CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of priority to European Patent Application No. 20179180.3, filed June 10, 2020, the entire contents of which are hereby incorporated by reference in their entirety.

FIELD OF INVENTION

[0002] The present invention generally relates to systems and methods for hydrocarbon dehydrogenation. More specifically, the present invention relates to systems and methods for hydrocarbon dehydrogenation that include oxidizing and reducing a catalyst before it is used to catalyze dehydrogenation of the hydrocarbon.

BACKGROUND OF THE INVENTION

[0003] Olefins, especially light olefins (C2 to C4 olefins), are building blocks for many chemical processes. Light olefins are used to produce polyethylene, polypropylene, ethylene oxide, ethylene chloride, propylene oxide, and acrylic acid, which, in turn, are used in a wide variety of industries such as the plastic processing, construction, textile, and automotive industries. Generally, light olefins are produced by steam cracking naphtha.

[0004] Over the last few decades, the demand for light olefins has been consistently increasing. Other methods, including catalytic dehydrogenation of paraffins, have been used for producing light olefins. Generally, the catalyst used in the catalytic dehydrogenation process includes platinum and/or chromium. However, platinum is an expensive metal, which makes platinum catalyzed processes expensive. The use of chromium based catalyst, on the other hand, can have negative environmental and health consequences. Reclaiming of chromium from used catalyst may be able to mitigate these adverse effects, but the currently available reclaiming process is cost prohibitive. Furthermore, the conventional catalytic dehydrogenation process includes a dehydrogenation and catalyst regeneration cycle, in which the activity of the regenerated catalyst is limited, leading to low conversion rate of the paraffins in each dehydrogenation cycle. [0005] Overall, while methods of dehydrogenating paraffins for producing olefins exist, the need for improvements in this field persists in light of at least the aforementioned drawbacks for the conventional methods.

BRIEF SUMMARY OF THE INVENTION

[0006] A solution to at least some of the above mentioned problems associated with conventional methods of dehydrogenating hydrocarbons has been discovered. The solution resides in a method of dehydrogenating a hydrocarbon to produce a dehydrogenated hydrocarbon that includes the use of a gallium based catalyst, thereby mitigating the negative impact on the environment and human health of chromium based catalyst and reducing the catalyst cost compared to platinum based catalyst. Additionally, the method includes a dehydrogenation-catalyst oxidation-catalyst reduction cycle that can increase the activity of regenerated dehydrogenation catalyst and the conversion rate of the hydrocarbons, compared to conventional methods. Therefore, the method of the present invention provides a technical solution to at least some of the problems associated with the conventional methods for dehydrogenating hydrocarbons.

[0007] Embodiments of the invention include a hydrocarbon dehydrogenation process.

The process comprises (a), passing an oxidizing gas through a reactor containing a catalyst comprising gallium (Ga), an alkali metal, and alumina. The process also comprises (b), passing a reducing gas through the reactor, and (c), contacting the catalyst with a hydrocarbon under reaction conditions sufficient to dehydrogenate the hydrocarbon. The method further comprises repeating step (a) to step (c).

[0008] Embodiments of the invention include a method of dehydrogenating a hydrocarbon. The method comprises (A), dehydrogenating a paraffin by contacting the paraffin with a catalyst comprising Ga2Ch, K2O and alumina under reaction conditions sufficient to produce an olefin. The method comprises (B), flowing a first inert gas through the catalyst to remove the trapped gaseous materials. The method comprises (C), oxidizing the catalyst with an oxidizing gas comprising oxygen to produce an oxidized catalyst. The method comprises (D), flowing a second inert gas through the oxidized catalyst to remove gaseous materials resulting from oxidizing the catalyst. The method further comprises (E), reducing the oxidized catalyst by flowing a reducing gas comprising hydrogen through the oxidized catalyst. The method further still comprises (F), repeating steps (A) to (E). The first inert gas and the second inert gas can be the same or different.

[0009] Embodiments of the invention include a method of dehydrogenating a light paraffin. The method comprises (I), dehydrogenating a light paraffin by contacting the light paraffin with a catalyst comprising Ga2Ch, K2O, and alumina under reaction conditions sufficient to produce a light olefin. The method comprises (II), after the dehydrogenation step, flowing a first inert gas through the catalyst to remove the trapped gaseous materials. The method comprises (III) oxidizing the catalyst with an oxidizing gas comprising oxygen to produce an oxidized catalyst. The method comprises (IV), after oxidizing the catalyst, flowing a second inert gas through the oxidized catalyst to remove residual oxygen and other gaseous materials resulting from oxidizing the catalyst. The method comprises (V), after removing residual gaseous materials, reducing the oxidized catalyst by flowing a reducing gas comprising hydrogen through the oxidized catalyst to produce a reduced catalyst. The method further still comprises (VI), repeating steps (I) to (V). [0010] The following includes definitions of various terms and phrases used throughout this specification.

