BACKGROUND

[0001] The dehydrogenation of hydrocarbons involves the breaking of two carbon-hydrogen (C- H) bonds with the simultaneous formation of a hydrogen molecule (H ₂ ) and a molecule containing a double carbon-carbon bond (C=C). The double bond is a highly reactive point that permits the use of double bond-containing molecules as intermediates for the production of typical petrochemical products such as polymers. Dehydrogenation processes that are of significant industrial interest include dehydrogenation of low paraffins (C ₂ -C5 alkanes especially ethane, propane, w-butane, isobutane and isopentane) to produce corresponding olefins or alkenes, dehydrogenation of C ₁₀ -C15 linear paraffins to yield linear-alkyl-benzenes and ethyl benzenes that provide starting points for the production of polystyrene plastics.

[0002] Dehydrogenation of alkanes is a highly endothermic reaction owing to the relatively high bond strength of C-H bonds (about 363 kilojoules per mole (kJ/mol)) and therefore a large energy barrier for reactivity. For example, for thermal dehydrogenation of ethane into ethylene and w-butane into butylene (1-butene, trans- and m-2-butene), reported values of AH at 827°C are +145 kJ/mol and +232 kJ/mol, respectively. As a result of the endothermic nature, a continuous heat supply is required to overcome the large energy barrier for reactivity and to initiate the dehydrogenation reaction.

Unfortunately, such high temperatures also affect the selectivity of the process as they tend to favor pyrolysis or cracking of the alkanes over dehydrogenation, since C-C bonds have a much lower bond strength (about 246 kJ/mol) than C-H bonds. One strategy to overcome energy barrier and to improve the selectivity and product yield of the alkane dehydrogenation processes is the use of catalysts, such as chromium-based, platinum-based and chromia-alumina catalysts. The catalyst is normally affixed to and distributed over a solid, inert support material, for the purpose of increasing or maximizing the surface area of the catalyst. The use of catalysts can lower the reaction temperature from 750-900°C or higher (non-catalytic, thermal or steam cracking) to about 500-700°C.

[0003] One example of a catalytic dehydrogenation process is the CATOFIN™ process. In the CATOFIN™ process, the dehydrogenation of the hydrocarbon feedstock and the regeneration of the catalyst, or decoking, alternate in a cyclic or repetitive manner. Both dehydrogenation and regeneration are designed to run adiabatically, with the catalyst on the hydrocarbon feed for very short cycles (7-15 minutes (min), for example, 2-25 min, 5-20 min or 8-10 min), followed by regeneration of the catalyst for a similar period of time. Since the CATOFIN™ process is designed to be adiabatic, and in order to prevent a decrease in alkane conversion, the consumption of heat during the endothermic

dehydrogenation process needs to be closely in balance with the heat restored to the bed during the exothermic regeneration cycles. In traditional CATOFIN™ processes, the reactor or the catalyst bed is purged with hot air during the regeneration cycle in order to reheat the catalyst and remove coke which has been deposited on the catalyst bed during the endothermic dehydrogenation step. However, since the duration of the regeneration cycle is short, there is a strong likelihood for the formation of a vertical temperature gradient and pressure drop across the catalyst bed, which adversely affects the overall yield of the olefin product. Hence, with hot air flow and combustion of coke as the sole heat sources, heat input to the catalyst bed remains a critical limiting factor to CATOFIN™ dehydrogenation processes.

[0004] More recently, an alternative approach towards heat transfer to the fixed CATOFIN™ catalyst bed was developed. The CATOFIN™ process, which operates in a cyclic, reduction/oxidation mode, can be improved by the inclusion of a "heat generating material" (HGM) that functions as a catalyst additive material. The HGM, which is usually a metal or an oxide thereof, is mounted on a catalyst support and improves several key performance parameters of the dehydrogenation catalyst such as the ability to produce heat in situ while remaining inactive or inert to the hydrocarbon or alkane feed and the olefin products, and the absence of any negative impact on the activity, selectivity or lifetime of the catalyst (U.S. Patents 7,622,623 and 7,973,207; Oviol, L, Brans, M, Fridman, V, Merriam, J, Urbancic, M, "Mind the gap", published by Clariant Catalysis and Energy, formerly Siid-Chemie - each incorporated herein by reference in its entirety). Nevertheless, the heat-generating material is not inert towards the reducing and/or oxidizing conditions of the CATOFIN™ process.

[0005] Hence, a delicate balance of multiple parameters and factors has to be maintained to ensure that dehydrogenation processes can have a high yield or high selectivity of the desired product(s) with as little external heat energy input as possible. Thus, there is a need for methods of improving processes for dehydrogenation of hydrocarbons, specifically dehydrogenation processes that incorporate the use of a catalyst and a heat-producing material. These methods utilize the heat property characteristics of the heat-producing material as a basis for modifying the dehydrogenation and regeneration cycles of industrial scale dehydrogenation processes.

BRIEF SUMMARY

[0006] A method of determining a remaining amount of a metal and a remaining amount of an oxide of the metal in a catalyst system present on a support material after a hydrocarbon has been dehydrogenated with the catalyst system, comprises: dehydrogenating a hydrocarbon in a

dehydrogenation reactor with the catalyst system to form a catalyst system product; separately reacting one or more amounts of the metal oxide loaded on the support material with a reducing gas to provide one or more enthalpies of reduction corresponding to the one or more amounts of the metal oxide; measuring the one or more enthalpies of reduction with a differential scanning calorimeter to obtain a plurality of reduction enthalpy data points; subjecting the plurality of reduction enthalpy data points to linear regression to obtain a first calibration curve of a DSC-measured reduction enthalpy versus metal oxide amount and a first equation thereof; separately reacting one or more amounts of the metal loaded in the catalyst system with an oxidizing gas to provide one or more enthalpies of oxidation corresponding to the one or more amounts of the metal; measuring the one or more enthalpies of oxidation with the differential scanning calorimeter to obtain a plurality of oxidation enthalpy data points; subjecting the plurality of oxidation data points to linear regression to obtain a second calibration curve of a DSC-measured oxidation enthalpy versus metal amount and a second equation thereof; measuring an enthalpy of dehydrogenation for the catalyst system product after dehydrogenating the hydrocarbon in the presence of the catalyst system; deriving the remaining amount of the metal oxide in the catalyst system product from the first calibration curve and the remaining amount of the metal in the catalyst system product from the second calibration curve based on the measured enthalpy of dehydrogenation; and calculating a ratio of M _Red /M(3o _x based on the remaining amount of the metal oxide and the remaining amount of the metal and replenishing or replacing the catalyst system present in the dehydrogenation reactor with a new catalyst system if the ratio is less than 0.8.

[0007] These and other features and characteristics are more particularly described below. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The following is a brief description of the drawings wherein like elements are numbered alike and which are presented for the purposes of illustrating the exemplary embodiments disclosed herein and not for the purposes of limiting the same.

