Process for conversion of olefins to distillate fuels by regeneration

Abstract

A process for oligomerizing and oligomerizing an olefin into a distillate fuel by regenerating a first stage oligomerization catalyst bed and / or a second oligomerization catalyst bed in situ by contacting with oxygen at an elevated temperature. The oligomerization catalyst may be restored to complete activity. And the regeneration process can realize continuous operation.

Description

[0001] Priority declaration

[0002] This application claims priority to Indian Provisional Patent Application No. 202211049525 filed on August 30, 2022, which is incorporated herein by reference in its entirety. Technical Field

[0003] The field is the conversion of olefins to distillates. The field may particularly relate to oligomerizing olefins and oligomerizing oligomerized olefins to distillate fuels. Background Art

[0004] Ethylene can be dimerized into olefins, such as C4, C6 and C8 olefins. Olefin oligomerization is the process by which smaller olefins can be oligomerized into larger olefins. More specifically, it can convert olefins (including dimerized olefins) into distillates (including jet fuel and diesel range products). The oligomeric distillates can be saturated to be used as transportation fuels.

[0005] The dimerization reaction of ethylene is highly exothermic. The exotherm generated by the dimerization of ethylene can be difficult to manage.

[0006] Jet fuel is one of the few petroleum fuels that cannot be easily replaced by electric motor systems because of the high energy output required to fuel an aircraft, which electric motors cannot provide. In some regions, there are currently large incentives for green jet fuel.

[0007] An efficient process for converting ethylene to distillate fuels is desired. Summary of the invention

[0008] We have described a process for the oligomerization of olefins to distillate fuels which regenerates the oligomerization catalyst bed in situ by contact with oxygen at elevated temperature. The process enables continuous oligomerization for extended periods of time without loss of performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 is a schematic diagram of the oligomerization section of the method and apparatus of the present disclosure.

[0010] Figure 2 is a schematic diagram of the hydrogenation section of the process and apparatus of the present disclosure.

[0011] Figure 3 Schematic diagram of the regeneration process of the oligomerization section of the method and apparatus of the present disclosure.

[0012] Figure 4 An additional schematic diagram of the regeneration process of the oligomerization section of the method and apparatus of the present disclosure is shown.

[0013] Figure 5is a table of continuous operation and regeneration schedules of the present disclosure.

[0014] Figure 6 is a plot of conversion over time before and after regeneration.

[0015] Figure 7 is a plot of selectivity over time before and after regeneration.

[0016] definition

[0017] The term "communication" means that fluid flow is operatively allowed between the enumerated components, which can be characterized as "fluid communication".

[0018] The term "downstream communication" means that at least a portion of the fluid flowing to the body in the downstream communication can operatively flow from the object in fluid communication therewith.

[0019] The term "upstream communication" means that at least a portion of the fluid flowing out of the body in the upstream communication can be operatively flowed to the object in fluid communication therewith.

[0020] The term "direct communication" means that the fluid flows from the upstream component into the downstream component without passing through any other intervening container.

[0021] The term "indirect communication" means that the fluid flow from the upstream component enters the downstream component after passing through an intervening container.

[0022] The term "bypass" means that the object loses downstream communication with the bypassed body at least within the scope of the bypass.

[0023] As used herein, the term "predominantly" or "majority" means greater than 50%, suitably greater than 75%, and preferably greater than 90%.

[0024] The term "tower" means one or more distillation towers for separating one or more components with different volatilities. Unless otherwise specified, each tower includes a condenser on the top of the tower for condensing a portion of the overhead stream and refluxing it back to the top of the tower, and a reboiler at the bottom of the tower for vaporizing a portion of the bottom stream and sending it back to the bottom of the tower. The feed to the tower can be preheated. The top pressure is the pressure of the overhead vapor at the vapor outlet of the tower. The bottom temperature is the liquid bottom outlet temperature. The top line and the bottom line refer to the net line from any reflux or reboil to the tower downstream. The stripping tower can omit the reboiler at the bottom of the tower, but provide heating requirements and separation power for the liquefied inert medium (such as steam). The stripping tower is usually fed from the top tray and the main product is taken out from the bottom.

[0025] As used herein, the term "separator" means a container having an inlet and at least one overhead vapor outlet and a bottom liquid outlet, and may also have an outlet for a water-containing stream from a storage tank (boot). A flash tank is a type of separator that can be communicated with a separator downstream that can operate at a higher pressure. As used herein, the term "boiling temperature" means the atmospheric pressure equivalent boiling point (AEBP) calculated from the observed boiling temperature and distillation pressure, such as using the formula provided in ASTM D1160 Appendix A7, entitled "Practice for Converting Observed Vapor Temperatures to Atmospheric Equivalent Temperatures".

[0026] As used herein, the term "true boiling point" (TBP) means a test method for determining the boiling point of a substance in accordance with ASTM D-2892 for producing standardized masses of liquefied gases, distillate fractions, and residues for which analytical data are available, and for determining the yields of the above fractions by both mass and volume from which a plot of distillation temperature versus mass % is obtained in a column having a reflux ratio of 5:1 using fifteen theoretical plates.

[0027] As used herein, the term "T5," "T90," or "T95" means the temperature at which 5 mass percent, 90 mass percent, or 95 mass percent, as the case may be, of a sample boils using ASTM D-86 or TBP, respectively.

[0028] As used herein, the term "initial boiling point" (IBP) means the temperature at which a sample begins to boil using ASTM D-7169, ASTM D-86, or TBP, as appropriate.

[0029] As used herein, the term "endpoint" (EP) means the temperature at which a sample is brought to a complete boil using ASTM D-7169, ASTM D-86, or TBP, as appropriate.

[0030] As used herein, the term "diesel" means hydrocarbons boiling in the following ranges: IBP between 125°C (257°F) and 175°C (347°F), or T5 between 150°C (302°F) and 200°C (392°F), and "diesel cut points" including T95 between 343°C (650°F) and 399°C (750°F) using the TBP distillation method, or T90 between 280°C (536°F) and 340°C (644°F) using ASTM D-86. The term "green diesel" means diesel that contains hydrocarbons not derived from fossil fuels.

[0031] As used herein, the term "jet fuel" refers to hydrocarbons that boil within the T10 range between 190°C (374°F) and 215°C (419°F) and have endpoints between 290°C (554°F) and 310°C (590°F). The term "green jet fuel" means a jet fuel that contains hydrocarbons that are not derived from fossil fuels. DETAILED DESCRIPTION

[0032] The disclosed process involves dimerizing and oligomerizing an olefin stream comprising ethylene, followed by further oligomerizing the ethylene oligomers. The process uses a zeolite catalyst for ethylene oligomerization in a first stage and a metal catalyst for olefin oligomerization in a second stage.

[0033] The method and apparatus may include Figure 1 The oligomeric segments 10 and Figure 2 The hydrogenation section 110 in the embodiment of the present invention.

[0034] Go to Figure 1 The oligomerization section 10 of the present invention provides the feed olefin stream in the pipeline 12 to the oligomerization section 10. The feed olefin stream may contain a large amount of ethylene. The feed olefin stream may mainly contain ethylene. On the one hand, the feed olefin stream may contain at least 95 mol% ethylene. The feed olefin stream in the pipeline 12 may be designed as an ethylene stream. The olefin stream may be provided by dehydration of ethanol or provided from an MTO unit. The temperature of the feed olefin stream may be 60°C (140°F) to 150°C (302°F), preferably 80°C (176°F) to 100°C (212°F), and the pressure may be 3.4MPag (500psig) to 8.4MPag (1200psig).

[0035] Olefin stream can first contact with first stage oligomerization catalyst so that ethylene and / or propylene oligomerization becomes oligomer, then contact with second stage oligomerization catalyst to further make ethylene and / or propylene oligomer and unreacted ethylene and propylene oligomerization.The oligomerization of ethylene generates a large amount of heat release.For example, the dimerization of ethylene can generate 612kcal / kg (1100BTU / lb) of heat.Therefore, this large amount of heat release must be managed.However, the dimerization of butene can generate 222kcal / kg (400BTU / lb) of heat.

[0036] Thus, the olefin stream in line 12 can be separated into a plurality of olefin streams. Figure 1 In one embodiment, the olefin feed stream is separated into four independent streams: the first olefin feed stream in feed line 12a, the second olefin feed stream in feed line 12b, the third olefin feed stream in feed line 12c and the fourth or last olefin feed stream in feed line 12d. In one embodiment, it is not allowed to flow through the control valve in feed line 12d or even through feed line 12c, so the feed olefin feed stream is only fed to the upstream first stage oligomerization catalyst bed 22a-22c or only 22a-22b respectively. More or less independent multiple olefin feed streams can be used. It is easy to imagine up to six olefin feed streams. The feed olefin feed stream in pipeline 12 can be separated into multiple olefin feed streams of equal equal parts. Alternatively, the feed olefin feed stream in pipeline 12 can be separated into unequal streams. For example, the feed olefin feed stream can be separated into the stream of rising flow, wherein subsequent olefin feed stream has a flow greater than the aforementioned stream. In one embodiment, the feed olefin stream is separated into three streams, the flow rate of the feed olefin stream from pipeline 12 is dominant, such as 40% to 60% in pipeline 12a, and the flow rate of the feed olefin stream from pipeline 12 in pipelines 12b and 12c is dominantly small, such as 15% to 40%, and there is no flow in pipeline 12d. Preferably, the feed olefin stream with more flow rate is fed to the upstream bed 22a of the upstream first stage oligomerization catalyst bed 22a to 22c. In one embodiment, the feed olefin stream from pipeline 12 can be separated into only pipelines 12a and 12b, which may be equal. In addition, all feed olefin streams in pipeline 12 can be guided through feed pipeline 12a.

