Process and production unit for producing olefin trimer

Abstract

The invention relates to a process and a production unit for producing olefin trimers. A process and a production unit for the catalytic production of olefin trimers from olefin monomers, wherein the olefin dimers are recycled after the dimerization reaction and reacted with olefin monomers in an addition reaction.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the processing of olefins, in particular to the highly selective production of olefin trimers from olefin monomers. BACKGROUND

[0002] Current processes for the polymerization of olefins generally produce a mixture of olefin polymers and have poor selectivity for a certain polymer. The production of a desired polymer species from such a mixture of polymers requires the use of complex separation techniques. It would therefore be beneficial to find a process for the highly selective production of a desired olefin polymer rather than a mixture of polymers and wherein the olefin monomers are efficiently converted to the desired polymer.

[0003] US4544791 discloses a two reactor process for the production of 75% dimers and 15% trimers from C4 monomers.

[0004] Isododecene is a trimer of isobutene which can be produced by the oligomerization of isobutene. These trimers were previously produced in small amounts as an undesired by-product in isooctene processes, but their amount was generally suppressed in isooctene production by the use of oxygenated moderator substances. However, since the olefin trimers can be considered as a meaningful product in their own right, there is a challenge as to how to direct the isobutene selectivity mainly to the trimers without producing and separating isooctene (dimers) or heavier oligomers (tetramers and higher polymers).

[0005] Acid catalyzed isobutene oligomerization generally produces a broad oligomer distribution as a function of increasing isobutene conversion. Therefore, previous processes were not efficient in producing isobutene trimers, i.e. isododecene. The present disclosure relates to a process which achieves high olefin conversion while at the same time achieving a trimer-rich product with selectivity of even more than 90%.

[0006] It is therefore an object of the present disclosure to provide products, processes and systems to alleviate the above-mentioned drawbacks. In particular, the present disclosure aims to provide a process and a production unit which can be used for the highly selective production of olefin trimers from olefin monomers. SUMMARY

[0007] The scope of protection sought for various embodiments of the present invention is set forth by the appended claims.

[0008] Disclosed herein is a process for the production of olefin trimers, comprising:

[0009] feeding to a reactor containing a dimerization catalyst:

[0010] operating the reactor at a temperature selected from the range of 40-140 °C and a pressure selected from the range of 10-40 bar to effect catalytic dimerization reactions between olefin monomers and addition reactions between olefin monomers and olefin dimers;

[0011] removing a reactor outlet stream from the reactor; and

[0012] subjecting the reactor outlet stream to distillation to separate at least one lighter product comprising olefin dimers and a heavier bottom product comprising olefin trimers; wherein

[0013] at least a portion of the lighter product is recycled to the reactor to provide a recycle feed,

[0014] olefin monomers are fed to the reactor primarily as fresh olefin monomer feed,

[0015] the amounts of fresh olefin monomer feed and recycle feed to the reactor are controlled such that the mass ratio of olefin monomers to olefin dimers entering the reactor is selected from the range of 1 :8 to 1 : 15,

[0016] and wherein the catalytic reactions are conducted at operating conditions where the olefins remain in the liquid phase.

[0017] An advantage of the process is the selectivity of the polymerization reactions (dimerization and addition reactions) of the olefin trimers. Another advantage is that with the process it is even possible to conduct the production of olefin trimers in a single reactor system, which simplifies the production process.

[0018] Since the dimers generated in the reactor can be recycled back to the reactor after distillation together with other lighter components, no further separation techniques are required to remove lighter components such as dimers from the olefin trimer product. Thus, the process simultaneously achieves the recovery of olefin trimers and the recycle of reactive species.

[0019] Alternatively, multiple reactor vessels can be used instead of a single reactor unit, which allows for even more controlled optimization of the selectivity of the trimer production process. The use of multiple reactor vessels is also compatible with the single step distillation described above. Furthermore, the process is flexible in allowing the recovery of olefin dimers and olefin trimers as separate product streams. It is also possible to implement the present invention with two distillation columns, which will be described later.

[0020] The present invention also discloses a production unit suitable for and configured to implement the process described above, comprising:

[0021] a. at least one reactor unit configured to receive an acid catalyst;

[0022] b. at least one distillation column configured to separate iso-octene from iso- dodecene;

[0023] c. at least one reactor feed line in fluid communication with the reactor unit or the plurality of reactor units and at least one olefin monomer reservoir;

[0024] d. at least one reactor outlet stream line in fluid communication with the reactor unit or the plurality of reactor units and the distillation column;

[0025] e. at least one recycle line in fluid communication with the distillation column and the reactor unit or the plurality of reactor units; and

[0026] f. a bottoms product line in fluid communication with the distillation column and a bottoms product reservoir. BRIEF DESCRIPTION OF DRAWINGS

[0027] The present invention will be described in greater detail by non-limiting preferred embodiments with reference to the attached drawings.

[0028] Figure 1 The composition of the bottoms product obtained with the preset process using recycled olefin dimers is shown. The conversion of monomer to trimers is close to 90%.

[0029] Figure 2 The composition of the comparative bottoms product obtained using a "once through" experimental design, i.e. without recycling of the olefin dimers, is shown.

[0030] Figure 3 An embodiment of the production unit 100 is shown.

