Process for forming light olefins utilizing an oxidation vessel

Abstract

Light olefins may be formed by a process that may include reacting a feed stream in the presence of a catalyst in a reactor to form a product stream and a deactivated catalyst containing coke, separating at least a portion of the product stream from the deactivated catalyst, sending the deactivated catalyst to an oxidation vessel and contacting the deactivated catalyst with a first oxygen-containing gas to remove at least a portion of the coke on the deactivated catalyst to produce a decoked catalyst. The process may further include sending the decoked catalyst to a combustor and burning an auxiliary fuel in the combustor to heat the decoked catalyst to produce a heated catalyst, sending the heated catalyst to an oxygen soak zone and contacting the heated catalyst with a second oxygen-containing gas to produce a reactivated catalyst, and sending the reactivated catalyst to the reactor.

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims the benefit of U.S. Provisional Patent Application No. 63 / 428,500, filed November 29, 2022, the entire disclosure of which is incorporated herein by reference.

[0002] FIELD OF THE INVENTION FIELD OF THE INVENTION Embodiments described herein relate generally to chemical processing, and more particularly to methods and systems for producing light olefins. [Background technology]

[0003] Light olefins such as propylene can be used as a base material to produce many different materials, such as polypropylene, isopropanol, and acrylic acid, which can be used, for example, in packaging, construction, and textiles. As a result of this utility, there is a global demand for light olefins. Suitable processes for producing light olefins generally depend on a given chemical feed and include those that utilize fluidized catalysts. For example, light olefins can be formed by catalytic dehydrogenation of alkanes in a fluidized bed reactor. However, improvements are needed in the systems and associated catalysts used to make light olefins. Summary of the Invention

[0004] Some methods for producing light olefins utilize catalysts that may coke after dehydrogenation. In conventional embodiments, this coked catalyst may then be introduced directly into a combustor, where the coke is removed from the catalyst by combustion of the coke with oxygen (e.g., air), and supplemental fuel in the combustor is further utilized to heat the catalyst. The heated catalyst may then be sent to an air-soaking zone, where the catalyst is reactivated with an oxygen-containing gas, such as air, before being sent back to the dehydrogenation reactor. It has now been discovered that, in some embodiments, catalyst reactivation is not efficient through conventional reactivation processes that utilize a single combustor for coke combustion. For example, it has been discovered that an insufficient amount of coke can be removed, or insufficient structural changes to the catalytic active sites (due to limited contact with oxygen before the catalyst interacts with the fuel gas), or both, may exist in such comparative embodiments. Described herein are methods for forming light olefins utilizing an oxidation vessel. The oxidation vessel may generally be upstream of the combustor. In some embodiments, some amount of coke may be burned and / or some structural changes of the catalytic active sites may occur in the presence of oxygen in the oxidation vessel before reaching the combustor.

[0005] According to one or more embodiments of the present disclosure, light olefins may be formed by a method that may include reacting a feed stream in the presence of a catalyst in a reactor to form a product stream and a deactivated catalyst containing coke, separating at least a portion of the product stream from the deactivated catalyst, sending the deactivated catalyst to an oxidation vessel and contacting the deactivated catalyst with a first oxygen-containing gas to remove at least a portion of the coke on the deactivated catalyst to produce a decoked catalyst. The method may further include sending the decoked catalyst to a combustor and burning an auxiliary fuel in the combustor to heat the decoked catalyst to produce a heated catalyst, sending the heated catalyst to an oxygen soak zone and contacting the heated catalyst with a second oxygen-containing gas to produce a reactivated catalyst, and sending the reactivated catalyst to the reactor.

[0006] It should be understood that both the foregoing general description and the following detailed description describe various embodiments and are intended to provide an overview or framework for understanding the nature and features of the claimed subject matter. Additional features and advantages of the embodiments are set forth in the detailed description, and in part will become readily apparent to those skilled in the art from that description, including the accompanying drawings and claims, or can be learned by practicing the described embodiments. The drawings are included to provide a further understanding of the embodiments and, together with the detailed description, serve to explain the principles and operation of the claimed subject matter. However, the embodiments shown in the drawings are illustrative and exemplary in nature and are not intended to limit the claimed subject matter. [Brief explanation of the drawings]

[0007] The following detailed description can be better understood when read in conjunction with the following drawings. [Figure 1] 1 illustrates a schematic diagram of a reactor system according to one or more embodiments of the present disclosure. [Figure 2] 1 illustrates a schematic diagram of another reactor system according to one or more embodiments of the present disclosure. [Figure 3] 1 illustrates a schematic diagram of another reactor system according to one or more embodiments of the present disclosure. [Figure 4] 1 illustrates a schematic diagram of another reactor system according to one or more embodiments of the present disclosure. [Figure 5] 1 illustrates a schematic diagram of another reactor system according to one or more embodiments of the present disclosure. [Figure 6] 1 illustrates a schematic diagram of another reactor system according to one or more embodiments of the present disclosure.

[0008] 1-6 do not include the numerous valves, temperature sensors, electronic controllers, etc. that may be used and that are well known to those skilled in the art. Additionally, they do not include associated components that are often included within such reactor systems, such as air supplies, heat exchangers, surge tanks, etc. However, it should be understood that these components are within the scope of the present disclosure.

[0009] Reference will now be made in more detail to various embodiments, some of which are illustrated in the accompanying drawings. DETAILED DESCRIPTION OF THE INVENTION

[0010] The embodiments disclosed herein are described in detail herein in the context of the reactor system of Figures 1-6 operating as a fluidized dehydrogenation reactor system to produce light olefins. However, it should be understood that the principles disclosed and taught herein may be applicable to other systems utilizing different system components oriented in a different manner, or different reaction schemes utilizing various catalyst compositions. For example, the concepts described may equally apply to other systems with alternative reactor and regeneration units, such as those operating under non-fluidized conditions or those including a downer rather than a riser. Additionally, light olefins may be produced from a wide variety of hydrocarbon feed streams by utilizing different reaction mechanisms. For example, light olefins may be catalytically produced by at least dehydrogenation reactions, cracking reactions, dehydration reactions, and methanol-to-olefins reactions. In some embodiments, oxygen carrier materials may also be utilized, as described herein. These reaction types may utilize different feed streams and / or different catalysts to produce light olefins. Furthermore, it should be understood that not all portions of Figures 1-6 should be construed as essential to the claimed subject matter.