[0011] The terms “about” or “approximately” are defined as being close to as understood by one of ordinary skill in the art. In one non-limiting embodiment the terms are defined to be within 10%, preferably, within 5%, more preferably, within 1%, and most preferably, within 0.5%.

[0012] The terms “wt.%”, “vol.%” or “mol.%” refer to a weight, volume, or molar percentage of a component, respectively, based on the total weight, the total volume, or the total moles of material that includes the component. In a non-limiting example, 10 moles of component in 100 moles of the material is 10 mol.% of component. [0013] The term “substantially” and its variations are defined to include ranges within

10%, within 5%, within 1%, or within 0.5%.

[0014] The terms “inhibiting” or “reducing” or “preventing” or “avoiding” or any variation of these terms, when used in the claims and/or the specification, include any measurable decrease or complete inhibition to achieve a desired result. [0015] The term “effective,” as that term is used in the specification and/or claims, means adequate to accomplish a desired, expected, or intended result.

[0016] The use of the words “a” or “an” when used in conjunction with the term

“comprising,” “including,” “containing,” or “having” in the claims or the specification may mean “one,” but it is also consistent with the meaning of “one or more,” “at least one,” and “one or more than one.”

[0017] The words “comprising” (and any form of comprising, such as “comprise” and

“comprises”), “having” (and any form of having, such as “have” and “has”), “including” (and any form of including, such as “includes” and “include”) or “containing” (and any form of containing, such as “contains” and “contain”) are inclusive or open-ended and do not exclude additional, unrecited elements or method steps.

[0018] The process of the present invention can “comprise,” “consist essentially of,” or “consist of’ particular ingredients, components, compositions, etc., disclosed throughout the specification.

[0019] Other objects, features and advantages of the present invention will become apparent from the following figures, detailed description, and examples. It should be understood, however, that the figures, detailed description, and examples, while indicating specific embodiments of the invention, are given by way of illustration only and are not meant to be limiting. Additionally, it is contemplated that changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. In further embodiments, features from specific embodiments may be combined with features from other embodiments. For example, features from one embodiment may be combined with features from any of the other embodiments. In further embodiments, additional features may be added to the specific embodiments described herein.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] For a more complete understanding, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:

[0021] FIG. 1 shows a schematic diagram of a system for dehydrogenating a hydrocarbon, according to embodiments of the invention; [0022] FIG. 2 shows schematic flowchart for a method of dehydrogenating a hydrocarbon, according to embodiments of the invention;

[0023] FIGS. 3A-3C show comparison of results for an isobutane dehydrogenation process that includes a catalyst reduction step and an isobutane dehydrogenation process that does not include a catalyst reduction step. FIG. 3 A shows comparison of isobutane conversion rate (mol.%) for each operating cycle; FIG. 3B shows comparison of isobutylene selectivity (mol.%) for each operating cycle; FIG. 3C shows comparison of isobutylene yield for each operating cycle; and

[0024] FIG. 4 shows schematic flowchart for a method of dehydrogenating a hydrocarbon, according to embodiments of the invention

DETAILED DESCRIPTION OF THE INVENTION

[0025] Currently, conventional methods of dehydrogenating hydrocarbons suffer several drawbacks, some of which limit the production efficiency of olefins. For the conventional methods, the commonly used chromium based catalyst can be hazardous to the environment and humans. Another commonly used catalyst in the conventional dehydrogenation method includes platinum, which is expensive. Additionally, the conventional methods for dehydrogenating include a catalyst regeneration step that results in limited catalytic activity for the regenerated catalyst, thereby limiting the conversion rate of the hydrocarbons and production efficiency for the dehydrogenated hydrocarbons. The present invention provides a solution to at least some of these problems. The solution is premised on a method of dehydrogenating a hydrocarbon that includes utilizing a gallium based catalyst for the dehydrogenation process. This can be beneficial for mitigating the negative environmental and health impact of chromium. Furthermore, the method includes a catalyst reduction step in the catalyst regeneration process, resulting in increased overall catalyst efficiency and in turn increased olefin production efficiency. These and other non-limiting aspects of the present invention are discussed in further detail in the following sections.

A. System for dehydrogenating hydrocarbons

[0026] In embodiments of the invention, the system for dehydrogenating a hydrocarbon can include one or more fixed bed reactors and/or one or more fluidized bed reactors, and a product separation unit. With reference to FIG. 1, a schematic diagram is shown of system 100 that is configured to dehydrogenate hydrocarbons with improved production efficiency and reduced production cost compared to conventional methods. According to embodiments of the invention, system 100 includes one or more dehydrogenation reactors 101 In embodiments of the invention, the one or more dehydrogenation reactors 101 may be operated in parallel.