[0009] FIG. 1 is a calibration curve of the change of metal oxide (MO) in weight percentage versus the heat of the reaction in the presence of a reducing gas as measured by DSC.

[0010] FIG. 2 is a calibration curve of the change of metal (M) in weight percentage versus the heat of the reaction in the presence of an oxidizing gas as measured by DSC.

[0011] FIG. 3 A is an XRD spectrum of pure and unsupported CuO (CuO- 100).

[0012] FIG. 3B is an XRD spectrum of CuO-5 on γ-Α1 ₂ 0 ₃ .

[0013] FIG. 3C is an XRD spectrum of unloaded γ-Α1 ₂ 0 _3.

[0014] FIG. 4A is a TPR profile of CuO-5 having a maximum reduction position at 191°C.

[0015] FIG. 4B is a TPR profile of a reference sample, CuO- 100, having a maximum reduction position at 213°C.

[0016] FIG. 4C is a graph showing temperature at maximum as a function of CuO loading on γ-

A1 ₂ 0 ₃ .

[0017] FIG. 5 A is a SEM image of Cu reduced from pure and unsupported CuO (CuO- 100) after a TPR experiment.

[0018] FIG. 5 B is an EDX spectrum showing a near complete reduction of unsupported CuO to Cu after a TPR experiment.

[0019] FIG. 5C is a BSE-SEM image of CuO-20 on γ-Α1 ₂ 0 ₃ after a TPR experiment.

[0020] FIG. 5D is an X-ray mapping image of CuO-20 on γ-Α1 ₂ 0 ₃ after a TPR experiment highlighting Al as bright Z particles.

[0021] FIG. 5E is an X-ray mapping image of CuO-20 on γ-Α1 ₂ 0 ₃ after a TPR experiment highlighting Cu as bright Z particles.

[0022] FIG. 5 F is an X-ray mapping image of CuO-20 on γ-Α1 ₂ 0 ₃ after a TPR experiment highlighting O as bright Z particles. [0023] FIG. 6A is a representative heat flow (W/g) curve for a reduction reaction of pure and unsupported CuO (CuO-100) in 5% H ₂ in Ar using dynamic scanning from room temperature to 600°C.

[0024] FIG. 6B is a representative heat flow (W/g) curve for a reduction reaction of pure and unsupported CuO (CuO-100) in 5% ¾ in Ar using isothermal scanning at 550°C.

[0025] FIG. 7A is a graph showing heat generation as a function of CuO loading in reducing and oxidizing environments as measured by DSC.

[0026] FIG. 7B is a graph showing heat generation as a function of CuO loading in a reducing environment as measured by DSC.

[0027] FIG. 7C is a graph showing heat generation as a function of CuO loading in an oxidizing environment as measured by DSC.

[0028] FIG. 8A is a SEM image showing the surface morphology of a sample pan used for DSC measurements of CuO- 10.

[0029] FIG. 8B is a SEM image showing the surface morphology of a sample pan used for DSC measurements of CuO-100 (pure and unsupported CuO).

[0030] FIG. 9 is a block diagram of an exemplary computer system through which the DSC enthalpy measurements, calibration processes, and quantifications of the oxidized and reduced forms of the heat-producing material of the present invention can be implemented.

DETAILED DESCRIPTION

[0031] In the present disclosure, there is provided a method of quantifying the amount of metal

(M) and the oxide thereof (MO) of a heat-producing material after dehydrogenation of dehydrogenatable hydrocarbons. The heat-producing material, including both of its oxidized and reduced forms, is usually deposited on a support material. In the method, several known amounts of a heat-producing material sample weighing, for example, no more than 20 milligrams (mg) (e.g. 1, 2.5, 5, 10, 15, 20 mg), together with a fixed amount of an inert material (e.g. alumina), are subjected to conditions that simulate reduction and oxidation cycles of the dehydrogenation process. The enthalpies of reduction and oxidation are then measured by differential scanning calorimetry (DSC) and two calibration curves of the change in mass for the metal oxide or metal versus the DSC-measured enthalpy of reduction or enthalpy of oxidation, such as the calibration curves shown in FIGS. 1 and 2 are obtained, respectively. FIG. 1 is a calibration curve of the change of metal oxide (MO) in weight percentage versus the heat of reduction as measured by DSC while FIG. 2 is a calibration curve of the change of metal (M) in weight percentage versus the heat of oxidation, also measured by DSC. The calibration curves in FIGS. 1 and 2 have been fit to a straight line, using linear regression analysis, thereby yielding the linear equation AH= a(MO) + b or AH= a(M) + b. It is noted that if the support material is inert or inactive towards the heat-producing material as well as the simulated reduction and oxidation cycles and the same heat-producing material is used, the calibration curves can be applied to heat-producing materials that are loaded on a different support material. The method can serve on a pilot scale, preliminary study that is conducted in order to evaluate factors such as feasibility, time, cost, statistical variability in an attempt to predict an appropriate amount of the heat- producing material, appropriate durations of the reduction and oxidation cycles for a full-scale dehydrogenation process.

[0032] Spectroscopy techniques such as X-ray photoemission spectroscopy (XPS), energy dispersive X-ray analysis (EDX) and X-ray diffraction analysis (XRD) are used to provide an accurate measurement of the elemental composition of a sample, including the empirical formula, chemical state and electronic state of the elements that exist within a material. The method proposed herein, which adopts a DSC thermal measurement followed by calibration approach, can allow the amount of the heat- producing material in both oxidized and reduced forms to be accurately determined after a

dehydrogenation process without using XPS, EDX or XRD processes or facilities.

[0033] In summary, as disclosed herein, the method of determining a remaining amount of a metal and a remaining amount of an oxide of the metal in a catalyst system present on a support material after a hydrocarbon has been dehydrogenated with the catalyst system can include:

(a) dehydrogenating a hydrocarbon in a dehydrogenation reactor with the catalyst system to form a catalyst system product,

(b) separately reacting one or more amounts of the metal oxide loaded on the support material with a reducing gas to provide one or more enthalpies of reduction corresponding to the one or more amounts of the metal oxide,

(c) measuring the one or more enthalpies of reduction with a differential scanning calorimeter to obtain a plurality of reduction enthalpy data points,

(d) subjecting the plurality of reduction enthalpy data points to linear regression to obtain a first calibration curve of a DSC-measured reduction enthalpy versus metal oxide amount and a first equation thereof,

(e) separately reacting one or more amounts of the metal loaded in the catalyst system with an oxidizing gas to provide one or more enthalpies of oxidation corresponding to the one or more amounts of the metal,

(f) measuring the one or more enthalpies of oxidation with the differential scanning calorimeter to obtain a plurality of oxidation enthalpy data points,

(g) subjecting the plurality of oxidation data points to linear regression to obtain a second calibration curve of a DSC-measured oxidation enthalpy versus metal amount and a second equation thereof,

(h) measuring an enthalpy of dehydrogenation for the catalyst system product after

dehydrogenating the hydrocarbon in the presence of the catalyst system,

(i) deriving the remaining amount of the metal oxide in the catalyst system product from the first calibration curve and the remaining amount of the metal in the catalyst system from the second calibration curve based on the measured enthalpy of dehydrogenation, and

(j) calculating a ratio of M _Red /M(¾x based on the remaining amount of the metal oxide and the remaining amount of the metal and replenishing or replacing the catalyst system present in the dehydrogenation reactor with a new catalyst system if the ratio is less than 0.8.

