Methods for producing olefinic compounds utilizing oxygen carrier materials that include iron and silica

Abstract

Olefinic compounds may be produced by a method that may include passing a feed stream into a reactor, wherein the feed stream including one or more hydrocarbons, and passing an oxygen carrier material into the reactor. In the reactor, the one or more hydrocarbons may be dehydrogenated to form hydrogen and one or more olefinic compounds, and at least a portion of the hydrogen may be reacted with oxygen from the oxygen carrier material to produce water. At least 95 wt.% of the oxygen carrier material may consist of 1 part by mole of iron; from 0 to 1 parts by mole of the combination of one or more of strontium, calcium, magnesium, titanium, lanthanum, cerium, praseodymium, neodymium, samarium, or yttrium; from 1 to 20 parts by mole of silica; and from 1 to 3 parts by mole of oxygen that are not included in the silica.

Description

METHODS FOR PRODUCING OLEFINIC COMPOUNDS UTILIZING OXYGEN CARRIER MATERIALS THAT INCLUDE IRON AND SILICACROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application Serial No. 63 / 595,979 filed November 3, 2023, 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 chemical processing that produces olefinic materials.BACKGROUND

[0003] Olefinic compounds, such as light olefins (e.g., ethylene, butene, and propylene), may be used as base materials to produce many different materials, such as polyethylene, polypropylene, isopropanol, and acrylic acid, which may be used in, e.g., packaging, construction, and textiles. As a result of this utility, there is a worldwide demand for light olefins. Suitable processes for producing light olefins generally depend on the given chemical feed and include those that utilize fluidized catalysts. For example, light olefins may be formed by the catalytic dehydrogenation of alkanes in a fluidized bed reactor. However, there is a need for improvement in the methods used to make light olefins.SUMMARY

[0004] There is a continued need for methods for producing olefinic compounds. Described herein are methods for producing olefinic compounds by a method that may generally include forming olefinic compounds by dehydrogenation of hydrocarbons, such as alkanes. In such embodiments, an oxygen carrier material may be utilized that supplies oxygen to combust the hydrogen formed by the dehydrogenation reaction. Combusting the hydrogen may generally shift the dehydrogenation reaction equilibrium towards the products (hydrogen and olefinic compounds). It has been found that particular oxygen carrier materials, described herein, may be well suited for such a process by having relatively high selectivity for combusting hydrogen gas over combusting hydrocarbons. Particularly, oxygen carrier materials that include at least iron, oxygen, and silica, as described herein, may have such selectivity and be well suited for the methods described herein. The use of silica as compared to other known binder materials may cause enhanced selectivity for combustion of hydrogen as opposed to combustion of alkanes and / or alkenes.

[0005] According to one or more embodiments of the present disclosure, olefinic compounds may be produced by a method that may comprise passing a feed stream into a reactor, wherein the feed stream comprising one or more hydrocarbons, and passing an oxygen carrier material into the reactor. In the reactor, the one or more hydrocarbons may be dehydrogenated to form hydrogen and one or more olefinic compounds, and at least a portion of the hydrogen may be reacted with oxygen from the oxygen carrier material to produce water. At least 95 wt.% of the oxygen carrier material may consist of 1 part by mole of iron; from 0 to 1 parts by mole of the combination of one or more of strontium, calcium, magnesium, titanium, lanthanum, cerium, praseodymium, neodymium, samarium, or yttrium; from 1 to 20 parts by mole of silica; and from 1 to 3 parts by mole of oxygen that are not included in the silica.

[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(s), 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 methods for producing olefinic compounds. According to one or more embodiments of the present disclosure, the methods for producing olefinic compounds utilize the oxygen carrier materials described herein (sometimes described herein simply as “oxygen carriers”). For example, the processes may utilize an oxygen carrier material that includes at least at least iron, oxygen, silica, and optionally one or more of strontium, calcium, magnesium, titanium, lanthanum, cerium, praseodymium, neodymium, samarium, or yttrium.

[0013] 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.

[0014] 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.

[0015] 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 reactor110 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.

[0016] 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.

[0017] 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, at least a portion 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 oxygendiminished 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.

[0018] According to some embodiments, the dehydrogenation reaction in the reactor 110 may be thermally driven (i.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 600 °C to 850 °C, which may be appropriate to promote thermal dehydrogenation. 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 600 °C to 850 °C may also be utilized. Suitable dehydrogenation catalysts include, without limitation, those including platinum, platinum and gallium, platinum and tin, or chromium. 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, which is incorporated herein by reference in its entirety.

[0019] 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-|3-butylene, trans-|3-butylene, and isobutylene. In some embodiments, the olefin- containing effluent 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 olefin-containing effluent 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 olefin-containing effluent 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 olefin-containing effluent 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 olefin-containing effluent 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 reactionproducts that are not considered olefinic compounds. The olefinic compounds may be separated from unreacted components in subsequent separation steps.

[0020] 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.

[0021] 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 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.

[0022] As described herein, the oxygen carrier material is passed into the reactor 110 and subsequently out of the reactor 110. Referring again to FIG. 1, in some embodiments, the oxygen carrier material is 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 passedfrom 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 oxygendiminished 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.

[0023] 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.

[0024] As described herein, a fuel gas, such as one comprising methane, may be combusted in the regeneration unit 120. 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. 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.