[0011] Referring now to FIG. 1 , an exemplary reactor system 101 that may be suitable for use with the methods and / or apparatus described herein is schematically illustrated. The reactor system 101 generally includes multiple system components, such as a reactor section 200 and a catalytic treater section 300. As described herein, a “system component” refers to a portion of the reactor system 101, such as, for example, a reactor, a separator, a transfer line, or a combination thereof. As used herein in the context of FIG. 1 , the reactor section 200 generally refers to the portion of the reactor system 101 where the primary process reaction (e.g., dehydrogenation) occurs to form a product stream. A feed stream enters the reactor section 200, is converted to a product stream (containing product and unreacted feed), and exits the reactor section 200. The reactor section 200 includes a reactor 202, which may include an upstream reactor section 250 and a downstream reactor section 230. 1, reactor section 200 may further include a catalyst separation section 210 that serves to separate the catalyst from the chemical products formed in reactor 202. Also, as used herein, catalytic treater 300 generally refers to a portion of reactor system 101 that treats catalyst in some manner, such as by combustion, to improve catalytic activity by, for example, decoking and / or heating the catalyst. Catalytic treater 300 may include oxidation vessel 500, combustor 350, riser 330, and may additionally include catalyst separation section 310. In one or more embodiments, catalyst separation section 210 of reactor section 200 may be in fluid communication with oxidation vessel 500 (e.g., via standpipe 426), and catalyst separation section 310 may be in fluid communication with upstream reactor section 250 (e.g., via standpipe 424 and transfer riser 430).

[0012] Generally, as described herein, the catalyst is circulated between the reactor section 200 and the catalyst treatment section 300. It should be understood that references to "catalyst" herein can refer to solid materials that are catalytically active for a desired reaction, or can equally refer to other particulate solids mentioned in connection with the system that do not necessarily have catalytic activity but influence the reaction, such as oxygen carriers. The terms "catalytic activity" and "catalyst activity" refer to the degree to which a catalyst is capable of catalyzing a reaction taking place in the reactor system 101. The catalyst exiting the reactor section 200 may be a deactivated catalyst. As used herein, "deactivated" may refer to a catalyst that is less catalytically active or cooler than the catalyst entering the reactor section 200. However, a deactivated catalyst may retain some catalytic activity. The loss of catalytic activity may result from contamination with materials such as coke. Reactivation (sometimes referred to herein as "regeneration") can remove contaminants such as coke, increase the temperature of the catalyst, or both. In embodiments, the deactivated catalyst may be reactivated by catalyst reactivation in the catalytic treater 300. The deactivated catalyst may be reactivated by, but not limited to, contacting the deactivated catalyst with an oxygen-containing gas to remove coke to produce a decoked catalyst, removing coke by combustion, restoring catalyst acidity, oxidizing the catalyst, other reactivation processes, or combinations thereof. In some embodiments, the catalyst may be heated during reactivation by combustion of an auxiliary fuel, such as hydrogen, methane, ethane, propane, natural gas, or combinations thereof, to produce a heated catalyst. The heated catalyst may be contacted with an oxygen-containing gas in the oxygen soak zone 370 of the catalytic treater 300 to produce a reactivated catalyst. The reactivated catalyst from the catalytic treater 300 may then be sent back to the reactor section 200.

[0013] 1, a feed stream may enter reactor 202 through feed inlet 434, and a product stream may exit reactor system 101 via pipe 420. According to one or more embodiments, reactor system 101 may be operated by supplying a chemical feed (e.g., in a feed stream) and a fluidized catalyst to upstream reactor section 250. The chemical feed contacts the catalyst in upstream reactor section 250, and each flows upward into and through downstream reactor section 230 to produce a chemical product.

[0014] The reactor section 200 may include an upstream reactor section 250, a transition section 258, and a downstream reactor section 230, such as a riser. The transition section 258 may connect the upstream reactor section 250 with the downstream reactor section 230. As shown in FIG. 1, the upstream reactor section 250 may be positioned below the downstream reactor section 230. Such a configuration may be referred to as an upflow configuration for the reactor 202. The upstream reactor section 250 may comprise a vessel, drum, barrel, vat, or other container suitable for a given chemical reaction. As shown in FIG. 1, the upstream reactor section 250 may be connected to the downstream reactor section 230 via the transition section 258. The upstream reactor section 250 may generally have a larger cross-sectional area than the downstream reactor section 230. The transition section 258 may taper from the cross-sectional size of the upstream reactor section 250 to the cross-sectional size of the downstream reactor section 230 such that the transition section 258 projects inward from the upstream reactor section 250 toward the downstream reactor section 230. For example, the transition section 258 may be a frustum.

[0015] The upstream reactor section 250 may be connected to a transfer riser 430, which may provide reactivated catalyst in a feed stream to the reactor section 200 during operation. The reactivated catalyst and / or reaction chemicals may be mixed in a distributor 260 housed within the upstream reactor section 250. Catalyst entering the upstream reactor section 250 via the transfer riser 430 may be sent to the transfer riser 430 through a standpipe 424, thus arriving from the catalyst treatment section 300. In some embodiments, the catalyst may enter the transfer riser 430 directly from the catalyst separation section 210 via a standpipe 422, in which case the catalyst enters the upstream reactor section 250; in such embodiments, a portion of the catalyst does not pass through the catalyst treatment section 300. Catalyst may also be fed directly to the upstream reactor section 250 via the standpipe 422 (not shown in FIG. 1 ). This catalyst may be somewhat deactivated but may still be suitable for reaction in the upstream reactor section 250 in some embodiments, especially when used in conjunction with a reactivated catalyst.

[0016] 1 , in one or more embodiments, based on the shape, size, and other process conditions (such as temperature and pressure) of the upstream reactor section 250 and the downstream reactor section 230, the upstream reactor section 250 can operate as a fluidized bed, such as a fast fluidized bed, turbulent bed, or bubbling bed upflow reactor, while the downstream reactor section 230 can operate more in a plug flow regime, such as a riser reactor. For example, the reactor 202 of FIG. 1 may have the upstream reactor section 250 operating as a fast fluidized bed, turbulent bed, or bubbling bed reactor and the downstream reactor section 230 operating as a dilute-phase riser reactor, such that the average catalyst and gas flows move upward simultaneously. "Average flow," as that term is used herein, refers to net flow, i.e., total upward flow minus countercurrent or reflux flow, as is generally typical of fluidized particle behavior. As used herein, a "fast-fluidization" reactor may refer to a reactor that utilizes a fluidization regime in which the superficial velocity of the gas phase is greater than the choking velocity and that may be semi-dense during operation. As used herein, a "turbulent" reactor may refer to a fluidization regime in which the superficial velocity is less than the choking velocity and that is denser than the fast-fluidization regime. As used herein, a "bubble-bed" reactor may refer to a fluidization regime in which well-defined gas bubbles within a dense bed exist in two distinct phases. "Choking velocity" refers to the minimum velocity required to maintain solids in a dilute-phase mode in a vertical transport line. As used herein, a "dilute-phase riser" may refer to a riser reactor that operates at a transport velocity, where the gas and catalyst have approximately the same velocity in the dilute phase.