[0034] The dehydrogenation processes to which the DSC quantification method can be applied generally follow but are not limited to the Houdry CATOFIN™ process as described in U.S. Patent 2,419,997 (incorporated herein by reference in its entirety), wherein light aliphatic hydrocarbons from crude oil, such as alkanes, are catalytically dehydrogenated to their corresponding mono- or di-olefins by a dehydrogenation catalyst, in an adiabatic, non-oxidative and repetitive manner. Advantageously, these dehydrogenation processes take place in equipment or a reactor that contains at least one fixed catalyst bed that is packed with a catalyst system. The catalyst system usually includes at least three main components: a dehydrogenation catalyst, a heat-reproducing material and a solid, inert material that serves as a carrier supporting the catalyst and the heat-producing material.

[0035] The enthalpy of reaction (AH), or heat of reaction, is the change in the enthalpy of a chemical reaction that occurs at a constant pressure. The enthalpy of reaction is the amount of heat that must be added or removed during a chemical reaction in order to keep all of the substances present at the same temperature. In a reduction or oxidation reaction, the heat of reaction can be referred to as the heat/enthalpy of reduction or heat/enthalpy of oxidation, respectively. If AH is positive, the reaction is endothermic because heat is absorbed by the system due to the products of the reaction having a greater enthalpy than the reactants. On the other hand, if AH is negative, the reaction is exothermic and the overall decrease in enthalpy in the reaction is achieved by the generation or release of heat. Also, as used herein, the enthalpy of dehydrogenation refers to the net enthalpy of a dehydrogenation process comprising at least one reduction cycle and at least one regeneration cycle. The information can be provided by a device capable of measuring the heat of chemical reactions, including but not limited to an adiabatic calorimeter, a heat flow calorimeter, a heat balance calorimeter, a bomb calorimeter, a constant- pressure calorimeter, a differential scanning calorimeter, an isothermal titration calorimeter and any other acceptable and equivalent enthalpy sensor, enthalpy meter or enthalpy/heat measuring device, which can be installed and connected to a laboratory-scale reactor wherein the dehydrogenation is carried out.

[0036] One way to measure the heat of reaction is by calorimetry. Calorimetry involves the experimental quantification of heat released in a chemical process, either a reaction or a conformational alteration. Calorimetry uses a closed system, which is a system separated from its surroundings by some boundary, through which heat and energy but not mass are able to flow. Calorimetry can be conducted at either constant pressure or volume and allows one to monitor the change in temperature as a result of the chemical process being investigated.

[0037] In the present disclosure, the pressure is held constant at atmospheric pressure for all

DSC measurements. Differential scanning calorimetry (DSC) is a specific type of calorimetry including both a sample substance and a reference substance, residing in separate chambers. In DSC, the difference in heat flow to the sample and a reference at the same temperature is recorded as a function of temperature. DSC can be executed in at least two different modes, namely dynamic scanning and isothermal scanning. In one embodiment, the DSC technique utilized for measuring the enthalpy of oxidation or reduction by the heat-producing material is an isothermal DSC technique. Isothermal DSC is accomplished by fixing the temperature for both the sample and the reference. In isothermal DSC, the sample and reference are preheated to a reaction temperature under an inert atmosphere, then switched to the reaction atmosphere and any heat flow changes are observed as a deviation from the baseline value at a constant temperature.

[0038] In one embodiment, the temperature of the sample and reference in the isothermal DSC process is increased prior to reduction with a heating ramp rate of 5-15°C/min, for example, 8-12°C/min.

[0039] In one embodiment, the temperature effective for reducing the heat-producing material and the temperature effective for oxidizing the heat-producing material in the isothermal process can be the same temperature, which can be 300-800°C, for example 400-700°C, for example, 500-600°C.

Durations for the simulated reduction and oxidation cycles can be 1-30 min, for example, 2-25 min, for example, 3-20 min, for example, 7-15 min.

[0040] Unlike isothermal DSC, a dynamic DSC technique which can also be used in the present disclosure measures the heat of reaction as a function of a linear thermal response. Therefore, the heat flow of the sample and reference are typically monitored across a varying temperature range, and the temperature is usually varied linearly at a fixed rate. Generally, the temperature program for a dynamic DSC analysis is designed such that the sample holder temperature increases linearly as a function of time. Since the DSC is at constant pressure, heat flow is equivalent to enthalpy changes:

H = dQ/dt) dt (Equation 1) (Equation 2)

[0041] In accordance with the present disclosure, the sample substances contain varying known amounts of the heat-producing material in a reduced or oxidized form and a known and fixed amount of a solid, inert material, simulating the heat-producing material being mounted on an inert catalyst support material. The sample substances of varying known amounts can weigh, for example, less than or equal to 20 mg (e.g. 1, 2.5, 5, 10, 15, 20 mg), for example, 10-20 mg (e.g. 10, 12, 14, 16, 18, 19, 20 mg). These sample substances can contain 0.1-50 weight percent (wt. %) of the heat-producing material, based on the total weight of the heat-producing material and the inert material, for example, 0.5-40 wt. %, for example, 1-30 wt. %, for example, 5-25 wt. %. The reference substance contains only the solid, inert material. These solid, inert materials are advantageously the same materials that catalyst supports are composed of, and are therefore alumina-based, magnesia-based, silica-based, zirconia-based, zeolite-based or a combination comprising at least one of the foregoing. The inert materials, like catalyst supports, should also be thermally stable, being able to withstand high temperatures of up to 800°C, for example, 500- 800°C, for example, 550-750°C, for example, 600-700°C. The inert materials should also be inert towards the heat-producing material (oxidized and reduced), the reducing gas and the oxidizing gas. In certain embodiments, the alumina-based inert material can be comprised of a plurality of different crystallographic phases. Examples of alumina-based inert material include but are not limited to aluminum oxide, alumina, alumina monohydrate, alumina trihydrate, alumina-silica, bauxite, calcined aluminum hydroxides such as gibbsite, bayerite and boehmite, a-alumina, transition aluminas such as γ- alumina, η-alumina and δ-alumina, calcined hydrotalcite, or a combination comprising at least one of the foregoing. In one embodiment, the inert material in the reference substance is γ-Α1 ₂ θ ₃ .

