Process for catalytic dehydrogenation

Abstract

A method for catalytic dehydrogenation is provided, the method comprising mixing a fluidizing gas comprising methane, natural gas, ethane, hydrogen, nitrogen or any combination thereof with a fluidized catalyst stream that has passed through a catalytic dehydrogenation reactor and has left a catalyst separation zone to form a catalyst recycle stream; and recycling the catalyst recycle stream directly or indirectly to the catalytic dehydrogenation reactor.

Description

[0001] This application is a divisional application of the invention patent application with Chinese application number 201780027420.0, application date May 3, 2017, and invention name “Method for catalytic dehydrogenation”.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application claims priority to U.S. Provisional Application No. 62 / 333,313, filed May 9, 2016, which is incorporated herein by reference in its entirety. Technical Field

[0004] The present disclosure relates to a process for catalytic dehydrogenation. Background Art

[0005] Known multiple lower olefins and diolefins are widely used in multiple chemical processes, as starting materials and as intermediate products. In non-limiting examples, these can include ethene, propylene, butylene, isobutylene and butadiene. Although olefins and diolefins may be by-products of some industrial processes, such as fluid catalytic cracking, the demand for olefins increases and promotes the development of "special" olefins and / or diolefins to produce. A kind of such "special" method is the catalytic dehydrogenation of paraffins and / or other dehydrogenable hydrocarbons.

[0006] In the method for catalytic dehydrogenation, the catalyst that has passed through the catalytic dehydrogenation reactor once or multiple times may still contain a significant level of activity. Such used catalysts that retain a certain activity are referred to as used catalysts. Catalysts that retain little or no activity are referred to as spent catalysts. Usually, the dehydrogenation catalyst is separated from the product stream after leaving the catalytic dehydrogenation reactor. After such separation, all or part of the catalyst particles can be sent for regeneration. Since some separated catalyst particles are used and a certain activity is maintained, recycling some separated catalysts can produce economic benefits. In addition, dehydrogenation catalyst recycling can make it possible to control the catalyst feed temperature and the reactor space velocity. It is beneficial to control the catalyst temperature in the reactor because too high a temperature can lead to poor selectivity. In addition, the reactor space velocity can be adjusted by means of a catalyst recycle stream, thereby allowing the process controller to respond to deactivated catalysts or potential miscalculations in amplification.

[0007] In conventional fluid catalytic cracking systems, steam is used as a stripping gas to remove any hydrocarbons entrained with the recycled catalyst. Steam is required in the catalytic dehydrogenation of paraffins because it will condense and be easily separated from the hydrocarbons by forming a separate and distinct phase. However, steam severely deactivates the catalyst at the relevant temperatures, such as Fig. 9 As can be seen in the figure, the activity decreased from 45% to 18%.

[0008] The present disclosure addresses these problems by providing a method for recycling spent dehydrogenation catalyst while maintaining catalyst activity and selectivity. Summary of the invention

[0009] In one embodiment, the present disclosure provides a method for catalytic dehydrogenation, comprising mixing a fluidizing gas comprising methane, natural gas, ethane, hydrogen, nitrogen, or any combination thereof with a fluidized catalyst stream that has passed through a catalytic dehydrogenation reactor and has exited a catalyst separation zone to form a catalyst recycle stream; and recycling the catalyst recycle stream directly or indirectly into the catalytic dehydrogenation reactor.

[0010] The present invention also relates to the following technical solutions:

[0011] 1. A method for catalytic dehydrogenation, comprising:

[0012] mixing a fluidizing gas comprising methane, natural gas, ethane, hydrogen, nitrogen, or any combination thereof with a fluidized catalyst stream that has passed through the catalytic dehydrogenation reactor and has exited the catalyst separation zone in a reactor recycle catalyst fluidization section to form a catalyst recycle stream;

[0013] sending at least a portion of the fluidized catalyst stream to a catalyst regeneration process; and

[0014] The catalyst recycle stream is recycled directly or indirectly to the catalytic dehydrogenation reactor.

[0015] 2. The method for catalytic dehydrogenation according to claim 1, further comprising:

[0016] conveying the catalyst recycle stream to a mixing zone, wherein the catalyst recycle stream is mixed with regenerated catalyst from the catalyst regeneration process to form a mixed catalyst stream, wherein the mixing is carried out at a temperature of 500 to 800° C. for a time of 1 second to 3 minutes as measured by a thermocouple in the mixing zone; and

[0017] The mixed catalyst stream is then fed into the catalytic dehydrogenation reactor.

[0018] 3. A process for the catalytic dehydrogenation of propane according to item 2, wherein the mixing is carried out at a temperature of 640 to 680°C as measured with a thermocouple at the outlet of the mixing zone.