[0037] In order to manage the exotherm, the olefin stream can be diluted with a diluent stream to provide a diluted olefin stream to absorb the exotherm. The diluent stream can be included in the paraffin stream in the diluent line 14. Before the feed olefin stream is separated into a plurality of olefin streams, the diluent stream in the diluent line 14 can be added to the feed olefin stream in the pipeline 12. Preferably, after being separated into a plurality of olefin streams, the diluent stream is added to the first olefin stream in the pipeline 12a to provide the first diluted olefin stream in the pipeline 16a, so that the diluent stream passes through all oligomerization reactions. Alternatively, the diluent stream can also be separated into a plurality of streams, wherein each diluent stream is added to the corresponding olefin stream. The diluent stream can have a mass flow rate of 2 to 8 times and preferably 3 to 6 times of the feed olefin stream volume flow rate. The first diluted olefin stream can include no more than 17 weight % of olefins, suitably no more than 10 weight % of olefins and preferably no more than 6 weight % of olefins. The first diluted olefin stream may contain no more than 14 wt % ethylene, suitably no more than 10 wt % ethylene and preferably no more than 6 wt % ethylene. Similarly, the first diluted olefin stream may contain no more than 14 wt % propylene, suitably no more than 10 wt % propylene and preferably no more than 6 wt % propylene. The first diluted olefin stream in line 16a may be cooled in the first feed cooler 18a to provide the first cooled diluted olefin stream in line 20a, and loaded into the first bed 22a of the first stage oligomerization catalyst in the first stage oligomerization reactor 22. The cooled diluted first feed olefin stream in line 20a may be loaded at a temperature of 180°C (356°F) to 260°C (500°F) and a pressure of 3.5MPag (500psig) to 8.4MPag (1200psig). The feed cooler 18a may include a steam generator.

[0038] The first stage oligomerization reactor 22 may include a series of first stage oligomerization catalyst beds 22a, 22b, 22c and 22d for respectively loading with a plurality of olefin streams 12a, 12b, 12c and 12d. As previously described, in one embodiment, there may be no feed olefin stream in line 12d, so the feed olefin stream from line 12 is only fed to the upstream first stage oligomerization catalyst beds 12a-12c. Alternatively, as previously described, in one embodiment, there may be no feed olefin stream in line 12c or 12d, so the feed olefin stream from line 12 is only fed to the upstream first stage oligomerization catalyst beds 12a and 12b. The first stage oligomerization reactor preferably contains four fixed oligomerization catalyst beds 22a, 22b, 22c and 22d. It is also contemplated that each oligomerization catalyst bed 22a, 22b, 22c, and 22d may be in a dedicated first stage oligomerization reactor, or that multiple first stage oligomerization catalyst beds may be in two or more separate first stage oligomerization reactors. Up to six first stage oligomerization catalyst beds are readily contemplated. When the first stage oligomerization reactor 22 has been deactivated, parallel first stage oligomerization reactors may be used during which the first stage oligomerization reactor 22 is regenerated in situ by burning coke from the catalyst, as described below.

[0039] The recycle olefin stream in line 26 can be loaded into the oligomerization catalyst beds 22a-22d. In one embodiment, the recycle olefin stream in line 26 is fed only to the downstream oligomerization catalyst beds 22c and 22d. The recycle olefin stream in line 26 can be separated into a plurality of recycle olefin streams in lines 26c and 26d, and is fed only to the oligomerization catalyst beds 22c and 22d, respectively. In one embodiment, line 26c can have a dominant flow rate, and 26d can have the remaining flow rate of the recycle olefin stream in line 26. Preferably, the recycle olefin stream with more flow rate is fed to the downstream catalyst bed 22d of the downstream catalyst beds 22c and 22d, to achieve similar light olefin concentrations, for managing heat release.

[0040] The first cooled diluted olefin stream can preferably be loaded into the upstream first first stage oligomerization catalyst bed 22a in the pipeline 20a with downward flow operation. However, upward flow operation may be suitable. When the oligomerization of ethylene and / or propylene occurs in the upstream first first stage oligomerization catalyst bed 22a, heat is generated due to the exothermic nature of the ethylene and / or propylene oligomerization reaction. Despite cooling and dilution, the oligomerization of the first olefin stream produces the first oligomerization olefin stream in the upstream first oligomerization effluent pipeline 24a at the elevated outlet temperature. The elevated outlet temperature is limited to between 25°C (45°F) and 61°C (110°F), which is higher than the inlet temperature to the upstream first first stage catalyst bed 22a.

[0041] The second olefin stream in line 12b can be diluted with the first oligomeric olefin stream in the upstream first oligomerization effluent line 24a removed from the upstream first first stage oligomerization reactor 22 to provide the second diluted olefin stream in line 16b. The upstream first oligomeric olefin stream in line 24a includes a diluent stream from the diluent line 14, which is added to the first olefin stream in line 12a. The second diluted olefin stream can include no more than 22 weight % olefins, suitably no more than 15 weight % olefins and preferably no more than 10 weight % olefins. The second diluted olefin stream can include no more than 15 weight % ethylene, suitably no more than 10 weight % ethylene and preferably no more than 6 weight % ethylene. The second diluted olefin stream can include no more than 15 weight % propylene, suitably no more than 10 weight % propylene and preferably no more than 6 weight % propylene. The second diluted olefin stream in line 16b can be cooled in a second charge cooler 18b positioned outside the downstream first first stage oligomerization reactor 22 to provide a second cooled diluted olefin stream in line 20b, and loaded into the downstream first first stage bed 22b of the oligomerization catalyst in the first stage oligomerization reactor 22. The charge cooler 18b may include a steam generator. The second cooled diluted olefin stream in line 20b can be loaded at a temperature of 180°C (356°F) to 260°C (500°F) and a pressure of 3.4MPag (500psig) to 8.4MPag (1200psig). The second diluted olefin stream will include a diluent and olefins from the first oligomerization olefin stream. Olefins from the first oligomerization olefin stream will be oligomerized in the downstream first first stage bed catalyst bed 22b. The oligomerization of ethylene, propylene and oligomers in the second olefin stream in the downstream first first stage bed 22b of the oligomerization catalyst produces a downstream first first stage oligomerization olefin stream in the downstream first oligomerization effluent line 24b at an elevated outlet temperature. The elevated outlet temperature may be limited to between 25°C (45°F) and 61°C (110°F), which is higher than the inlet temperature to the catalyst bed 22b.

[0042] The third olefin stream in line 12c can be diluted with the downstream first first stage oligomerization olefin stream in line 24b removed from the second first stage oligomerization reactor 22b, and mixed with the first recycle olefin stream in line 26c to provide the upstream second first stage dilution olefin stream in line 16c. The downstream first stage oligomerization olefin stream in line 24b includes a diluent stream from diluent line 14, which is added to the first olefin stream in line 12a. The third diluted olefin stream can include no more than 23 weight % olefins, suitably no more than 15 weight % olefins and preferably no more than 10 weight % olefins. The third diluted olefin stream can include no more than 13 weight % ethylene, suitably no more than 10 weight % ethylene and preferably no more than 6 weight % ethylene. The third diluted olefin stream can include no more than 13 weight % propylene, suitably no more than 10 weight % propylene and preferably no more than 6 weight % propylene. The third diluted olefin stream in line 16c can be cooled in a third feed cooler 18c positioned outside the first stage oligomerization reactor 22 to provide a third cooled diluted olefin stream in line 20c and loaded into the third bed 22c of the oligomerization catalyst in the first stage oligomerization reactor 22. The feed cooler 18c may include a steam generator. The third cooled diluted olefin stream in line 20c can be loaded at a temperature of 180°C (356°F) to 260°C (500°F) and a pressure of 3.4MPag (500psig) to 8.4MPag (1200psig). The third diluted olefin stream will include diluent and olefins from the second downstream first stage oligomerization olefin stream and from the first recycled olefin stream. Olefins from the first downstream first stage oligomerization olefin stream and the first recycled olefin stream will be oligomerized in the second upstream first stage catalyst bed 22c. The oligomerization of ethylene and propylene in the third dilute olefin stream in the upstream second first stage bed 22c of the oligomerization catalyst produces an upstream second first stage oligomerization olefin stream in the upstream second first stage oligomerization effluent line 24c at an elevated outlet temperature. In one embodiment, the upstream second first stage oligomerization olefin stream is the penultimate oligomerization olefin stream, and the upstream second first stage oligomerization effluent line 24c is the penultimate oligomerization effluent line 24c. The elevated outlet temperature is limited to between 25°C (45°F) and 61°C (110°F), which is higher than the inlet temperature to the catalyst bed 22c.