[0042] While the reference chamber contains only a reference substance, the sample chamber contains an equal amount of the same reference substance in addition to the substance of interest. In one embodiment the DSC measurement is therefore a thermoanalytical technique in which the difference in the amount of heat required to increase the temperature of a sample and a reference sample is measured as a function of temperature. Both the sample and reference are maintained at nearly the same temperature throughout the experiment. The reference sample should have a well-defined heat capacity over the range of temperatures to be scanned. The basic principle underlying DSC is that when the sample undergoes a physical transformation or transition such as a redox reaction, more or less heat will need to flow to it than the reference to maintain both at the same temperature. By observing the difference in heat flow between the sample and reference, differential scanning calorimeters are able to measure the amount of heat absorbed or released during such transitions.

[0043] To simulate the reduction cycle of a dehydrogenation process, the sample- and reference- containing DSC pans and chambers are initially purged with pure N ₂ or pure Ar to create an inert atmosphere. To measure the enthalpy of reduction, the varying, known amounts of heat-producing material (oxidized form, MO) as previously described are reduced in the presence of a reducing gas. A reducing gas can be any gas with a low oxidation number, and which is usually, but not always, hydrogen-rich. Examples of such reducing gases include, but are not limited to, CI¾, H ₂ , NH ₃ , H ₂ S, CO, or a combination comprising at least one of the foregoing. In one embodiment, the reducing gas is H ₂ .

[0044] In one embodiment, the reducing gas is a gaseous mixture comprising H ₂ and Ar, wherein the H ₂ is present in gaseous mixture in 1-95%, for example, 1-75%, for example, 1-50%, for example, 1-40%, for example, 1-30%, for example, 1-10% by volume relative to the total volume of the gaseous mixture.

[0045] In an alternative embodiment, the reducing gas is substantially pure H ₂ .

[0046] Similarly, to simulate the regeneration cycle of a dehydrogenation process, after the inert gas purging, the varying, known amounts of heat-producing material (reduced form, M) are oxidized in the presence of an oxidizing gas such as 0 ₂ or air.

[0047] In one embodiment, the oxidizing gas is natural air. Natural air refers to the gaseous mixture that makes up the earth's atmosphere. Natural air consists essentially of 77-79% N ₂ , 20-21% 0 ₂ , 0.9-1.0% Ar, and 0.03-0.04% C0 ₂ in terms of % volume.

[0048] In one embodiment the oxidizing gas is synthetic air. Synthetic air is a gaseous mixture consisting essentially of 75-85% N ₂ and 15-25% 0 ₂ by volume.

[0049] In one embodiment, the oxidizing gas is substantially pure 0 ₂ .

[0050] Dehydrogenatable hydrocarbons, as used herein refer to any hydrocarbon molecule that can be aliphatic or aromatic, cyclic or non-cyclic, linear or branched, substituted or unsubstituted (e.g. with a halide group), that can be thermally and/or chemically induced to have two of its carbon-hydrogen (C-H) bonds broken with the simultaneous formation of either a hydrogen molecule (non-oxidative dehydrogenation) or a water molecule (oxidative dehydrogenation where the hydrogen is oxidized to water) and a molecule containing at least one double or triple carbon-carbon bond (C=C or C≡C). For example, an alkane which is a saturated hydrocarbon can be dehydrogenated into a corresponding alkene. An alkene can be dehydrogenated into a corresponding alkyne having at least one C≡C bond or a corresponding diene having two C=C bonds. In some embodiments, dehydrogenation of hydrocarbons refer generally to dehydrogenation of alkanes, especially aliphatic, low alkanes such as but not limited to ethane, propane, w-butane, isobutane and isopentane, each of which can individually be dehydrogenated into ethylene, propylene, butylene (1-butene, trans- and m-2-butene), isobutylene and isoprene, respectively.

[0051] The dehydrogenation catalyst is selected from a noble metal or a Group VII metal such as platinum that is optionally alloyed with tin (e.g. PtSn, PtSn ₂ , Pt ₂ Sn ₃ and Pt ₃ Sn), a transition metal such as chromium, iron and copper, an oxide and a mixture and/or an alloy thereof, and a post-transition metal such as gallium, an oxide and/or an alloy thereof. In certain embodiments, the dehydrogenation catalyst is chromium-based (i.e. chromium/chromium oxide or chromia). The dehydrogenation catalyst must be able to accept repeated cycles of the CATOFIN™ process which alternate between reducing and oxidizing atmospheres. In certain embodiments, the dehydrogenation catalyst can be regenerated using steam. In some embodiments, the average particle size of the dehydrogenation catalyst can exceed 100 nanometers (nm), for example, 0.1-100 micrometers (μπι), for example, 10-90 μπι, for example, 25-75 μπι. In other embodiments, the dehydrogenation catalyst can be classified as a nanocatalyst or a nanomaterial-based catalyst wherein at least one dimension of the catalyst particle is of nanoscale and the average particle size is 1-100 nm, for example, 10-90 nm, for example, 20-75 nm. Particle sizes can be determined by techniques such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction analysis (XRD), or a combination comprising at least one of the foregoing.

[0052] The heat-producing material, as previously explained herein, is a catalyst additive material that is capable of producing heat in situ while remaining inactive or inert to the hydrocarbon or alkane feed and the olefin products. The characteristics and properties of one type of the heat-producing material are as defined in U.S. Patent 7,622,623, which is incorporated herein by reference in its entirety. An accepted mechanism of heat generation by the heat-producing material is as follows: During the reduction stage of a CATOFIN™ process, wherein a catalyst bed is evacuated and reduced with hydrogen, the oxide of the heat-producing material (MO) is reduced with the generation of heat (Reaction 1). During the regeneration stage of the cycle which exposes the heat-producing material to an oxidizing condition, the reduced heat-producing material (M) is converted to the oxide form providing an additional amount of heat (Reaction 2):

MO + H ₂ → M + H ₂ 0; ΔΗ < 0 (Reaction 1) M + 0 ₂ → MO; ΔΗ < 0 (Reaction 2)

[0053] In other words, both the oxidation and reduction reactions of the heat -producing material are advantageously exothermic and accompanied by the release of heat. After performing a deliberate calibration process with DSC and obtaining the calibration curves of FIGS. 1 and 2 as previously described, the quantification method provided herein can determine the following:

i. MO _Red - The amount of MO that remains unreduced after a reduction cycle (Reaction 1); ii. Ai _Red : The amount of M that is generated after a reduction cycle (Reaction 1);

iii. MOo _x :The amount of MO that is recovered from oxidation after a regeneration cycle

(Reaction 2);

iv. M ₀ : The amount of M that remains unoxidized after a regeneration cycle (Reaction 2); v. MO _aet : The net amount of MO at the end of a dehydrogenation process comprising both the reduction and regeneration cycles (Reaction 1 + Reaction 2); and

vi. M _aet : The net amount of M at the end of a dehydrogenation process comprising both the reduction and regeneration cycles.

