisher Scientific) was dissolved in water. The aqueous solution of potassium carbonate was added to the paste and calcined at 950 °C for 6 hours.

[0097] Sample 12: A stoichiometric amount of iron oxide (Fe2O3, Noah Chemical), mesoporous silica (SBA-15, Sigma Aldrich), and tungsten oxide (WO3, Sigma Aldrich) powders were weighed. The powders were mixed in a mortar and pestle until homogenized. In a separate vial, a stoichiometric amount of potassium carbonate (K2CO3, Fisher Scientific) was dissolved in water. The aqueous solution of potassium carbonate was added to the paste and calcined at 950 °C for 6 hours.

[0098] Sample 13: A stoichiometric amount of iron oxide (Fe2O3, Noah Chemical) and fumed silica (Evonik) were dry mixed. In a separate vial, a stoichiometric amount of potassium tungstate (K2WO4, Thermofisher) was dissolved in water. The aqueous solution of potassium tungstate was added to the dry powder mix and mixed in a mortar and pestle to make a paste. The paste was calcined at 950 °C for 6 hours.

[0099] Samples 14-16: A stoichiometric amount of hydrophilic fumed silica (Cabosil M5) was dispersed in water to make paste. The paste was then added to a stoichiometric amount of iron oxide (Fe2O3, Noah Chemical) in a mortar and pestle and mixed until a homogeneous colored paste formed. Tungsten oxide (WO3, Sigma Aldrich) powder was added to the iron oxide and silica paste and mixed again until homogenized. In a separate vial, a stoichiometric amount of potassium carbonate (K2CO3, Fisher scientific) was dissolved in water. The aqueous solution of potassium carbonate was added to the paste and calcined at 950 °C for 6 hours.

[0100] Samples 17-19: A stoichiometric amount of K2WO4 powder was wettened in 2 - 3 mE of deionized H2O. The slurry was then introduced with a stoichiometric amount of Comparative Sample F, then grinded and pasted for 5 min. The paste was transferred to an alumina crucible and dried for at least 2 hours at 120 °C in air. The dried mixture was calcined in air at 950 °C for 24 hours.

[0101] Samples 20, 21, 22, and 32: A stoichiometric amount of Fe20s and K2WO4 was weighed into a mortar. The dry powders were first grinded with a pestle for 5 min. The powders were then shaken for 1 min in a separate container and replaced back into the mortar. The mixing and shaking were repeated for two times (in total 10 min grinding + 2 min shaking). Subsequently, the powders were grinded and pasted for 5 min after introducing a stoichiometric amount of TUDOX AS-40. The paste was transferred to an alumina crucible and dried for at least 2 hours at 120 °C in air. The dried mixture was calcined in air at 950 °C for 6 hours.

[0102] Samples 23, 24, 25, 33, 34, 37, 38, and 39: A stoichiometric amount of Fe20s, K2CO3 (Armand Products Company) and WO3 was weighed into a mortar. The dry powders were first grinded with a pestle for 5 min. The powders were then shaken for 1 min in a separate container and replaced back into the mortar. The mixing and shaking were repeated for two times (in total 10 min grinding + 2 min shaking). Subsequently, the powders were grinded and pasted for 5 min after introducing a stoichiometric amount of TUDOX AS-40. The paste was transferred to an alumina crucible and dried for at least 2 hours at 120 °C in air. The dried mixture was calcined in air at 950 °C for 6 hours.

[0103] Sample 26: A stoichiometric amount of Fe2O3 and WO3 was weighed into a mortar. The dry powders were first grinded with a pestle for 5 min. The powders were then shaken for 1 min in a separate container and replaced back into the mortar. The mixing and shaking were repeated for two times (in total 10 min grinding + 2 min shaking). Subsequently, the powders were grinded and pasted for 5 min after introducing a stoichiometric amount of Zacsil 30 solution. The paste was transferred to an alumina crucible and dried for at least 2 hours at 120 °C in air. The dried mixture was calcined in air at 950 °C for 6 hours.

[0104] Samples 27-29: Samples 27-29 were made in a similar way as Sample 14, but different types of fumed silica were used. Sample 27 used Aerosil 200, Sample 28 used Aerosil 380, and Sample 29 used Aerosil 0X50 fumed silica from Evonik.

[0105] Sample 30: A stoichiometric amount of SBA15 mesoporous silica, iron oxide (Fe2O3, Noah Chemical), and tungsten oxide (WO3, Sigma Aldrich) powder were dry mixed in a mortar and pestle until homogenized. In a separate vial, a stoichiometric amount of potassium carbonate (K2CO3, Fisher Scientific) was dissolved in water. The aqueous solution of potassium carbonate was added to the paste and calcined at 950 °C for 6 hours.