[0017] According to an embodiment, the chemical products and catalyst may be discharged from downstream reactor section 230 and sent to a separator 220 in catalyst separation section 210, where the catalyst is separated from the chemical products and the chemical products are transported from catalyst separation section 210. According to one or more embodiments, following separation from the vapors in separator 220, the catalyst may generally travel through stripper 224 to catalyst outlet port 222, where it is transported out of reactor section 200 via standpipe 426 to catalyst treatment section 300.

[0018] According to one or more embodiments, separator 220 may be a cyclonic separation system that may include two or more stages of cyclonic separation. In embodiments in which separator 220 includes two or more stages of cyclonic separation, the first separator into which the fluidized stream enters is referred to as the primary cyclonic separator. The fluidized effluent from the primary cyclonic separator may enter a secondary cyclonic separator for further separation. Primary cyclonic separators may include, for example, primary cyclones and systems commercially available under the names VSS (commercially available from UOP), LD2 (commercially available from Stone and Webster), and RS2 (commercially available from Stone and Webster). Primary cyclones are described, for example, in U.S. Pat. Nos. 4,579,716, 5,190,650, and 5,275,641, each of which is incorporated herein by reference in its entirety. Some separation systems utilizing a primary cyclone as the primary cyclone separator use one or more sets of additional cyclones, e.g., secondary and tertiary cyclones, to further separate the catalyst from the product gas. It should be understood that any primary cyclone separator may be used in embodiments of the present invention.

[0019] According to one or more embodiments, and referring to FIG. 1 , the deactivated catalyst may be delivered from reactor section 200 to oxidation vessel 500 via standpipe 426. A first oxygen-containing gas, such as air, may enter oxidation vessel 500 via pipe 428, for example, and contact the deactivated catalyst. The first oxygen-containing gas may contact the deactivated catalyst in oxidation vessel 500 for 0.1 to 10 minutes. The fluidization regime of the deactivated catalyst in oxidation vessel 500 may be a dense phase transfer, bubbling bed, turbulent fluidized bed, or fast fluidized bed fluidization regime. The oxidation vessel 500 may include an inlet port 504 that may be in fluid communication with combustor 350 such that the oxidation vessel 500 is directly connected to the combustor 350 and the decoked catalyst is delivered directly from the oxidation vessel 500 to the combustor 350. Contacting the deactivated catalyst with the first oxygen-containing gas for a time period between 0.1 and 10 minutes may remove at least a portion of the coke deposited on the deactivated catalyst to produce a decoked catalyst. It is contemplated that the “decoked” catalyst may still contain some amount of coke, but may contain less coke than the catalyst entering the oxidation vessel 500. The decoked catalyst may enter the combustor 350 through the inlet port 504 of the oxidation vessel 500. Without being bound by theory, it is believed that contacting the deactivated catalyst with the first oxygen-containing gas in the oxidation vessel 500 removes at least a portion of the coke from the deactivated catalyst, thereby preventing excessive oxygen depletion in the combustor 350 in the event of catalyst maldistribution in the combustor 350.

[0020] In one or more embodiments, the deactivated catalyst may comprise 0.01 wt. % to 0.4 wt. % coke, based on the total weight of the catalyst, as it enters the oxidation vessel 500 and after exiting the reactor section 200 via the standpipe 426. In additional embodiments, the deactivated catalyst may comprise 0.01 wt. % to 0.1 wt. %, 0.1 wt. % to 0.2 wt. %, 0.2 wt. % to 0.3 wt. %, 0.3 wt. % to 0.4 wt. % coke, or any combination of these ranges, based on the total weight of the catalyst, as it enters the oxidation vessel 500 and after exiting the reactor section 200 via the standpipe 426.

[0021] Without being bound by any particular theory, it is believed that the coke present on the deactivated catalyst may include different types of coke, referred to herein as "hard" and "soft" coke, and that hard coke may be more difficult to combust than soft coke. In one or more embodiments, the process in oxidation vessel 500 may combust the hard coke, which, if not removed, may reduce the catalyst regeneration experienced by the catalyst in combustor 350 and oxygen soak zone 370.

[0022] In one or more embodiments, at least 70% by weight of the coke is removed from the deactivated catalyst in oxidation vessel 500 to produce a decoked catalyst. For example, in some embodiments, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 99%, or even 100% by weight of the coke is removed from the deactivated catalyst in oxidation vessel 500 to produce a decoked catalyst.

[0023] In one or more embodiments, between 0% and 30% by weight of coke may be present in the decoked catalyst as it is passed from oxidation vessel 500 to combustor 350. For example, between 0% and 5%, between 5% and 10%, between 10% and 15%, between 15% and 20%, between 20% and 25%, between 25% and 30%, or any combination of these ranges of coke may be present in the decoked catalyst as it is passed from oxidation vessel 500 to combustor 350.

[0024] In one or more embodiments, at least 95% by weight of the coke on the deactivated catalyst is combusted in the oxidation vessel. In additional embodiments, at least 96%, at least 97%, at least 98%, at least 99%, or even 100% by weight of the coke on the deactivated catalyst is combusted in the oxidation vessel.

[0025] As shown in FIG. 1 , the oxidation vessel 500 may have a shape similar to or identical to that described in the context of the reactor 202. For example, the oxidation vessel 500 may include an upstream section 550, a transition section 558, and a downstream section 530. As shown in FIG. 1 , the upstream section 550 may be positioned below the downstream section 530. Such a configuration may be referred to as an upflow configuration for the oxidation vessel 500. The upstream section 550 may comprise a vessel, drum, barrel, vat, or other container suitable for a given chemical reaction. As shown in FIG. 1 , the upstream section 550 may be connected to the downstream section 530 via the transition section 558. The upstream section 550 may generally have a larger cross-sectional area than the downstream section 530. The transition section 558 may taper from the cross-sectional size of the upstream section 550 to the cross-sectional size of the downstream section 530 such that the transition section 558 projects inward from the upstream section 550 toward the downstream section 530. For example, the transition section 558 may be a frustum.