[0054] In some embodiments, the MO and M amounts can be expressed as weight ratios such as MO _Re JM _eA , M ₀ JMOo , M _a MO _aet , M _Red /M(¾x and MO _aet IMOo . These indices can be used as a measure of the efficiency of a dehydrogenation process. For example, when a dehydrogenation process operates with all conditions being fully optimized (e.g. reduction/regeneration temperatures,

reduction/regeneration durations, dehydrogenation catalyst amount and heat-producing material's amount) and all reactant hydrocarbons and reducing/oxidizing gases being in stoichiometric equilibrium, the amount of MO that remains unreduced after a reduction cycle, the amount of M that remains unoxidized after a regeneration cycle and the net amount of M at the end of a dehydrogenation process comprising both the reduction and regeneration cycles should be close to zero and therefore the indices MO _Re JM _eA , MoJMOo _x and M _aet IMO _aet should also be approximately equal to 0. For a new catalyst system that has not been used or spent, each of these indices has a value equal to 0. The amount of M that is generated after a reduction cycle should be closely similar to the amount of MO that is recovered from oxidation after a regeneration cycle and therefore M _Re MOo^ should also be approximately 1. Similarly, the net amount of MO at the end of a dehydrogenation process comprising the reduction and regeneration cycles should also be closely similar to the amount of MO that is recovered from oxidation after a regeneration cycle so MO _net /M0 _0x should also be approximately equal to 1. For a new catalyst system that has not been used or spent, each of these indices has a value equal to 1.

[0055] In certain embodiments, the catalyst system is replenished or replaced when at least one of the MO _Red /M _Red , M ₀ M0 _0x and M _a JMO _aet , as well as M _Red /M0 ₀ and MO _a JM0 ₀ indices as defined above reaches a threshold level, i.e. greater than 0.2 for MO _Re M _Re i, Mo MOo^ and M _n JMO _net and/or less than 0.8 for M _Re MOo^ and MO _n MOo^. To replenish the catalyst system, the catalyst system can be subjected to presulfiding during the regeneration cycle of the CATOFIN dehydrogenation process. As used herein, presulfiding is a practice whereby sulfur is deposited on the surface of the catalyst in situ or ex situ through the use of a sulfiding agent such as but not limited hydrogen sulfide, methyl mercaptan, dimethyl sulfide or dimethyl sulfoxide. The presulfiding practice reduces the extent of early catalyst deactivation by preventing coking or carbon deposits. If one or more of the indices continue to measure below 0.8 after the presulfiding treatment, the catalyst system in the dehydrogenation reactor is replaced with a new one. In general, the heat-producing material according to the present disclosure comprises a metal and an oxide thereof. In some embodiments, the heat-producing material is a metal and an oxide thereof selected from transition metals, post-transition metals and lanthanide metals.

[0056] The oxidation and reduction reactions of these metals can both be exothermic, where the metals can be selected from copper, chromium, molybdenum, vanadium, yttrium, scandium, tungsten, manganese, iron, cobalt, nickel, silver, bismuth, cerium, or a combination comprising at least one of the foregoing. In one embodiment, the heat-producing material is CuO/Cu of a partially reduced form. In some embodiments, the heat-producing material can be a semimetal chosen from boron, silicon, germanium, arsenic, antimony, tellurium, polonium, astatine, or a combination comprising at least one of the foregoing. Due to the toxicity or radioactivity of some of these semimetal elements, boron, silicon, germanium, antimony and tellurium can be desired.

[0057] The heat-producing material is inert towards dehydrogenation reactions including the hydrocarbon feed, the olefin products and other side reactions of the CATOFIN process such as cracking or coking. In this sense the term "inert" is used to mean that under the conditions of the dehydrogenation reaction, the heat-producing material does not catalyze the dehydrogenation of alkanes. The heat- producing material which is in direct contact with the dehydrogenation catalyst, does not participate in, is unaffected by, and/or is inactive, in the dehydrogenation reaction. For example, the heat-producing material is inert in a dehydrogenation reaction that produces propylene from propane. In the context of catalysts, where a metal/metal oxide catalyst useful in dehydrogenation reactions is mixed with the heat- producing material, the heat-producing material is considered to be inert and, as such, is understood to not directly affect, and not be directly affected by, the dehydrogenation reaction being catalyzed by the metal/metal oxide catalyst. However, without being bound by theory, it is believed that the heat- producing material can affect the conversion, selectivity, etc., of the dehydrogenation reaction.

[0058] As used herein, the "alkane conversion" or simply "conversion" refers to the percentage of the total moles of feed (C ₂ -C ₂₀ , for example, C ₂ -C5 alkanes) that have been consumed by the reaction, i.e. the portion of the feed that has been consumed that is actually converted to the desired product (e.g. an olefin), regardless of other products. In general, selectivity is calculated as follows:

moles o f feed converted . .

feed conversion (%) = x 100 (Equation 3)

moles of feed supplied

[0059] The "selectivity of a particular product", or simply "selectivity", is the percentage of the percentage of the total moles of feed that have been consumed by the reaction, i.e. the portion of the feed that has been consumed that is actually converted to the desired product, regardless of other products. In general, selectivity is calculated as follows: selectivity (%)

moles of desired product produced number of carbon atoms in product

= x x 100 moles of feed converted number of carbon atoms in feed

(Equation 4)

[0060] The "product yield", or simply "yield", as used herein, refers to the percentage of the total moles of the desired product (olefin) that would have been formed if all of the feed is converted to the product, as opposed to unwanted side products, e.g. acetic acid and CO _x compounds), and is generally calculated as follows:

moles of product produced number of carbon atoms in product product yield (%) = —— x . . , x 100

moles of feed supplied number of carbon atoms in feed

(Equation 5)

[0061] The heat-producing material is reactive towards the reducing and/or oxidizing conditions of a CATOFIN™ process (reduction and regeneration stages). Further, the heat-producing material does not adversely affect the activity, selectivity or lifetime of the dehydrogenation catalyst. In certain embodiments, the inclusion of the heat-producing material in the fixed catalyst bed can permit the use of lower air inlet temperatures to the reactor and reduce the combustion of coke and coke buildup, thereby eliminating the exposure of the olefin product to high temperatures that can otherwise result in byproduct formation and impairment of product selectivity. The generation of heat internal to a reactor reduces the necessity of additional heat supply through hot air and coke combustion, leading to the reduction of overall utility cost and increases the overall olefin yield for a given size of a reactor.