[0025] In some embodiments the oxygen-rich state 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 amountof remaining oxygen is still suitable for supplying oxygen to the reactor 110 for combustion of hydrogen, as disclosed herein.

[0026] In embodiments disclosed herein, the oxygen carrier material may have a particular composition. As described herein, at least 95 wt.% of the oxygen carrier materials may consist of iron, oxygen, silica, and optionally one or more of strontium, calcium, magnesium, titanium, lanthanum, cerium, praseodymium, neodymium, samarium, or yttrium. In one or more embodiments, the oxygen carrier material may comprise or consist of active materials, which are materials that, in general, contribute to the oxygen carrying of the oxygen carrier materials described herein. Such active materials may also affect the combustion of fuels during regeneration, as is described hereinafter. In general, and as described herein, the materials aside from silica may act as active materials. In one or more embodiments, the silica may act as a binder. In some embodiments, the binder 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. As described herein, the silica may also contribute to functionality of the oxygen carrier material with respect to promotion of combustion of hydrogen over alkanes and / or alkenes in the reactor 110.

[0027] As described herein, the relative amounts of the materials of the oxygen carrier material are described in terms of relative amounts of atoms of each element that are included in the oxygen carrier material. 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 part by mole to 3 parts by mole, which means all compositions which 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.

[0028] Now turning to the oxygen carrier material of the oxygen carrier material, in one or more embodiments, 95 wt.% of the oxygen carrier material may consist of 1 part by mole iron; from 0to 1 parts by mole of the combination of one or more of strontium, calcium, magnesium, titanium, lanthanum, cerium, praseodymium, neodymium, samarium, or yttrium; from 1 to 20 parts by mole of silica; and from 1 to 3 parts by mole of oxygen that are not included in the silica. 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 oxygen carrier material may consist of 1 part by mole iron; from 0 to 1 parts by mole of the combination of one or more of strontium, calcium, magnesium, titanium, lanthanum, cerium, praseodymium, neodymium, samarium, or yttrium; from 1 to 20 parts by mole of silica; and from 1 to 3 parts by mole of oxygen that are not included in the silica.

[0029] In one or more embodiments, iron may be present in the oxygen carrier material, where iron is present in the oxygen carrier material 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.

[0030] In one or more embodiments, oxygen may be present in the oxygen carrier material in a relative amount of from 1 part by mole to 3 parts by mole, independent of the oxygen in the silica. 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 olefins, as is described herein.

[0031] In some embodiments, oxygen may be present in the oxygen carrier material, independent of the oxygen in the silica, in a relative amount of less than or equal to 3 parts by mole and at least 1.2 parts by mole, at least 1.4 parts by mole, at least 1.6 parts by mole, at least 1.8 parts by mole, at least 2 parts by mole, at least 2.2 parts by mole, at least 2.4 parts by mole, at least 2.6 parts by mole, or at least 2.8 parts by mole.

[0032] In additional embodiments, oxygen may be present in the oxygen carrier material, independent of the oxygen in the silica, in a relative amount of at least 1 part by mole and less than or equal to 2.8 parts by mole, less than or equal to 2.6 parts by mole, less than or equal to 2.4 parts by mole, less than or equal to 2.2 parts by mole, less than or equal to 2 parts by mole, less than or equal to 1.8 parts by mole, less than or equal to 1.6 parts by mole, less than or equal to 1.4 parts by mole, or less than or equal to 1.2 parts by mole.

[0033] In additional embodiments, oxygen may be present in the oxygen carrier material, independent of the oxygen in the silica, in a relative amount of from 1 part by mole to 1.2 parts by mole, from 1.2 parts by mole to 1.4 parts by mole, from 1.4 parts by mole to 1.6 parts by mole, from 1.6 parts by mole to 1.8 parts by mole, from 1.8 parts by mole to 2 parts by mole, from 2 parts by mole to 2.2 parts by mole, from 2.2 parts by mole to 2.4 parts by mole, from 2.4 parts by mole to 2.6 parts by mole, from 2.6 parts by mole to 2.8 parts by mole, from 2.8 parts by mole to 3 parts by mole, or any combination of one or more of these ranges.

[0034] In one or more embodiments, silica (i.e., silicon dioxide) may be present in the oxygen carrier material in a relative amount of from 1 part by mole to 20 parts by mole. As described herein, silica may function to enhance the physical properties of the oxygen carrier material, which may allow for the oxygen carrier to function longer without attrition from mechanical damage. Additionally, without being bound by theory, it is believed that the incorporation of silica may enhance the functionality of the oxygen carrier material by promoting combustion of hydrogen, which forms water, rather than the unfavorable combustion of alkanes and / or alkenes that forms carbon dioxide and / or carbon monoxide. For example, oxygen carrier materials that include iron and silica may better promote combustion of hydrogen than oxygen carrier materials that include iron and another binder. Other conventional binders include, without limitation, oxides of aluminum, calcium, magnesium, zirconium, niobium, or combinations thereof (including those that include silica, such as alumino-silicates). Additional conventional binders are 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, conventional binders not utilized according to some embodiments described herein include alumina (alpha, theta, or gamma crystal phases), CaAlxOy, MgALC , zirconia, and inorganic clays (e.g., kaolin, other alumina-silicates).