[0043] The fourth olefin stream in line 12d can be diluted with the upstream second first stage or penultimate oligomerization olefin stream in line 24c removed from the upstream second first stage oligomerization reactor 22 and the second recycle olefin stream in line 26d to provide the fourth diluted olefin stream in line 16d. The upstream second first stage or penultimate oligomerization olefin stream in line 24c includes a diluent stream from diluent line 14, which is added to the first olefin stream in line 12a. The fourth diluted olefin stream can include no more than 24 weight % olefins, suitably no more than 18 weight % olefins and preferably no more than 10 weight % olefins. The fourth diluted olefin stream can include no more than 11 weight % ethylene, suitably no more than 8 weight % ethylene and preferably no more than 6 weight % ethylene. The fourth diluted olefin stream can include no more than 11 weight % propylene, suitably no more than 8 weight % propylene and preferably no more than 6 weight % propylene. The fourth diluted olefin stream in line 16d can be cooled in a fourth feed cooler 18d positioned outside the first stage oligomerization reactor 22 to provide a fourth cooled diluted olefin stream in line 20d and loaded into the downstream second first stage bed 22d of the oligomerization catalyst in the first stage oligomerization reactor 22. The feed cooler 18d may include a steam generator. The fourth cooled diluted olefin stream in line 20d can be loaded at a temperature of 180°C (356°F) to 260°C (500°F) and a pressure of 3.4MPag (500psig) to 8.4MPag (1200psig). The fourth or last diluted olefin stream will include diluent and olefins from the upstream, second first stage or penultimate oligomerization olefin stream and the second recycled olefin stream. Olefins from the upstream, second first stage or penultimate oligomerization olefin stream and the second recycled olefin stream will be oligomerized in the downstream, second first stage catalyst bed 22d. The oligomerization of ethylene and propylene in the fourth olefin stream in the downstream second first stage bed 22d of the oligomerization catalyst produces a downstream second first stage oligomerization olefin stream in the fourth oligomerization effluent line 24d at an elevated outlet temperature. The elevated outlet temperature is limited to between 25°C (45°F) and 61°C (110°F), which is higher than the inlet temperature to the downstream second first stage catalyst bed 22d.

[0044] Recycle olefin streams 26c and 26d provide olefins that may be oligomerized on catalyst beds 22c and 22d, respectively, but may also help control the exotherm generated during the ethylene oligomerization process.

[0045] In one embodiment, the downstream second first stage oligomerized olefin stream is the last olefin stream and the downstream second first stage oligomerized effluent line 24d is the last oligomerized effluent line 24d.

[0046] The oligomerization reaction is carried out mainly in the liquid phase or in a mixed liquid and gas phase based on olefins at a rate of 0.5 hr -1 Up to 10 hours -1 The LHSV occurs. We have found that the major fraction of ethylene in the olefin stream is converted to higher olefins. Typically, at least 20 mol% to 40 mol% of the ethylene will be oligomerized by the oligomerization catalyst bed. The ethylene will initially oligomerize to butenes over the catalyst.

[0047] The first stage oligomerization catalyst may include a zeolite catalyst. The first stage oligomerization catalyst may be considered as a solid acid catalyst. Zeolite may account for between 5% and 95% by weight of the catalyst, for example, between 5% and 85% by weight. Suitable zeolites include zeolites having a structure of one of the following categories: MFI, MEL, ITH, IMF, TUN, FER, BEA, FAU, BPH, MEI, MSE, MWW, UZM-8, MOR, OFF, MTW, TON, MTT, AFO, ATO and AEL. The 3-letter code indicating a zeolite is defined by the Structure Commission of the International Zeolite Association and is maintained at http: / / www.iza-structure.org / databases. UZM-8 is as described in U.S. Patent No. 6,756,030. In a preferred aspect, the first stage oligomerization catalyst may include a zeolite having a skeleton with a ten-ring pore structure. The example of suitable zeolite with ten ring pore structure comprises TON, MTT, MFI, MEL, AFO, AEL, EUO and FER. In further preferred aspect, the first stage oligomerization catalyst comprising the zeolite with ten ring pore structure can comprise one-dimensional pore structure. One-dimensional pore structure indicates the zeolite containing the non-crossed pores substantially parallel to one of the crystal axis. The hole preferably extends through the zeolite crystal. The suitable example of the zeolite with ten ring one-dimensional pore structure can comprise MTT. In other aspect, the first stage oligomerization catalyst comprises MTT zeolite.

[0048] The first stage oligomerization catalyst can be formed by combining the zeolite with a binder and then forming the catalyst into pellets. The pellets can be optionally treated with a phosphorus reagent to produce a zeolite having a phosphorus component of between 0.5% and 15% by weight of the treated catalyst. The binder is used to impart hardness and strength to the catalyst. The binder includes alumina, aluminum phosphate, silica, silica alumina, zirconium oxide, titanium dioxide and combinations of these metal oxides, as well as other refractory oxides, and clays such as montmorillonite, kaolin, palygorskite, smectite and attapulgite. Preferred binders are aluminum-based binders such as alumina, aluminum phosphate, silica alumina and clay.

[0049] One of the components of the catalyst binder used in the present disclosure is alumina. The alumina source can be any of various hydrated aluminum oxides or alumina gels such as alpha-alumina monohydrate of boehmite or pseudo-boehmite structure, alpha-alumina trihydrate of gibbsite structure, beta-alumina trihydrate of bayerite structure, and the like. Suitable alumina can be purchased from UOP LLC under the trade name VERSAL. Preferred alumina can be purchased from Sasol North American Alumina Products Group under the trade name Catapal. This material is an extremely high purity alpha-alumina monohydrate (pseudo-boehmite) that has been shown to produce high purity gamma-alumina after calcination at high temperatures.

[0050] Suitable first stage oligomerization catalysts are prepared by mixing proportional volumes of zeolite and alumina to achieve the desired zeolite to alumina ratio. In one embodiment, the MTT content may be from 5 wt % to 85 wt %, such as 20 wt % to 82 wt % MTT zeolite, and the balance of alumina powder will provide a suitably supported catalyst. Silica supports are also contemplated.

[0051] A monoacid such as nitric acid or formic acid may be added to the mixture in aqueous solution to gelatinize the alumina in the binder. Additional water may be added to the mixture to provide sufficient moisture to form a dough of sufficient consistency to be extruded or spray dried. An extrusion aid such as a cellulose ether powder may also be added. A preferred extrusion aid is available from Dow Chemical Company under the trade name Methocel.

[0052] The paste or dough may be prepared in the form of shaped particles, preferably by extruding the dough through a die having an opening of the desired size and shape therein, after which the extruded material is broken into extrudates of the desired length and dried. A further calcination step may be employed to impart increased strength to the extrudates. Typically, calcination is carried out in an air stream at a temperature of 260°C (500°F) to 815°C (1500°F). The MTT catalyst is not selectively neutralized at the acid sites, such as with an amine.

[0053] The extruded particles may have any suitable cross-sectional shape, i.e. symmetrical or asymmetrical, but most typically have a symmetrical cross-sectional shape, preferably spherical, cylindrical or multilobed. The cross-sectional diameter of the particles may be as small as 40 μm; however, it is typically 0.635 mm (0.25 in) to 12.7 mm (0.5 in), preferably 0.79 mm (1 / 32 in) to 6.35 mm (0.25 in), and most preferably 0.06 mm (1 / 24 in) to 4.23 mm (1 / 6 in).

[0054] In an exemplary embodiment, an MTT-type zeolite catalyst disposed on a high purity pseudo-boehmite alumina substrate in a ratio of 90 / 10 to 20 / 80 and preferably between 20 / 80 and 50 / 50 is provided in the catalyst bed or beds in the first stage oligomerization reactor 22 .

[0055] The first stage oligomerization catalyst can be regenerated when deactivated. Suitable regeneration conditions include subjecting the first stage oligomerization catalyst to hot air at 500°C for 3 hours, for example, in situ. In practice, regeneration can be achieved by purging with hot nitrogen at 300°C to 500°C, suitably 350°C to 450°C, to strip heavy hydrocarbon materials from the spent catalyst. Alternatively, the spent catalyst can be purged with a light olefin stream, washed with a solvent, or washed with another hydrocarbon stream. The purging or washing step is followed by burning coke in 0.3 mol% to 0.7 mol% of oxygen for 20 to 40 hours, and verifying combustion in 3 mol% to 10 mol% of oxygen until all coke is burned, or the coke on the catalyst is at least no more than 1.2 wt%. In order to promote regeneration without stopping work, a swing bed arrangement can be used with an alternative first stage oligomerization reactor. Alternatively, a lead-lag swing bed arrangement can be used. The regeneration gas stream can be made to enter the first stage oligomerization reactor 22 that needs to be regenerated. The regeneration gas can include air with an increased or decreased oxygen concentration. The activity and selectivity of the regenerated catalyst were comparable to those of the fresh catalyst.

[0056] Zeolite catalysts are advantageous as first stage oligomerization catalysts. Zeolite catalysts have relatively low sensitivity to oxygenate contamination. Therefore, the olefin feed in line 12 requires less oxygenate removal if produced by an ethanol dehydration process.

[0057] Compared with the feed olefin stream in pipeline 12, the last oligomerization olefin stream in the last oligomerization effluent pipeline 24d has increased ethylene dimer and oligomer concentration.The oligomerization olefin stream is cooled in steam generator 27 to generate steam, then cooled by heat exchange with the oligomerization stream in pipeline 37 in heat exchanger 29, and then cooled in air cooler 31 before it is loaded into second stage oligomerization reactor 32 in oligomerization feed pipeline 28.The second stage oligomerization reactor 32 can include a series of second stage oligomerization catalyst beds 32a and 32b in series.It is also expected that each second stage oligomerization catalyst bed 32a and 32b can be in a dedicated second stage oligomerization reactor, or a plurality of second stage oligomerization catalyst beds can be in two or more separate second stage oligomerization reactors.It is easy to imagine more than two second stage oligomerization catalyst beds.When the second stage oligomerization reactor 32 has been passivated, a parallel second stage oligomerization reactor can be used, during which the second stage oligomerization reactor 32 is regenerated in situ by burning coke from the catalyst.