[0026] 1 , in one or more embodiments, based on the shape, size, and other process conditions (such as temperature and pressure) of the upstream section 530 and the downstream section 550, the upstream section 530 can operate as a fluidized bed, such as a fast fluidized bed, turbulent bed, or bubbling bed upflow reactor, while the downstream section 550 can operate more in a plug flow manner, such as a riser reactor. For example, the oxidation vessel 500 of FIG. 1 may have the upstream section 530 operating as a fast fluidized bed, turbulent bed, or bubbling bed reactor and the downstream section 550 operating as a dilute phase riser reactor, such that the average catalyst and gas flows move upward simultaneously.

[0027] In one or more embodiments, the oxidation vessel 500 may operate at a superficial gas velocity of less than 8 ft / sec in at least the upstream section 550. In one or more embodiments, the oxidation vessel 500 may operate at a superficial gas velocity of 0.1 ft / sec to 8 ft / sec, such as 0.1 ft / sec to 1 ft / sec, 1 ft / sec to 2 ft / sec, 2 ft / sec to 3 ft / sec, 3 ft / sec to 4 ft / sec, 4 ft / sec to 5 ft / sec, 5 ft / sec to 6 ft / sec, 6 ft / sec to 7 ft / sec, 7 ft / sec to 8 ft / sec, or any combination of these ranges. In one or more embodiments, the decoked catalyst in the combustor 350 may operate at a superficial gas velocity of less than 20 lb / ft 3 ~30lb / ft 3 , 30 lb / ft 3 ~40lb / ft 3 , 40 lb / ft 3 ~50lb / ft 3 , 50lb / ft 3 ~60lb / ft 3 20 lb / ft, or any combination of these ranges 3 ~60lb / ft 3 The superficial gas velocity may be substantially accelerated through the downstream section 550 of the oxidation vessel 500. In one or more embodiments, the oxidation vessel 500 may have a catalyst bed density of 100 to 150 lb / ft 2 seconds, 150~200lb / ft 2 seconds, 200~250lb / ft 2 seconds, 250~300lb / ft 2 100 to 300 lb / ft sec, or any combination of these ranges 2 The catalyst may operate with a catalyst flow of 1000 s. These catalyst characteristics may also be present in embodiments such as those shown in Figures 2 or 5 that utilize pipe 438 as an oxidation vessel. Catalyst residence in this pipe configuration may range from 10 to 240 s, 20 to 120 s, or 25 to 60 s.

[0028] As shown in FIG. 1, the oxidation vessel 500 may be directly connected to the combustor 350 such that the catalyst is fluidized while in the oxidation vessel 500 and fed directly to the combustor 350 .

[0029] 1 , in combustor 350, the catalyst may be treated, for example, by combustion of oxygen with an auxiliary fuel. For example, without limitation, the catalyst may be further decoked and / or the auxiliary fuel may be burned to heat the catalyst. Burning the auxiliary fuel in combustor 350 may raise the temperature of the decoked catalyst to 660°C or higher. The catalyst may then exit combustor 350 and be sent through riser 330 to end-of-riser separator 378, where gas and solid components from riser 330 are at least partially separated. The vapor and remaining solids are transferred to secondary separator 320 in catalyst separation section 310, where the remaining catalyst is separated from gases from the catalytic treatment (e.g., gases emitted by combustion of spent catalyst or auxiliary fuel, referred to herein as flue gas). The flue gas may exit catalytic treatment section 300 via outlet pipe 432. The separated catalyst is then sent through oxygen soak zone 370 in catalyst separation section 310 via standpipe 424 and transfer riser 430 to upstream reactor section 250 for further utilization in catalytic reactions. Thus, the catalyst can be circulated between reactor section 200 and catalyst treatment section 300 during operation. Generally, the treated chemical streams, including the feed stream and product stream, can be gaseous, and the catalyst can be a fluidized particulate solid.

[0030] As described herein, since the majority of the coke is removed in the oxidation vessel 500, according to one or more embodiments, such potential maldistribution of catalyst in the combustor 350 may not result in extreme local concentration differences of oxygen in the combustor 350.

[0031] Without being bound by any particular theory, it is believed that in conventional embodiments, coked and deactivated catalyst may not be fully stoichiometrically distributed with air when it enters the combustor and subsequently contacts the fuel gas. This lack of localized oxygen may be the result of uneven catalyst distribution in the combustor. Such uneven distribution may result in reduced coke removal from the catalyst, which may result in a lack of activity for burning the auxiliary fuel. Therefore, in some embodiments described herein, the above-mentioned effects of uneven catalyst distribution in the combustor may be minimized because less coke is available to locally reduce the oxygen concentration in the combustor.

[0032] Additionally, without being bound by any theory, it is believed that in some embodiments, maldistribution of the catalyst due to coke can result in insufficient oxygen concentration in regions of the combustor due to localized combustion of the coke (reducing the local oxygen concentration in those regions). Therefore, these regions may have insufficient oxygen to burn the auxiliary fuel at a desired rate, and thus, system inefficiencies may exist. Without being bound by any particular theory, it is believed that such catalysts (conventional methods) require longer reactivation to reach the same dehydrogenation activity. Therefore, the embodiments described herein may improve catalyst performance and overall system efficiency and product yield production.

[0033] In additional embodiments, without being bound by theory, it is believed that other mechanisms may exist in conventional processes (e.g., processes that do not utilize an oxidation vessel as described herein) where the catalyst has limited contact with oxygen prior to contact with the fuel gas, such as a lack of structural changes necessary for catalytically active sites. Thus, in some embodiments, utilization of an oxidation vessel may improve the structural changes of the catalyst, which are sometimes desirable, upon contact with the fuel gas.

[0034] Referring now to catalytic treat section 300, as illustrated in FIG. 1 , combustor 350 of catalytic treat section 300 may be in fluid communication with riser 330. Oxygen-containing gas, such as air, may be routed through oxidation vessel 500 via pipe 428, or a separate oxygen-containing gas line may enter combustor 350 directly (not shown). Combustor 350 and riser 330, collectively referred to as catalytic combustion reactor 302, may operate in a similar or identical fluidization regime to that disclosed with respect to upstream reactor section 250 and downstream reactor section 230 of reactor section 200. That is, combustor 350 may operate as a fluidized bed, such as in a fast fluidized bed, turbulent bed, or bubbling bed upflow reactor, while riser 330 may operate in a plug flow regime, such as a riser reactor. The geometries described with respect to upstream reactor section 250 and downstream reactor section 230 are equally applicable to combustor 350 and riser 330. Additionally, the combustor 350 may also include a fuel inlet 354 through which a fuel, such as a hydrocarbon stream, may be supplied to the combustor 350 .