[0106] Samples 31 and 40: Samples 31 and 40 were made in a similar way as Sample 27, but calcined at 1150 °C for 6 hours (Sample 31) and 1350 °C for 6 hours (Sample 40).

[0107] Samples 35 and 36: Samples 35 and 36 were made in a similar way as Sample 27, but instead of potassium carbonate salt, sodium carbonate (TSfeCCb, Sigma Aldrich) and lithium carbonate (Li2CC>3, Sigma Aldrich) were used to make the aqueous solution, respectively.

[0108] Samples 41 and 42: A stoichiometric amount of hydrophilic fumed silica (Aerosil 200) was dispersed in water to make paste. The paste was then added to a stoichiometric amount of iron oxide (Fe2O3, Noah Chemical) in a mortar and pestle and mixed until a homogeneous colored paste formed. Tungsten oxide (WO3, Sigma Aldrich) powder was added to the iron oxide and silica paste and mixed again until homogenized. In a separate vial, a stoichiometric amount of potassium carbonate (K2CO3, Fisher Scientific) was dissolved in water. The aqueous solution of potassium carbonate was added to the paste and calcined at 950 °C for 6 hours.

[0109] Example 2 - Selective Hydrogen Combustion Performance

[0110] Testing of the oxygen-carrying material samples of Example 1 was performed in a fixed-bed laboratory reactor. A 0.5 gram (g) portion of the sample was loaded into a 0.5 inch outer diameter (OD) quartz bulb connected to 6.5 millimeter (mm) OD quartz tubing. The sample bed was supported on a pill of quartz wool and a layer of 0.5- 1.0 mm quartz chips. The empty space in the quartz bulb above the sample bed was filled with 0.5-1.0 mm quartz chips. The reactor was installed into a clamshell furnace and a flow of helium at 50 standard cubic centimeters (seem) was started through the reactor tube. The reactor was then heated, under 50 seem of air flow, from room temperature to 780 °C.

[0111] The oxy gen-carrying material samples were subjected to several cyclic sequences.

Each cycle included ethane dehydrogenation, 1^st air regeneration, fuel combustion, and 2^nd air regeneration with inert helium purging of the reactor tube in between reduction and oxidation pulses. The ethane dehydrogenation steps were done at a weight hourly space velocity (WHSV) of 5.3 hr'¹. Specifically, 40 seem of a gas mixture containing 90 mol.% ethane and 10 mol.% helium was fed through the reactor for 60 seconds while the reactor was held at 780 °C. Analysis of the product gas composition was taken at 30 seconds into the dehydrogenation reaction pulse (which corresponds to halfway through the pulse). During the 1^st air regeneration steps, 40 seem of air was fed through the reactor for 2 minutes. The fuel combustion steps were done at a WHSV of 0.079 hr'¹. Specifically, 40 seem of a gas mixture containing 2.5 mol.% methane, and 9 mol.% oxygen in balance nitrogen was fed through the reactor for 180 seconds while the reactor was held at 780 °C. Analysis of the product gas composition was taken at 60 seconds into the fuel combustion pulse. Finally, 40 seem of air was fed through the reactor for 4 minutes to conduct the 2^nd air regeneration. The product gas compositions were analyzed by a Siemens Maxim Process Gas Chromatograph. For each oxy gen-carrying material, multiple replicate reduction-oxidation cycles were performed and the C2H6 conversion, C2H4 selectivity, CO_X selectivity, FF^FU ratio, and CH4 conversion were reported at cycle 9.

[0112] Ethane conversion and carbon-based selectivities were calculated using the following equations, where [X] corresponds to the molar fraction and [IS] corresponds to internal standard.

Table 1: Selective hydrogen combustion performance of materials evaluated using the method of Example 2

[0113] As shown in Table 1, samples with silicon have improved methane combustion as compared to samples without silicon. Comparative Sample B has no silicon and has a CH4 conversion of 79.42%. Samples 1-14, which include various amounts of silicon, generally show improved CH4 conversion. For example, Sample 6 with Sii .33 has a 92.22% CH4 conversion, which is an increase of more than 12%. Additionally, samples with silicon also show improved fuel combustion and improvements in other areas compared to Comparative Sample A, which has titanium instead of silicon. Thus, the presence of silicon in oxygen carrier materials improves fuel combustion, along with other performance parameters such as H2/C2H4 ratio and ethylene conversion, as compared to oxygen carrier materials with titanium or without silicon.