[0019] 4. A method for catalytic dehydrogenation according to claim 1, wherein the mixing of the fluidizing gas with the fluidized catalyst stream is carried out in the reactor recycle catalyst fluidizing section at a temperature of 500 to 800° C. for a period of 1 second to 3 minutes as measured by a thermocouple in the stripping section.

[0020] 5. The method for catalytic dehydrogenation according to item 1, further comprising reacting propane in the presence of the catalyst recycle stream in the catalytic dehydrogenation reactor.

[0021] 6. The method for catalytic dehydrogenation according to item 5, wherein in the catalytic dehydrogenation reactor, the conversion rate of propane to propylene is 30 to 55 wt%.

[0022] 7. A process for catalytic dehydrogenation according to any of the preceding clauses, wherein the recycle catalyst stream has a dehydrogenation activity greater than 80% of the fluidized catalyst stream leaving the catalyst separation unit.

[0023] 8. The method for catalytic dehydrogenation according to any one of the preceding items, further comprising injecting a hydrocarbon feed into the catalytic dehydrogenation reactor.

[0024] 9. A method for catalytic dehydrogenation according to item 8, wherein the hydrocarbon feed comprises one or more selected from the group consisting of ethane, propane, n-butane, isobutane, isobutylene, ethylbenzene, propylbenzene and methylethylbenzene.

[0025] 10. A process for catalytic dehydrogenation according to item 1, wherein the catalyst separation step in the catalyst separation zone ends at a stripping section and a reactor recycle catalyst fluidization section, and the process further comprises:

[0026] sending at least a portion of the spent catalyst entering the stripping section to the catalyst regeneration process; and

[0027] At least a portion of the fluidized spent catalyst stream from the reactor recycle catalyst fluidization section is sent directly to the catalytic dehydrogenation reactor or to a mixing zone prior to being sent to the catalytic dehydrogenation reactor.

[0028] 11. A method for catalytic dehydrogenation, comprising:

[0029] sending spent catalyst, which has passed through the catalytic dehydrogenation reactor and has exited the catalyst separation zone, to a reactor recycle catalyst fluidizing section and a stripping section separate from the reactor recycle catalyst fluidizing section;

[0030] In the reactor recycle catalyst fluidization section, a fluidizing gas is mixed with a spent catalyst stream fed to the reactor recycle catalyst fluidization section to form a catalyst recycle stream, the fluidizing gas comprising methane, natural gas, ethane, hydrogen, nitrogen or any combination thereof;

[0031] in the stripping section, contacting a stripping gas with the spent catalyst fed to the stripping section to produce stripped spent catalyst;

[0032] directly or indirectly recycling the catalyst recycle stream to the catalytic dehydrogenation reactor; and

[0033] At least a portion of the stripped spent catalyst is sent to a catalyst regeneration process.

[0034] 12. A process for catalytic dehydrogenation according to item 11, comprising recycling the catalyst recycle stream directly into the catalytic dehydrogenation reactor.

[0035] 13. A process for catalytic dehydrogenation according to item 11, comprising recycling the catalyst recycle stream into a mixing zone upstream of the catalytic dehydrogenation reactor.

[0036] 14. Process for catalytic dehydrogenation according to any of the preceding items, wherein the fluidizing gas comprises 60 vol.% methane.

[0037] 15. A process for catalytic dehydrogenation according to any one of the preceding clauses, comprising mixing the fluidized catalyst stream with a gas stream comprising at least 40 vol.% fluidizing gas in the reactor recycle catalyst fluidizing section. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 is a flow chart illustrating a first embodiment of the process of the present invention, wherein the stripping zone of the catalyst separation section is also the reactor recycle catalyst fluidizing zone;

[0039] Figure 2 is a flow chart illustrating a second embodiment of the process of the present invention, wherein the stripping zone of the catalyst separation section is also the reactor recycle catalyst fluidizing zone;

[0040] Figure 3 Is the description Figure 1 The flow chart of the first embodiment of the process of the present invention shown in FIG. 1 is different in that the stripping zone of the catalyst separation section is separated from the reactor recycle catalyst fluidization zone;

[0041] Figure 4 Is the description Figure 2 A flow chart of a second embodiment of the process of the present invention shown in FIG. 1 , except that the stripping zone of the catalyst separation section is separated from the reactor recycle catalyst fluidization zone;

[0042] Figure 5 is a schematic diagram illustrating one equipment configuration for operating one embodiment of the process of the present invention, wherein the catalyst recycle stream is sent directly to the reactor;

[0043] Figure 6 is a schematic diagram illustrating one equipment configuration for operating another embodiment of the process of the present invention, wherein the catalyst recycle stream is sent to a mixing zone before being sent to the reactor;