[0035] In one or more embodiments, the combustor 350 may operate at a superficial gas velocity of less than 4 ft / sec. In one or more embodiments, the combustor 350 may operate at a superficial gas velocity of 0.1 ft / sec to 4 ft / sec, such as 0.1 ft / sec to 3.5 ft / sec, 0.1 ft / sec to 3 ft / sec, 0.1 ft / sec to 2.5 ft / sec, 0.1 ft / sec to 2 ft / sec, 0.1 ft / sec to 1.5 ft / sec, 0.1 ft / sec to 1 ft / sec, 0.5 ft / sec to 4 ft / sec, 1 ft / sec to 4 ft / sec, 1.5 ft / sec to 4 ft / sec, 2 ft / sec to 4 ft / sec, 2.5 ft / sec to 4 ft / sec, 3 ft / sec to 4 ft / sec, 0.5 ft / sec to 3.5 ft / sec, 1 ft / sec to 3 ft / sec, or 1.5 ft / sec to 2.5 ft / sec. In one or more embodiments, the decoked catalyst in the combustor 350 is 25 lb / ft 3 ~35lb / ft 3 , 30 lb / ft 3 ~35lb / ft 3 , 20 lb / ft 3 ~30lb / ft 3 , or 20 lb / ft3 ~25lb / ft 3 Such as 20 lb / ft 3 ~40lb / ft 3 The catalyst bed density may be

[0036] As described in one or more embodiments, following separation of the flue gas from the catalyst in the end-of-riser separator 378 and secondary separation unit 320, treatment of the treated catalyst with a second oxygen-containing gas occurs in the oxygen soak zone 370. In some embodiments, the oxygen soak zone 370 comprises a fluid-solid contactor. The fluid-solid contactor may include a baffle or grid structure to facilitate contact of the treated catalyst with the second oxygen-containing gas. Examples of fluid-solid contactors are described in further detail in U.S. Pat. Nos. 9,827,543 and 9,815,040. The fluidization regime within the oxygen soak zone 370 may be bubbling bed fluidization. The oxygen soak zone 370 may include an oxygen-containing gas inlet 372 that may deliver a second oxygen-containing gas to the oxygen soak zone 370 for oxygen treatment of the catalyst. The temperature of the heated catalyst may be 660° C. or higher while the heated catalyst is in the oxygen soak zone 370. Without being bound by theory, it is believed that contacting the heated catalyst with an oxygen-containing gas in oxygen soak zone 370 increases the catalytic activity for dehydrogenating alkanes, resulting in increased alkane conversion in reactor section 200.

[0037] In one or more embodiments, the reactivated catalyst produced from treating the heated catalyst with a second oxygen-containing gas in oxygen soak zone 370 may be further contacted with a stripping gas before passing the reactivated catalyst to reactor section 200. In some embodiments, the stripping gas may be nitrogen, methane, or steam, or one or more inert gases. Without being bound by theory, it is believed that contacting the reactivated catalyst with the stripping gas removes at least a portion of the molecular oxygen trapped within or between the catalyst particles, which reduces the amount of oxygen carried into reactor 200.

[0038] 1 , in one or more embodiments, a portion of the heated catalyst may exit catalytic treater 300 before being sent to oxygen soak zone 370. In some embodiments, a recycled portion of the heated catalyst from catalytic treater 300 may be sent directly to oxidation vessel 500 via line 385. Such recycled catalyst may be exposed to some oxygen, but not the normal amount of oxygen associated with oxygen soak zone 370.

[0039] Referring now to Figure 3, there is illustrated another embodiment of reactor system 103 that is similar to or identical to that of Figure 1, except for the differences described below. In the Figure 3 embodiment, recycled catalyst in line 385 is sent to combustor 350 rather than oxidation vessel 500 (as described in the Figure 1 embodiment). Such a scheme can be effective because the recycled catalyst is largely free of coke, and therefore catalyst maldistribution in combustor 350 is less likely to cause problems.

[0040] Another embodiment is shown in FIG. 2 , which illustrates a reactor system 102, which is similar to or identical to that of FIG. 1 , except for the differences described below. In the embodiment of FIG. 2 , the oxidation vessel 500 and the combustor 350 may be physically separated from one another. In such an embodiment, the oxidation vessel 500 and the combustor 350 are connected via one or more pipelines, and the catalyst may not be exposed to oxygen and / or may not be fluidized throughout such pipelines. As shown in FIG. 2 , the oxidation vessel 500 may be a separate reaction vessel operating as a fluidized bed. An oxygen-containing gas (inlet not shown in FIG. 2 ) may contact the deactivated catalyst entering the oxidation vessel 500 via line 426. Here, line 506 may deliver the decoked catalyst to pipe 438, through which the oxygen-containing gas fluidizes the catalyst and delivers it to the combustor 350. Some additional coke combustion may occur in pipe 438, but the majority of the coke combustion may occur in oxidation vessel 500. Line 510 may route the gas (after treatment) from oxidation vessel 500 to catalyst separation section 310, as shown in Figure 2, where existing cyclones in catalyst treatment system 300 may be used to separate the gas and small amounts of catalyst carryover.

[0041] Another embodiment is illustrated in FIG. 4, which shows a reactor system 104 that is in many respects similar or identical to the embodiment of FIG. 2. In the embodiment of FIG. 4, a separate oxidation vessel 500 decoks the catalyst (as previously described in the context of FIG. 4). However, rather than sending the catalyst via line 506 to pipe 438 and having an oxygen-containing gas fluidize the catalyst, the catalyst is sent directly into combustor 350 via line 506. In such an embodiment, it is believed that little or no coke will burn in the passage between oxidation vessel 500 and combustor 350, as compared to the embodiment of FIG. 2, in which combustion may occur in pipe 438 in addition to oxidation vessel 500.

[0042] Referring now to reactor system 105 of FIG. 5, another embodiment is illustrated, which may be similar or identical in many respects to FIG. 1. In FIG. 5, oxidation vessel 500 is pipe 438, and oxygen-containing gas is routed from port 428 via line 429 into pipe 438 to fluidize the catalyst and route it upward to combustor 350. In such an embodiment, no separate reaction drum is included. Rather, oxidation vessel 500 is a pipe that may have dilute-phase fluidization. FIG. 5 illustrates an embodiment in which catalyst is recycled to oxidation vessel 50 via line 385, similar to the embodiment of FIG. 1. FIG. 6 illustrates yet another embodiment, reactor system 106, which is similar or identical to that of FIG. 5, but which recycles catalyst via line 385 directly to combustor 350 rather than to oxidation vessel 500.