[0114] Further, samples with an alkali metal (e.g., potassium) have improved H2/C2H4 ratios than samples without potassium. For example, Samples 4 and 5 are almost identical to Comparative Sample C in their relative amounts of components, except Comparative Sample C does not have an alkali metal. Samples 4 and 5 have H2/C2H4 ratios of 0.06 and 0.05, respectively. Comparative Sample C has a H2/C2H4 ratio of 0.15. This shows that the presence of an alkali metal such as potassium improves selectivity to combustion of hydrogen over combustion of hydrocarbons, such as ethylene. Samples with potassium also show a vastly improved CO_X selectivity than Comparative Sample C, which has a CO_X selectivity of 16.43%.

[0115] Samples with tungsten also show improvement in the performance data of Table 1. Comparative Sample D has no tungsten and has a CH4 conversion of only 54.79%, which is much lower than Samples 1-12 that contain tungsten.

[0116] The performance data of Table 1 indicates that oxygen carrier materials including one or more alkali metals (such as potassium), tungsten, iron, silicon, and oxygen, such as the oxygen carrier materials described herein, may have relatively high selectivity for combusting hydrogen gas over combusting hydrocarbons. Additionally, the oxygen carrier materials described herein may have acceptable or improved levels of fuel gas combustion, such as methane combustion.

[0117] Example 3 - Selective Hydrogen Combustion Performance

[0118] The selective hydrogen combustion performance of the samples was evaluated in a U-shape fixed-bed reactor made from quartz. Typically, a 125 mg sample was sized to 100-200 mesh and diluted with 400 mg quartz chips (100-200 mesh) before being loaded into the reactor. Once the sample was loaded, the upstream empty space was filled with 18-35 mesh quartz chips. The sample was heated to 750 °C under air flow, purged with helium, and then subjected to three cycles at 750 °C under 12 seem total gas flow rate. Within each cycle, the sample was first exposed to 90% C₂H₆/10% N2 for 1 min, purged with helium, and finally regenerated in air for 15 min. Outlet gas composition was analyzed using gas chromatography after 23 seconds of the ethane exposure. The presented data is the mean values across three cycles, which included C2H6 conversion, C2H4 selectivity, CO_X selectivity, and H2:C2H4 ratio.

[0119] Carbon-based ethane conversion and product selectivities were calculated using the following equations, where [X] corresponds to the molar fraction.

Table 2: Selective hydrogen combustion performance of materials evaluated using the method of Example 3

[0120] As shown in Table 2, oxygen carrier material samples with compositions as described herein have improved performance as compared to other oxygen carrier material compositions. For example, Samples 13-42 all have H2/C2H4 ratios of 0.50 or less. A lower H2/C2H4 ratio signifies that the sample has improved selectivity to combustion of hydrogen over combustion of hydrocarbons, such as ethylene. Combusting the hydrogen may generally shift the dehydrogenation reaction equilibrium towards the products. As such, a low H2/C2H4 ratio of the product effluent is generally desired.

[0121] Comparative Samples I, J, and K include titanium instead of silicon and have H2/C2H4 ratios of 0.95, 0.69, and 0.65, respectively. Comparative Sample H does not include iron. These samples all have higher H2/C2H4 ratios of Samples 13-42. Additionally, the C2H6 conversion, C2H4 selectivity, and CO_X selectivity values of Comparative Samples I, J, and K are similar to Samples 13-42. This shows that the presence of silicon improves selectivity of combustion of hydrogen over combustion of hydrocarbons while maintaining adequate or improved C2H6 conversion, C2H4 selectivity, and CO_X selectivity, and the presence of silicon and iron in oxygen carrier materials shows similar improvements.

[0122] Comparative Sample E includes only iron oxide. While Comparative Sample E does have a low H2/C2H4 ratio, this sample has poor C2H4 selectivity (58.5%) and poor CO_X selectivity (24.6%). In comparison, Samples 13-42 have C2H4 selectivity values greater than 90% and CO_X selectivity values of lower than 2%.

[0123] The performance data of Table 2 indicates that oxygen carrier materials including one or more alkali metals, tungsten, iron, silicon, and oxygen, such as the oxygen carrier materials described herein, may have relatively high selectivity for combusting hydrogen gas over combusting hydrocarbons. Additionally, the oxygen carrier materials described herein may have acceptable or improved levels of fuel gas combustion, such as methane combustion. [0124] It will be apparent to those skilled in the art that various modifications and variations can be made to the presently disclosed technology without departing from the spirit and scope of the technology. Since modifications combinations, sub-combinations and variations of the disclosed embodiments incorporating the spirit and substance of the presently disclosed technology may occur to persons skilled in the art, the technology should be construed to include everything within the scope of the appended claims and their equivalents. Additionally, although some aspects of the present disclosure may be identified herein as preferred or particularly advantageous, it is contemplated that the present disclosure is not limited to these aspects.