[0062] The differential scanning calorimeter can be connected to and coordinated with a computer system. Hence, the DSC laboratory-scale enthalpy measurements, calibration, derivation of the calibration curves and determination of oxidized heat -producing material and reduced heat-producing material amounts after a full-scale dehydrogenation (including index calculations) are all computer- implemented processes. FIG. 9 is a block diagram of an exemplary computer system through which all of the aforementioned processes can be implemented. A hardware description of the computer system 900 with reference to FIG. 9 is provided in the following paragraphs. In FIG. 9, the computer system 900 includes a CPU 930 which performs the processes described above. The process data and instructions can be stored in memory 902. These processes and instructions can also be stored on a storage medium disk 904 such as a hard drive (HDD) or portable storage medium or can be stored remotely. Further, the claimed advancements are not limited by the form of the computer-readable media on which the instructions of the inventive process are stored. For example, the instructions can be stored on CDs, DVDs, in FLASH memory, RAM, ROM, PROM, EPROM, EEPROM, hard disk or any other information processing device with which the computer system 900 communicates, such as a server or computer.

[0063] Further, the claimed advancements can be provided as a utility application, background daemon, or component of an operating system, or combination thereof, executing in conjunction with CPU 930 and an operating system such as Microsoft Windows 7, UNIX, Solaris, LINUX, Apple MAC- OS and other systems known to those skilled in the art.

[0064] CPU 930 can be a Xenon or Core processor from Intel of America or an Opteron processor from AMD of America, or can be other processor types that would be recognized by one of ordinary skill in the art. Alternatively, the CPU 930 can be implemented on an FPGA, ASIC, PLD or using discrete logic circuits, as one of ordinary skill in the art would recognize. Further, CPU 930 can be implemented as multiple processors cooperatively working in parallel to perform the instructions of the inventive processes described above.

[0065] The computer system 900 in FIG. 9 also includes a network controller 906, such as an Intel Ethernet PRO network interface card from Intel Corporation of America, for interfacing with network 928. As can be appreciated, the network 928 can be a public network, such as the Internet, or a private network such as an LAN or WAN network, or any combination thereof and can also include PSTN or ISDN sub-networks. The network 928 can also be wired, such as an Ethernet network, or can be wireless such as a cellular network including EDGE, 3G and 4G wireless cellular systems. The wireless network can also be WiFi, Bluetooth, or any other wireless form of communication that is known.

[0066] The computer system 900 further includes a display controller 908, such as a NVIDIA GeForce GTX or Quadro graphics adaptor from NVIDIA Corporation of America for interfacing with display 910, such as a Hewlett Packard HPL2445w LCD monitor. A general purpose I O interface 912 interfaces with a keyboard and/or mouse 914 as well as a touch screen panel 916 on or separate from display 910. General purpose I/O interface also connects to a variety of peripherals 218 including printers and scanners, such as an OfficeJet or DeskJet from Hewlett Packard. A sound controller 920 is also provided in the computer system 920, such as Sound Blaster X-Fi Titanium from Creative, to interface with speakers/microphone 922 thereby providing sounds and/or music. The general purpose storage controller 924 connects the storage medium disk 904 with communication bus 926, which can be an ISA, EISA, VESA, PCI, or similar, for interconnecting all of the components of the computer system 900. A description of the general features and functionality of the display 910, keyboard and/or mouse 914, as well as the display controller 908, storage controller 924, network controller 906, sound controller 920, and general purpose I/O interface 912 is omitted herein for brevity as these features are known.

[0067] Further, the quantification method as described in the present disclosure, including the pilot scale DSC enthalpy measurement, calibration, derivation of calibration curves and calculations of indices, and whether or not the method is being computer-implemented or not, can be adapted and utilized for any other reaction or process other than hydrocarbon dehydrogenation, as long as redox reactions are involved and the process includes at least one material that is capable of being oxidized and reduced.

[0068] The following examples further illustrate the use of CuO as an exemplary heat-producing material in CuO/Cu quantification experiments by DSC, including methods of preparing CuO supported on y-A^Os _, methods of characterizing the CuO-y-Al ₂ 0 ₃ composites and methods of simulating the reducing and oxidizing cycles of dehydrogenation processes. These examples are not intended to limit the scope of the claims.

EXAMPLES

EXAMPLE 1 : Compilation of heat of reduction and heat of oxidation of various metals

[0069] The enthalpies and melting points of various metal/metal oxide pairs based on their heat of oxidation, heat of reduction and melting points are recorded in Table 1. The CuO/Cu pair is considered a good candidate as a heat-producing material for alkane dehydrogenation based on the exothermicity of both the reduction and oxidation cycles, high melting point and lack of potential catalytic effect on the dehydrogenation (i.e. the heat-producing material having a catalytic effect is not desirable).

EXAMPLE 2: Preparation of CuO-y-Al ₂ 0 ₃ samples

[0070] In order to support the DSC quantification process, CuO as the heat-producing material on γ-Α1 ₂ θ3 support was prepared using the wet impregnation method. Three samples (CuO/y-Al ₂ 0 ₃ ) having varying nominal CuO weight percentages were prepared: 5, 10 and 20 wt. % based on the weight of the final CuO-y-Al ₂ 0 ₃ composite. Briefly, an appropriate amount of Cu(N(¾) ₂ -3H ₂ 0 (Sigma- Aldrich) was dissolved in a minimum amount of distilled water, and then, it was mixed with γ-Α1 ₂ (¾ powder. Until it became gel-like, the copper nitrate-alumina mixture was stirred and dried for 3 hours (h) at 120°C in an oven, followed by calcination in air at 700°C for 3 h. In addition, to prepare pure CuO, a precipitation method was used by adding ammonium hydroxide solution (3 M, Sigma- Aldrich) into the copper nitrate solution at pH 12.0. After washing the precipitate using distilled water, the precipitate was placed inside an oven at 120°C overnight. Then it was ground and calcined in air at 650°C for 3 h.

EXAMPLE 3: Characterization of CuO-y-Al ₂ 0 ₃ samples

[0071] X-ray diffraction (XRD) analyses of the three prepared ΟιΟ-γ-Α1 ₂ θ ₃ samples as well as pure CuO were carried out using a Phillips 3100 diffractometer equipped with a CuKa source (1.54056 Angstroms (A)). The elemental compositions of the materials were determined by energy dispersive X- ray (EDX) analysis using a Quanta scanning electron microscope (SEM). To examine the reduction behavior of the materials, temperature-programmed reduction (TPR) experiments was carried out using Micro meri tics AutoChem II 2920 in 3% H ₂ in N ₂ and at 30 milliliters per minute (mL/min). Differential scanning calorimeter (TA instruments) was used to measure heat flow of materials prepared in this study up to 550°C. After the TPR and DSC experiments, the samples were examined by using SEM/EDX.