[0058] To achieve the most desirable olefin products, the second stage oligomerization reactor 32 is operated at a temperature of 38°C (100°F) to 180°C (356°F). The second stage oligomerization reactor 32 is operated at a pressure of 4.9 MPa (700 psig) to 7.6 MPa (1100 psig) and more preferably 3.4 MPa (500 psig) to 6.9 MPa (1000 psig). The first oligomer stream from the first second stage oligomerization catalyst bed 32a can be withdrawn from the first second stage oligomerization reactor 32 in line 33, cooled back to a temperature of 38°C (100°F) to 180°C (356°F) in cooler 34 and charged to the second second stage oligomerization catalyst bed 32b in line 35.

[0059] The second stage oligomerization reactor 32 can be connected to the first stage oligomerization reactor 22 downstream. The second stage oligomerization reactor 32 is preferably operated in a downward flow operation. However, an upward flow operation may be suitable. The feed oligomerization olefin stream contacts with the second stage oligomerization catalyst, resulting in C2-C8 olefin dimerization and trimerization, to provide a distillate range olefin. About the second stage oligomerization reactor 32, select process conditions to produce a higher percentage of injection range olefins, when hydrogenated in the subsequent steps described below, it produces the desired injection range hydrocarbon product. Most of the unconverted ethylene in the feed oligomerization olefin stream is oligomerized in the second stage oligomerization reactor 32. In one embodiment, at least 90 mole % of the ethylene in the feed oligomerization olefin stream is oligomerized in the second stage oligomerization reactor 32. Metal, second stage oligomerization catalyst is effective in dimerization of undimerized ethylene. The oligomer olefin stream having an average carbon number higher than the oligomer olefin stream loaded in the oligomerization feed line 28 leaves the oligomerization reactor 32 in the pipeline 37.

[0060] The second stage oligomerization catalyst is preferably an amorphous silica alumina base material with metals from Group VIII and / or Group VIB of the periodic table using Chemical Abstracts Service symbols. In one aspect, the catalyst has a Group VIII metal promoted with a Group VIB metal. Typically, the silica and alumina are only in the base material, so the silica / alumina ratio of the catalyst is the same as the base material. The metal can be impregnated onto the silica alumina base material or ion exchanged with the silica alumina base material. Co-grinding is also considered. The catalyst used in the present invention can have a low temperature acidity ratio of at least 0.15, suitably 0.2 and preferably greater than 0.25, as determined by ammonia programmed temperature desorption (ammonia TPD) as described below. In addition, a suitable second stage oligomerization catalyst will have a low temperature acidity ratio of at least 0.15, suitably 0.2 and preferably greater than 0.25. 2 / g and 400m 2 The surface area is between 1.1777 W and 1.137 W / g as determined by nitrogen BET.

[0061] The preferred second stage oligomerization catalyst comprises an amorphous silica alumina support. One of the components of the catalyst support for the present invention is alumina. Alumina can be any of various hydrated aluminum oxides or alumina gels such as α-alumina monohydrate of boehmite or pseudo-boehmite structure, α-alumina trihydrate of gibbsite structure, β-alumina trihydrate of bayerite structure, etc. Particularly preferred alumina can be purchased from Sasol North America Alumina Product Group under the trade name Catapal. This material is an extremely high purity α-alumina monohydrate (pseudo-boehmite) that has been shown to produce high purity γ-alumina after calcination at high temperatures. Another component of the catalyst support is amorphous silica alumina. Suitable silica alumina having a silica to alumina ratio of 2.6 was purchased from CCIC of Japan (a subsidiary of JGC).

[0062] Another component used to prepare the second stage oligomerization catalyst used in the present invention is a surfactant. The surfactant is preferably mixed with the above-mentioned aluminum oxide and silica alumina powder. The resulting mixture of surfactant, aluminum oxide and silica alumina is then formed as described below, dried and calcined. Calcination effectively removes the organic components of the surfactant by combustion, but only after the surfactant has faithfully performed its function according to the present invention. Any suitable surfactant can be utilized. A preferred surfactant is a surfactant selected from a series of commercial surfactants sold by Solvay SA under the trade name "Antarox". "Antarox" surfactants are generally characterized as modified linear aliphatic polyethers and are low foaming biodegradable detergents and wetting agents.

[0063] Suitable silica alumina mixtures are prepared by mixing proportions of silica alumina and alumina in volume to achieve the desired silica to alumina ratio. In one embodiment, 75 to 95 weight percent amorphous silica alumina and 10 to 20 weight percent alumina powder will provide a suitable support with a silica to alumina ratio of 2.6. In one embodiment, other ratios of amorphous silica alumina to alumina may be suitable.

[0064] The surfactant may be combined with the silica alumina and alumina mixture using any convenient method. The surfactant is preferably mixed during the mixing and forming of the alumina and silica alumina. A preferred method is to mix an aqueous solution of the surfactant with the blend of alumina and silica alumina prior to final formation of the carrier. Preferably, the surfactant is present in the paste or dough in an amount of 0.01 wt % to 10 wt % based on the weight of the alumina and silica alumina.

[0065] A monoprotic acid such as nitric acid or formic acid may be added to the mixture in aqueous solution to peptize the alumina in the binder.Additional water may be added to the mixture to provide sufficient moisture to form a dough of sufficient consistency to be extruded or spray dried.

[0066] The paste or dough may be prepared in the form of shaped particles, preferably by extruding a dough mixture of alumina, silica alumina, surfactant and water through a die having openings of the desired size and shape therein, after which the extruded mass is broken into extrudates of the desired length and dried. A further calcination step may be employed to impart increased strength to the extrudates. Typically, calcination is carried out in a dry air stream at a temperature of 260°C (500°F) to 815°C (1500°F).

[0067] The extruded particles may have any suitable cross-sectional shape, i.e. symmetrical or asymmetrical, but most typically have a symmetrical cross-sectional shape, preferably spherical, cylindrical or multilobed. The cross-sectional diameter of the particles may be as small as 40 μm; however, it is typically 0.635 mm (0.25 in) to 12.7 mm (0.5 in), preferably 0.79 mm (1 / 32 in) to 6.35 mm (0.25 in), and most preferably 0.06 mm (1 / 24 in) to 4.23 mm (1 / 6 in).

[0068] The typical characteristics of the amorphous silica alumina support used herein are that the total pore volume, average pore size and surface area are large enough to provide a large amount of space and area for depositing active metal components. As measured by conventional mercury intrusion instrument method, the total pore volume of the support is generally 0.2cc / gram to 2.0cc / gram, preferably 0.25cc / gram to 1.0cc / gram, and most preferably 0.3cc / gram to 0.9cc / gram. Typically, the pore volume of the support in pores with a diameter greater than 100 angstroms is less than 0.1cc / gram, preferably less than 0.08cc / gram, and most preferably less than 0.05cc / gram. As measured by the BET method, the surface area is generally above 50m 2 / g, for example, higher than 200m 2 / g, preferably at least 250m 2 / gram, and most preferably 300m 2g to 400m 2 / gram.

[0069] To prepare the catalyst, the support material is compounded with one or more precursors of at least one metal component from Group VIII or VIB of the periodic table (e.g., by single or multiple impregnations of calcined amorphous refractory oxide support particles). The Group VIII metal (preferably nickel) should be present in a concentration of 0.5% to 15% by weight, and the Group VIB metal (preferably tungsten) should be present in a concentration of 0 to 12% by weight. Impregnation can be achieved by any method known in the art (e.g., by spray impregnation), wherein a solution containing a metal precursor in dissolved form is sprayed onto the support particles. Another method is a multi-dip procedure, in which the support material is repeatedly contacted with the impregnation solution with or without intermittent drying. Other methods involve immersing the support in a large volume of impregnation solution or circulating the support therein, and yet another method is a pore volume or pore saturation technique, in which the support particles are introduced into an impregnation solution of a volume just sufficient to fill the pores of the support. Sometimes, the pore saturation technique can be modified to utilize an impregnation solution having a volume that is 10% less to 10% greater than that which just fills the pores.

[0070] If the active metal precursors are combined by impregnation, a subsequent or second calcination at an elevated temperature, such as, for example, between 399°C (750°F) and 760°C (1400°F), converts the metals to their corresponding oxide forms. In some cases, calcination can be performed after each impregnation of the individual active metals. Subsequent calcinations will produce a catalyst containing the active metals in their corresponding oxide forms.

[0071] The preferred second stage oligomerization catalyst of the present invention has an amorphous silica alumina base material impregnated with 0.5 wt % to 15 wt % nickel in the form of 3.175 mm (0.125 inch) extrudates and a density of 0.45 g / ml to 0.65 g / ml. It is also contemplated that the metals may be incorporated into the support by other methods such as ion exchange and co-grinding.

[0072] The second stage oligomerization catalyst can be regenerated when deactivated. Suitable regeneration conditions include subjecting the catalyst to hot air at 500°C for 3 hours in situ, for example. In practice, regeneration can be achieved by purging with hot nitrogen at 300°C to 500°C, suitably 350°C to 450°C, to strip heavy hydrocarbon materials from the spent catalyst. Alternatively, the spent catalyst can be purged with a light olefin stream, washed with a solvent, or washed with another hydrocarbon stream. The purging or washing step is followed by burning coke in 0.3 mol % to 0.7 mol % of oxygen for 20 to 40 hours, and verifying combustion in 3 mol % to 10 mol % of oxygen until all coke is burned. In order to promote regeneration without stopping production, a swing bed arrangement can be used together with an alternative second stage oligomerization reactor. The regeneration gas can include air with an increased or decreased oxygen concentration. The activity and selectivity of the regenerated catalyst are comparable to those of a fresh catalyst.