[0044] Figure 7 is a schematic diagram illustrating one equipment configuration for operating one embodiment of the process of the present invention, wherein the catalyst separation zone comprises a side stripper serving as a reactor recycle catalyst fluidization zone, and the catalyst recycle stream is sent directly to the reactor;

[0045] Figure 8 is a schematic diagram illustrating an apparatus configuration for operating another embodiment of the process of the present invention, wherein the catalyst separation zone comprises a side stripper that serves as a reactor recycle catalyst fluidization zone, and the catalyst recycle stream is sent to a mixing zone before being sent to the reactor; and

[0046] Fig. 9 is a diagram depicting the deactivation of a dehydrogenation catalyst by steam. DETAILED DESCRIPTION

[0047] The present disclosure provides a method for catalytic dehydrogenation, which includes mixing a fluidizing gas fluidizing gas with a fluidized catalyst stream, the fluidizing gas including methane, natural gas, ethane, hydrogen, nitrogen or any combination thereof, the fluidized catalyst stream having passed through a catalytic dehydrogenation reactor and having left a catalyst separation zone to form a catalyst recycle stream; and recycling the catalyst recycle stream directly or indirectly to the catalytic dehydrogenation reactor. The fluidizing gas used in embodiments of the methods disclosed herein is a fluidizing gas including methane, natural gas, ethane, hydrogen, nitrogen or any combination thereof.

[0048] The process of the present invention can be used in combination with any dedicated catalytic dehydrogenation process to produce olefins and / or dienes. U.S. Patent Application 62 / 139938, PCT Published Application WO 2005 / 077867 and PCT / US16 / 2112 describe certain such production methods, and the disclosures of the applications are incorporated herein in their entirety. The feedstock for such catalytic dehydrogenation processes comprises saturated or partially saturated hydrocarbons ("hydrocarbon feed"). The hydrocarbon feed may comprise one or more of the following: 1) a paraffinic compound, preferably a lower alkane having 2 to 6 carbon atoms but more preferably less than 5 carbon atoms, such as ethane, propane, isobutane and n-butane; corresponding olefins, i.e. ethylene, propylene, isobutene and n-butene; and 2) an alkyl aromatic compound, preferably a lower alkyl aromatic compound, such as ethylbenzene, propylbenzene, isopropylbenzene and methylethylbenzene; corresponding vinyl aromatic compounds, (i.e., "alkenyl aromatics"), i.e. styrene, isopropylbenzene or α-methylstyrene. Several embodiments of the present invention are described, including the simultaneous and separate dehydrogenation of lower alkanes and alkyl aromatic compounds. The present invention can be used to prepare styrene and ethylene from ethylbenzene and ethane, respectively. Similarly, cumene and propylene can be prepared from propylbenzene and propane, respectively. Those of ordinary skill in the art will readily recognize other potential hydrocarbon feeds.

[0049] Figure 1 and 2 are flow charts illustrating two main methods for operating embodiments of the present invention. Figure 1 The catalytic dehydrogenation of hydrocarbons in the presence of a dehydrogenation catalyst is described. The resulting fluidized dehydrogenation product and spent catalyst stream are subjected to a catalyst separation process, from which an olefin product stream is extracted and sent to product recovery. The separated fluidized spent catalyst particles are then subjected to a combined stripping and reactor recycle catalyst fluidization step. Figure 1 and 2 As shown in , a certain portion of the separated fluidized spent catalyst particles will enter the catalyst regeneration process. After the reactor recycle catalyst fluidization step, the fluidized spent catalyst stream is returned to the catalytic dehydrogenation step. Figure 2 A substantially similar process is described, except that after a combined catalyst stripping and reactor recycle catalyst fluidization step, the fluidized spent catalyst stream is then sent to a mixing step where it is mixed with regenerated and / or fresh dehydrogenation catalyst. After such mixing step, the fluidized spent catalyst is sent to a catalytic dehydrogenation step along with one or both of the regenerated and fresh catalyst.

[0050] Figure 3 and 4 Further explanation Figure 1 and 2The method described in , except that the reactor recycle catalyst fluidization step is performed only on a portion of the separated fluidized catalyst particles and is performed separately from the catalyst stripping step. Figure 3 and 4 As shown in FIG. 1 , the catalyst particles passing through the reactor recycle catalyst fluidization step are sent directly to the catalytic dehydrogenation step ( Figure 3 ) or mixed zone ( Figure 4 ).