[0043] In one or more embodiments, light olefins may be present in and may comprise a "product stream," sometimes referred to as an "olefin-containing effluent." Such a stream may exit reactor system 102 and be subsequently processed. As used in this disclosure, the term "light olefins" refers to one or more of styrene, ethylene, propylene, and butene. The term butene includes any isomer of butene, such as α-butylene, cis-β-butylene, trans-β-butylene, and isobutylene. In some embodiments, the olefin-containing effluent comprises at least 25 wt.% light olefins, based on the total weight of the olefin-containing effluent. For example, the olefin-containing effluent may comprise at least 35 wt.% light olefins, at least 45 wt.% light olefins, at least 55 wt.% light olefins, at least 65 wt.% light olefins, or at least 75 wt.% light olefins, based on the total weight of the olefin-containing effluent. The olefin-containing effluent may further comprise unreacted components of the feed stream and other reaction products not considered light olefins. The light olefins can be separated from the unreacted components in a subsequent separation step.

[0044] In a non-limiting example, the reactor systems described herein may be utilized to produce light olefins from a hydrocarbon feed stream. Light olefins may be produced from a wide variety of hydrocarbon feed streams by utilizing different reaction mechanisms. For example, light olefins may be produced by at least dehydrogenation reactions, cracking reactions, dehydration reactions, and methanol-to-olefins reactions. These reaction types may utilize different feed streams and different particulate solids to produce light olefins. It should be understood that when "catalysts" are referred to herein, they may equally refer to the particulate solids referred to with respect to the system of FIG. 1.

[0045] According to one or more embodiments, the reaction may be a dehydrogenation reaction. According to such embodiments, the hydrocarbon feed stream may comprise one or more of ethylbenzene, ethane, propane, n-butane, and i-butane. In one or more embodiments, the hydrocarbon feed stream may comprise at least 50 wt%, at least 60 wt%, at least 70 wt%, at least 80 wt%, at least 90 wt%, at least 95 wt%, or even at least 99 wt% ethylbenzene. In one or more embodiments, the hydrocarbon feed stream may comprise at least 50 wt%, at least 60 wt%, at least 70 wt%, at least 80 wt%, at least 90 wt%, at least 95 wt%, or even at least 99 wt% ethane. In additional embodiments, the hydrocarbon feed stream may comprise at least 50 wt%, at least 60 wt%, at least 70 wt%, at least 80 wt%, at least 90 wt%, at least 95 wt%, or even at least 99 wt% propane. In additional embodiments, the hydrocarbon feed stream may comprise at least 50 wt%, at least 60 wt%, at least 70 wt%, at least 80 wt%, at least 90 wt%, at least 95 wt%, or even at least 99 wt% n-butane. In additional embodiments, the hydrocarbon feed stream may comprise at least 50 wt%, at least 60 wt%, at least 70 wt%, at least 80 wt%, at least 90 wt%, at least 95 wt%, or even at least 99 wt% i-butane. In additional embodiments, the hydrocarbon feed stream may comprise at least 50 wt%, at least 60 wt%, at least 70 wt%, at least 80 wt%, at least 90 wt%, at least 95 wt%, or even at least 99 wt% of the total of ethane, propane, n-butane, and i-butane.

[0046] In one or more embodiments, the dehydrogenation reaction may utilize a gallium and / or platinum particulate solid as a catalyst. In such embodiments, the particulate solid may include a gallium and / or platinum catalyst. As described herein, a gallium and / or platinum catalyst includes gallium, platinum, or both. The gallium and / or platinum catalyst may be supported on an alumina or alumina-silica support and may optionally include potassium. Such gallium and / or platinum catalysts are disclosed in U.S. Pat. No. 8,669,406, which is incorporated herein by reference in its entirety. However, it should be understood that other suitable catalysts may be utilized to carry out the dehydrogenation reaction.

[0047] In one or more embodiments, the reaction mechanism may be dehydrogenation followed by combustion (in the same chamber). In such embodiments, the dehydrogenation reaction may produce hydrogen as a by-product, and the oxygen carrier material may contact the hydrogen to promote combustion of the hydrogen to form water. Examples of such reaction mechanisms contemplated as possible reaction mechanisms for the systems and methods described herein are disclosed in WO 2020 / 046978, the teachings of which are incorporated herein by reference in their entirety.

[0048] According to one or more embodiments, the reaction may be a cracking reaction. According to such embodiments, the hydrocarbon feed stream may comprise one or more of naphtha, n-butane, or i-butane. According to one or more embodiments, the hydrocarbon feed stream may comprise at least 50 wt%, at least 60 wt%, at least 70 wt%, at least 80 wt%, at least 90 wt%, at least 95 wt%, or even at least 99 wt% naphtha. In additional embodiments, the hydrocarbon feed stream may comprise at least 50 wt%, at least 60 wt%, at least 70 wt%, at least 80 wt%, at least 90 wt%, at least 95 wt%, or even at least 99 wt% n-butane. In additional embodiments, the hydrocarbon feed stream may comprise at least 50 wt%, at least 60 wt%, at least 70 wt%, at least 80 wt%, at least 90 wt%, at least 95 wt%, or even at least 99 wt% i-butane. In additional embodiments, the hydrocarbon feed stream may comprise a total of at least 50 wt%, at least 60 wt%, at least 70 wt%, at least 80 wt%, at least 90 wt%, at least 95 wt%, or even at least 99 wt% naphtha, n-butane, and i-butane.

[0049] In one or more embodiments, the cracking reaction may utilize one or more zeolites as a catalyst. In such embodiments, the particulate solid may include one or more zeolites. In some embodiments, the one or more zeolites utilized in the cracking reaction may include ZSM-5 zeolite. However, it should be understood that other suitable catalysts may be utilized to carry out the cracking reaction. For example, suitable commercially available catalysts may include Intercat Super Z Excel or Intercat Super Z Exceed. In additional embodiments, the cracking catalyst may include platinum in addition to the catalytically active material. For example, the cracking catalyst may include 0.001% to 0.05% by weight of platinum. The platinum may be sprayed as platinum nitrate and calcined at a high temperature, such as about 700°C. Without being bound by theory, it is believed that the addition of platinum to the catalyst may enable easier combustion of auxiliary fuels, such as methane.