[0031] Figure 4 Another embodiment of the production unit 100 is shown. DETAILED DESCRIPTION

[0032] The term oxygen-containing regulator refers to a compound containing oxygen, such as an oxygen-containing compound or a compound containing oxygen, carbon and hydrogen.

[0033] The term "comprising" as used herein includes the more broad "including", "containing", and "encompassing" as well as the more narrow "consisting essentially of" and "consisting of".

[0034] In one embodiment, the process is carried out on an industrial scale, preferably as a continuous process.

[0035] In one embodiment, the process steps are carried out in the order determined in any aspect, embodiment or claim. In another embodiment, any process step specified to be carried out on a product or intermediate obtained in a preceding process step is carried out directly on said product or intermediate, i.e. without additional, optional or auxiliary processing steps that can chemically or physically alter said product or intermediate between said two consecutive steps.

[0036] In the context of the present application, the term reactor feed refers to any feed into the reactor. For the sake of brevity, when at least one identical component, such as an olefin monomer, is fed into the reactor by multiple feeds, the reactor feed of olefin monomer or olefin monomer reactor feed can in this case refer to the total feed of the olefin monomer into the reactor.

[0037] The terms fresh olefin monomer feed and fresh olefin monomer refer to fresh, i.e. non-recycled, and fed into the reactor to provide an olefin monomer source to replenish the amount of olefin monomer consumed during the catalytic reaction in the reactor and removed from the reactor mainly as recovered or consumed dimer or trimer product. The fresh olefin monomer is fed in an amount sufficient to maintain the monomer to dimer mass ratio at a desired level. Thus, when the olefin trimer production is run as a continuous process, no fresh monomer enters the reactor prior to being fed into the reactor through a reactor feed line and the olefin trimer is removed from the process as a reaction product.

[0038] In one embodiment, the olefin monomer is mainly fed into the reactor as fresh olefin feed, i.e. the fresh olefin monomer constitutes more than 50 wt% of the total olefin monomer entering the reactor. In another embodiment, at least 55 wt%, 60 wt%, 70 wt%, 80 wt% or 90 wt% of the olefin monomer entering the reactor is fresh.

[0039] In one embodiment, the recycle feed comprises unreacted olefin monomer.

[0040] The term reactor refers to a reactor in which the catalytic reaction is carried out, such as at least one reactor unit or at least one reactor vessel. The reactor can comprise at least one catalyst bed and an opening for introducing and removing fluids into and from the reactor.

[0041] Olefins are compounds consisting of at least hydrogen and carbon and having at least one double bond between two carbon atoms. Suitable olefins for use in the present process comprise two or more carbon atoms and they can be linear or branched. The preferred olefin monomer in the present application is isobutene.

[0042] Olefin mixtures can also be used in the present process and fed to the reactor, such as mixtures of olefin monomers, olefin dimers and heavier polymers, or mixtures containing olefins having different numbers of carbon atoms and double bonds. In one embodiment, the feed comprising an olefin mixture is fed to the reactor as a mixed feed.

[0043] In the context of the present application, mixed feed or mixed monomer feed refers to a mixture of olefins having different carbon numbers, or olefin isomers having the same carbon number, and combinations thereof. In one embodiment, the mixed feed comprises C4-C5 olefins. In another embodiment, the mixed feed comprises olefins having a carbon number of C4 + / - 1. In one embodiment, the reactive components lighter than C4 olefins are removed from the feed entering the reactor to facilitate the distillation of the reaction product.

[0044] In one embodiment, the olefin monomer feed comprises at least one of the following: C4 olefins, C5 olefins, a mixed feed of C4 and C5 olefins, isobutylene, 1-butene, cis-2-butene, trans-2-butene; and optionally at least one of inert, n-butane, isobutane, butadiene, a distillation cut, or any mixture thereof.

[0045] In another embodiment, the olefin monomer feed or mixed feed comprises or consists essentially of isobutylene and at least one of the following: C4 olefins, C5 olefins, a mixed feed of C4 and C5 olefins, 1-butene, cis-2-butene, trans-2-butene, inert, n-butane, isobutane, butadiene, a distillation cut, or any mixture thereof. In a preferred embodiment, isobutylene is the major component of the mixed feed.

[0046] In one embodiment, the amount of non-reactive components such as inert, n-butane, isobutane in the reactor outlet stream exiting the reactor is so low that they do not significantly hinder the separation of the olefin dimers and olefin trimers in the distillation step.

[0047] The advantage of using a mixed feed in the present process is that the removal of the inerts present in the mixed feed is efficient and the removal of the inerts does not have a significant impact on the product yield. When a mixed feed is used in the present process, since the monomer conversion per pass is high, only very little reactive monomer remains in the reactor outlet stream exiting the reactor and thus very little monomer is lost in the inert removal step.

[0048] The reactor outlet stream taken from the reactor contains at least olefin dimers and olefin trimers, and optionally smaller amounts of olefin monomers, moderators and inerts.

[0049] One embodiment of a production unit 100 for carrying out the present process is shown in Figure 1.Figure 3 As shown in the diagram. Production unit 100 includes reactor unit 110 and distillation column 210. Olefin monomers are fed into the reactor from storage tank 410 via reactor feed line 420, which in turn feeds... Figure 3 The reactor is in fluid communication with the first recirculation feed 220 and the second recirculation feed 230. The reaction products are transferred from reactor unit 110 to distillation column 210 via reactor outlet stream 120. From distillation column 210, the first recirculation line 220 transfers the lighter product, containing at least one of olefin monomers, diluent, and regulator, back to reactor unit 110. The second recirculation line 230 transfers a stream consisting primarily of olefin dimers back to reactor unit 110. The heavier bottom product, containing olefin trimers, is directed from distillation column to bottom product reservoir 510 via bottom product line 250. Inert substances can optionally be removed via inert substance removal line 240.