[0073] The second stage oligomerization reaction is also substantially exothermic. The last oligomerized olefin stream in line 24d comprises a diluent stream from diluent line 14, which is added to the first olefin stream in line 12a and carried through the first stage oligomerization catalyst beds 22a to 22d. The diluent stream is then transported in line 28 to the second stage oligomerization reactor 32 to absorb the exothermic heat in the second stage oligomerization reactor. It is contemplated that the diluent is introduced into the second stage oligomerization catalyst beds 22a-22d, which may or may not first pass through the first stage oligomerization catalyst beds.

[0074] When the oligomerization reaction is performed according to the above process conditions, a C4 olefin conversion of greater than or equal to 95%, or greater than or equal to 97% is achieved. The resulting oligomer olefin stream in line 37 includes a variety of olefin products that are distillate range hydrocarbons.

[0075] The oligomer olefin stream in line 37, having an increased concentration of C9+ olefins compared to the oligomer olefin stream in line 28, is heat exchanged with the last oligomer olefin stream in line 24d in heat exchanger 29 and the olefin splitter bottoms stream in line 41 in heat exchanger 43, reduced in pressure and fed to olefin splitter column 36. The oligomer olefin stream in line 37 has a temperature of 140° C. (284° F.) to 200° C. (392° F.) and a pressure of 3.9 MPa (gauge) (550 psig) to 6.3 MPa (gauge) (900 psig).

[0076] In olefin splitter column 36, oligomers having boiling points below the jet range hydrocarbons (typically C8 hydrocarbons having atmospheric boiling points below 150°C) are separated in an olefin splitter overhead stream in overhead line 38 from a bottoms stream comprising distillate range C9+ hydrocarbons (typically C9-C22 olefins) in bottoms line 40. Olefin splitter column 36 may be operated at a bottoms temperature of 200°C (400°F) to 315°C (600°F) and an overhead pressure of 35 kPa(g) (5 psig) to 350 kPa(g) (50 psig). It is contemplated that olefin splitter column 36 may be two columns.

[0077] The olefin splitter overhead stream may be cooled to between 66° C. (150° F.) and 93° C. (200° F.), and the resulting condensate portion refluxed from the olefin splitter receiver 42 back to the olefin splitter column 36. The net vapor stream in receiver overhead line 44 from the olefin splitter receiver 42 may be compressed up to the oligomerization pressure in an offgas compressor 46 to provide a light oligomer stream in line 48 that is in the vapor or liquid phase after cooling. Alternatively, the olefin splitter overhead stream in the receiver overhead line 44 may be completely condensed by cooling (perhaps in an external refrigeration loop) to provide a liquid light oligomer stream in line 48. Line 48 may also be taken from the receiver 42. The light oligomer stream in line 48 may be separated between a light olefin drag stream in line 50 and an oligomer recycle stream in line 26, which may be recycled to the second stage oligomerization reactor 32 or the first stage oligomerization reactor 22. The light olefin drag stream in line 50 may comprise 1 wt % to 15 wt % of the light oligomer stream in line 48. The light oligomer stream in line 48 may comprise 30 wt % to 80 wt % light olefins.

[0078] In one embodiment, the oligomer recycle stream in line 26 can be mixed with the last oligomerized olefin stream in the last dimerization effluent line 24d to provide a feed oligomer stream in line 28 for loading into the second stage oligomerization reactor 32. The oligomer recycle stream in line 26 can be mixed with the first diluted olefin stream in line 16a or more suitably distributed between the first to fourth diluted olefin streams in lines 16a to 16d to oligomerize unreacted C4-C7 olefins. In a preferred embodiment, the oligomer recycle stream in line 26 can be separated into a first oligomer recycle stream in line 26c and a second oligomer recycle stream in line 26d. The first oligomer recycle stream in line 26c may be mixed with the upstream second first stage oligomerization olefin stream in the downstream first first stage oligomerization effluent line 24b, and possibly with the third olefin stream in the third olefin line 12c, to provide a third diluted olefin stream in line 16c for loading into the upstream second first stage oligomerization catalyst bed 22c. The second oligomer recycle stream in line 26d may be mixed with the upstream second first stage oligomerization olefin stream in the upstream second first stage oligomerization effluent line 24c, and possibly with the third olefin stream in the third olefin line 12c, to provide a fourth diluted olefin stream in line 16d for loading into the downstream second first stage oligomerization catalyst bed 22d.

[0079] The heavy olefin stream in splitter bottoms line 40 can be separated between a reboiled stream in line 51 which is reboiled and fed back to the olefin splitter column 36 and a heavy olefin stream in net splitter bottoms line 41. The heavy olefin stream in net bottoms line 30 is cooled by heat exchange with the oligomerized olefin stream in line 37 and then transported to Figure 2 The reboiler stream in line 51 may be heated by heat exchange with the reboiler stream in line 83 from the jet fractionation tower bottom line 76, which is heated by heat exchange with the reboiler stream in line 83 from the jet fractionation tower bottom line 76. Figure 2 The aqueous phase is returned to the jet fractionator via line 85.

[0080] Go to Figure 2 The hydrogenation section 110 in Figure 1 The heavy olefin stream in the net olefin splitter bottoms line 30 containing distillate range C9+ oligomerized olefins can be hydrogenated in the hydrogenation reactor 52 to saturate the olefinic bonds to provide fuel. This step is performed to ensure that the motor fuel product meets or exceeds the thermal oxidation requirements specified in ASTM D7566-10a for hydrotreated synthetic paraffinic kerosene (SPK). In addition, saturating the oligomerized heavy olefins will provide a paraffin stream that can be used as a diluent stream in line 14. The heavy olefin stream in line 30 can be cooled to produce steam and can be mixed with steam also from Figure 1The light olefin drag stream in line 50 comprising C2 to C8 olefins is combined with a hydrogen stream in line 56 to produce a combined olefin stream in line 54. The combined olefin stream in line 54 may also be combined with a hydrogen stream in line 56 to provide a combined hydrogenation feed stream in line 58, which is cooled and charged to hydrogenation reactor 52 at 125° C. (257° F.) to 315° C. (600° F.) and 3.5 MPag (500 psig) to 6.9 MPag (1000 psig). Excess hydrogen may be used to ensure full saturation, such as 1.5 to 2.5 stoichiometric amounts of hydrogen.

[0081] Hydrogenation is usually carried out using conventional hydrogenation or hydroprocessing catalysts and may include metal catalysts containing, for example, palladium, rhodium, nickel, ruthenium, platinum, rhenium, cobalt, molybdenum or combinations thereof and supported forms thereof. The catalyst support may be any solid, inert material, including but not limited to oxides such as silicon dioxide, aluminum oxide, titanium dioxide, calcium carbonate, barium sulfate and carbon. The catalyst support may be in the form of powders, particles, pellets, etc.

[0082] In an exemplary embodiment, hydrogenation is performed in a hydrogenation reactor 52 that includes a platinum catalyst on alumina, such as 0.5 wt % to 0.9 wt % platinum catalyst on alumina. The hydrogenation reactor 52 converts the olefins to paraffin products having the same carbon number distribution as the olefins, thereby forming distillate range paraffins suitable for use as jet fuel and diesel fuel.

[0083] The saturated heavy stream in line 60 discharged from the hydrogenation reactor 52 can be cooled by heat exchange with the saturated heavy liquid stream in the separator bottoms line 66 and fed to the hydrogenation separator 62. In the hydrogenation separator 62, the saturated heavy stream is separated into a hydrogenation separator vapor stream in the overhead line 64 and a saturated heavy liquid stream in the hydrogenation separator bottoms line 66. A purge in line 65 can be taken from the hydrogenation separator vapor stream in line 64, and the remainder can be compressed and combined with make-up hydrogen in line 68 to provide a hydrogen stream in line 56. The saturated heavy liquid stream in the bottoms line 66 can be heated by heat exchange with the saturated heavy stream in line 60 and the diluent stream in line 14, and fed to the jet fractionation column 70. In one embodiment, a hot separator and a cold separator system can replace the single hydrogenation separator 62.

[0084] The saturated heavy liquid stream in the bottoms line 66 can be fed to the jet fractionation tower 70 without prior stripping in a stripper. Alternatively, a stripper can be utilized upstream of the jet fractionation tower 70. In the jet fractionation tower 70, the saturated heavy liquid stream can be separated into a net off-gas stream in a net overhead line 80, a green jet stream in a net liquid overhead line 74, and a green diesel stream in a net bottoms line 82. The jet fractionation tower 70 can be operated at a bottoms temperature of 316° C. (600° F.) to 482° C. (900° F.) and an overhead pressure of 35 kPa (5 psig) to 350 kPa (50 psig).

[0085] The jet fractionation overhead stream in overhead line 72 may be cooled and the resulting condensate stream produced in line 79 from the bottom of receiver 78. A portion of the condensate in line 79 is refluxed to the jet fractionation column 70 while the jet fuel stream in line 84 is transported to the jet stripper 90. A net off-gas stream comprising C8- hydrocarbons is withdrawn from the jet fractionation receiver 78 into receiver overhead line 80. Most of the hydrocarbons in the net off-gas stream in receiver overhead line 80 are lighter hydrocarbons and may be used to fuel the reboiler of the jet fractionation column 70, the olefin splitter column 36, and / or other fired heaters in the complex.

[0086] Jet stripper 90 strips light ends from the jet fuel stream in line 84 and returns them in overhead line 92 to condenser 73 along with the jet fractionation overhead stream in line 72. The stripped jet fuel product enters jet stripper bottoms line 94 while a portion is reboiled and fed back to jet stripper 90. A jet fuel product stream in line 74 is withdrawn from the stripped jet fuel product in line 94, cooled in cooler 95 and recovered as a jet fuel product. The green jet stream withdrawn in line 74 contains kerosene range C9-C17 hydrocarbons and can be cooled and withdrawn as a product meeting applicable SPK standards. In an alternative embodiment, the green jet stream can be withdrawn from a side line on the side of the jet fractionation column 70.