[0027] According to embodiments of the invention, dehydrogenation reactor 101 is configured to receive feed stream 11 comprising one or more hydrocarbons and to dehydrogenate the one or more hydrocarbons in the presence of a catalyst to produce dehydrogenated hydrocarbons. In embodiments of the invention, the one or more hydrocarbons can include a C2 to Cx hydrocarbon. The C2 to Cx hydrocarbon can include a paraffin, an aromatic hydrocarbon, or any combination thereof. The dehydrogenated hydrocarbons may include an olefin, a dehydrogenated aromatic hydrocarbon, or any combination thereof. In embodiments of the invention, the paraffin can include ethane, propane, n-butane, isobutane, n-pentane, isopentane, or any combination thereof. Non-limiting examples of the olefin can include ethylene, propylene, butylene, pentene, and combinations thereof. The aromatic hydrocarbon can include ethyl benzene, and the dehydrogenated aromatic hydrocarbon can include styrene. In embodiments of the invention, dehydrogenation reactor 101 comprises reactor shell 102 for hosting the hydrocarbon dehydrogenation reaction. In embodiments of the invention, reactor shell 102 is substantially cylindrical. According to embodiments of the invention, shell 102 includes a feed inlet configured to receive feed stream 11 therein and an effluent outlet configured to release effluent stream 12 there from. Effluent stream 12 may comprise the dehydrogenated hydrocarbon, and/or unreacted hydrocarbons.

[0028] According to embodiments of the invention, dehydrogenation reactor 101 comprises catalyst bed 103 comprising a catalyst capable of catalyzing the dehydrogenation of hydrocarbons. Catalyst bed 103 may include a fixed catalyst bed and/or a fluidized bed. In embodiments of the invention, the catalyst comprises gallium. The catalyst may further comprise an alkali metal such as Li (lithium), Na (sodium), K (potassium), Rb (rubidium), Cs (cesium), Fr (francium), or any combination thereof. The catalyst may further include alumina as the support. In embodiments of the invention, the gallium in the catalyst is in the form of gallium oxide (Ga2Ch). The alkali metal in the catalyst may be in the form of an oxide. In embodiments of the invention, the catalyst comprises 0.5 to 25 wt.% Ga2Ch and 0.1 to 5 wt.% K2O. [0029] In embodiments of the invention, the catalyst has a Ga metal to support ratio of

0.004 to 0.25 and all ranges and values there between. According to embodiments of the invention, the catalyst has a specific surface area in a range of 50 to 250 m ² /g and all ranges and values there between including ranges of 50 to 70 m ² /g, 70 to 90 m ² /g, 90 to 110 m ² /g, 110 to 130 m ² /g, 130 to 150 m ² /g, 150 to 170 m ² /g, 170 to 190 m ² /g, 190 to 210 m ² /g, 210 to 230 m ² /g, and 230 to 250 m ² /g. The nitrogen pore volume of the catalyst may be in a range of 0.2 to 1 ml/g and all ranges and values there between including ranges of 0.2 to 0.3 ml/g, 0.3 to 0.4 ml/g, 0.4 to 0.5 ml/g, 0.5 to 0.6 ml/g, 0.6 to 0.7 ml/g, 0.7 to 0.8 ml/g, 0.8 to 0.9 ml/g, and 0.9 to 1 ml/g. The catalyst may be prepared by an incipient wetness impregnation method comprising impregnating alumina extrudates with gallium (III) salt and alkali metal salt, drying the impregnated alumina extrudates, and calcining the dried impregnated alumina extrudates. In embodiments of the invention, the gallium (III) salt includes gallium (III) nitrate hydrate. The alkali metal salt may include potassium nitrate.

[0030] According to embodiments of the invention, system 100 comprises oxidizing gas source 104 configured to supply oxidizing gas stream 13 to catalyst bed 103 of reactor 101 to produce oxidized catalyst and spent oxidizing gas stream 17. Oxidizing gas stream 13 may include oxygen, air, carbon dioxide, or combinations thereof. Spent oxidizing gas stream 17 may include oxygen, air, carbon dioxide, or combinations thereof. System 100 may comprise reducing gas source 105 configured to supply reducing gas stream 14 to catalyst bed 103 containing oxidized catalyst to produce reduced catalyst and spent reducing gas stream 18. Reducing gas stream 14 may include hydrogen, carbon monoxide, or combinations thereof. Spent reducing gas stream 18 may comprise hydrogen, carbon monoxide, or combinations thereof. In embodiments of the invention, system 100 comprises purge gas source 106 configured to supply purge gas stream 15 through catalyst bed 103 to remove residue oxidizing gas, reducing gas, and/or hydrocarbons from catalyst bed 103 and produce spent purge gas stream 19. Purge gas stream 15 may include an inert gas comprising nitrogen, argon, helium, steam, or combinations thereof. Spent purge gas stream 19 may include the inert gas, argon, helium, steam, or combinations thereof.