[0072] For more reliable quantitative analyses using SEM/EDX, two mixtures of CuO and AI ₂ O ₃ were prepared SEM/EDX calibrations were carried. Using the known concentration of CuO on AI ₂ O ₃ , the actual concentration of CuO in each of the three prepared CuO-y-Al ₂ 0 ₃ samples and pure CuO negative control (CuO-100) was determined by SEM/EDX and summarized in Table 2. Therefore, throughout the present disclosure, the ΟιΟ-γ-Α1 ₂ θ ₃ samples are named according to their respective nominal CuO concentrations on ALO ₃ (i.e. CuO-5, CuO- 10, CuO-20 and CuO-100) but the actual CuO loadings were defined to be 7.4, 12.4, 23.2 and 100.0 wt. % of the final composites.

CuO-100 is pure CuO without γ-Α1 ₂ 0 ₃ support.

[0073] Shown in FIGS. 3A, 3B and 3C are the XRD spectra for pure CuO without γ-Α1 ₂ 0 ₃ support (CuO-100), CuO-5-y-Al ₂ 0 ₃ and γ-Α1 ₂ θ ₃ without CuO loading respectively. The spectra suggest that CuO is monoclinic while Α1 ₂ θ ₃ is rhombohedral, which is in good agreement with previous reports in the literature. By comparing the spectra pattern of pure CuO or CuO-100 (FIG. 3 A), CuO-loaded (FIG. 3B) and unloaded γ-Α1 ₂ 0 ₃ (FIG. 3C) structures, it was confirmed that CuO was well deposited on γ-Α1 ₂ 0 ₃ using the wet-impregnation method.

[0074] Before carrying out DSC measurements in reduction and oxidation conditions, TPR (temperature programmed reduction) measures were performed in 5% H ₂ in N ₂ at a flow rate of 40 mL/min. The TPR system was first calibrated using an unsupported CuO reference sample, producing a maximum reduction position at 213°C. As shown in FIGS. 4A and 4B, the unsupported CuO prepared in this study has a maximum reduction position at 191°C, while it has a shoulder after the peak. In addition, as shown in FIG. 4A, it was observed that the reduction behavior of the supported CuO on AI ₂ O ₃ (CuO-5) is affected, leading to a lower maximum temperature than CuO- 100. FIG. 4C clearly shows that as the CuO loading reduces, the maximum temperature decreases. This implies that the thermal behavior of the CuO-contained materials is affected by the concentration within an experimental uncertainty, implying a potential correlation of CuO loading wt. % versus heat in reduction condition.

[0075] Further to composition analyses, SEM/EDX measurements were also carried out to examine the conversion from CuO to Cu after the reduction process. As shown in FIGS. 5A and 5B, most of unsupported CuO was reduced to Cu (> 98%). Similarly, more than 98% of the supported CuO was reduced to Cu, as shown in the BSE-SEM results in FIGS. 5C-5F. Therefore, since approximately 40 mg of samples were shown to be almost fully reduced in 5% H ₂ , it is unsupported and supported CuO samples can be used for reduction and oxidation studies using DSC, where the sample sizes used for the DSC analyses were approximately 20 mg.

EXAMPLE 4: Differential scanning calorimetry measurements

[0076] Differential scanning calorimetry (DSC) can be executed in at least two different modes, namely dynamic scanning and isothermal scanning. Dynamic scanning was executed by increasing temperature to measure heat of reaction according to Equation 1 :

H = f (dQ/dt) dt (Equation 1)

[0077] To simulate the practical condition for reduction and oxidation used in plants, hydrogen (5% H ₂ in Ar) and air were used, respectively. Aluminum pans were used for containing each sample. Typically, the powder samples were varied between 10 mg and 20 mg. Before starting any reaction, the pan with the sample was purged with Ar gas. Dynamic scanning with CuO was carried out initially in reduction by changing temperatures as shown in FIG. 6A, followed by oxidation after cooling down to room temperature with thorough purging using Ar. In addition, heat released at the simulated

temperatures in reduction and oxidation conditions was measured by isothermal scanning by fixing a temperature (FIG. 6B). Dynamic scanning was carried out from room temperature to 600°C at 10°C/min, while isothermal scanning was performed at 550°C. With the heat flow (W/g) curves of FIGS. 6A and 6B, positive heat flows are indicative of exothermic reactions. The area under each curve is the enthalpy of the reduction reaction.

[0078] Similar to the dynamic scanning, the isothermal scanning system was thoroughly purged using Ar before starting the reduction (Reaction 3) or oxidation (regeneration) (Reaction 4). As shown below, CuO on AI ₂ O ₃ is reduced and transformed into elementary Cu during reduction, while Cu on A1 ₂ 0 ₃ is oxidized to CuO during oxidation. A1 ₂ 0 ₃ was assumed to remain inert and unchanged in the temperature range.

CuO + H ₂ → Cu + H ₂ 0, AH = -85.8 kJ/mol at 298 K (Reaction 3)

Cu + I/2O ₂ → CuO, AH = -153.8 kJ/mol at 298 K (Reaction 4)

[0079] Isothermal scanning can be more suitable than dynamic scanning since the feedstock temperature is fixed under practical condition. By using isothermal scanning at 550°C, the effect of heat generation as CuO loading was being varied, was examined (FIGS. 7A-7C). According to the heat of reaction at 298 K (Reactions 1 and 2), the oxidation process produces more heat than reduction, which is supported by the DSC results as shown in FIGS. 7A-7C. Also, as shown in FIG. 7B, using the linear regression with the data points, a calibration curve of the change in CuO (in wt. % with 100 wt. % being the initial, known weight of CuO used as a heat-producing material) versus the measured heat of reduction (CuO→ Cu) was obtained as y = 0.951759x - 11.46497. As an example, according to FIG. 7B, if the heat of reduction of a CuO containing material is 400 Joules per gram (J/g), the CuO amount that remains after reduction 43.2 wt. %.

[0080] These experiments prove the viability of the DSC technique in providing an insight into the amount of metal and/or the oxide thereof that is remained after dehydrogenation (reduction + oxidation cycles) or the metal/metal oxide ratio after dehydrogenation. As shown in FIGS. 8A and 8B, the effect of the thermal reaction between DSC sample pans and the CuO or CuO-y-Al ₂ 03 samples during reduction and oxidation processes was examined. The pan used for CuO- 10 showed no evidence of reactions between the pan and the sample (FIG. 8A), while the pan used for pure CuO shows eutectic-like features, which is presumably the Al-Cu composition (FIG. 8B). However, based on linear DSC plots in FIGS. 7A-7C, it could be concluded that the reactions may not be affected by the interaction between the pan and samples, especially when the heat-producing material, CuO, was supported on γ-Α1 ₂ θ3.