[0050] According to one or more embodiments, the reaction may be a dehydration reaction. According to such embodiments, the hydrocarbon feed stream may comprise one or more of ethanol, propanol, or butanol. According to one or more embodiments, the hydrocarbon feed stream may comprise at least 50 wt%, at least 60 wt%, at least 70 wt%, at least 80 wt%, at least 90 wt%, at least 95 wt%, or even at least 99 wt% ethanol. In additional embodiments, the hydrocarbon feed stream may comprise at least 50 wt%, at least 60 wt%, at least 70 wt%, at least 80 wt%, at least 90 wt%, at least 95 wt%, or even at least 99 wt% propanol. In additional embodiments, the hydrocarbon feed stream may comprise at least 50 wt%, at least 60 wt%, at least 70 wt%, at least 80 wt%, at least 90 wt%, at least 95 wt%, or even at least 99 wt% butanol. In additional embodiments, the hydrocarbon feed stream may comprise a total of at least 50 wt%, at least 60 wt%, at least 70 wt%, at least 80 wt%, at least 90 wt%, at least 95 wt%, or even at least 99 wt% ethanol, propanol, and butanol.

[0051] In one or more embodiments, the dehydration reaction may utilize one or more acid catalysts. In such embodiments, the particulate solid may include one or more acid catalysts. In some embodiments, the one or more acid catalysts utilized in the dehydration reaction may include a zeolite (such as ZSM-5 zeolite), alumina, an amorphous aluminosilicate, an acid clay, or a combination thereof. For example, commercially available alumina catalysts that may be suitable, according to one or more embodiments, include SynDol (available from Scientific Design Company), V200 (available from UOP), or P200 (available from Sasol). Commercially available zeolite catalysts that may be suitable include CBV 8014, CBV 28014 (each available from Zeolyst). Commercially available amorphous aluminosilicate catalysts that may be suitable include silica-alumina catalyst support, grade 135 (available from Sigma-Aldrich). However, it should be understood that other suitable catalysts may be utilized to carry out the dehydration reaction.

[0052] According to one or more embodiments, the reaction can be a methanol to olefins reaction. According to such embodiments, the hydrocarbon feed stream can include methanol. According to one or more embodiments, the hydrocarbon feed stream can include at least 50 wt%, at least 60 wt%, at least 70 wt%, at least 80 wt%, at least 90 wt%, at least 95 wt%, or even at least 99 wt% methanol.

[0053] In one or more embodiments, the methanol-to-olefins reaction may utilize one or more zeolites as a catalyst. In such embodiments, the particulate solid may comprise one or more zeolites. In some embodiments, the one or more zeolites utilized in the methanol-to-olefins reaction may comprise one or more of ZSM-5 zeolite or SAPO-34 zeolite. However, it should be understood that other suitable catalysts may be utilized to carry out the methanol-to-olefins reaction. [Example]

[0054] Examples are provided herein that may disclose one or more embodiments of the present disclosure. However, the examples should not be construed as limiting the claimed embodiments provided below.

[0055] Example 1 The catalysts used in these experiments were prepared by the conventional incipient wetness method and contain platinum and gallium on alumina. The fresh catalyst had 300 ppm platinum, while the aged catalyst, recovered from a pilot-scale run after 9 months on stream, had 75 ppm platinum. Both catalysts had 1.6 wt. % gallium.

[0056] Experiments were conducted in a fixed-bed laboratory-scale unit using simulated dehydrogenation, pre-combustion contact with air, combustion, and air soaking steps. The catalyst was diluted with silicon carbide, 99.8 wt% purity, 220 mesh Go Products, at a 1:2 dilution by weight. The catalyst bed was held in place in a reactor with upstream and downstream sections of 20-40 mesh silicon carbide, 98.5 wt% purity, 20-40 mesh Go Products. The cycle was constructed as follows: first gas flow for 7.1 hours; -1 and the temperature and length of time the catalyst is in contact with the first gas stream are provided in Tables 1-3; -1 The fuel gas stream was contacted with the catalyst at 730°C for 3 minutes, and the second gas stream was contacted with the catalyst at 730°C for 7.1 hours. -1 and the hydrocarbon stream was air having a weight hourly space velocity of 1000 psi for propane, and the second gas stream was contacted with the catalyst at 730°C for the length of time provided in Tables 1-3. -1 The feed was 90 mol % propane / 10 mol % N with a weight hourly space velocity of 100 Hz, and the hydrocarbon stream was contacted with the catalyst for 1 minute at 625° C. Dehydrogenation performance data was collected at an on-stream time of 25 seconds, and combustion data was collected at an on-stream time of 75 seconds.

[0057] Intermediate purge steps with inert gas were performed to establish clear starts and stops for the air soak, combustion, and dehydrogenation steps. Generally, a 3 or 4 minute N purge step (approximately 7 hours) was used. -1 For steps with temperature changes, the catalyst was purged with N2 (approximately 7 hours) until the temperature stabilized before introducing the gas flow for the next step. -1 The mixture was heated / cooled under a constant temperature (at 2000 K). Tables 1-3 below illustrate the propane conversion, propylene selectivity, and methane conversion achieved according to these experimental procedures by varying the temperature and reaction time of certain steps of the procedure. As can be seen, higher propane conversion and propylene selectivity were achieved when a pre-combustion step was utilized, and lower temperatures for the pre-combustion step were shown to achieve higher propane conversion and propylene selectivity.

[0058] [Table 1]

[0059] [Table 2]

[0060] [Table 3]

[0061] Example 2 The propane dehydrogenation performance after each step of the process was studied. Five cases were run for a total of 79 cycles: a dehydrogenation step at 625°C for 1 minute, a pre-combustion air treatment step at 625°C for 3 minutes, a combustion step at 730°C for 3 minutes using 2.5% methane / 97.5% synthetic air by volume, and an air soak step at 730°C for 7 minutes. The cycles were varied for each case to determine the dehydrogenation performance after each step. In the first set with pre-combustion air treatment, the pre-combustion air treatment step was performed at 625°C for 3 minutes, a combustion step at 730°C for 3 minutes using 2.5% methane / 97.5% synthetic air by volume, and an air soak step at 730°C for 7 minutes. In the second set, the pre-combustion air treatment was omitted, and the combustion step was carried out at 730°C for 3 minutes using 2.5% methane / 97.5% synthetic air by volume, and the air soak step was carried out at 730°C for 7 minutes. Dehydrogenation performance data was collected with a 25 second run time. Table 4 shows the results of these experiments. As can be seen, the propane conversion percentage increased after each step of the cycle that utilized the initial pre-combustion step.

[0062] [Table 4]

[0063] The present disclosure includes several embodiments. A first embodiment is a method for forming light olefins, the method including: reacting a feed stream in the presence of a catalyst in a reactor to form a product stream and a deactivated catalyst comprising coke; separating at least a portion of the product stream from the deactivated catalyst; passing the deactivated catalyst to an oxidation vessel and contacting the deactivated catalyst with a first oxygen-containing gas to remove at least a portion of the coke on the deactivated catalyst to produce a decoked catalyst; passing the decoked catalyst to a combustor and burning an auxiliary fuel in the combustor to heat the decoked catalyst to produce a heated catalyst; passing the heated catalyst to an oxygen soak zone and contacting the heated catalyst with a second oxygen-containing gas to produce a reactivated catalyst; and passing the reactivated catalyst to the reactor.