[0050] exist Figure 3 In this embodiment, the recirculation feed consists of two recirculation feeds guided to reactor unit 110 via a first recirculation line 220 and a second recirculation line 230. Figure 3 In this diagram, the recirculation line is shown as fluidly connected to the reactor feed line 420 entering reactor unit 110. Alternatively, the recirculation line can be connected to reactor unit 110 via a separate opening in reactor unit 110.

[0051] Instead of the two recirculation lines 220 and 230 mentioned above, a single recirculation feed line can also be used. In this embodiment, the single recirculation line recycles the olefin dimer and olefin monomer, as well as optional regulators, back to the reactor.

[0052] In one embodiment, the olefin monomer storage 410 is configured to provide a mixed feed.

[0053] In another embodiment, the olefin monomer reservoir 410 is configured to provide fluid communication with a plurality of reactor units or reactor vessels. In the case of multiple reactor vessels provided in series, it is preferable to feed the olefin monomer into the first reactor vessel in series, and alternatively, subsequent reactor vessels may receive feed only from the reactor outlet stream from the preceding reactor vessel.

[0054] Another embodiment of production unit 100 is as follows: Figure 4 As shown, a mixed feed is preferably used. In this embodiment, the production unit 100 includes a reactor unit 110 and a distillation column 210. Fresh olefins are fed from a storage tank 410 into the reactor through a reactor feed line 420, which... Figure 4The reactor unit 110 is in fluid communication with a first recycle feed line 220, with a second recycle feed 230, and with an optional dimer feed line 430. Reaction products are transferred from the reactor unit 110 to a distillation column 210 by a reactor outlet stream line 120. From the distillation column 210, a first recycle line 220 conveys lighter products comprising at least one of olefin monomers, diluent, and moderators back into the reactor unit 110. A second recycle line 230 conveys a stream consisting primarily of olefin dimers back into the reactor unit 110. Heavier bottom products comprising olefin trimers and optionally compounds having a higher boiling point than the olefin dimers are directed from the distillation column to a bottom product reservoir 510 by a bottom product line 250. Inert materials can optionally be removed by an inert removal line 240. Figure 4 An optional heat exchanger 310 is also shown which can be used to recover heat from the outlet stream leaving the distillation column and heat the reactor outlet stream line 120 before it enters the distillation column. In Figure 4 In one embodiment, the olefin dimers are removed from the distillation column by a second recycle line 230 which is in fluid communication with a side of the distillation column to provide a side stream. Preferably the side stream is withdrawn from the distillation column as a vapor outlet stream which is condensed after recovering heat in a heat exchanger and before entering the reactor unit 110 as a recycle feed.

[0055] As shown, the bottom product line 250 can direct through an optional heat exchanger 310 to heat the reactor outlet stream line 120 before the stream enters the distillation column. Figure 4

[0056] In one embodiment, an olefin monomer feed, preferably a high purity olefin monomer feed, is fed to a reactor unit which is a single reactor vessel in embodiments of Figure 3 and Figure 4 Alternatively, a reactor unit comprising multiple reactor vessels can be used.

[0057] The reactor unit 110 contains a dimerization catalyst which catalyzes the formation of olefin dimers in a dimerization reaction between two olefin monomers and the formation of olefin trimers in an addition reaction between olefin monomers and olefin dimers. In addition, a small amount of heavier olefin oligomers can be formed. The reaction products are directed from the reactor to a distillation column 210 as a reactor outlet stream 120 which separates unreacted inert materials, olefin monomers, and olefin dimers from a heavier bottom product which contains at least olefin trimers and optionally compounds having a higher boiling point than the olefin dimers. An optional heat exchanger 310 can be used to recover heat from the bottom product containing olefin trimers and use the recovered heat to heat the reactor outlet stream before it enters the distillation column.

[0058] In​Figure 3 and Figure 4 In an embodiment of the process, the modifier can be fed to the reactor through the reactor feed line 420 along with the olefin monomer feed, along with the recycle feed directed to the reactor unit from the distillation column via recycle lines 220, 230, or directly into the reactor through a separate inlet (not shown). It is preferred to feed the modifier with the reactor feed to the reactor, such as reactor feed line 420 or recycle lines 220, 230, to ensure good mixing.

[0059] In an embodiment, fresh monomer is fed to the reactor as a high purity monomer feed. High purity olefins preferably have a purity of at least 95 wt%. The use of high purity olefins in a single column system is particularly advantageous as it results in a reaction product feed that contains only a small amount of components with overlapping boiling points with the olefin dimers or olefin trimers.

[0060] After the olefin stream passes through the reactor unit or multiple reactor units, the resulting reactor outlet stream is directed to a distillation column that separates out unreacted olefins (primarily dimers) as a lighter product from the olefin trimers that are discharged as a bottom product. It is preferred that the lighter product is substantially free of olefin monomers, which indicates a high conversion. In an embodiment, the process parameters are selected such that the single pass conversion of the olefin monomers is at least 96%, whereby the lighter product contains primarily dimers and only a small amount of olefin monomers. Since the monomers are completely or almost completely consumed in the catalytic conversion, it is easier to control the feed to the reactor since the monomers are almost completely added to the feed by the fresh olefin monomer feed and only a small amount of monomers can be present in the recycled dimer feed. If the lighter product contains dissolved gases, they can be separated from the lighter product by methods known in the art.