[0031] According to embodiments of the invention, system 100 includes feed heater

107 configured to heat feed stream 11 to a temperature sufficient for the dehydrogenation process in dehydrogenation reactor 101. In embodiments of the invention, system 100 includes separation unit 108 configured to separate effluent stream 12 to form olefin stream 16 comprising the one or more olefins.

[0032] In embodiments of the invention, system 100 includes one or more dehydrogenation reactors 101 on-stream for dehydrogenating hydrocarbons and one or more dehydrogenation reactors 101 in regeneration mode where the catalyst in reactor 101 is regenerated by the following steps of catalyst oxidation, catalyst reduction, and/or purging by inert gas.

B. Method of dehydrogenating hydrocarbons

[0033] Methods of dehydrogenating hydrocarbons via catalytic dehydrogenation have been discovered. The methods may be capable of increasing catalytic activity of regenerated catalyst for hydrocarbon dehydrogenation, resulting in increased olefin production efficiency compared to conventional methods. As shown in FIG. 2, embodiments of the invention include method 200 for dehydrogenating a hydrocarbon. Method 200 may be implemented by system 100, as shown in FIG. 1.

[0034] According to embodiments of the invention, as shown in block 201 , method 200 includes passing oxidizing gas stream 13 comprising an oxidizing gas through dehydrogenation reactor 101 containing catalyst bed 103 that comprises the dehydrogenation catalyst comprising the catalyst containing gallium (Ga), an alkali metal, and alumina. Catalyst bed 103, in embodiments of the invention, includes a fixed catalyst bed. Catalyst bed 103 may include fluidized catalyst bed. In embodiments of the invention, the catalyst at block 201 is partially deactivated or fully deactivated by coke formation, phase transformation, structural changes, or combinations thereof during dehydrogenation of a hydrocarbon. In embodiments of the invention, oxidizing gas stream 13 may include oxygen, air, carbon dioxide, or combinations thereof. Oxidizing gas stream 13 may include 1 to 100 wt.% oxygen.

[0035] In embodiments of the invention, at block 201, the passing of oxidizing gas stream 13 is performed under oxidizing conditions sufficient to remove deposited coke or carbonaceous material and produce oxidized catalyst in catalyst bed 103. At block 201, oxidizing gas stream 13 is passed through catalyst bed 103 at a gas hourly space velocity of 100 to 10000 hr ¹ and all ranges and values there between including ranges of 100 to 200 hr ¹ , 200 to 300 hr ¹ , 300 to 400 hr ¹ , 400 to 500 hr ¹ , 500 to 600 hr ¹ , 600 to 700 hr ¹ , 700 to 800 hr 800 to 900 hr ¹ , 900 to 1000 hr ¹ , 1000 to 2000 hr ¹ , 2000 to 3000 hr ¹ , 3000 to 4000 hr ¹ , 4000 to 5000 hr ¹ , 5000 to 6000 hr ¹ , 6000 to 7000 hr ¹ , 7000 to 8000 hr ¹ , 8000 to 9000 hr ¹ , and 9000 to 10000 hr ¹ . At block 201, the passing may be performed at a temperature of 500 to 800 °C and all ranges and values there between including ranges of 500 to 520 °C, 520 to 540 °C, 540 to 560 °C, 560 to 580 °C, 580 to 600 °C, 600 to 620 °C, 620 to 640 °C, 640 to 660 °C, 660 to 680 °C, 680 to 700 °C, 700 to 720 °C, 720 to 740 °C, 740 to 760 °C, 760 to 780 °C, and 780 to 800 °C. The passing of oxidizing gas stream 13 at block 201 may last for a duration of 2 to 120 minutes and all ranges and values there between including ranges of 2 to 10 minutes, 10 to 20 minutes, 20 to 30 minutes, 30 to 40 minutes, 40 to 50 minutes, 50 to 60 minutes, 60 to 70 minutes, 70 to 80 minutes, 80 to 90 minutes, 90 to 100 minutes, 100 to 110 minutes, and 110 to 120 minutes.