[0051] See also Figure 5 , shows a dedicated catalytic dehydrogenation system 1 for producing propylene, for example. The catalytic dehydrogenation system 1 comprises a catalytic dehydrogenation reactor 10 into which one or more hydrocarbon feeds are injected via feed line 15. The regenerated catalyst may first be fed into line 25 via line 20 and then into the fluidized bed dehydrogenation reactor 10. The product stream leaves the reactor 10 and enters a catalyst separation zone 30, where the fluidized catalyst particles are separated from the gaseous components of the product stream. Figure 5 In the embodiment shown in , the catalyst separation zone 30 includes a plurality of cyclone separators 35, each cyclone separator terminating in a dip tube 40, which empties into a stripping section 45. The fluidizing gas enters the reactor recycle catalyst fluidizing / stripping section 45 through a feed line 75, which distributes the fluidizing gas over the entire annular cross-section in a distributor commonly used for fluidizing applications. The separated catalyst particles are contacted with a gaseous mixture that includes at least 40 vol% of the fluidizing gas in the reactor recycle catalyst fluidizing / stripping section 45. All individual values ​​and subranges of at least 40 vol% are included and disclosed herein. For example, the gaseous component may include at least 40, 50, 60, 70, 80, 90 or 100 vol% of the fluidizing gas. In a specific embodiment, the gaseous component in the reactor recycle catalyst fluidizing / stripping section 45 includes 60 vol% of methane. In those embodiments where the methane gaseous component in stripping section 45 is less than 100 vol%, the remainder of the gaseous component may include, for example, nitrogen, hydrogen, ethane, and propane. A portion of the separated catalyst particles may enter spent catalyst feed line 55 and into catalyst regenerator system 60.

[0052] In a specific embodiment, the gaseous component contains no more than 30 vol% steam. All individual values ​​and subranges equal to or less than 30 vol% are included and disclosed herein. For example, the gaseous component may include no more than 30 vol% steam, or alternatively, no more than 20 vol% steam, or alternatively, no more than 10 vol%.

[0053] Reactor recycle catalyst fluidization conditions

[0054] In the reactor recycle catalyst fluidization / stripping section 45, the spent catalyst is contacted with a gaseous component comprising at least 40 vol% fluidizing gas at a temperature of 500 to 800° C. for a time of 1 second to 3 minutes. More preferably 10 seconds to 2 minutes, and more preferably 30 seconds to 90 seconds. All individual values ​​and subranges of 500 to 800° C. are included and disclosed herein; for example, the temperature in the reactor recycle catalyst fluidization / stripping section 45 can range from a lower limit of 500, 575, 625, 700, or 775° C. to an upper limit of 550, 600, 650, 700, 750, or 800° C. The time and temperature of such contact depends at least in part on the specific hydrocarbon feed content and the concentration and characteristics of the fluidizing gas in the gaseous component.

[0055] For example, for the catalytic dehydrogenation of ethylbenzene, the temperature in the reactor recycle catalyst fluidization / stripping section 45 can range from 560 to 620° C. All individual values ​​and subranges from 560 to 620° C. are included and disclosed herein; for example, the temperature range of the reactor recycle catalyst fluidization / stripping section 45 for the dehydrogenation of ethylbenzene can range from a lower limit of 560, 580, 590, 600, or 610° C. to an upper limit of 585, 592, 604, 616, or 620° C. For example, the temperature range of the reactor recycle catalyst fluidization / stripping section 45 for ethylbenzene can range from 560 to 620° C., or alternatively, 580 to 600° C., or alternatively, 600 to 620° C., or alternatively, 585 to 615° C.

[0056] For the catalytic dehydrogenation of propane, the temperature range of the reactor recycle catalyst fluidization / stripping section 45 may be 580 to 640° C. All individual values ​​and subranges from 580 to 640° C. are included and disclosed herein; for example, the temperature range of the reactor recycle catalyst fluidization / stripping section 45 for the catalytic dehydrogenation of propane may be from a lower limit of 580, 600, 610, 620, or 630° C. to an upper limit of 605, 613, 622, 634, or 640° C. For example, the temperature range of the reactor recycle catalyst fluidization / stripping section 45 for the catalytic dehydrogenation of propane may be 580 to 640° C., or alternatively, 600 to 620° C., or alternatively, 620 to 640° C., or alternatively, 610 to 630° C.

[0057] The spent catalyst is contacted with the fluidizing gas in the reactor recycle catalyst fluidizing / stripping section 45 for a time period of from 1 second to 3 minutes. All individual values ​​and subranges from 1 second to 3 minutes are included and disclosed herein; for example, the contact time can range from a lower limit of 1, 5, 10, 30, 60, 90, 120, or 150 seconds to an upper limit of 10, 20, 50, 100, 120, 150, or 180 seconds. For example, contact can occur for a time period of from 1 to 180 seconds, or alternatively, from 10 to 95 seconds, or alternatively, from 95 to 120 seconds, or alternatively, from 20 to 120 seconds.