[0061] In an embodiment, the lighter product does not contain olefin trimers. The separation of the olefin trimers can be controlled by the distillation parameters. In the present process, the olefin trimers are enriched in the bottom product during distillation and are removed from the process. Thus, the recycle feed contains olefin dimers while at the same time olefin trimers are preferably not present in any significant amount in the recycle feed.

[0062] In an embodiment, the bottom product contains less than 15 wt% of olefin tetramers and optionally at least 80 wt% of olefin trimers, based on the total weight of the bottom product. In an embodiment, the bottom product contains less than 12 wt% of olefin tetramers and optionally at least 80 wt% of olefin trimers, based on the total weight of the bottom product. Instead of 80 wt%, the amount of olefin trimers in the bottom product can also be at least 85 wt% or at least 88 wt%.

[0063] In one embodiment, the single pass conversion of olefin monomer is at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, or at least 96%, and optionally the selectivity of olefin trimer production is at least 85% or at least 90%, expressed as a weight percentage of olefin monomer.

[0064] In the context of the present application, the term diluent refers to any inert agent, or an agent that is less reactive than the olefin in the present process. The addition of a diluent to the reactor thus reduces the concentration of the olefin in the reactor, and by selecting the appropriate amount of diluent, the rate of catalytic conversion of the olefin in the process can be controlled.

[0065] In one embodiment, the recycle feed can be withdrawn from a side of the first distillation column as a side recycle stream. In one embodiment, the recycle feed comprises olefin monomer and olefin dimer. In another embodiment, the recycle feed comprises olefin dimer. The location at which the side recycle stream is withdrawn can thus be selected so that the dimer is at least partially removed from the distillation column, while at the same time the recycle feed does not comprise significant amounts of heavier and lighter compounds.

[0066] In Figure 4 In one embodiment, the monomer-containing product and the dimer-containing lighter product can be mixed with a fresh olefin stream before entering the reactor. The amount of recycle feed and the amount of fresh olefin can be controlled so that the mass ratio of olefin monomer to olefin dimer in the feed to the reactor is maintained at a desired level. The optional dimer feed line 430 can also be used to feed dimer to the reactor, allowing for further control of the process.

[0067] The embodiments described herein are suitable for the selective production of trimer from olefin monomer, and they allow for the control of the olefin feed and the moderator so that the selectivity of the catalytic reaction promotes the formation of olefin trimer.

[0068] The moderator is used to slightly inhibit the reaction rate and ensure a prolonged catalyst life. The appropriate amount of moderator is specific to the target main product, and the skilled person can select it by analyzing the reaction products and process conditions. For the production of olefin trimer, the advantageous amount is much less than that used in the production of olefin dimer. The moderator can be recycled from the distillation column back to the reactor together with the recycle feed comprising olefin monomer.

[0069] Surprisingly, the inventors found that, in contrast to iso-octene production, no solvent alone is necessary in the present process for optimizing the production of olefin trimers. Thus, in one embodiment, the present process is carried out without additional solvent. In one embodiment, the olefin feed to the reactor comprises iso-butene and recycled olefins (mainly iso-octene) recovered after the feed has passed through the reactor. The present process is advantageous because, in a preferred embodiment, it can be carried out without the use of a diluent. Existing processes designed primarily for the production of olefin dimers require the use of a diluent, which makes the process uneconomical, especially when using high purity and high concentration feeds. Advantageously, by the high conversion of olefin monomers in the present process, the removal of inerts does not result in a significant loss of unreacted olefin monomers, which increases the efficiency of the process and improves the removal of inerts.

[0070] In addition to using a single reactor unit, the reactor unit can be scaled and distributed into separate vessels. By increasing the number of reactor vessels and reactor beds, the reaction conditions are more easily controlled and, as a result, almost complete conversion of the olefin monomers, such as iso-butene, per pass can be achieved. When using multiple reactor units, the thermal control of the adiabatic temperature rise is also more easily controlled.

[0071] In one embodiment, the reactor unit consists of multiple reaction vessels arranged as series reactors or parallel reactors or a combination thereof.

[0072] In one embodiment, the reactor comprises more than one reactor vessel, such as two, three, four or five reactor vessels, each reactor vessel having at least one reactor bed. The use of more than one reactor vessel is advantageous because it allows for more detailed control of the temperature and further allows for control of the amount of moderator and catalyst in each individual reactor vessel. Between the reactor vessels, the temperature of the feed can be controlled by temperature control units that can cool or heat the feed. In one embodiment, the reaction conditions, such as temperature and pressure, are essentially the same in each reactor vessel.