[0035] In some embodiments, silica may be present in the oxygen carrier material in a relative amount of less than or equal to 20 parts by mole and at least 3 parts by mole, at least 5 parts by mole, at least 7 parts by mole, at least 9 parts by mole, at least 11 parts by mole, at least 13 parts by mole, at least 15 parts by mole, at least 17 parts by mole, or at least 19 parts by mole. In additional embodiments, silica may be present in the oxygen carrier material in a relative amount of at least 1 part by mole and less than or equal to 18 parts by mole, less than or equal to 16 parts by mole, less than or equal to 14 parts by mole, less than or equal to 12 parts by mole, less thanor equal to 10 parts by mole, less than or equal to 8 parts by mole, less than or equal to 6 parts by mole, less than or equal to 4 parts by mole, or less than or equal to 2 parts by mole.

[0036] In additional embodiments, silica may be present in the oxygen carrier material in a relative amount of from 1 part by mole to 3 parts by mole, from 3 parts by mole to 5 parts by mole, from 5 parts by mole to 7 parts by mole, from 7 parts by mole to 9 parts by mole, from 9 parts by mole to 11 parts by mole, from 11 parts by mole to 13 parts by mole, from 13 parts by mole to 15 parts by mole, from 15 parts by mole to 17 parts by mole, from 17 parts by mole to 19 parts by mole, from 19 parts by mole to 20 parts by mole, or any combination of one or more of these ranges.

[0037] In one or more embodiments, the oxygen carrier material may optionally comprise a combination of one or more of strontium, calcium, magnesium, titanium, lanthanum, cerium, praseodymium, neodymium, samarium, or yttrium (sometimes referred to as “dopants” herein, where “dopants” refers to this listing of elements). That is, in some embodiments, a combination of one or more of dopants may not be present in the oxygen carrier material. Without being bound by any particular theory, it is believed that strontium, calcium, magnesium, titanium, lanthanum, cerium, praseodymium, neodymium, samarium, or yttrium may work as constituents that bind and unbind from oxygen in redox reactions by changing oxidation state. Moreover, the incorporation of these dopants may enhance combustion of hydrogen over the undesirable combustion of alkanes and / or alkenes, as is described herein, in the reactor 110.

[0038] In one or more embodiments, a combination of one or more of strontium, calcium, magnesium, titanium, lanthanum, cerium, praseodymium, neodymium, samarium, or yttrium may be present in the oxygen carrier material in a relative amount of from 0 parts by mole to 1 part by mole. In some embodiments, a combination of one or more of strontium, calcium, magnesium, titanium, lanthanum, cerium, praseodymium, neodymium, samarium, or yttrium may be present in the oxygen carrier material in a relative amount of from 0.001 parts by mole to 1 part by mole.

[0039] In some embodiments, the combination of one or more of strontium, calcium, magnesium, titanium, lanthanum, cerium, praseodymium, neodymium, samarium, or yttrium may be present in the oxygen carrier material in a relative amount of less than or equal to 1 part by mole and at least 0.05 parts by mole, at least 0.1 parts by mole, at least 0.15 parts by mole, at least 0.2 parts by mole, at least 0.25 parts by mole, at least 0.3 parts by mole, at least 0.35 parts by mole, at least 0.4 parts by mole, at least 0.45 parts by mole, at least 0.5 parts by mole, at least 0.55 parts by mole, at least 0.6 parts by mole, at least 0.65 parts by mole, at least 0.7 parts by mole, atleast 0.75 parts by mole, at least 0.8 parts by mole, at least 0.85 parts by mole, at least 0.90 parts by mole, or at least 0.95 parts by mole.

[0040] In additional embodiments, the combination of one or more of strontium, calcium, magnesium, titanium, lanthanum, cerium, praseodymium, neodymium, samarium, or yttrium may be present in the oxygen carrier material in a relative amount of at least 0.001 parts by mole and less than or equal to 0.95 parts by mole, less than or equal to 0.9 parts by mole, less than or equal to 0.85 parts by mole, less than or equal to 0.8 parts by mole, less than or equal to 0.75 parts by mole, less than or equal to 0.7 parts by mole, less than or equal to 0.65 parts by mole, less than or equal to 0.6 parts by mole, less than or equal to 0.55 parts by mole, less than or equal to 0.5 parts by mole, less than or equal to 0.45 parts by mole, less than or equal to 0.4 parts by mole, less than or equal to 0.35 parts by mole, less than or equal to 0.3 parts by mole, less than or equal to 0.25 parts by mole, less than or equal to 0.2 parts by mole, less than or equal to 0.15 parts by mole, less than or equal to 0.1 parts by mole, or less than or equal to 0.05 parts by mole.

[0041] In additional embodiments, the combination of one or more of strontium, calcium, magnesium, titanium, lanthanum, cerium, praseodymium, neodymium, samarium, or yttrium may be present in the oxygen carrier material in a relative amount of from 0 parts by mole to 0.1 parts by mole, from 0.1 parts by mole to 0.2 parts by mole, from 0.2 parts by mole to 0.3 parts by mole, from 0.3 parts by mole to 0.4 parts by mole, from 0.4 parts by mole to 0.5 parts by mole, from 0.5 parts by mole to 0.6 parts by mole, from 0.6 parts by mole to 0.7 parts by mole, from 0.7 parts by mole to 0.8 parts by mole, from 0.8 parts by mole to 0.9 parts by mole, from 0.9 parts by mole to 1 part by mole, or any combination of one or more of these ranges.