[0087] The green diesel bottoms stream in bottoms line 76 may be separated between a reboiled stream in line 81 which is reboiled and fed back to the jet fractionator 70, a green diesel product stream in line 82, and a diluent stream in line 14. The diluent stream in line 14 may be cooled by heat exchange with separator bottoms line 66 and by steam generation and recycled back to the jet fractionator 70. Figure 1The olefin stream in line 12 in the oligomerization section 10 (preferably the first olefin stream in line 12a) is mixed to provide a first diluted olefin stream in line 16a to absorb the exotherm in the first stage oligomerization reactor 22. The green diesel in diluent line 14 is paraffinic, so it is inert to the oligomerization and hydrogenation reactions it may undergo. Both the jet fuel stream in line 74 and the diesel stream in line 82 can be cooled and fed to their respective fuel pools. The diesel stream will meet the ASTM D975 standard for diesel. The reboiled stream in line 81 can be transferred to the olefin splitter column 70 in line 83 to allow the reboiled stream from the olefin splitter column 70 to be cooled. Figure 1 The reboiled stream in line 51 of the olefin splitter bottoms stream in line 40 is reboiled. The cooled reboiled stream may be returned in line 85 and heated to boiling in a heater and returned to the jet fractionation column 70.

[0088] Starting from ethylene, the disclosed method can efficiently produce green jet fuel and green diesel fuel that meet applicable fuel requirements while managing exothermic generation. The carbon recovery rate in the method can exceed 95%.

[0089] At the end of 15 days or 20 days, suitably after the end of two weeks or more preferably at least after 30 days, after reaching the maximum temperature to compensate for the decreased catalytic activity, the catalytic cycle in the first stage oligomerization reactor 22 and / or the second stage oligomerization reactor 32 must be restarted. The catalyst must be regenerated to restore their initial activity. The regeneration of the zeolite oligomerization catalyst in the first stage oligomerization reactor 22 is carried out by taking the first stage oligomerization reactor 22 off-line (by interrupting the olefin feed therein). The reactor is depressurized to 280kPa (g) (40psig) to 600kPa (g) (85psig), and the liquid may be discharged by pumping the liquid to the olefin splitter tower 36. The first stage oligomerization reactor 22 is then purged with a hot dry purge gas to strip heavy hydrocarbons C8 to C21 from the first stage oligomerization catalyst. An inert gas (such as nitrogen, a hydrocarbon stream or a solvent) can be used as a purge gas. The purge gas may be introduced into the first stage oligomerization reactor 22 in a downward flow at 350°C to 450°C and 175 kPa(g) (25 psig) to 280 kPa(g) (40 psig), which is high enough to recover light olefins in the liquid phase. Once the liquid olefins are fully recovered, the flow of the purge gas to the first stage oligomerization reactor 22 is terminated. The air supply is then fed into the first stage oligomerization reactor for 10 to 25 hours. At the inlet, the oxygen concentration should not exceed 0.3 mol% to 0.7 mol%, and at the outlet, the temperature should not exceed 400°C to 500°C. Once the exotherm from the combustion no longer rises, the oxygen concentration may be increased to 5 mol% to 10 mol% to demonstrate that the carbon is fully burned. The GHSV based on the total flow rate is 400hr -1Up to 4000hr -1 , preferably not more than 1000hr -1 Oxygen may then be purged from the first stage oligomerization reactor by purging with an inert gas or by filling with a paraffinic liquid. Regeneration of the second stage oligomerization catalyst in the second stage oligomerization reactor 32 comprising a metal on a support may be performed according to the same procedure.

[0090] We have developed a method of regenerating both catalyst systems in the first stage oligomerization reactor 22 and the second stage oligomerization reactor 32 that allows for continuous operation. Figure 3 A method for regenerating the first stage oligomerization reactor 22 is described.

[0091] The process may use three first stage oligomerization reactors 22: a first reactor 22A, a second reactor 22B, and a third reactor 22C. The three reactors are switched between advance, lag, and regeneration modes. Figure 3 In the embodiment, the first reactor 22A is in the lead mode, the second reactor 22B is in the lag mode, and the third reactor 22C is in the regeneration mode. Figure 3 and Figure 1 Related. Figure 3 In the example, the unfilled valve is open and the filled valve is closed. In addition, the upper case letters in the reference characters are different from the lower case letters.

[0092] Figure 1 The pipeline 20a of the first reactor 22A is connected to the pipeline 120 through the open valve to load the first cooled diluted olefin stream into the upstream first first stage oligomerization catalyst bed 22a of the first reactor 22A in advance mode, so that the feed olefin stream is oligomerized on the upstream first first stage oligomerization catalyst bed 22a to produce the upstream first oligomerization olefin stream. The corresponding valves on the connecting pipeline 121 of the second reactor 22B and the connecting pipeline 122 of the third reactor 22C that are connected to the pipeline 20a downstream are closed in this mode. The upstream first stage oligomerization catalyst bed 22a of the first reactor 22A was previously regenerated in the regeneration mode. The upstream first stage oligomerization catalyst bed 22a of the first reactor 22A can preliminarily oligomerize the olefin stream loaded in the hysteresis mode to produce the upstream second oligomerization olefin stream before regeneration. The upstream first oligomerization olefin stream is discharged from the upstream first first stage oligomerization catalyst bed 22a in the upstream first oligomerization effluent line 24a through the open valve on the connecting line 124 and transported to the lines 12b and Figure 1 The corresponding valves on the connecting lines 125 and 126 from the second reactor 22B and the third reactor 22C in upstream communication with the line 24a are closed in this mode.

[0093] From Figure 1The second cooled diluted olefin stream in the pipeline 20b of the first reactor 22A is loaded into the first downstream first stage oligomerization catalyst bed 22b in advance mode through the open valve on the connecting pipeline 130, so that the loaded olefin stream is oligomerized through the first downstream first stage oligomerization catalyst bed to produce the first downstream oligomerization olefin stream. The corresponding valves on the connecting pipeline 131 of the second reactor 22B connected to the downstream of the pipeline 20b and the connecting pipeline 132 of the third reactor 22C are closed in this mode. The first downstream first stage oligomerization catalyst bed of the first reactor 22A was previously regenerated in the regeneration mode. The first downstream first stage oligomerization catalyst bed 22b of the first reactor 22A can preliminarily oligomerize the loaded olefin stream in the lag mode to produce the second upstream oligomerization olefin stream before regeneration. The first downstream oligomerization olefin stream is discharged from the first downstream first stage oligomerization catalyst bed 22b in the first downstream oligomerization effluent pipeline 24b through the open valve on the connecting pipeline 135, and transported to the pipelines 12c and 12d. Figure 1 The third feed cooler 18c for the second reactor 22B is used in the first reactor 22A. The corresponding valves on the connecting lines 136 and 137 for the second reactor 22B and the third reactor 22C respectively connected to the pipeline 24b upstream are closed when the first reactor 22A is in the advance mode.

[0094] Figure 1 The pipeline 20c of the first reactor 22A of the first reactor 22B is connected to the pipeline 141 through the open valve to load the third cooled diluted olefin stream into the upstream second first stage oligomerization catalyst bed 22c of the second reactor 22B in a lag mode, so that the loaded olefin stream is oligomerized on the upstream second first stage oligomerization catalyst bed to produce the upstream second oligomerization olefin stream. The corresponding valves on the connecting pipeline 140 of the first reactor 22A and the connecting pipeline 142 of the third reactor 22C, which are connected to the downstream of the pipeline 20c, are closed in this mode. The upstream second first stage oligomerization catalyst bed 22c of the second reactor 22B was previously regenerated in a regeneration mode. The upstream second first stage oligomerization catalyst bed 22c of the second reactor 22B can preliminarily oligomerize the loaded olefin stream in an advance mode to produce the upstream second oligomerization olefin stream after regeneration. The upstream second oligomerization olefin stream is discharged from the upstream second first stage oligomerization catalyst bed 22c in the upstream second oligomerization effluent pipeline 24c through the open valve on the connecting pipeline 145, and transported to the pipelines 12d and 12d. Figure 1 The fourth feed cooler 18d is shown in FIG. The corresponding valves on the connecting lines 144 and 146 from the second reactor 22B and the third reactor 22C, respectively, which communicate with the line 24a upstream, are closed in this mode.

[0095] From Figure 1The fourth cooled diluted olefin stream in the pipeline 20d of the second reactor 22B is loaded into the second first stage oligomerization catalyst bed 22d downstream in a hysteresis mode through the open valve on the connecting pipeline 151, so that the loaded olefin stream is oligomerized by the second first stage oligomerization catalyst bed downstream to produce the second oligomerization olefin stream downstream. The corresponding valves on the connecting pipeline 150 of the first reactor 22A and the connecting pipeline 152 of the third reactor 22C that are communicated with the downstream of the pipeline 20d are closed in this mode. The second first stage oligomerization catalyst bed 22d downstream of the second reactor 22B was previously regenerated in a regeneration mode. The second first stage oligomerization catalyst bed 22d downstream of the second reactor 22B can make the loaded olefin stream oligomerized in advance in advance mode to produce the second oligomerization olefin stream upstream after regeneration. The second oligomerization olefin stream downstream is discharged from the second first stage oligomerization catalyst bed 22d downstream in the second oligomerization effluent pipeline 24d downstream by the open valve on the connecting pipeline 156, and transported to Figure 1 The corresponding valves on the connecting lines 155 and 157 for the first reactor 22A and the third reactor 22C respectively connected to the upstream of the line 24d are closed when the second reactor 22B is in the advance mode.