[0036] According to embodiments of the invention, as shown in block 202, method 200 includes optionally purging dehydrogenation reactor 101 with purge gas stream 15 to remove residue oxidizing gas in dehydrogenation reactor 101. Purging gas stream 15 may comprise an inert gas comprising nitrogen, argon, helium, steam, or combinations thereof. In embodiments of the invention, purging gas stream 15 may comprise 5 to 100 wt.% nitrogen. Purging at block 202 may be performed at a gas hourly space velocity of 100 to 10000 hr ¹ and all ranges and values there between including ranges of 100 to 200 hr ¹ , 200 to 300 hr ¹ , 300 to 400 hr ¹ , 400 to 500 hr ¹ , 500 to 600 hr ¹ , 600 to 700 hr ¹ , 700 to 800 hr ¹ , 800 to 900 hr ¹ , 900 to 1000 hr ¹ , 1000 to 2000 hr ¹ , 2000 to 3000 hr ¹ , 3000 to 4000 hr ¹ , 4000 to 5000 hr ¹ , 5000 to 6000 hr ¹ , 6000 to 7000 hr ¹ , 7000 to 8000 hr ¹ , 8000 to 9000 hr ¹ , and 9000 to 10000 hr ¹ .

[0037] According to embodiments of the invention, as shown in block 203, method 200 includes passing reducing gas stream 14 through dehydrogenation reactor 101. Reducing gas stream 14 may include hydrogen, carbon monoxide, or combinations thereof. In embodiments of the invention, reducing gas stream 14 includes 5 to 100 wt.% hydrogen and all ranges and values there between including ranges of 5 to 10 wt.%, 10 to 15 wt.%, 15 to 20 wt.%, 20 to 25 wt.%, 25 to 30 wt.%, 30 to 35 wt.%, 35 to 40 wt.%, 40 to 45 wt.%. 45 to 50 wt.%, 50 to 55 wt.%, 55 to 60 wt.%, 60 to 65 wt.%, 65 to 70 wt.%, 70 to 75 wt.%, 75 to 80 wt.%, 80 to 85 wt.%, 85 to 90 wt.%, 90 to 95 wt.%, and 95 to 100 wt.%. In embodiments of the invention, the passing of the reducing gas stream 14 at block 203 is configured to reduce the oxidized catalyst produced at block 201 to form reduced catalyst in catalyst bed 103. The passing at block 203 may be performed at a temperature of 500 to 800 °C and all ranges and values there between including ranges of 500 to 520 °C, 520 to 540 °C, 540 to 560 °C, 560 to 580 °C, 580 to 600 °C, 600 to 620 °C, 620 to 640 °C, 640 to 660 °C, 660 to 680 °C, 680 to 700 °C, 700 to 720 °C, 720 to 740 °C, 740 to 760 °C, 760 to 780 °C, and 780 to 800 °C. Passing at block 203 may be performed at a gas hourly space velocity of 100 to 1000 hr ¹ and all ranges and values there between including ranges of 100 to 200 hr ¹ , 200 to 300 hr ¹ , 300 to 400 hr ¹ , 400 to 500 hr ¹ , 500 to 600 hr ¹ , 600 to 700 hr ¹ , 700 to 800 hr ¹ , 800 to 900 hr ¹ , and 900 to 1000 hr ¹ . In embodiments of the invention, a duration of the passing step at block 203 is in a range of 2 to 120 minutes and all ranges and values there between including ranges of 2 to 10 minutes, 10 to 20 minutes, 20 to 30 minutes, 30 to 40 minutes, 40 to 50 minutes, 50 to 60 minutes, 60 to 70 minutes, 70 to 80 minutes, 80 to 90 minutes, 90 to 100 minutes, 100 to 110 minutes, and 110 to 120 minutes.

[0038] According to embodiments of the invention, as shown in block 204, method 200 includes optionally purging the reduced catalyst in dehydrogenation reactor 101 with purge gas stream 15 to remove residue reducing gas. In embodiments of the invention, purging at block 204 is further configured to cool the reduced catalyst to a temperature of 500 to 800 °C. Purging at block 204 may be performed at a gas hourly space velocity of 100 to 10000 hr ¹ and all ranges and values there between including ranges of 100 to 200 hr ¹ , 200 to 300 hr ¹ , 300 to 400 hr ¹ , 400 to 500 hr ¹ , 500 to 600 hr ¹ , 600 to 700 hr ¹ , 700 to 800 hr ¹ , 800 to 900 hr ¹ , 900 to 1000 hr ¹ , 1000 to 2000 hr ¹ , 2000 to 3000 hr ¹ , 3000 to 4000 hr ¹ , 4000 to 5000 hr ¹ , 5000 to 6000 hr ¹ , 6000 to 7000 hr ¹ , 7000 to 8000 hr ¹ , 8000 to 9000 hr ¹ , and 9000 to 10000 hr ¹ .