[0042] According to some embodiments, any one, two, three, four, five, six, seven, eight, nine, or all ten of strontium, calcium, magnesium, titanium, lanthanum, cerium, praseodymium, neodymium, samarium, or yttrium may be utilized as described herein. Disclosed herein are embodiments where any combination of one or more (e.g., one, two, three, four, ..., or all ten) of these elements are present in the ranges disclosed herein. In some embodiments, one or more alkaline earth metals of strontium, calcium, or magnesium may be present in the oxygen carrier material, in any of the ranges described herein. In additional embodiments, one or more of the lanthanide elements of lanthanum, cerium, praseodymium, neodymium, or samarium may be present in the oxygen carrier material, in the ranges described herein. In additional embodiments, titanium may be present in the oxygen carrier material, in the ranges described herein.

[0043] According to one or more embodiments, the oxygen carrier material does not comprise alkali metals, such as lithium, sodium, potassium, rubidium, or cesium. It is believed that the presently disclosed oxygen carrier materials may function adequately without alkali metals, which some conventional embodiments may utilize alkali metals to improve selectivity to hydrogen combustion over combustion of hydrocarbons.

[0044] 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 50 pm to 300 pm, such as from 50 pm to 250 pm, from 50 pm to 200 pm, from 50 pm to 150 pm, from 50 pm to 100 pm, from 100 pm to 300 pm, from 100 pm to 250 pm, from 100 pm to 200 pm, from 100 pm to 150 pm, from 150 pm to 300 pm, from 150 pm to 250 pm, from 150 pm to 200 pm, from 200 pm to 300 pm, from 200 pm to 250 pm, or from 250 pm to 300 pm.

[0045] In some embodiments, the oxygen-carrier material may exhibit properties known in the industry as “Geldart A” or “Geldart B” properties. Particles may be classified as “Group A” or “Group B” according to D. Geldart, Gas Fluidization Technology, John Wiley & Sons (New York, 1986), 34-37; and D. Geldart, “Types of Gas Fluidization,” Powder Technol. 7 (1973) 285-292, which are incorporated herein by reference in their entireties.

[0046] 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.

[0047] 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; no limits on bubble size; moderate levels of solids mixing and gas backmixing, assuming equal U-Umf; bothaxisymmetric 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 / cm3and 250 pm <cfp <100 pm when the density (pp) is 1 g / cm3.

[0048] 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 oxygen carrier 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 oxygen carrier 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. Silica can be added during the synthesis of the oxygen carrier to provide physical strength and stability.

[0049] In some embodiments, as described hereinabove, the oxygen carrier 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 oxygen carrier. For example, in various embodiments, the aqueous solution may comprise the one or more precursors of elements contained in the oxygen carrier material. 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.

[0050] 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, the impregnated material may be dried between each impregnation.

[0051] 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 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.

[0052] 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.

[0053] The present disclosure incudes numerous aspects, including aspects 1-15 described below.

[0054] Aspect 1. A method for producing olefinic compounds, the method comprising: passing a feed stream into a reactor, wherein the feed stream comprises one or more hydrocarbons; passing an oxygen carrier material into the reactor, wherein in the reactor: the one or more hydrocarbons are dehydrogenated to form hydrogen and one or more olefinic compounds; and at least a portion of the hydrogen is reacted with oxygen from the oxygen carrier material to produce water; wherein at least 95 wt.% of the oxygen carrier material consists of: 1 part by mole of iron; from 1 to 20 parts by mole of silica; from 1 to 3 parts by mole of oxygen that are not included in the silica; and from 0 to 1 parts by mole of the combination of one or more of strontium, calcium, magnesium, titanium, lanthanum, cerium, praseodymium, neodymium, samarium, or yttrium.

[0055] Aspect 2. The method of any previous aspect, wherein the oxygen carrier material comprises one or more of strontium, calcium, magnesium, titanium, lanthanum, cerium, praseodymium, neodymium, samarium, or yttrium.

[0056] Aspect 3. The method of any previous aspect, wherein the oxygen carrier material comprises one or more of strontium, calcium, or magnesium.

[0057] Aspect 4. The method of any previous aspect, wherein the oxygen carrier material comprises one or more of lanthanum, cerium, praseodymium, neodymium, or samarium.

[0058] Aspect 5. The method of any previous aspect, wherein the oxygen carrier material comprises one or both of titanium or yttrium.

[0059] Aspect 6. The method of any previous aspect, wherein at least 99 wt.% of the oxygen carrier material consists of: 1 part by mole of iron; from 1 to 20 parts by mole of silica; from 1 to 3 parts by mole of oxygen that are not included in the silica; and from 0 to 1 parts by mole of the combination of one or more of strontium, calcium, magnesium, titanium, lanthanum, cerium, praseodymium, neodymium, samarium, or yttrium.

[0060] Aspect 7. The method of any previous aspect, wherein the oxygen carrier material consists of: 1 part by mole of iron; from 1 to 20 parts by mole of silica; from 1 to 3 parts by mole of oxygen that are not included in the silica; and from 0 to 1 parts by mole of the combination of one or more of strontium, calcium, magnesium, titanium, lanthanum, cerium, praseodymium, neodymium, samarium, or yttrium.

[0061] Aspect 8. The method of any previous aspect, wherein: the one or more hydrocarbons comprise ethane, ethylbenzene, propane, butane, or combinations thereof; and the one or more olefinic compounds comprise ethylene, styrene, propylene, butylene, or combinations thereof.