[0125] It is noted that the various details described in this disclosure should not be taken to imply that these details relate to elements that are essential components of the various embodiments described in this disclosure, even in cases where a particular element is illustrated in each of the drawings that accompany the present description. Unless specifically identified as such, no feature disclosed and described herein should be construed as “essential”. Contemplated embodiments of the present technology include those that include some or all of the features of the appended claims.

[0126] For the purposes of describing and defining the present disclosure it is noted that the term “about” are utilized in this disclosure to represent the inherent degree of uncertainty that may be attributed to any quantitative comparison, value, measurement, or other representation. The term “about” are also utilized in this disclosure to represent the degree by which a quantitative representation may vary from a stated reference without resulting in a change in the basic function of the subject matter at issue.

[0127] In relevant cases, where a composition is described as “comprising” one or more elements, embodiments of that composition “consisting of’ or “consisting essentially of’ those one or more elements is contemplated herein.

[0128] It should be appreciated that compositional ranges of a chemical constituent in a stream or in a reactor should be appreciated as containing, in some embodiments, a mixture of isomers of that constituent. For example, a compositional range specifying butene may include a mixture of various isomers of butene. It should be appreciated that the examples supply compositional ranges for various streams, and that the total amount of isomers of a particular chemical composition can constitute a range. [0129] It is noted that one or more of the following claims and the detailed description utilize the terms “where” or “wherein” as a transitional phrase. For the purposes of defining the present technology, it is noted that this term is introduced in the claims as an open-ended transitional phrase that is used to introduce a recitation of a series of characteristics of the structure and should be interpreted in like manner as the more commonly used open-ended preamble term “comprising.”

[0130] It should be understood that any two quantitative values assigned to a property may constitute a range of that property, and all combinations of ranges formed from all stated quantitative values of a given property are contemplated in this disclosure. Where multiple ranges for a quantitative value are provided, these ranges may be combined to form a broader range, which is contemplated in the embodiments described herein.

[0131] As would be understood in the context of the term as used herein, the term “passing” may include directly passing a substance between two portions of the disclosed system and, in some other instances, to mean indirectly passing a substance between two portions of the disclosed system. For example, indirect passing may include steps where the named substance passes through an intermediate operations unit, valve, sensor, etc.

Claims

1. An oxygen carrier material comprising a first composition, wherein at least 95 wt.% of the first composition consists of:

1 part by mole iron; from 0.001 parts by mole to 0.15 parts by mole of one or more alkali metals; from 0.001 parts by mole to 0.08 parts by mole of tungsten; from 0.05 parts by mole to 10 parts by mole of silicon; and from 1.6 parts by mole to 22 parts by mole of oxygen.

2. The oxygen carrier material of claim 1, further comprising one or more additional materials chosen from oxides of aluminum, calcium, magnesium, zirconium, boron, phosphorus, sulfur or combinations thereof.

3. The oxygen carrier material of claim 2, wherein the one or more additional materials function as binders.

4. The oxygen carrier material of claim 2, wherein at least 99 wt.% of the oxygen carrier material is the first composition and the one or more additional materials.

5. The oxygen carrier material of claim 2, wherein the oxygen carrier material comprises less than or equal to 5 wt.% of the one or more additional materials.

6. The oxygen carrier material of claim 5, wherein the oxygen carrier material comprises greater than or equal to 95 wt.% of the first composition.

7. The oxygen carrier material of any previous claim, wherein the one or more alkali metals are chosen from lithium, sodium, and potassium.

8. The oxygen carrier material of any previous claim, wherein the one or more alkali metals comprise potassium.

9. The oxygen carrier material of any previous claim, wherein at least 99 wt.% of the first composition consists of:

1 part by mole iron; from 0.001 parts by mole to 0.15 parts by mole of one or more alkali metals; from 0.001 parts by mole to 0.08 parts by mole of tungsten; from 0.05 parts by mole to 10 parts by mole of silicon; and from 1.6 parts by mole to 22 parts by mole of oxygen.

10. The oxygen carrier material of any previous claim, wherein the first composition consists of:

1 part by mole iron; from 0.001 parts by mole to 0.15 parts by mole of one or more alkali metals; from 0.001 parts by mole to 0.08 parts by mole of tungsten; from 0.05 parts by mole to 10 parts by mole of silicon; and from 1.6 parts by mole to 22 parts by mole of oxygen.

11. The oxygen carrier material of any previous claim, wherein the first composition comprises from 0.007 parts by mole to 0.08 parts by mole of tungsten.

12. The oxygen carrier material of any previous claim, wherein the oxygen carrier material has a median particle size of from 20 pm to 1000 pm.

13. A method for making the oxygen carrier material of any previous claim.

14. The method of claim 13, wherein the method comprises wet or dry impregnation.

15. The method of claim 13, wherein the method comprise solid state synthesis.