[0073] When multiple reactor vessels are used as a reactor unit instead of a single reactor vessel, each reactor vessel contains a dimerization catalyst, preferably an acidic ion exchange resin catalyst. It is preferred that the same catalyst is used in each reactor vessel. It is preferred that the amount of catalyst is kept low in the first reactor vessel and that the amount is increased in subsequent reactor vessels in the downstream direction of the process. By limiting the amount of catalyst in the first reactor vessel, for example, the temperature is more easily controlled and the reaction conditions are more easily kept within a selected range. For example, when multiple reactor vessels are used and the olefin stream is cooled between reactor vessels, it is possible to keep the olefin in the liquid phase and the mass ratio of olefin monomer to olefin dimer is more easily kept at a desired level. It is preferred that no further olefin is fed to the subsequent reactor vessels during the process, i.e., the olefin mixture being fed is not supplemented with further olefin as the mixture flows through the reactor vessels, in addition to the reactor feed entering the first reactor vessel. When multiple reactor vessels are used with a single reactor bed in each reactor vessel, the amount of catalyst in the reactor vessels can be increased. In a multiple reactor configuration, the upstream reactor vessels are charged with more catalyst than the downstream reactor vessels. In one embodiment, the multiple reactor configuration includes 3 or 4 reactor vessels.

[0074] In a reactor unit comprising multiple reactor vessels, the volume of the reactor vessels can increase in the downstream direction from the first reactor vessel to the subsequent one or more reactor vessels. In one embodiment, the first and second reactor vessels have substantially the same volume. In another embodiment, the third and fourth reactor vessels have substantially the same volume. In still another embodiment, the third and fourth reactor vessels have substantially the same volume as each other, but they have a larger volume than the first or second reactor vessels, which can have substantially the same volume.

[0075] In one embodiment, the oxygen-containing moderator or moderator is an oxygenate, such as salt water (deionized water) or t-butyl alcohol (TBA). Alternatively or additionally, the moderator comprises an alcohol generated inside the reactor as a result of a reaction between water and an olefin. Thus, for example, 2-butanol can be formed from isobutylene inside the reactor.

[0076] After the olefin stream passes through the reactor unit, the resulting reactor outlet stream is directed to a distillation column, which separates the unreacted olefins (mainly isooctene) and the moderator components as lighter products from the olefin trimers, which are discharged as a bottom product. In the lighter products, which consist mainly of olefin dimers, olefin monomers can be present as a minority. Since the monomers are almost completely consumed in the catalytic conversion, it is easier to control the feed composition in the reactor, since the monomers are only added by the fresh olefin monomer feed. If the lighter products contain dissolved gases, they can be separated from the lighter products by known methods.

[0077] The moderator can be recycled in the recirculation reactor loop together with the lighter components and replenished to keep its amount at a substantially constant level. The moderator is preferably used in an amount that exceeds the amount of water that can be present in the fresh olefin feed or the recirculation feed, which can also serve as a source of oxygenates, but which is not sufficient in the present invention. The moderator can be fed to the reactor by mixing it with the feed to the reactor, such as the reactor feed comprising fresh olefin monomers. Alternatively, the moderator can be mixed with the recirculation olefin dimer stream before mixing with the fresh olefin monomers. The use of added moderator in the present process is advantageous because it improves the selectivity of the trimer production.

[0078] At least a portion of the olefin dimers that are separated during distillation can be recycled back to the reactor. Alternatively or additionally, an external source of olefin dimers, preferably isooctene, is fed to the reactor together with the olefin monomers.

[0079] In one embodiment, the reactor outlet stream is distilled to separate the olefin dimers that are recycled back to the reactor.

[0080] In one embodiment, the unreacted components in the reactor are separated as distillates in the distillation column. The distilled components can be removed from the process or recycled back to the reactor.

[0081] In one embodiment, the present process is a continuous process. Advantageously, the present process allows the process to be run for a long period of time, even for months, without interruption of the process for maintenance. Prior art processes use batch processes on a laboratory scale, which are not suitable for industrial scale use due to instability issues. In particular, when multiple reactor vessels are used, the trimerization process is effectively controlled in the present process, and the continuous process can be run for a long time.

[0082] The term dimerization catalyst or catalyst refers to a catalyst that catalyzes the dimerization of olefin monomers to olefin dimers and the addition reaction between olefin dimers and olefin monomers to provide olefin trimers. In one embodiment of the process, the majority of the feed to the reactor comprises olefin dimers and the amount of olefin monomers is kept relatively low. Accordingly, in the present invention the conditions of the reactor are selected so that the dimerization catalyst catalyzes a reaction in which the olefin dimers formed in the reactor preferably react with olefin monomers to form olefin trimers.

[0083] In a preferred embodiment, the reactor contains a single catalyst. Preferably, the reactor does not contain two different catalysts, wherein the first catalyst is specific for the dimerization reaction between the two monomers and does not catalyze the reaction between monomers and dimers, and the second catalyst is specific for the reaction between monomers and dimers and does not catalyze the dimerization reaction between the two monomers. Accordingly, the present process has the advantage of being simpler compared to prior systems that use multiple catalysts.

[0084] In one embodiment, water is not removed from the reactor or from the lighter products obtained from the distillation column.

[0085] In one embodiment, the catalytic reaction is carried out under operating conditions in which the olefins remain in the liquid phase and optionally in which the moderator also remains in the liquid phase. Preferably, at least the temperature and pressure of the reactor are selected so that the olefins are in the liquid phase in the reactor. The advantage of at least keeping the olefins in the liquid phase is that the control of the reactor can be easier to achieve compared to processes that comprise gaseous olefins.

[0086] In one embodiment, fresh olefin monomer is fed to the reactor and the fresh olefin monomer comprises an olefin having four carbon atoms, preferably isobutene.