[0081] The methods disclosed herein include(s) at least the following embodiments:

[0082] Embodiment 1: A method of determining a remaining amount of a metal and a remaining amount of an oxide of the metal in a catalyst system present on a support material after a hydrocarbon has been dehydrogenated with the catalyst system, comprising: dehydrogenating a hydrocarbon in a dehydrogenation reactor with the catalyst system to form a catalyst system product; separately reacting one or more amounts of the metal oxide loaded on the support material with a reducing gas to provide one or more enthalpies of reduction corresponding to the one or more amounts of the metal oxide; measuring the one or more enthalpies of reduction with a differential scanning calorimeter to obtain a plurality of reduction enthalpy data points; subjecting the plurality of reduction enthalpy data points to linear regression to obtain a first calibration curve of a DSC-measured reduction enthalpy versus metal oxide amount and a first equation thereof; separately reacting one or more amounts of the metal loaded in the catalyst system with an oxidizing gas to provide one or more enthalpies of oxidation corresponding to the one or more amounts of the metal; measuring the one or more enthalpies of oxidation with the differential scanning calorimeter to obtain a plurality of oxidation enthalpy data points; subjecting the plurality of oxidation data points to linear regression to obtain a second calibration curve of a DSC-measured oxidation enthalpy versus metal amount and a second equation thereof; measuring an enthalpy of dehydrogenation for the catalyst system product after dehydrogenating the hydrocarbon in the presence of the catalyst system; deriving the remaining amount of the metal oxide in the catalyst system product from the first calibration curve and the remaining amount of the metal in the catalyst system product from the second calibration curve based on the measured enthalpy of dehydrogenation; and calculating a ratio of M _Red /M(3o _x based on the remaining amount of the metal oxide and the remaining amount of the metal and replenishing or replacing the catalyst system present in the dehydrogenation reactor with a new catalyst system if the ratio is less than 0.8.

[0083] Embodiment 2: The method of Embodiment 1, wherein the one or more amounts of the metal oxide and the one or more amounts of the metal are each reacted at 500-600°C with the reducing gas and the oxidizing gas, respectively.

[0084] Embodiment 3: The method of Embodiment 1 or Embodiment 2, wherein the one or more small amounts of the metal oxide and the one or more small amounts of the metal are each reacted for 1-30 minutes with the reducing gas and the oxidizing gas, respectively.

[0085] Embodiment 4: The method of Embodiment 3, wherein the one or more small amounts of the metal oxide and the one or more small amounts of the metal are each reacted for 7-15 minutes with the reducing gas and the oxidizing gas, respectively.

[0086] Embodiment 5: The method of any of Embodiments 1-4, wherein the reducing gas comprises CI¾, H ₂ , NH ₃ , H ₂ S, CO, or a combination comprising at least one of the foregoing.

[0087] Embodiment 6: The method of Embodiment 5, wherein the reducing gas is a gaseous mixture comprising H ₂ and Ar.

[0088] Embodiment 7: The method of Embodiment 5 or Embodiment 6, wherein the gaseous mixture comprises 1-10% of H ₂ by volume relative to the total volume of the gaseous mixture.

[0089] Embodiment 8: The method of any of Embodiments 1-7, wherein the oxidizing gas is pure 0 ₂ or air.

[0090] Embodiment 9: The method of any of Embodiments 1-8, wherein the support material is inert towards the metal oxide, the metal, the reducing gas, the oxidizing gas, or a combination comprising at least one of the foregoing.

[0091] Embodiment 10: The method of any of Embodiments 1-9, wherein the support material is alumina-based and is selected from aluminum oxide, alumina, alumina monohydrate, alumina trihydrate, alumina-silica, bauxite, gibbsite, bayerite and boehmite, a-alumina, γ-alumina, η-alumina and δ-alumina, calcined hydrotalcite, or a combination comprising at least one of the foregoing.

[0092] Embodiment 11 : The method of any of Embodiments 1-10, wherein the one or more amounts of the metal oxide loaded upon the support material are 10-20 mg in weight.

[0093] Embodiment 12: The method of any of Embodiments 1-11, wherein the one or more amounts of the metal oxide constitute 5-25% of the total weight of the metal oxide loaded upon the support material.

[0094] Embodiment 13: The method of any of Embodiments 1-12, wherein the reacting of the one or more amounts of the metal oxide with the reducing gas and the reacting of the one or more amounts of the metal with the oxidizing gas in the differential scanning calorimeter are carried out isothermally.

[0095] Embodiment 14: The method of any of Embodiments 1-13, wherein the hydrocarbon is an aliphatic alkane selected from ethane, propane, w-butane, isobutane, isopentane, or a combination comprising at least of the foregoing.

[0096] Embodiment 15: The method of any of Embodiments 1-14, wherein the metal oxide is copper oxide.

[0097] In general, the invention may alternately comprise, consist of, or consist essentially of, any appropriate components herein disclosed. The endpoints of all ranges directed to the same component or property are inclusive and independently combinable (e.g., ranges of "less than or equal to 25 wt%, or 5 wt% to 20 wt%," is inclusive of the endpoints and all intermediate values of the ranges of "5 wt% to 25 wt%," etc.). Disclosure of a narrower range or more specific group in addition to a broader range is not a disclaimer of the broader range or larger group. The terms "a" and "an" and "the" herein do not denote a limitation of quantity, and are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. "Or" means "and/or." The suffix "(s)" as used herein is intended to include both the singular and the plural of the term that it modifies, thereby including one or more of that term (e.g., the film(s) includes one or more films). Reference throughout the specification to "one embodiment", "another embodiment", "an embodiment", and so forth, means that a particular element (e.g., feature, structure, and/or characteristic) described in connection with the embodiment is included in at least one embodiment described herein, and may or may not be present in other embodiments. In addition, it is to be understood that the described elements may be combined in any suitable manner in the various embodiments.

[0098] The modifier "about" used in connection with a quantity is inclusive of the stated value and has the meaning dictated by the context (e.g., includes the degree of error associated with measurement of the particular quantity "Optional" or "optionally" means that the subsequently described event or circumstance can or cannot occur, and that the description includes instances where the event occurs and instances where it does not. Unless defined otherwise, technical and scientific terms used herein have the same meaning as is commonly understood by one of skill in the art to which this invention belongs. A "combination" is inclusive of blends, mixtures, alloys, reaction products, and the like. All cited patents, patent applications, and other references are incorporated herein by reference in their entirety. However, if a term in the present application contradicts or conflicts with a term in the incorporated reference, the term from the present application takes precedence over the conflicting term from the incorporated reference. While particular embodiments have been described, alternatives, modifications, variations, improvements, and substantial equivalents that are or may be presently unforeseen may arise to applicants or others skilled in the art. Accordingly, the appended claims as filed and as they may be amended are intended to embrace all such alternatives, modifications variations, improvements, and substantial equivalents.