[0096] After the upstream first first stage oligomerization catalyst bed 22a and the downstream first stage oligomerization catalyst bed 22b in the first reactor 22A are exhausted in the advance mode, the charging of the olefin stream to the corresponding beds can be interrupted and regeneration can be started. Alternatively, after the upstream second first stage oligomerization catalyst bed 22c and the downstream second first stage oligomerization catalyst bed 22d of the second reactor 22B in the lag mode are exhausted, the charging of the olefin stream to the upstream first stage oligomerization catalyst bed 22a and the downstream first stage oligomerization catalyst bed 22b in the first reactor 22A can continue, but in the lag mode, while the second reactor 22B moves to the regeneration mode.

[0097] exist Figure 3In the embodiment of the present invention, the third reactor is in regeneration mode. Pipeline 100 is loaded with the regeneration gas stream into the third first stage oligomerization catalyst bed 22e of the upstream of the third first stage reactor 22C in regeneration mode by connecting pipeline 162 and the open valve thereon. Close the corresponding valves on the connecting pipeline 160 of the first first stage reactor 22A in advance mode and the connecting pipeline 161 of the second first stage reactor 22B in lag mode that are communicated with pipeline 100 downstream. The regeneration gas can include oxygen and be at an elevated temperature. The third first stage oligomerization catalyst bed 22e in the upstream was previously in advance mode, and alternatively, was recently in lag mode. The regeneration gas from the third first stage oligomerization catalyst bed 22e in the upstream can be fed to the third first stage oligomerization catalyst bed 22f in the downstream to regenerate the catalyst therein by the open valve on pipeline 102c. The corresponding valves on the lines 102a and 102b on the first first stage reactor 22A and the second first stage reactor 22B in downstream communication with the upstream first stage catalyst beds 22a and 22b are closed. The regenerated flue gas leaves the downstream third first stage oligomerization catalyst bed 22f in the connecting line 167 having an open valve thereon and discharged in the line 106. The corresponding valves on the connecting line 165 for the first first stage reactor 22A and the connecting line 166 for the second first stage reactor 22B in upstream communication with the line 106 are closed when the third reactor 22C is in the regeneration mode. After regeneration, the third reactor 22C can move from the regeneration reactor to the leading reactor, while the first reactor 22A moves from the leading reactor to the lagging reactor, and the second reactor 22B enters the regeneration mode from the lagging mode.

[0098] Figure 4 A method for regenerating the second stage oligomerization reactor 32 is described. The regeneration method may use three second stage oligomerization reactors 32: a first reactor 32A, a second reactor 32B, and a third reactor 32C. The three reactors are switched between advance, lag, and regeneration modes. Figure 4 In the embodiment, the first reactor 32A is in the lead mode, the second reactor 32B is in the lag mode, and the third reactor 32C is in the regeneration mode. Figure 4 and Figure 1 Related. Figure 4 In the example, the unfilled valve is open and the filled valve is closed. In addition, the upper case letters in the reference characters are different from the lower case letters.

[0099] Figure 1The pipeline 28 of the first reactor 32A is connected to the first second stage oligomerization catalyst bed 32a of the second reactor 32A through the open valve on the connecting line 220 to load the cooled oligomerized olefin stream in advance mode, so that the oligomerized olefin stream is oligomerized on the first second stage oligomerization catalyst bed 32a to produce the first oligomer stream. The corresponding valves on the connecting line 221 of the second second stage reactor 32B and the connecting line 222 of the third reactor 32C, which are connected to the downstream of the pipeline 28, are closed in this mode. The first second stage oligomerization catalyst bed 32a of the first reactor 32A was previously regenerated in the regeneration mode. The first second stage oligomerization catalyst bed 32a of the first reactor 32A can preliminarily oligomerize the charged olefin stream in the lag mode to produce the second oligomer stream before regeneration. The first oligomer stream is discharged from the first second stage oligomerization catalyst bed 32a in the first oligomer pipeline 33 through the open valve on the connecting line 235, and is transported to the first oligomer stream in the pipeline 33. Figure 1 The second feed cooler 34 is shown in FIG. The corresponding valves on the connecting lines 236 and 237 from the second reactor 32B and the third reactor 32C, respectively, which are connected upstream to the line 33, are closed in this mode.

[0100] From Figure 1 The first cooled oligomer stream in the pipeline 35 is loaded into the second second-stage oligomerization catalyst bed 32b in the second second-stage oligomerization catalyst bed 32b in a lag mode through the open valve on the connecting line 241, so that the oligomer stream is oligomerized on the second second-stage oligomerization catalyst bed to produce a second oligomer stream. The corresponding valves on the connecting line 240 of the first reactor 32A connected to the downstream of the pipeline 35 and the connecting line 242 of the third reactor 32C are closed in this mode. The second second-stage oligomerization catalyst bed of the second second-stage reactor 32B was previously regenerated in a regeneration mode. The second second-stage oligomerization catalyst bed 32b of the second reactor 32A can pre-oligomerize the oligomer stream in an advance mode to produce the first oligomer stream after regeneration. The second oligomer stream is discharged from the second second-stage oligomerization catalyst bed 32b in the second second-stage reactor 32B through the open valve on the connecting line 256, and is transported to the second oligomer pipeline 37. Figure 1 The heat exchanger 29 in the olefin splitter column 36 is finally fractionated. The corresponding valves on the connecting lines 255 and 257 for the first second-stage reactor 32A and the third second-stage reactor 32C connected to the upstream of the line 37 are closed when the second reactor 32B is in the lag mode.

[0101] After the first second stage oligomerization catalyst bed 32a in the first second stage reactor 32A is exhausted in the advance mode, the feeding of the oligomer stream into the first second stage oligomerization reactor can be discontinued and regeneration can be initiated. Alternatively, after the second second stage oligomerization catalyst bed 32b of the second second stage reactor 32B in the lag mode is exhausted, the feeding of the oligomer stream into the first second stage oligomerization catalyst bed 32a in the first second stage reactor 32A can continue, but in the lag mode, while the second second stage reactor 32B is moved to the regeneration mode.

[0102] exist Figure 4 In the embodiment of the present invention, the third reactor 32C is in regeneration mode. The pipeline 200 is loaded with the regeneration gas stream into the third second-stage oligomerization catalyst bed 32c of the third second-stage reactor 32C in regeneration mode through the connecting pipeline 262 and the open valve thereon. Close the corresponding valves on the connecting pipeline 260 of the first second-stage reactor 32A in advance mode and the connecting pipeline 261 of the second second-stage reactor 22B in lag mode that are connected to the downstream of the pipeline 200. The regeneration gas may include oxygen and be at an elevated temperature. The third second-stage oligomerization catalyst bed 32c was previously in advance mode, and alternatively, was in lag mode most recently before the regeneration mode. The regenerated flue gas leaves the downstream third second-stage oligomerization catalyst bed 32c in the connecting pipeline 267 having an open valve thereon and discharged in the pipeline 206. The corresponding valves on the connecting line 265 for the first second-stage reactor 32A and the connecting line 266 for the second second-stage reactor 32B, which are connected upstream to the pipeline 206, are closed when the third reactor 32C is in the regeneration mode. After regeneration, the third reactor 32C can be moved from the regeneration reactor to the leading reactor, while the first reactor 32A can be moved from the leading reactor to the lagging reactor, and the second reactor 22B is moved from the lagging reactor to the regeneration mode.

[0103] In order to allow a regeneration system to regenerate each catalyst over a two-week period, a Figure 5 The scheduling system shown in , to accommodate the requirements of regeneration timing and still allow some flexibility in the scheduling of planned downtime. Regeneration can be no more than twice per reactor per month, more preferably no more than once per reactor per month, or more preferably no more than once per reactor every 5 weeks.

[0104] Example

[0105] Example 1

[0106] The spent first stage oligomeric MTT zeolite catalyst and second stage oligomeric nickel catalyst on amorphous silica alumina from the first pilot plant cycle test in contact with ethylene feed and light paraffin diluent in a stacked bed configuration were regenerated ex situ. The regeneration procedure consisted of heating at 400 °C for 600 h. -1 Up to 800h -1 The gas space velocity was high temperature nitrogen purged, and then N 2 2 wt% and 7 wt% O 2 Controlled O 2 Coke combustion was carried out at 450 °C in an atmosphere, and 2 Coke combustion was verified under 18 wt% O2 in 400°C nitrogen purge. As shown in Table 1, a large amount of carbonaceous materials were removed by 400°C nitrogen purge. Based on gas chromatography analysis, the purged hydrocarbon materials were C8-C20 olefins. The carbon combustion step completely removed the coke on the second-stage Ni / ASA catalyst, however, the regenerated first-stage zeolite MTT catalyst contained 1 wt% of difficult-to-burn coke. As experimentally demonstrated, the difficult-to-burn coke on the first-stage oligomerization catalyst does not negatively affect catalyst performance. After continuous regeneration in all subsequent cycles, the difficult-to-burn coke remained at the same level and did not accumulate to more than 1 wt%.

[0107] Table 1. Carbon, hydrogen and nitrogen analysis of the spent and hot nitrogen purged Stage 1 and Stage 2 oligomerization catalysts.

[0108]

[0109] Example 2

[0110] Pilot plant tests using a first stage oligomerization catalyst comprising MTT zeolite and a second stage oligomerization catalyst comprising nickel on amorphous silica alumina demonstrated operation for two weeks or longer, providing satisfactory conversion at acceptable temperatures in the first cycle, with full performance recovery in the second cycle after ex situ regeneration.