[0039] According to embodiments of the invention, as shown in block 205, method 200 includes contacting the catalyst of catalyst bed 103 with a hydrocarbon under reaction conditions sufficient to dehydrogenate the hydrocarbon. The hydrocarbons may include a paraffin, an aromatic hydrocarbon, or any combination thereof. The dehydrogenated hydrocarbons may include an olefin, a dehydrogenated aromatic hydrocarbon, or any combination thereof. In embodiments of the invention, the paraffin can include ethane, propane, n-butane, isobutane, n-pentane, isopentane, or any combination thereof. Non-limiting examples of the olefin can include ethylene, propylene, butylene, pentene, and combinations thereof. The aromatic hydrocarbon can include ethyl benzene, and the dehydrogenated aromatic hydrocarbon can include styrene. The reaction conditions at block 205 may include a reaction temperature of 500 to 800 °C and all ranges and values there between including ranges of 500 to 520 °C, 520 to 540 °C, 540 to 560 °C, 560 to 580 °C, 580 to 600 °C, 600 to 620 °C, 620 to 640 °C, 640 to 660 °C, 660 to 680 °C, 680 to 700 °C, 700 to 720 °C, 720 to 740 °C, 740 to 760 °C, 760 to 780 °C, and 780 to 800 °C. The reaction conditions at block 205 may include a reaction pressure of 0.2 to 5 bar and all ranges and values there between including ranges of 0.2 to 0.5 bar, 0.5 to 1.0 bar, 1.0 to 1.5 bar, 1.5 to 2.0 bar, 2.0 to 2.5 bar, 2.5 to 3.0 bar, 3.0 to 3.5 bar, 3.5 to 4.0 bar, 4.0 to 4.5 bar, and 4.5 to 5.0 bar. In embodiments of the invention, the reaction conditions at block 205 further include gas hourly space velocity in a range of 100 to 1000 hr ¹ and all ranges and values there between including ranges of 100 to 200 hr ¹ , 200 to 300 hr ¹ , 300 to 400 hr ¹ , 400 to 500 hr ¹ , 500 to 600 hr ¹ , 600 to 700 hr ¹ , 700 to 800 hr ¹ , 800 to 900 hr ¹ , and 900 to 1000 hr ¹ . In embodiments of the invention, a conversion rate of the paraffin at block 205 is in a range of 30 to 60% and all ranges and values there between including ranges of 30 to 33%, 33 to 36%, 36 to 39%, 39 to 42%, 42 to 45%, 45 to 48%, 48 to 51%, 51 to 54%, 54 to 57%, and 57 to 60%.

[0040] According to embodiments of the invention, method 200 includes repeating block 201, optionally block 202, block 203, optionally block 204, and block 205 in a cyclic mode. Dehydrogenation reactor 101 may be purged after with purge gas stream 15 after block 205 to remove residual hydrocarbon in the dehydrogenation reactor in each cycle of repeating blocks 201 to 205 (See block 206 in FIG. 4, which when performed, the method will have cycles repeating blocks 201 to 206). In embodiments of the invention, blocks 201 to 205 are repeated till catalytic activity of the reduced catalyst is less than 30 mol.% of the catalytic activity of fresh catalyst.

[0041] Although embodiments of the present invention have been described with reference to blocks of FIG. 2, it should be appreciated that operation of the present invention is not limited to the particular blocks and/or the particular order of the blocks illustrated in FIG. 2. Accordingly, embodiments of the invention may provide functionality as described herein using various blocks in a sequence different than that of FIG. 2.

[0042] The systems and processes described herein can also include various equipment that is not shown and is known to one of skill in the art of chemical processing. For example, some controllers, piping, computers, valves, pumps, heaters, thermocouples, pressure indicators, mixers, heat exchangers, and the like may not be shown.

[0043] As part of the disclosure of the present invention, specific examples are included below. The examples are for illustrative purposes only and are not intended to limit the invention. Those of ordinary skill in the art will readily recognize parameters that can be changed or modified to yield essentially the same results.

Example 1

(Preparation of the gallium oxide based catalyst for paraffin dehydrogenation)

[0044] Alumina extrudates mainly in delta alumina (d-AbCh) form were prepared using the following procedure. The boehmite (G-250) material was extrudated using acetic acid as a peptizing agent. Acetic acid (5 vol.%, about 370 ml) was added to boehmite powder (500 g) dropwise and the resulting mixture was continuously agitated for about 30 minutes. The obtained dough was then extruded using a lab extruder (Sunsai™) with a die having circular openings of 3.5 mm in diameter. The prepared wet extrudates were dried at 120 °C for 16 hours in an air oven. The dried extrudates (160 g) were then calcined at 900 °C for 10 hours in a muffle furnace with a heating rate of 5 °C/min and air flow rate of 480±10 ml/min.