[0064] Another embodiment is any preceding embodiment or combination of the preceding embodiments, wherein the deactivated catalyst contains 0.01 wt. % to 0.4 wt. % coke upon entering the oxidation vessel.

[0065] Another embodiment is any preceding embodiment or combination of the preceding embodiments, wherein from 0 wt. % to 30 wt. % coke is present in the decoked catalyst.

[0066] Another embodiment is any preceding embodiment or combination of the preceding embodiments, wherein at least 70 wt. % of the coke on the deactivated catalyst is combusted in the oxidation vessel.

[0067] Another embodiment is any preceding embodiment or combination of the preceding embodiments, wherein the first oxygen-containing gas is air.

[0068] Another embodiment is where the oxidation vessel operates at a superficial gas velocity of less than 8 ft / sec and the deactivated catalyst in the oxidation vessel is less than 20 lb / ft 3 ~60lb / ft 3 any preceding aspect or combination of the preceding aspects, wherein the catalyst bed density is

[0069] Another embodiment is where the combustor operates at a superficial gas velocity of less than 4 ft / sec when burning auxiliary fuel, and the decoked catalyst in the combustor is at a superficial gas velocity of less than 20 lb / ft 3 ~40lb / ft 3 any preceding aspect or combination of the preceding aspects, wherein the catalyst bed density is

[0070] Another embodiment is any preceding embodiment or combination of the preceding embodiments, wherein the temperature of the decoked catalyst is increased to 660° C. or greater by burning a supplemental fuel in the combustor.

[0071] Another embodiment is any preceding embodiment or combination of the preceding embodiments, wherein the temperature of the heated catalyst is 660° C. or greater while the heated catalyst is in the oxygen soak zone.

[0072] Another embodiment is any preceding embodiment or combination of the preceding embodiments, further comprising contacting the reactivated catalyst with a stripping gas prior to passing the reactivated catalyst to the reactor.

[0073] Another embodiment is any preceding embodiment or combination of the preceding embodiments, wherein the oxidation vessel is a fluidized bed reactor.

[0074] Another embodiment is any preceding embodiment or combination of the preceding embodiments, wherein the oxidation vessel is a flow pipe.

[0075] Another embodiment is any of the preceding embodiments or combinations of the preceding embodiments, wherein the oxidation vessel is physically separated from the combustor.

[0076] Another embodiment is any preceding embodiment or combination of the preceding embodiments, further comprising sending the recycled portion of the heated catalyst directly to the oxidation vessel.

[0077] Another aspect is any preceding aspect or combination of the preceding aspects, further comprising directing the recycled portion of the heated catalyst directly to the combustor.

[0078] The subject matter of the present disclosure has been described in detail with reference to specific embodiments. It should be understood that any detailed description of an element or feature of an embodiment does not necessarily mean that the element or feature is essential to the particular embodiment or any other embodiment. Furthermore, it will be apparent to those skilled in the art that various modifications and variations can be made to the described embodiments without departing from the spirit and scope of the claimed subject matter.

[0079] It should be noted that one or more of the following claims utilize the term "wherein" as a transitional phrase. For purposes of defining the art, it should be noted that this term is introduced in the claims as an open-ended transitional phrase used to introduce the recitation of a series of features of a structure, and should be interpreted in a similar manner to the more commonly used open-ended preamble term "comprising."

[0080] It should be understood that when a first component is described as "comprising" a second component, in some embodiments it is contemplated that the first component "consists of" or "consists essentially of" that second component. It should further be understood that when a first component is described as "comprising" a second component, in some embodiments it is contemplated that the first component comprises at least 10%, at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, or even at least 99% of that second component (where % can be by weight or mole %).

[0081] It should be noted that for purposes of describing and defining the techniques of the present invention, a reference herein to a parameter or a variable that is a "function" of another variable is not intended to indicate that the variable is exclusively a function of the listed parameters or variables. Rather, a reference herein to a variable that is a "function" of listed parameters is intended to be open-ended, such that the variable may be a function of a single parameter or multiple parameters.

[0082] It should also be noted that references herein to "at least one" component, element, etc. should not be used to create an inference that the alternative use of the article "a" or "an" should be limited to a single component, element, etc.

[0083] It should be noted that any recitation herein of components of the present disclosure that are "configured" in a particular way to embody certain properties or to function in a particular manner is a structural recitation, as opposed to a recitation of intended use. More specifically, reference herein to the manner in which a component is "configured" indicates the existing physical state of the component and, therefore, should be considered a definitive recitation of the component's structural characteristics.

[0084] As understood in the context of the term as used herein, the term "transfer" can include directly transferring a substance between two portions of the disclosed system, and in some other instances, can refer to indirectly transferring a substance between two portions of the disclosed system. For example, indirectly transferring can include passing the specified substance through intermediate separation devices, valves, sensors, etc.

[0085] For purposes of describing and defining the technology of the present invention, it should be noted that the terms "substantially" and "about" are utilized herein to represent the inherent degree of uncertainty that may result from any quantitative comparison, value, measurement, or other representation. The terms "substantially" and "about" are also utilized herein to represent the degree to which a quantitative representation may vary from the stated basis without resulting in a change in the basic functionality of the subject matter in question.

Claims

1. 1. A process for forming light olefins comprising: reacting the feed stream in the presence of a catalyst in a reactor to form a product stream and a deactivated catalyst containing coke; separating at least a portion of the product stream from the deactivated catalyst; passing the deactivated catalyst to an oxidation vessel and contacting the deactivated catalyst with a first oxygen-containing gas to remove at least a portion of the coke on the deactivated catalyst to produce a decoked catalyst; passing the decoked catalyst to a combustor and burning an auxiliary fuel in the combustor to heat the decoked catalyst and produce a heated catalyst; passing the heated catalyst to an oxygen soak zone and contacting the heated catalyst with a second oxygen-containing gas to produce a reactivated catalyst; and passing the reactivated catalyst to the reactor.

2. 10. The method of claim 1, wherein the deactivated catalyst contains 0.01 wt. % to 0.4 wt. % coke upon entering the oxidation vessel.

3. 3. The method of claim 1 or 2, wherein 0 to 30 wt. % coke is present in the decoked catalyst.

Images