[0111] Figure 6 The ethylene conversion over time for three cycles is shown. The first cycle is with fresh MTT zeolite catalyst and nickel on amorphous silica alumina catalyst arranged in a stacked bed configuration in a pilot plant reactor, indicated by the dashed line. The second cycle in the triangles and the third cycle in the circles represent the conversion on the regenerated catalyst. The regenerated cycles have conversions comparable to fresh catalyst before any regeneration.

[0112] Figure 7The change in oligomer selectivity over time for three cycles is shown. Here, the first cycle is with fresh MTT zeolite catalyst and nickel catalyst on amorphous silica alumina arranged in a stacked bed configuration in a pilot plant reactor, represented by the dashed line. The second cycle in the triangle and the third cycle in the circle represent the conversion on the regenerated catalyst. The regenerated cycle has a selectivity comparable to the fresh catalyst before any regeneration.

[0113] Specific implementation plan

[0114] While the following is described in conjunction with specific embodiments, it should be understood that this description is intended to illustrate and not to limit the scope of the foregoing description and the appended claims.

[0115] A first embodiment of the present disclosure is a method for oligomerizing an olefin stream, comprising oligomerizing a feed olefin stream on a first first-stage oligomerization catalyst bed to produce a first oligomerized olefin stream; regenerating the first oligomerization catalyst bed; oligomerizing the feed olefin stream on a second first-stage oligomerization catalyst bed to produce a second oligomerized olefin stream; oligomerizing the feed olefin stream on the first first-stage oligomerization catalyst bed to produce a first oligomerized olefin stream. One embodiment of the present disclosure is one, any one, or all of the previous embodiments in this paragraph to the first embodiment in this paragraph, and further comprises regenerating the second oligomerization catalyst bed. One embodiment of the present disclosure is one, any one, or all of the previous embodiments in this paragraph to the first embodiment in this paragraph, and further comprises regenerating the first first-stage oligomerization catalyst bed by feeding oxygen to the catalyst bed at an elevated temperature. One embodiment of the present disclosure is one, any one, or all of the previous embodiments in this paragraph to the third embodiment in this paragraph, and further comprises oligomerizing the feed olefin stream on a third first-stage oligomerization catalyst bed to produce an oligomerized olefin stream. One embodiment of the present disclosure is one, any or all of the previous embodiments in this paragraph to the first embodiment in this paragraph, further comprising interrupting the oligomerization of the feed olefin stream on the first first-stage oligomerization catalyst bed before regenerating the first first-stage oligomerization catalyst bed. One embodiment of the present disclosure is one, any or all of the previous embodiments in this paragraph to the first embodiment in this paragraph, further comprising interrupting the oligomerization of the feed olefin stream on the second first-stage oligomerization catalyst bed before regenerating the second first-stage oligomerization catalyst bed. One embodiment of the present disclosure is one, any or all of the previous embodiments in this paragraph to the first embodiment in this paragraph, further comprising oligomerizing the oligomerized olefin stream on the first second-stage oligomerization catalyst bed to produce a first oligomer stream; regenerating the first second-stage oligomerization catalyst bed; and oligomerizing the oligomerized olefin stream on the second second-stage oligomerization catalyst bed to produce a second oligomer stream. One embodiment of the present disclosure is one, any or all of the previous embodiments in this paragraph to the first embodiment in this paragraph, further comprising regenerating the second second-stage oligomerization catalyst bed. One embodiment of the present disclosure is one, any or all of the previous embodiments in this paragraph to the first embodiment in this paragraph, further comprising regenerating the first second stage oligomerization catalyst bed by feeding oxygen to the catalyst bed at an elevated temperature. One embodiment of the present disclosure is one, any or all of the previous embodiments in this paragraph to the first embodiment in this paragraph, further comprising regenerating the first second stage oligomerization catalyst bed while oligomerizing the oligomerized olefin feed stream on the second second stage oligomerization catalyst bed.One embodiment of the present disclosure is one, any or all of the previous embodiments in this paragraph to the first embodiment in this paragraph, comprising continuously oligomerizing the feed olefin stream over the first stage oligomerization catalyst for at least one month. One embodiment of the present disclosure is one, any or all of the previous embodiments in this paragraph to the first embodiment in this paragraph, further comprising continuously oligomerizing the oligomerized olefin stream over the second stage oligomerization catalyst for at least two weeks.

[0116] A second embodiment of the present disclosure is a method for oligomerizing an olefin stream, comprising oligomerizing a feed olefin stream on a first first-stage oligomerization catalyst bed to produce a first oligomerized olefin stream; oligomerizing the first oligomerized olefin stream on a first second-stage oligomerization catalyst bed to produce a first oligomer stream; regenerating the first second-stage oligomerization catalyst bed; and oligomerizing the first oligomerized olefin stream on a second second-stage oligomerization catalyst bed to produce a second oligomer stream. An embodiment of the present disclosure is one, any, or all of the previous embodiments in this paragraph to the second embodiment in this paragraph, further comprising regenerating the second second-stage oligomerization catalyst bed. An embodiment of the present disclosure is one, any, or all of the previous embodiments in this paragraph to the second embodiment in this paragraph, further comprising regenerating the first second-stage oligomerization catalyst bed by feeding oxygen to the catalyst bed at an elevated temperature. An embodiment of the present disclosure is one, any, or all of the previous embodiments in this paragraph to the second embodiment in this paragraph, further comprising interrupting the oligomerization of the oligomerized olefin stream on the first second-stage oligomerization catalyst bed before regenerating the first second-stage oligomerization catalyst bed. One embodiment of the present disclosure is one, any or all of the previous embodiments in this paragraph to the second embodiment in this paragraph, further comprising interrupting the oligomerization of the oligomerized olefin stream on the second second-stage oligomerization catalyst bed before regenerating the second second-stage oligomerization catalyst bed. One embodiment of the present disclosure is one, any or all of the previous embodiments in this paragraph to the second embodiment in this paragraph, further comprising continuously oligomerizing the oligomerized olefin stream on the second-stage oligomerization catalyst for at least two weeks.

[0117] The third embodiment of the present disclosure is a method for oligomerizing an olefin stream, comprising oligomerizing a feed olefin stream on a first first-stage oligomerization catalyst bed to produce a first oligomerized olefin stream; regenerating the first oligomerization catalyst bed; oligomerizing the feed olefin stream on a second first-stage oligomerization catalyst bed to produce a second oligomerized olefin stream; oligomerizing the first oligomerized olefin stream or the second oligomerized olefin stream on a first second-stage oligomerization catalyst bed to produce a first oligomer stream; regenerating the first second-stage oligomerization catalyst bed; oligomerizing the first oligomerized olefin stream or the second oligomerized olefin stream on a second second-stage oligomerization catalyst bed to produce a second oligomer stream. An embodiment of the present disclosure is one, any one, or all of the previous embodiments in this paragraph to the third embodiment in this paragraph, and further comprises interrupting the oligomerization of the feed olefin stream on the first first-stage oligomerization catalyst bed before regenerating the first first-stage oligomerization catalyst bed.

[0118] Although there is no further detailed description, it is believed that those skilled in the art can make the most of the present disclosure by using the foregoing description and can easily determine the essential characteristics of the present disclosure without departing from the spirit and scope of the present invention, and can make various changes and modifications of the present disclosure and adapt it to various usages and conditions. Therefore, the aforementioned preferred specific embodiments should be understood as merely illustrative and not to limit the rest of the present disclosure in any way, and are intended to cover various modifications and equivalent arrangements included within the scope of the appended claims.

[0119] In the foregoing, all temperatures are set forth in degrees Celsius and all parts and percentages are by weight unless otherwise indicated.

Claims

1. A process for oligomerizing an olefin stream, the process comprising: oligomerizing a feed olefin stream over a first stage oligomerization catalyst bed to produce a first oligomerized olefin stream; regenerating the first first stage oligomerization catalyst bed; oligomerizing the feed olefin stream over a second first stage oligomerization catalyst bed to produce a second oligomerized olefin stream; The feed olefin stream is oligomerized over the first first stage oligomerization catalyst bed to produce the first oligomerized olefin stream.

2. The method of claim 1 further comprising regenerating the second first stage oligomerization catalyst bed.

3. The method of claim 1 further comprising regenerating the first first stage oligomerization catalyst bed by feeding oxygen at an elevated temperature to the first first stage oligomerization catalyst bed.

4. The process of claim 1 further comprising oligomerizing the feed olefin stream over a third first stage oligomerization catalyst bed to produce an oligomerized olefin stream.

5. The method of claim 1, further comprising interrupting oligomerization of the feed olefin stream on the first first stage oligomerization catalyst bed prior to regenerating the first first stage oligomerization catalyst bed.

6. The method of claim 1, further comprising interrupting oligomerization of the feed olefin stream on the second first stage oligomerization catalyst bed prior to regenerating the second first stage oligomerization catalyst bed.

7. The process of claim 1 further comprising regenerating the first stage oligomerization catalyst bed by feeding an inert gas, a hydrocarbon or a solvent to the catalyst bed at an elevated temperature.

8. The method of claim 7, further comprising feeding oxygen to the catalyst bed at an elevated temperature.

9. The method according to claim 1, further comprising: oligomerizing an oligomerized olefin stream over a first second stage oligomerization catalyst bed to produce a first oligomer stream; regenerating the first second stage oligomerization catalyst bed; The oligomerized olefin stream is oligomerized over a second second stage oligomerization catalyst bed to produce a second oligomer stream.

10. The method of claim 9 further comprising regenerating the second second stage oligomerization catalyst bed.

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