[0045] The obtained calcined extrudates support (size: about 3 mm in diameter, and 6-

8 mm in length) with a surface area of 145 m ² /g was used for catalyst preparation. The alumina extrudate support (about 100 g) was heat treated in an oven at 120 °C for 16 hours in the presence of air to remove moisture. The dried alumina extrudate support, after cooling to room temperature, was used for catalyst preparation by incipient wetness impregnation method. More specifically, the catalyst (30 g) was prepared by incipient wetness impregnation of the support with an aqueous solution of gallium (III) nitrate hydrate (4.91 g, based on anhydrous) and potassium nitrate (0.258 g). The impregnation was carried out by contacting the impregnation solution (12 ml) with the alumina extrudate support (28.02 g) at room temperature. The impregnated alumina support was then kept at room temperature for 12 hours and dried at 120 °C for 16 hours. The dried impregnated alumina was calcined at 750 °C for 4 hours with heating rate 5 °C/min in the presence of air (flow rate, 8 ml gamin ¹ ) in a down flow tubular furnace to produce the catalyst. After calcination, the catalyst was cooled in the presence of air and the catalyst was stored in an airtight container. Based on calculation, the final catalyst includes 6.0 wt.% Ga2Cb and 0.4 wt.% K2O with remaining part as AI2O3.

Example 2

(Comparative example for dehydrogenation of isobutane) [0046] The catalyst prepared in Example 1 was tested for dehydrogenation of isobutane. The testing process included isobutane dehydrogenation and catalyst regeneration conducted in cyclic mode. The dehydrogenation activity of the catalyst was measured in a tubular fixed-bed quartz reactor. The details of catalyst loading and the reactor setup were as follows: the catalyst weight was 4.0 g, the catalyst particle size was 0.4-0.5 mm, the reactor inner diameter was 16 mm, and the reactor outer diameter was 19 mm. Isobutane (99.9 vol.%) was used as the feed. Quartz chips with size of 1-1.4 mm were loaded above the catalyst bed. Nitrogen purge was used between the step of dehydrogenation and catalyst regeneration/oxidation. The gas hourly space velocity (GHSV) for the dehydrogenation step was about 600 ml-h ^g ¹ . The reactor outlet gases were analyzed by online gas chromatograph (Agilent™ 6890, Agilent Scientific Instruments, USA) equipped with a flame ionization detector for hydrocarbon analysis and a thermal conductivity detector for hydrogen analysis. The reactant and products flow rates were measured using Ritter type wet gas flow meter. The reactor was operated at atmospheric pressure and in a cyclic mode with the following steps: (1) oxidizing the catalyst in air at 650 °C for 20 min; (2) purging the catalyst with nitrogen at 650 °C for 5 minutes; (3) cooling the catalyst with nitrogen from 650 °C to 585 °C for 20 minutes and maintaining the temperature at 585 °C; (4) dehydrogenating isobutane at 585 °C for 21 min; and (5) analyzing the product from the dehydrogenating step using gas chromatography at 20th minute from the start of the isobutane feed; (6) repeating steps (l)-(5) for 30 cycles.

Example 3

(Dehydrogenation of isobutane with a process that includes catalyst reduction)

[0047] The catalyst prepared in Example 1 was tested for dehydrogenation of isobutane in a process that included isobutane dehydrogenation, catalyst regeneration, and catalyst reduction conducted in cyclic mode. The dehydrogenation activities of the catalyst was measured in a tubular fixed-bed quartz reactor. The details of catalyst loading and reactor were as follows: the catalyst weight was about 4.0 g, the catalyst particle size was 0.4-0.5 mm, the reactor inner diameter was 16 mm, and the reactor outer diameter was 19 mm. Isobutane (99.9 vol.%) was used as the feed. Quartz chips with size of 1-1.4 mm were loaded above the catalyst bed. Nitrogen purge was conducted between isobutane dehydrogenation and catalyst regeneration/oxidation, and between catalyst regeneration/oxidation and catalyst reduction with hydrogen. The gas hourly space velocity (GHSV) for the isobutane dehydrogenation step was about 600 ml-h ^g ¹ . The reactor outlet gases were analyzed by online gas chromatograph (Agilent™ 6890, Agilent Scientific Instruments, USA) equipped with a flame ionization detector for hydrocarbon analysis and a thermal conductivity detector for hydrogen analysis. The reactant and products flow rates were measured using Ritter type wet gas flow meter. The reactor was operated at atmospheric pressure and in a cyclic mode with the following steps: (1) oxidizing the catalyst in air at 650 °C for 20 min; (2) purging the catalyst with nitrogen at 650 °C for 5 minutes; (3) reducing the catalyst with hydrogen at 650 °C for 6 minutes; (4) cooling the catalyst with nitrogen from 650 °C to 585 °C for 20 minutes and maintaining the temperature at 585 °C; (5) dehydrogenating isobutane at 585 °C for 21 min; and (6) analyzing the product from the dehydrogenating step using gas chromatography at 20th minute from the start of the isobutane feed; (7) repeating steps (1) to (6) for 30 cycles.