[0087] In one embodiment, the olefin dimers are recycled to the reactor by mixing the recycle feed with fresh olefin monomer prior to feeding the combined feed to the reactor. In one embodiment, the olefin dimers are mixed with the reactor feed prior to the combined mixture entering the reactor. Mixing the olefin dimers with the reactor feed is advantageous because it ensures efficient mixing prior to contact with the first catalyst. In addition, potential differences in the temperature of the two feeds can be dissipated.

[0088] In one embodiment, the recycle feed comprises at least 95 wt% of olefin dimers.

[0089] In one embodiment, the recycle contains less than 5 wt%, preferably less than 3 wt%, 2 wt% or 1 wt% of olefin trimer. Maintaining the amount of olefin trimer in the recycle feed to a low level further improves the selectivity of the process to olefin trimer production and prevents the formation of olefin oligomers having more than three monomer units.

[0090] In a preferred embodiment, the mass ratio of olefin monomer to olefin dimer in the reactor feed is at least about 1 :50, 1 :40, 1 :30, 1 :20, 1 :15, 1 :14, 1 :13, 1 :12, 1 :1 1, 1 :10, 1 :9, 1 :8, 1 :7, 1 :6, 1 :5, 1 :4, 1 :3 or 1 :2. In a more preferred embodiment, the mass feed ratio, expressed as the mass ratio of olefin monomer to olefin dimer in the feed entering the reactor, is selected from the range of 1 :8 to 1 :15 or 1 :8 to 1 :10. The use of an excess of olefin dimer in the amounts specified above directs the catalytic reaction towards the formation of olefin trimer without significantly reducing the conversion of monomer.

[0091] In one embodiment, the selectivity to olefin trimer production is at least about 85%, preferably about 90%, expressed as a wt% based on the olefin monomer. Depending on the process conditions, selectivity of even about 99% can be achieved. A selectivity of at least 85% means that at least 85% of the olefin monomer is used in the catalytic conversion when forming olefin dimer and olefin trimer.

[0092] In one embodiment, the single pass conversion of olefin monomer is at least 60%, at least 70%, at least 80%, at least 90%, at least 95% or at least 96%.

[0093] In one embodiment, the dimerization catalyst is an acid catalyst, preferably a strongly acidic ion exchange resin catalyst, most preferably a macroporous network acidic ion exchange resin catalyst.

[0094] In one embodiment, the catalyst is a solid.

[0095] In one embodiment, the catalyst catalyzes the dimerization reaction of two olefin monomers, as well as the addition reaction of olefin monomer and olefin dimer.

[0096] Advantageously, the present process uses a catalyst and a moderator to improve the selectivity of the trimer formation process. It was previously assumed that moderators such as t-butanol or alcohols only promote dimer formation, and the presence of water in the reactor would lead to the formation of alcohols or ethers, thereby inhibiting trimer and oligomer formation. As a result, polar compounds such as alcohols or ethers have been previously removed from the olefin feedstock prior to entering the reactor.

[0097] In one embodiment, the conditioning agent comprises water, desalted water, alcohol, t-butanol, or any combination thereof.

[0098] In one embodiment, the amount of conditioning agent is selected from the range of 0.01 wt% to 0.5 wt%, preferably 0.1 wt% to 0.4 wt%, more preferably 0.2 wt% to 0.3 wt% of the total feed to the reactor. The total feed to the reactor includes all feeds to the reactor.

[0099] In one embodiment, the temperature inside the reactor is selected from the range of 40 to 140 °C, preferably from the range of 50 to 130 °C, more preferably from the range of 60 to 120 °C.

[0100] In one preferred embodiment, the pressure inside the reactor is selected from the range of 15 to 35 bar, more preferably from the range of 20 to 30 bar.

[0101] In one preferred embodiment, the reactor is operated at 50 to 130 °C and 15 to 35 bar, 50 to 130 °C and 20 to 30 bar, 60 to 120 °C and 15 to 35 bar, or 60 to 120 °C and 20 to 30 bar. Preferably, the operating conditions of the reactor are selected such that the olefin monomer and the olefin dimer are in liquid phase in the reactor. In one embodiment, the residence time of the feed through the reactor is 0.25 to 2 1 / h, expressed as weight hourly space velocity (WHSV), preferably 0.25 to 0.4 1 / h.

[0102] Weight hourly space velocity (WHSV) is defined as the weight of fresh feed that flows through per unit weight of dry catalyst per hour.

[0103] In one embodiment, the distillation is carried out at a pressure selected from the range of 1.8 to 2 bar and a T max of 250 °C.

[0104] In one embodiment, the process further comprises recovering heat from at least one of the feeds obtained from the distillation column.

[0105] In one embodiment of the process, the recovered heat is used to heat the reactor outlet stream before it enters the distillation column. In another embodiment, the heat is used to heat the reactor feed before it enters the reactor.

[0106] In one embodiment, the distillation column is a non-reactive distillation column that does not contain catalytic material or a reaction zone, and wherein the olefins do not undergo significant chemical reactions. Thus, the non-reactive distillation column is distinguished from, for example, a reactive distillation column that has a reaction zone or catalytic zone, which reactive distillation column chemically converts feed components, in particular, olefin monomers or olefin dimers or olefin trimers.