[0062] Aspect 9. The method of any previous aspect, wherein the oxygen carrier material is cycled between the reactor and a regeneration unit, wherein the oxygen carrier material exiting the reactor is in an oxygen-diminished state and the oxygen carrier material exiting the regeneration unit is in an oxygen-rich state.

[0063] Aspect 10. The method of aspect 9, wherein a fuel gas is combusted in the regeneration unit to heat the oxygen carrier material.

[0064] Aspect 11. The method of aspect 10, wherein the fuel gas comprises methane, ethane, propane, or combinations thereof.

[0065] Aspect 12. The method of any previous aspect, wherein the oxygen carrier material does not include any alkali metals.

[0066] Aspect 13. The method of any previous aspect, wherein the reactor operates as a fluidized bed reactor.

[0067] Aspect 14. The method of any previous aspect, wherein the reactor operates at a temperature of from 600 °C to 850 °C.

[0068] Aspect 15. The method of any previous aspect, wherein a dehydrogenation catalyst is not utilized in the dehydrogenation reactor.EXAMPLES

[0069] 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.

[0070] Example 1 - Sample Preparation

[0071] Comparative Sample X was prepared by first obtaining quartz chips sourced commercially from Pyromatics and then sieving the quartz chips to 100-200 mesh before use.

[0072] Comparative Sample A was prepared by first obtaining lanthanum nitrate hexahydrate (La(NO3)3'6H2O, Sigma- Aldrich 99.999%), strontium nitrate (Sr(NO3)2, Sigma- Aldrich 99.0%), iron nitrate nonahydrate (Fe(NO3)3 -OThO, Sigma-Aldrich 98%), citric acid (CA, Alfa Aesar 99 %) and ethylene glycol (EG, Fisher Scientific 99%), all sourced commercially and used as-is. Comparative Sample A was synthesized by the Pechini method: La(NO3)3'6H2O, Sr(NC>3)2 and Fe(NO3)3'9H2O were dissolved in deionized water. Citric acid was then added in a molar ratio of CA:Fe = 5:1. The reaction mixture was stirred for 2 hours at 80 °C to ensure all of the citric acid was dissolved. Ethylene glycol was then added in a molar ratio of EG:Fe = 7.5:1. A gel precursor was then prepared by heating the clear solution to 130 °C for calcination at 10 hours. The gel was further calcined in static air at 450 °C for 3 hours and at 750 °C for 10 hours.

[0073] Comparative Sample B was prepared by first obtaining iron oxide (Fe2O3, Noah Technologies Corporation, -325 mesh, 99.95%) and titanium oxide (TiC , Sigma- Aldrich, 21 nm nanopowder, 99.5 %), both sourced commercially and used as-is. A stoichiometric amount of Fe2O3 and TiCh was weighed into a mortar. The dry powders were first ground with a pestle for 5 min. The powders were then shaken for 1 minute (min) in a separate container and replaced back into the mortar. The grinding and shaking steps were repeated for two times (in total 10 min grinding and 2 min shaking). Subsequently, the powders were ground and pasted for 5 min after introducing 5 - 10 mL of deionized H2O. 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 800 °C for 24 hours.

[0074] Comparative Sample C was prepared in the same manner as Comparative Sample B with Fe2C>3 only and the calcination was conducted at 950 °C for 6 hours.

[0075] Comparative Sample D was prepared by first obtaining SIRALOX 1.5 / 70 (Sasol, 1.5 wt. % SiC>2 / 98.5 wt. % AI2O3 dry basis), sourced commercially and used as-is. A stoichiometric amount of La(NO3)3'6H2O, Sr(NO3)2, and Fe(NO3)3'9H2O and citric acid was added to deionized water to form a concentrated solution following a molar ratio of Fe:CA = 1 :2.2. The solution was added slowly to ajar containing a desired amount of SIRALOX 1.5 / 70 while gently stirring. After addition the mixture was heated on a hot plate at 100 °C until the content became mostly dry, transferred to an alumina boat, heated stepwise at 120 °C for 5 hours, then 450 °C for 1 hour, and finally calcined at 750 °C for 6 hours.

[0076] Comparative Sample E was prepared by first obtaining SIRAL 5 (Sasol, 5 wt. % SiO2 / 95 wt. % AI2O3 dry basis), sourced commercially and used as-is. A stoichiometric amount of La(NO3)3 '61420, Sr(NO3)2, and Fe(NO3)3'9H2O was weighed and then dissolved in 100 mL deionized H2O in a 1 L beaker under vigorous stirring. Subsequently, citric acid and ethylene glycol were weighed and added to the solution according to a molar ratio of (La + Sr + Fe):CA:EG = 1 : 1 : 1. A desired amount of SIRAL 5 powder was then added to the solution while stirring. The slurry was heated to 80 °C and stirring was constant at 80 °C until gelation occurred, which was identified by < 10 mL of remaining liquid in a non- free flowing state. The gel was transferred to an alumina crucible and dried for at least 5 hours at 120 °C in air. The dried gel was calcined at 450 °C for 1 hours and finally at 750 °C for 6 hours.

[0077] Comparative Sample F was prepared by first obtaining SIRAL 40 (Sasol, 40 wt. % SiC>2 / 60 wt. % AI2O3 dry basis), sourced commercially and used as-is. Comparative Sample F was prepared in the same manner as Comparative Sample E, where SIRAL 40 was used instead of SIRAL 5.