[0048] The conversion rates of isobutane for the processes of both example 2 and example 3 were calculated and plotted against number of cycles in FIG. 3 A. The isobutylene selectivities for the processes of both example 2 and example 3 were calculated and plotted against number of cycles in FIG. 3B. Finally, the isobutylene yields for the processes of both example 2 and example 3 were calculated and plotted against number of cycles in FIG. 3C. The results show that by adding a catalyst reduction step after catalyst oxidation (catalyst regeneration) step, both the overall isobutylene selectivity and the isobutylene yield for the isobutane dehydrogenation process were improved compared to the process that did not include a catalyst reduction step.

[0049] In the context of the present invention, at least the following 19 embodiments are described. Embodiment 1 is a hydrocarbon dehydrogenation process. The process includes: (a) passing an oxidizing gas through a reactor containing a catalyst containing gallium (Ga), an alkali metal, and alumina; (b) passing a reducing gas through the reactor; (c) contacting the catalyst with a hydrocarbon under reaction conditions sufficient to dehydrogenate the hydrocarbon; and repeating steps (a) to (c). Embodiment 2 is the hydrocarbon dehydrogenation process of embodiment 1, further including purging the reactor with an inert gas prior to and/or after step (b). Embodiment 3 is the hydrocarbon dehydrogenation process of embodiment 2, wherein the inert gas contains nitrogen, argon, steam, or combinations thereof. Embodiment 4 is the hydrocarbon dehydrogenation process of any of embodiments 1 to 3, wherein the catalyst contains Ga2Ch, K2O and alumina. Embodiment 5 is the hydrocarbon dehydrogenation process of embodiments 1 to 4, wherein the catalyst contains 0.5 to 25 wt.% Ga2Ch and 0.1 to 5 wt.% K2O. Embodiment 6 is the hydrocarbon dehydrogenation process of any of embodiments 1 to 5, wherein the catalyst has a specific surface of 50 to 250 m ² /g and a nitrogen pore volume of 0.2 to 1 ml/g. Embodiment 7 is the hydrocarbon dehydrogenation process of any of embodiments 1 to 6, wherein the catalyst has a Ga metal to support ratio of 0.004 to 0.25. Embodiment 8 is the hydrocarbon dehydrogenation process of any of embodiments 1 to 7, wherein the oxidizing gas is configured to oxidize the catalyst and remove carbon deposit formed on the catalyst during step (c). Embodiment 9 is the hydrocarbon dehydrogenation process of any of embodiments 1 to 8, wherein step (a) is performed at an oxidation temperature of 500 to 800 °C for 2 to 120 minutes. Embodiment 10 is the hydrocarbon dehydrogenation process of any of embodiments 1 to 9, wherein the oxidizing gas contains oxygen, air, oxygen enriched air, carbon dioxide, water, or combinations thereof. Embodiment 11 is the hydrocarbon dehydrogenation process of any of embodiments 1 to 10, wherein the reducing gas contains hydrogen, carbon monoxide, or combinations thereof. Embodiment 12 is the hydrocarbon dehydrogenation process of embodiment 11, wherein the reducing gas contains 1 to 100 vol.% hydrogen. Embodiment 13 is the hydrocarbon dehydrogenation process of any of embodiments 1 to 12, wherein step (b) is performed at a reducing temperature of 500 to 800 °C for a duration of 2 to 120 minutes. Embodiment 14 is the hydrocarbon dehydrogenation process of any of embodiments 1 to 13, wherein step (c) is performed at a reaction temperature 500 to 800 °C, a reaction pressure of 0.2 to 5 bar, and a gas hour space velocity of 100 to 1000 hr ¹ . Embodiment 15 is the hydrocarbon dehydrogenation process of any of embodiments 1 to 14, wherein the hydrocarbon contains one or more C2 to Cx hydrocarbons. Embodiment 16 is the hydrocarbon dehydrogenation process of embodiment 15, wherein the C2 to Cx hydrocarbons include C2 to C5 paraffins and the C2 to C5 paraffin is dehydrogenated to produce an olefin containing ethylene, propene, butylene, pentene, or combinations thereof. Embodiment 17 is the hydrocarbon dehydrogenation process of either of embodiments 15 or 16, wherein the C2 to Cx hydrocarbons include ethyl benzene, and the ethyl benzene is dehydrogenated to produce styrene. Embodiment 18 is the hydrocarbon dehydrogenation process of any of embodiments 1 to 17, wherein the hydrocarbon dehydrogenation process is capable of dehydrogenating a paraffin at a conversion rate of greater than 40%. Embodiment 19 is the hydrocarbon dehydrogenation process of any of embodiments 1 to 18, wherein the reactor includes a fixed bed reactor. Embodiment 20 is the hydrocarbon dehydrogenation process of any of embodiments 1 to 19, wherein the reactor includes a fluidized bed reactor. [0050] Although embodiments of the present application and their advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the embodiments as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the above disclosure, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.