[0058] After the contact time in the reactor recycle catalyst fluidizing / stripping section 45 , the spent catalyst and gaseous components (collectively referred to as the catalyst recycle stream) are directed through line 50 into the catalytic dehydrogenation reactor 10 . Figure 6 Description Figure 5 , except that the catalyst recycle stream first enters the mixing zone 65 through pipeline 57, where the catalyst recycle stream can be mixed with the regenerated catalyst leaving the catalyst regenerator system 60 before entering the dehydrogenation reactor 10.

[0059] Reactor conditions

[0060] In those embodiments where the catalyst recycle stream enters the catalytic dehydrogenation reactor 10 directly from the reactor recycle catalyst fluidizing / stripping section 45, the temperature in the reactor 10 is typically 10 to 40°C higher than the temperature in the reactor recycle catalyst fluidizing zone 50.

[0061] Mixing zone conditions

[0062] In those embodiments where the catalyst recycle stream enters the mixing zone 65 prior to entering the catalytic dehydrogenation reactor 10, the temperature in the mixing zone 65 is typically 10°C to 100°C higher than the temperature in the reactor recycle catalyst fluidizing / stripping section 45.

[0063] For example, for the catalytic dehydrogenation of propane, the temperature in the mixing zone 65 can range from 640 to 680° C. All individual values ​​and subranges from 640 to 680° C. are included and disclosed herein; for example, the temperature in the mixing zone 65 can range from a lower limit of 640, 650, 660, or 670° C. to an upper limit of 644, 655, 663, 672, or 680° C. For example, the temperature in the mixing zone 65 can range from 640 to 680° C., or alternatively, 640 to 660° C., or alternatively, 660 to 680° C., or alternatively, 650 to 670° C.

[0064] For example, for the catalytic dehydrogenation of ethylbenzene, the temperature in the mixing zone 65 can range from 620 to 670° C. All individual values ​​and subranges from 620 to 670° C. are included and disclosed herein; for example, the temperature in the mixing zone 65 can range from a lower limit of 620, 630, 640, 650, or 660° C. to an upper limit of 628, 637, 646, 655, 666, or 670° C. For example, the temperature in the mixing zone 65 can range from 620 to 670° C., or alternatively, 620 to 645° C., or alternatively, 645 to 670° C., or alternatively, 630 to 660° C.

[0065] Additional Embodiments

[0066] Figure 7 and 8 An alternative embodiment of the invention is described in which the catalyst separation step terminates in two sections - a stripping section 80 and an additional reactor recycle catalyst fluidizing zone 70. When such a reactor recycle catalyst fluidizing section 70 is present, the separated spent catalyst particles entering the reactor recycle catalyst fluidizing section 70 are contacted with a fluidizing gas entering through line 75, such as methane, natural gas, ethane, hydrogen and / or nitrogen. The stripping gas enters the stripping section 80 through line 85. Any suitable stripping gas may be used, including, for example, methane, hydrogen, steam, and nitrogen. The spent catalyst entering the stripping section 80 then enters the catalyst regeneration system 60 through line 55. At Figure 7 In the embodiment, the fluidized spent catalyst stream is sent directly to the catalytic dehydrogenation reactor 10 after exposure to the fluidizing gas via line 50. Figure 8 In the embodiment of the present invention, the fluidized spent catalyst stream exposed to the fluidizing gas is first sent to the mixing zone 65 through the pipeline 57 before being sent to the catalytic dehydrogenation reactor 10. Alternatively, the fluidized spent catalyst stream from the reactor recycle catalyst fluidizing section 70 can be sent to the catalyst regenerator system 60, and the fluidized spent catalyst stream from the stripping section 80 can be sent to the dehydrogenation reactor 10 or the mixing zone 65.

[0067] Embodiments of the inventive process permit recycling of the dehydrogenation catalyst while maintaining an acceptable level of catalyst activity. For example, in the case of propane dehydrogenation, the total conversion of propane to propylene in the catalytic dehydrogenation reactor in the presence of recycled catalyst and regenerated catalyst may range from 30 to 55%. All individual values ​​and subranges of 30 to 55% are included and disclosed herein; for example, the total propane conversion may range from a lower limit of 30, 35, 40, 45, or 50% to an upper limit of 38, 47, or 55%. For example, the total propane conversion may range from 30 to 42%, or alternatively, 43 to 55%, or alternatively, 35 to 50%, or alternatively, 30 to 55%.

[0068] In another embodiment, the recycle catalyst stream has greater than 80% of the dehydrogenation activity of the fluidized catalyst stream leaving the dehydrogenation reactor after contacting the fluidizing gas in the reactor recycle catalyst fluidizing zone 50. All individual values ​​and subranges greater than 80% are included and disclosed herein. For example, the recycle catalyst stream after contacting the fluidizing gas has greater than 80, 82, 84, 86, or 88% of the dehydrogenation activity of the fluidized catalyst stream leaving the dehydrogenation reactor. In a specific embodiment, the recycle catalyst stream after contacting the fluidizing gas has greater than 80% to less than 100% of the dehydrogenation activity of the fluidized catalyst stream leaving the dehydrogenation reactor.