[0107] In one embodiment, the distillation is carried out using two distillation columns in series. This embodiment can be particularly advantageous when using a feed mixture having components with boiling points that can be lower than the boiling points of the olefin dimers or containing inert materials with boiling points lower than the boiling points of the olefin dimers. Thus, the inert materials can be effectively removed by using a dual distillation column configuration and their enrichment can be avoided.

[0108] When using a dual distillation column, light inert materials are removed in the first distillation column and optionally one of the olefin monomers, diluent and moderator is separated and recycled back to the reactor, while the olefin dimers and optionally heavier compounds are removed as an intermediate bottoms product and passed to the second distillation column which separates at least one of the olefin dimers, diluent and moderator for recycle back to the reactor and the olefin trimers and optionally heavier compounds are recovered as a bottoms product. In the dual distillation column process, the olefin dimers can optionally be recovered from the recycle feed to the second distillation column.

[0109] In one embodiment, the chemical reaction is carried out in a single reactor. In this embodiment, the recycled olefin dimers are introduced into the same reactor in which the olefin monomers are dimerized by the dimerization catalyst.

[0110] The olefin trimers obtained from the distillation column contain olefin polymers formed by polymerizing three olefin monomers together. In one embodiment, the olefin monomer components forming the trimers can be chemically identical olefin monomers, such as a certain type of C4 olefin, such as isobutylene, or the trimers can contain at least one lighter or heavier olefin monomer component having a different number of carbon atoms, or olefin monomers having the same number of carbon atoms but different numbers of double bonds and / or degrees of isomerization.

[0111] In one embodiment, the reactor is not a trickle bed reactor.

[0112] In one embodiment, the catalytic reaction is carried out in a unit that is different from the unit in which the distillation is carried out. Thus, in one embodiment, the reaction is not carried out in a catalytic distillation column.

[0113] In one embodiment, the distillation column is operated in an environment in which olefin dimerization or oligomerization does not occur.

[0114] In one embodiment, the process is carried out without the addition of an additional solvent and / or without the addition of an additional inert agent. It is advantageous to the process that the dimers themselves can be used as the agent to control the rate of the chemical conversion. In addition, the moderator can be recycled to the reactor to control the rate of the catalytic conversion in the reactor.

[0115] Figure 3 and Figure 4 Embodiments of a production unit 100 suitable for carrying out the process of the first aspect are provided in

[0116] The production unit optionally comprises a heat recovery unit, a heat transfer unit and / or a heater unit.

[0117] The heater unit can be arranged in the production unit such that it heats at least one of the reactor feed line, the reactor outlet stream line before it enters the distillation column, and the distillation column reboiler.

[0118] When using multiple reactor vessels, a heat recovery unit or a cooler unit can be arranged between the reactor vessels. The heat recovered from the feed moving from one reactor vessel to the next reactor vessel can preferably be used in the heater unit of the production unit to improve the economics of the process.

[0119] In one embodiment of the production unit, the reactor comprises multiple reactor vessels, wherein each downstream reactor unit is charged with a larger amount of acid catalyst than the preceding upstream reactor vessel.

[0120] In one embodiment of the production unit, at least one heat exchange unit is further included, which is configured to recover heat from the bottom product containing the olefin trimer and use it to heat the reactor outlet stream before it enters the first distillation column.

[0121] In one embodiment, the production further comprises a first recycle line configured to recycle at least one of the olefin monomer, the diluent and the modifier through the first recycle line into the at least one reactor, and a second recycle line configured to recycle the olefin dimer into the at least one reactor unit.

[0122] Examples

[0123] The following examples are provided to better illustrate the claimed application and are not to be construed as limiting the scope of the application. To the extent that specific materials are mentioned, it is merely for purposes of illustration and is not intended to limit the scope of the application. One skilled in the art can develop equivalent means or reactants without departing from the scope of the application and the examples are not intended to limit the scope of the application. It will be understood that many changes can be made to the steps described herein without departing from the scope of the present application.

[0124] One exemplary embodiment of the process is carried out by running a process with isobutene: Recycle feed ratio = 0.12, modifier TBA content in total feed to reactor section 0.37 wt%. There are three reactors in series, with an outlet temperature of 90°C for each reactor. The catalyst is an acidic ion exchange resin (5.2 mmol acid equivalent / g).

[0125] Result: Bottom product composition: 0.0% dimer, 89.2% trimer, 10.8% tetramer based on the total weight of the bottom product. The results are shown in Table 1. Figure 1

[0126] In a comparative example under similar experimental conditions as described above, the reaction section is run in a once-through mode with the same isobutene feed and isobutane solvent (50 wt%) and similar modifier TBA content.

[0127] Result: Bottom product composition: 68% dimer, 23% trimer, 9% tetramer based on the total weight of the bottom product. The analytical results are shown in Table 2. Figure 2

[0128] While the dimer content in a once-through operation can be further minimized by reducing the dosage of the modifier TBA in the feed, the amount of tetramer will increase at the same time, and eventually even higher oligomers will occur. Therefore, the significant trimer selectivity requires a process configuration with the properties described in the present disclosure, and an appropriate dosage of the modifier.