[0078] Comparative Sample G was prepared by first obtaining PURALOX L3 (Sasol, 3 wt. % La2O3 / 97 wt. % AI2O3 dry basis), sourced commercially and used as-is. Comparative Sample G was prepared in the same manner as Comparative Sample E, where PURALOX L3 was used instead of SIRAL 5.

[0079] Comparative Samples H, I, J, and K were prepared by first obtaining cerium dioxide (CeO2, Sigma- Aldrich, < 50 nm particle size, 99.95 %), zirconium dioxide (ZrO2, Sigma- Aldrich, 5 pm, 99 %), titanium dioxide (TiO2, Sigma- Aldrich, 21 nm nanopowder, 99.5 %) and TiSol A colloidal titanium dioxide (NYACOL, 20 wt. % TiO2), all sourced commercially and used as-is.Comparative Samples H, I, J, and K were prepared in the same manner as Comparative Sample D, where CeCh solid, ZrC solid, TiCh solid, and TiSol A solution were used, respectively, instead of SIRALOX 1.5 / 70.

[0080] Comparative Sample L was prepared in the same manner as Comparative Sample K with the amount of precursors (La(NO3)3'6H2O, Sr(NC>3)2, Fe(NO3)3'9H2O, CA and TiSol A) adjusted to give a different Lao sSro JeC to TiCh weight ratio.

[0081] Comparative Sample M was prepared by first obtaining cobalt nitrate hexahydrate (CO(NO3)2-6H2O, Sigma- Aldrich 98 %) and ES757 silica (ES757 SiCh, INEOS), both sourced commercially and used as-is. A stoichiometric amount of Sr(NO3)2, Co(NO3)2'6H2O and citric acid was added to deionized water to form a concentrated solution following a molar ratio of Co:CA = 1 :2.2. The solution was added dropwise to ajar containing a desired amount of ES757 SiC>2 with gentle stirring. After addition, the mixture was heated on a hot plate at 100 °C until the mixture became mostly dry. The mixture was then transferred to an alumina boat, heated stepwise at 120 °C for 5 hours, then 450 °C for 1 hour, and finally calcined at 750 °C for 6 hours.

[0082] Comparative Sample N was prepared by first adding a stoichiometric amount of La(NO3)3'6H2O, Sr(NC>3)2, and Fe(NO3)3'9H2O and citric acid to deionized water to form a concentrated solution following a molar ratio of Fe:CA = 1 :2.2. The solution was added slowly to ajar containing a desired amount of ES757 SiCh with gentle stirring. After addition, the mixture was heated on a hot plate at 100 °C until the mixture became mostly dry. The mixture was then transferred to an alumina boat, heated stepwise at 120 °C for 5 hours, then 450 °C for 1 hour, and finally calcined at 750 °C for 6 hours.

[0083] Comparative Sample O was prepared in the same manner as Comparative Sample N, except the mixture was calcined at 450 °C for 1 hour and then 900 °C for 6 hours.

[0084] Comparative Sample P was prepared by first obtaining LUDOX® AS-30 colloidal silica (Sigma- Aldrich, 30 wt. % SiO2), sourced commercially and used as-is. Dry Fe2O3 was weighed into a mortar. Subsequently, the powders were introduced with LUDOX® AS-30 solution based on a desired final SiO2 content and ground for 10 min. The mixture was then transferred to an alumina crucible and dried for at least 2 hours at 120 °C in air. The dried mixture was then calcined in air at 750 °C for 6 hours.

[0085] Sample 1 was prepared by first obtaining fumed SiO2 (S-5505 SiO2, 0.2-0.3 pm average particle size, Sigma- Aldrich), sourced commercially and used as-is. Sample 1 was prepared in thesame manner as Comparative Sample D, where the S-5505 SiCh was used instead of SIRALOX 1.5 / 70.

[0086] Samples 2 and 3 were prepared in the same manner as Comparative Sample N, with the amount of precursors (La(NO3)3'6H2O, Sr(NC>3)2, Fe(NO3)3'9H2O, CA and ES757 SiCh) adjusted to give a different Lao sSro JeC to SiCh weight ratio.

[0087] Sample 4 were prepared in the same manner as Sample 3, except that the dried gel was calcined at 450 °C for 1 hours and finally 900 °C for 6 hours.

[0088] Sample 5 was prepared by an impregnation method. Fe(NO3)3'9H2O was dissolved in deionized water to form a concentrated solution while stirring. The solution was added dropwise to ajar containing Ineos ES757 SiCh with gentle stirring. After addition, the mixture was heated on a hot plate at 100 °C until the content was mostly dry, then transferred to an alumina boat, heated stepwise at 120 °C for 5 hours, then 450 °C for 1 hour, and finally calcined at 750 °C for 6 hours.

[0089] Sample 6 was prepared in the same manner as Sample 3, with the amount of precursors (La(NO3)3'6H2O, Fe(NO3)3'9H2O and CA) adjusted to yield LaFeCh instead of Lao sSrmFeCh.

[0090] Sample 7 was prepared in the same manner as Sample 3, with the amount of precursors (La(NO3)3'6H2O, Fe(NO3)3'9H2O and CA) adjusted to yield Lao4Fei e03 instead of Lao sSnnFeCh.