[0069] To obtain the activity of the catalyst, a sample must be taken from the apparatus in a reference area of ​​the process, heated under nitrogen in a fixed bed reactor, and should be kept at 10 hr. -1 The weight hourly space velocity (WHSV) of propane conversion is measured by a gas chromatograph (lb / hr propane / lb of catalyst in the reactor) at approximately the same catalyst to propane feed ratio as observed in the facility. For example, if the catalyst to propane feed ratio is 20, then the experiment should be fed 20 times more propane mass than the catalyst in the experiment and the composition of the product should be measured.

[0070] The catalytic selectivity of the propane catalytic reaction is expected to be greater than 95 mol% of carbon to propylene. Alternatively, it is suspected that the thermal reaction of propane provides a selectivity of about 45 mol% of carbon to propylene. By using catalyst recycle to cool the average temperature of the catalyst entering the reactor, the same amount of heat can be added at a lower temperature, which allows the catalytic activity to be maintained while minimizing the thermal reaction of propane. The result is an overall higher selectivity to propylene.

[0071] Embodiments of the disclosed methods also permit the combined regenerated and recycled catalyst stream to maintain an acceptable propylene yield (equal to or greater than 30%) for propane dehydrogenation. All individual values ​​and subranges of propylene yield equal to or greater than 30% are included and disclosed herein; for example, the combined regenerated catalyst and recycled catalyst stream can exhibit a propylene yield of at least 30, 35, 40, 42, 44, 48, 52, or 55%. In specific embodiments, the propylene yield is 30 to 40%, or alternatively, 30 to 55%, or alternatively, 40 to 55%, or alternatively, 35 to 50%.

[0072] Dehydrogenation catalyst

[0073] The preferred catalysts used in the present invention are active and capable of dehydrogenating the selected hydrocarbon feed in less than 10 seconds at the dehydrogenation reaction temperature. Therefore, catalyst selection to meet the reaction time preference is important to ensure that the benefits of short contact time can be achieved, including driving equilibrium reactions to increase conversion, increase selectivity, reduce byproduct formation and product degradation, and ensure and support appropriate catalyst regeneration. These preferred catalysts include solid particle types that are capable of fluidization and, preferably, exhibit properties known in the industry as "Geldart A" properties. In addition, Geldart B catalysts may also be used, but in some embodiments, such catalysts may be less preferred. According to D. Geldart, Gas Fluidization Technology, John Wiley & Sons (New York, 1986), 34-37; and D. Geldart, "Types of Gas Fluidization", Powder Technol. 7 (1973) 285-292, the entire contents of which are incorporated herein by reference, these catalysts are classified as "Group A" or "Group B". A technician in the field will classify the average particle size of the particles under ambient conditions based on the average particle size of the particles. and particle density (ρ p ) are familiar with the classification of particles which determine the fluidization characteristics in a given carrier, but for further understanding of the present invention, a simplified "Geldart fluidization diagram" is provided. Figure 1 , as disclosed in D. Geldart, "Types of Gas Fluidization" in 1973, as described above. Figure 1 Four Geldart "group" classifications A to D are shown in , of which the groups suitable for the method of the present invention, Group A and Group B are generally referred to as "inflatable" and "sand-like", respectively.

[0074] Those skilled in the art understand Group A to represent aerated powders with a bubble-free range of fluidization; a high degree of bed expansion; a slow and linear degassing rate; bubble characteristics including a predominance of ruptured / rejoined bubbles with maximum bubble size and large wakes; a high level of solid mixing and gas backmixing, assuming the same UU mf (U is the velocity of the carrier gas, and U mf is the minimum fluidization velocity, usually but not necessarily measured in meters per second, m / s, i.e., there is excess gas velocity); axisymmetric slug characteristics; and no jetting except in very shallow beds. The listed characteristics tend to decrease with average particle size, assuming the same Or with the proportion of <45 microns (μm); or with the pressure, temperature, viscosity and density of the gas. Generally speaking, the particles have a small average particle size and / or a low particle density (<~1.4 grams / cubic centimeter, g / cm 3), fluidizes easily with smooth fluidization at low gas velocities, and exhibits controlled bubbling at higher gas velocities.

[0075] Those skilled in the art understand that group B represents mf "Sand-like" powder that starts bubbling at low temperatures; exhibits moderate bed expansion; rapid degassing; no limit on bubble size; moderate levels of solid mixing and gas backmixing, assuming the same UU mf ; both axisymmetric and asymmetric slugs; and injection only in shallow beds. These properties tend to improve as the average particle size decreases, but the particle size distribution and some uncertainty in the gas, pressure, temperature, viscosity, or density appear to have little effect on improving the properties. In general, when the density (ρ p ) is 1.4<ρ p <4g / cm 3 When the particle size of most particles is for And preferably, when the density (ρ p ) is 4g / cm 3 Time When the density (ρ p ) is 1g / cm 3 Time These particles fluidize well under vigorous bubbling action and large bubble growth.

[0076] It should be noted that various closely related but alternative definitions of the Geldart group are provided in additional literature works, and that powder technology is considered an active area of ​​research, but the above definition generally applies to the present invention and its scope.

[0077] Suitable examples of defined catalysts include gallium-based catalysts such as those described in U.S. Pat. No. 6,031,143 and WO 2002 / 096844, the disclosures of which are incorporated herein by reference in their entireties. One such catalyst that can be prepared such that it meets the Geldart A or Geldart B definition includes a catalyst in the delta or theta phase, or in a mixture of the delta plus theta phase, or theta plus alpha phase, or the delta plus theta plus alpha phase, modified with silica, and preferably having a surface area of ​​less than about 100 square meters per gram (m 2 / g) (as determined by the BET method) of gallium and platinum supported on alumina. In a preferred embodiment, the catalyst comprises:

[0078] i) 0.1 to 34 wt %, preferably 0.2 to 3.8 wt % of gallium oxide (Ga2O3);

[0079] ii) 1 to 300 parts per million (ppm), preferably 50 to 300 ppm, by weight, of platinum;

[0080] iii) 0 to 5 wt%, preferably 0.01 to 1 wt% of an alkali metal and / or alkaline earth metal, such as potassium;

[0081] iv) 0.08 to 3 wt% silicon dioxide;

[0082] v) The balance is 100 wt% of alumina.

[0083] Similar gallium-based catalysts (further comprising manganese) are described in more detail in WO 2003 / 053567, US Patent Publication 2004 / 02242945 (further comprising zinc) and EP 0637578 (B1). The descriptions of the catalysts in these documents are expressly incorporated herein by reference in their entirety.

[0084] Another suitable catalyst for the dehydrogenation reaction is based on chromium and includes:

[0085] i) 6 to 30 weight % (wt %), preferably 13 to 25 wt % chromium oxide (Cr2O3);

[0086] ii) 0.1 to 3.5 wt%, most preferably 0.2 to 2.8 wt% tin oxide (SnO);

[0087] iii) 0.4 to 3 wt%, most preferably 0.5 to 2.5 wt% of an alkali metal oxide, such as potassium oxide;

[0088] iv) 0.08 to 3 wt% silicon dioxide;

[0089] v) Alumina in the delta or theta phase, or a mixture of delta plus theta phase, or theta plus alpha phase, or delta plus theta plus alpha phase, with the balance being 100 wt%.

[0090] The catalyst described above may be used as such or in combination with one or more additional materials, for example inert materials, such as alpha-alumina and / or modified with alkali metal oxides and / or silica, at a concentration of the inert material in the range of 0 to 50 wt%.

[0091] Those skilled in the art will be familiar with the above-mentioned catalyst types and how to prepare or commercially obtain them without further instructions. However, additional details on the preparation of the aforementioned catalysts and their more preferred species can be found in, for example, U.S. Patent 6,031,143 and EP 0637578 (B1), the disclosures of which are incorporated herein by reference in their entirety. Generally, the method for preparing the aforementioned dehydrogenation catalyst includes dispersing a precursor of the catalyst metal, for example, a solution of a soluble salt of the selected catalyst metal, onto a carrier including alumina, silica, or a combination thereof. Examples of applicable dispersion methods may include impregnating the carrier with one or more solutions containing a precursor of the selected catalyst metal (e.g., gallium and platinum, chromium and tin, etc.), followed by drying and calcining the impregnated carrier. Alternative methods may include ion adsorption of the catalyst metal, followed by separation of the liquid portion of the adsorption solution; drying; and activating the resulting solid.

[0092] Examples

[0093] The following examples illustrate the invention but are not intended to limit the scope of the invention.

[0094] The following propane conversion activity and propylene selectivity were tested using several examples of spent dehydrogenation catalysts that were passed through the reactor recycle catalyst fluidization zone at different times and temperatures. The catalysts used in the examples included:

[0095] i) 0.1 to 34 wt %, preferably 0.2 to 3.8 wt % of gallium oxide (Ga2O3);

[0096] ii) 1 to 300 parts per million (ppm), preferably 50 to 300 ppm, by weight, of platinum;

[0097] iii) 0 to 5 wt%, preferably 0.01 to 1 wt% of an alkali metal and / or alkaline earth metal, such as potassium;

[0098] iv) 0.08 wt% to 3 wt% of silicon dioxide;

[0099] v) The balance is 100 wt% of alumina.