[0091] Sample 8 was prepared by first obtaining calcium nitrate tetrahydrate (Ca(NO3)3'4H2O, Sigma-Aldrich 99 %), sourced commercially and used as-is. Sample 8 was prepared in the same manner as Sample 3, with the amount of precursors (Ca(NC>3)3 ALLO, Fe(NO3)3'9H2O and CA) adjusted to yield CaFeOxinstead of Lao sSro^FeCL.

[0092] Sample 9 was prepared by first obtaining magnesium nitrate hexahydrate (Mg(NO3)2'6H2O, Sigma- Aldrich 99 %), sourced commercially and used as-is. Sample 9 was prepared in the same manner as Sample 3, with the amount of precursors (Mg(NO3)3'6Ll2O, Fe(NO3)3'9H2O and CA) were adjusted to yield MgFeOxinstead of Lao sSro^FeCL.

[0093] Sample 10 was prepared by first weighing a stoichiometric amount of La(NO3)3 -61420, Sr(NO3)2, and Fe(NO3)3'9H2O. The mixture was dissolved in 30 mL of deionized H2O in a 50 mL vial while stirring. Subsequently, citric acid and ethylene glycol were weighed and added to the metal nitrate solution according to a molar ratio of (La + Sr + Fe):CA:EG = 1 :1 :1. Separately, a desired amount of LUDOX® AS-30 solution was diluted with 70 mL of deionized H2O in a 1 L beaker. Under vigorous stirring, the metal nitrate solution was added dropwise to the diluteLUDOX® AS-30 solution. The mixed solution was heated to 80 °C with constant stirring at 80 °C until gelation occurred, which was identified by < 10 mL of remaining liquid in a non- free flowing state. The gel was transferred to an alumina crucible and dried for at least 5 hours at 120 °C in air. The dried gel was calcined at 450 °C for 1 hours and finally 750 °C for 6 hours.

[0094] Sample 11 was prepared by first obtaining LUDOX® AS-40 colloidal silica (Sigma- Aldrich, 40 wt. % SiO2), sourced commercially and used as-is. Sample 11 was prepared in the same manner as Sample 10 with LUDOX® AS-40 used instead of LUDOX® AS-30.

[0095] Samples 12 and 13 were prepared in the same manner and recipe as Samples 10 and 11, except that the dried gel was calcined at 450 °C for 1 hours and finally 900 °C for 6 hours.

[0096] Sample 14 was prepared by first dissolving Fe(NO3)3 91420 in deionized water to form a concentrated solution while stirring. Subsequently, a desired amount of LUDOX® AS-30 solution was added to the Fe-containing solution. The mixed solution was heated on a hot plate at 80 °C until the liquid was almost non-free flowing. The viscous liquid was transferred to an alumina boat, heated stepwise at 120 °C for 5 hours, then 450 °C for 1 hour, and finally calcined at 750 °C for 6 hours.

[0097] Sample 15 was prepared by first dissolving Fe(NO3)3'9H2O in deionized water to form a concentrated solution while stirring. Subsequently, citric acid and ethylene glycol were weighed and added to the metal nitrate solution according to a molar ratio of Fe:CA:EG = 1 : 1 : 1.5. A desired amount of LUDOX® AS-30 solution was added dropwise to the Fe-containing solution. The mixed solution was heated to 80 °C with constant stirring at 80 °C until gelation occurred, which was identified by < 10 mL of remaining liquid in a non-free flowing state. The gel was transferred to an alumina crucible and dried for at least 5 hours at 120 °C in air. The dried gel was calcined at 450 °C for 1 hours and finally 750 °C for 6 hours.

[0098] Sample 16 was prepared in the same manner as Comparative Sample P with the ratio between Fe2O3 and LUDOX® AS-30 altered.

[0099] Sample 17 was prepared by first obtaining iron titanium oxide (FeTiO3, Thermoscientific 99.8 %), sourced commercially and used as-is. Sample 17 was prepared in the same manner as Comparative Sample P where Fe2O3 was replaced with FeTiO3 in a different ratio between FeTiO3 and LUDOX® AS-30.

[0100] Example 2 - Selective Hydrogen Combustion Performance

[0101] The selective hydrogen combustion performance of the samples was evaluated in a U- shape fixed-bed reactor made from quartz. First, a 125 milligram (mg) sample was sized to 100-200 mesh and diluted with 400 mg quartz chips (100-200 mesh) before being loaded into the reactor. The sample was heated to 750 °C under air flow, purged with helium, and then subjected to three cycles at 750 °C under 12 standard cubic centimeters (seem) total gas flow rate. Within each cycle, the sample was first exposed to 90 % C2H6 / IO % N2 for 1 minute, purge with helium, and finally regenerated in air for 15 minutes. Outlet gas composition was analyzed using gas chromatography after 23 seconds of the ethane exposure. The presented data in Table 1 below is the averaged values across three cycles.

[0102] 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 measured at 750 °C

[0103] As shown in Table 1, samples with silica (SiCh) have improved COXselectivity and H2 / C2H4 ratio than samples without silica. For example, Comparative Sample A with no bindermaterial has a COXselectivity of 26.0% and H2 / C2H4 ratio of 5.96. Sample 1 with (SiC>2)387 has a COXselectivity of 4.0% and H2 / C2H4 ratio 0.50.