[0100] All inventive examples ("Inv#") were immersed in a fluidizing gas containing 60 vol% methane and 40 vol% nitrogen. Comparative Example 1 ("Comparative 1") used a catalyst as described above and a fluidizing gas of 100% nitrogen. Table 1 provides the results of such tests. These tests were conducted in a fixed bed laboratory reactor. During the experiment, the catalyst was slowly heated to the reaction temperature with inertia, then the catalyst was treated with air at 750°C for 15 minutes, the catalyst was cooled to the target temperature with nitrogen, then methane was fed for the required time, nitrogen cooled the catalyst to the reaction temperature, and then propane was fed at 625°C at a weight hourly space velocity (WHSV) of 10, and the composition of the product was measured after 30 seconds of operation. As can be seen in Table 1, exposure to methane under the expected reactor recycle fluidization section conditions (620°C, 120 seconds) did not deactivate the catalyst, as seen when the catalyst was exposed to steam. Second, exposure to methane under the expected catalyst mixing conditions (640 to 680° C., 120 seconds) does not significantly deactivate the regenerated and recycled catalyst.

[0101] Table 1

[0102]

[0103] Test Method

[0104] The test methods include the following:

[0105] The conversion and selectivity of the crude propylene product were calculated based on the composition measured from the gas chromatograph after the catalyst was exposed to propane for 30 seconds at the operating temperature.

[0106] The present invention may be embodied in other forms without departing from the spirit and essential characteristics thereof, and, accordingly, reference should be made to the appended claims rather than to the foregoing specification as indicating the scope of the invention.

Claims

1. A method for catalytic dehydrogenation, comprising: catalytically dehydrogenating a hydrocarbon feed in the presence of a dehydrogenation catalyst in a fluidized bed catalytic dehydrogenation reactor to produce a product stream comprising spent catalyst and at least one dehydrogenated hydrocarbon; separating the spent catalyst from gaseous components of the product stream; sending the spent catalyst to a reactor recycle catalyst fluidizing section and to a stripping section separate from the catalyst fluidizing section; In the catalyst fluidizing section at 575° C. to 650° C., mixing a fluidizing gas with the spent catalyst stream fed to the catalyst fluidizing section for a period of 1 second to 3 minutes to form a catalyst recycle stream, the fluidizing gas comprising methane, natural gas, ethane, hydrogen, nitrogen or any combination thereof; contacting a stripping gas with the spent catalyst fed to the stripping zone in the stripping zone at 575° C. to 650° C. for a period of 1 second to 3 minutes to produce stripped spent catalyst; recycling at least a portion of the catalyst recycle stream to a mixing zone upstream of the catalytic dehydrogenation reactor, wherein in the mixing zone, the catalyst recycle stream is mixed with regenerated catalyst to form a mixed catalyst stream, wherein the mixing is carried out for a time of 1 second to 3 minutes at a temperature of 640 to 680° C. for the catalytic dehydrogenation of propane as measured by a thermocouple in the mixing zone; and At least a portion of the stripped spent catalyst is sent to a catalyst regeneration process.

2. The process for catalytic dehydrogenation according to claim 1, comprising recycling at least a portion of the catalyst recycle stream directly into the fluidized bed catalytic dehydrogenation reactor.

3. The method for catalytic dehydrogenation according to claim 1, further comprising feeding the mixed catalyst stream into the fluidized bed catalytic dehydrogenation reactor.

4. The process for catalytic dehydrogenation according to any one of claims 1 to 3, wherein the fluidizing gas comprises 60 vol.% of methane.

5. A process for catalytic dehydrogenation according to any one of claims 1 to 3, comprising mixing a fluidized catalyst stream with a gas stream comprising at least 40 vol.% of a fluidizing gas in the catalyst fluidization section.

6. A process for catalytic dehydrogenation according to any one of claims 1 to 3, wherein mixing the fluidizing gas with at least a portion of the spent catalyst occurs in the catalyst fluidizing section at a temperature of 625 to 650° C. for a time of 10 to 150 seconds as measured by a thermocouple in the fluidizing section.

7. A process for catalytic dehydrogenation according to any one of claims 1 to 3, wherein the catalyst recycle stream has greater than 80% of the dehydrogenation activity of the spent catalyst stream exiting the catalyst separation zone.

8. The process for catalytic dehydrogenation according to any one of claims 1 to 3, wherein the hydrocarbon feed comprises propane and the at least one dehydrogenated hydrocarbon comprises propylene.

9. The method for catalytic dehydrogenation according to claim 8, wherein the conversion rate of propane to propylene in the fluidized bed catalytic dehydrogenation reactor is 30 to 55 wt%.

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