[0104] Additionally, samples with both iron and silica perform better than samples without iron and with silica and samples without both iron and silica. For example, Comparative Sample M with no iron and (SiC>2)324 has a C2H4 selectivity of 64.6%, a COXselectivity of 31.0%, and a H2 / C2H4 ratio of 3.17. In contrast, Sample 1 with iron present and (SiC>2)387 has a C2H4 selectivity 89.0%, a COx selectivity of 4.0%, and a H2 / C2H4 ratio of 0.50, showing improvement in all three measurements. Further, Comparative Sample X with no iron and no silica has a higher H2 / C2H4 ratio than samples with both iron and SiCh, such as Sample 1, indicating that the presence of iron and silica together improves selective hydrogen combustion.

[0105] Table 1 also indicates that other binder materials do not work as well as silica. Comparative Samples D-L all have different binder materials than silica and have worse performance data than samples with silica as the binder material. For example, Comparative Sample D with SiCh-doped AI2O3 as the binder has a C2H4 selectivity of 0.7%, a COXselectivity of 28.0%, and a H2 / C2H4 ratio of 1077. Sample 1 with SiCh as the binder has a C2H4 selectivity of 89.0%, a COx selectivity of 4.0%, and a H2 / C2H4 ratio of 0.50.

[0106] Finally, samples with silica present in amounts less than 1 part by mole perform worse than samples with silica present in amounts greater than 1 part by mole. For example, Comparative Samples N and O both have silica present in an amount of 0.97 parts by mole. Even an increase to 3.87 parts by mole of silica results in better overall performance in measured data, as shown in Sample 1. Additionally, Comparative Sample P, with a base composition of FeOi .5 and (Si02)o.33, has worse performance than Sample 5, with the same base composition FeOi .5 but with (SiC>2)i 33.

[0107] Therefore, Table 1 indicates that the presence of SiCh, in addition with iron, improves the selectivity of hydrogen combustion over hydrocarbons, resulting in lower amounts of COXformation, thus greatly improving ethylene selectivity, COXselectivity, and / or H2 / C2H4 ratio.

[0108] 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 ofthe present disclosure may be identified herein as preferred or particularly advantageous, it is contemplated that the present disclosure is not limited to these aspects.

[0109] 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.

[0110] 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.

[0111] 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.

[0112] 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.

[0113] 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.”

[0114] 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 statedquantitative 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.

[0115] 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

CLAIMS1. A method for producing olefinic compounds, the method comprising: passing a feed stream into a reactor, wherein the feed stream comprises one or more hydrocarbons; passing an oxygen carrier material into the reactor, wherein in the reactor: the one or more hydrocarbons are dehydrogenated to form hydrogen and one or more olefinic compounds; and at least a portion of the hydrogen is reacted with oxygen from the oxygen carrier material to produce water; wherein at least 95 wt.% of the oxygen carrier material consists of:1 part by mole of iron; from 1 to 20 parts by mole of silica; from 1 to 3 parts by mole of oxygen that are not included in the silica; and from 0 to 1 parts by mole of the combination of one or more of strontium, calcium, magnesium, titanium, lanthanum, cerium, praseodymium, neodymium, samarium, or yttrium.

2. The method of any previous claim, wherein the oxygen carrier material comprises one or more of strontium, calcium, magnesium, titanium, lanthanum, cerium, praseodymium, neodymium, samarium, or yttrium.

3. The method of any previous claim, wherein the oxygen carrier material comprises one or more of strontium, calcium, or magnesium.

4. The method of any previous claim, wherein the oxygen carrier material comprises one or more of lanthanum, cerium, praseodymium, neodymium, or samarium.

5. The method of any previous claim, wherein the oxygen carrier material comprises one or both of titanium or yttrium.

6. The method of any previous claim, wherein at least 99 wt.% of the oxygen carrier material consists of:1 part by mole of iron; from 1 to 20 parts by mole of silica; from 1 to 3 parts by mole of oxygen that are not included in the silica; and from 0 to 1 parts by mole of the combination of one or more of strontium, calcium, magnesium, titanium, lanthanum, cerium, praseodymium, neodymium, samarium, or yttrium.

7. The method of any previous claim, wherein the oxygen carrier material consists of:1 part by mole of iron; from 1 to 20 parts by mole of silica; from 1 to 3 parts by mole of oxygen that are not included in the silica; and from 0 to 1 parts by mole of the combination of one or more of strontium, calcium, magnesium, titanium, lanthanum, cerium, praseodymium, neodymium, samarium, or yttrium.

8. The method of any previous claim, wherein: the one or more hydrocarbons comprise ethane, ethylbenzene, propane, butane, or combinations thereof; andthe one or more olefinic compounds comprise ethylene, styrene, propylene, butylene, or combinations thereof.

9. The method of any previous claim, wherein the oxygen carrier material is cycled between the reactor and a regeneration unit, wherein the oxygen carrier material exiting the reactor is in an oxygen-diminished state and the oxygen carrier material exiting the regeneration unit is in an oxygen-rich state.

10. The method of claim 9, wherein a fuel gas is combusted in the regeneration unit to heat the oxygen carrier material.

11. The method of claim 10, wherein the fuel gas comprises methane, ethane, propane, or combinations thereof.

12. The method of any previous claim, wherein the oxygen carrier material does not include any alkali metals.

13. The method of any previous claim, wherein the reactor operates as a fluidized bed reactor.

14. The method of any previous claim, wherein the reactor operates at a temperature of from600 °C to 850 °C.

15. The method of any previous claim, wherein a dehydrogenation catalyst is not utilized in the dehydrogenation reactor.

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