[0129] The foregoing has outlined some of the more pertinent examples of the application. This implementation is for the purpose of illustrating select aspects of the application. Some implementations can be presented herein only in connection with a certain aspect of the application. It should be understood that such implementations might be applied to other aspects of the application, as well. Therefore, any combination of the aspects and implementations might be made and still be within the scope of the application. Any combination of aspects or implementations disclosed herein can be made without employing at least one non-essential feature of one aspect, implementation or embodiment disclosed herein.​​

Claims

1. A process for producing olefin trimers comprising: feeding to a reactor containing a dimerization catalyst an olefin monomer feed and at least one oxygen containing modifier; the olefin monomer feed comprising at least one of: C4 olefins, C5 olefins, a mixed feed of C4 olefins and C5 olefins, isobutylene, 1-butene, cis-2-butene, trans-2-butene, the oxygen containing modifier comprising water, an alcohol, or any combination thereof; operating the reactor at a temperature selected from the range of 40-140 °C and a pressure selected from the range of 10-40 bar to carry out catalytic dimerization reactions between olefin monomers and addition reactions between olefin monomers and olefin dimers; withdrawing a reactor outlet stream from the reactor; and subjecting the reactor outlet stream to distillation to separate at least one light product comprising olefin dimers and a heavy bottom product comprising olefin trimers; wherein recycling at least a portion of the light product to the reactor to provide a recycle feed, feeding olefin monomers to the reactor primarily as a fresh olefin monomer feed, controlling the amounts of fresh olefin monomer feed and recycle feed fed to the reactor such that the mass ratio of olefin monomers to olefin dimers entering the reactor is selected from the range of 1 :8-1 : 15, and wherein the catalytic reactions are carried out under operating conditions in which the olefins remain in the liquid phase.

2. The process of claim 1, wherein a fresh olefin monomer feed is fed to the reactor and the fresh olefin monomer comprises an olefin having four carbon atoms.

3. The process of claim 1, wherein a fresh olefin monomer feed is fed to the reactor and the fresh olefin monomer comprises isobutylene.

4. The process of claim 1, wherein the olefin monomer feed comprises at least one of: an inert, n-butane, isobutane, butadiene, a distillation fraction, or any mixture thereof.

5. The process of claim 1, wherein olefin dimers are recycled to the reactor by mixing the recycle feed with a fresh olefin monomer feed prior to feeding the combined feed to the reactor.

6. The process of claim 1, wherein the mass ratio of olefin monomers to olefin dimers is selected from the range of 1 :8-1 :

10.

7. The process of claim 1, wherein the selectivity for olefin trimer production is at least 85% based on olefin monomers expressed as wt%.

8. The process of claim 1, wherein the selectivity for olefin trimer production is at least 90% based on olefin monomers expressed as wt%.

9. The process of claim 1, wherein the single pass conversion of olefin monomers is at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, or at least 96%.

10. The process of claim 1, wherein the dimerization catalyst is an acid catalyst.

11. The process of claim 1, wherein the dimerization catalyst is a strongly acidic ion exchange resin catalyst.

12. The process of claim 1, wherein the dimerization catalyst is a macroporous network acidic ion exchange resin catalyst.

13. The process of claim 1, wherein the water is desalinated water.

14. The process of claim 1, wherein the alcohol is t-butanol.

15. The process of claim 1, wherein the amount of the modifier is selected from the range of 0.01 wt% to 0.5 wt% of the total feed to the reactor.

16. The process of claim 1, wherein the amount of the modifier is selected from the range of 0.1 wt% to 0.4 wt% of the total feed to the reactor.

17. The process of claim 1, wherein the amount of the modifier is selected from the range of 0.2 wt% to 0.3 wt% of the total feed to the reactor.

18. The process of claim 1, wherein the operating temperature of the reactor is selected from the range of 50-130 °C.

19. The process of claim 1, wherein the operating temperature of the reactor is selected from the range of 60-120 °C.

20. The process of claim 1, wherein the operating pressure of the reactor is selected from the range of 15-35 bar.

21. The process of claim 1, wherein the operating pressure of the reactor is selected from the range of 20-30 bar.

22. The process of claim 1, wherein the residence time of the feed through the reactor is 0.25-2 1 / h, expressed as weight hourly space velocity, WHSV.

23. The process of claim 1, wherein the residence time of the feed through the reactor is 0.25-0.4 1 / h, expressed as weight hourly space velocity, WHSV.

24. The process of claim 1, wherein the distillation is carried out at a pressure selected from the range of 1.8-2 bar and a T of 250°C. max 250°C.

25. The process of claim 1, wherein the recycle feed comprises at least 95 wt% of the olefin dimer.

26. A production unit configured to carry out the process of any one of claims 1-25, comprising: a. at least one reactor unit configured to receive an acid catalyst; b. at least one distillation column configured to separate isooctene from isododecene; c. at least one reactor feed line in fluid communication with the reactor unit and a reservoir of olefin monomer; d. at least one reactor outlet stream line in fluid communication with the reactor unit and the distillation column; e. at least one recycle line in fluid communication with the distillation column and the reactor unit; and f. a bottoms product line in fluid communication with the distillation column and a bottoms product reservoir; and wherein the production unit further comprises a first recycle line configured to recycle at least one of an olefin monomer, a diluent, and a modifier to at least one of the reactor units via the first recycle line, and a second recycle line configured to recycle an olefin dimer to at least one of the reactor units.

27. The production unit of claim 26, wherein the reactor unit comprises a plurality of reactor vessels, and wherein each downstream reactor vessel is charged with a greater amount of acid catalyst than a previous upstream reactor vessel.

28. The production unit of claim 27, further comprising at least one heat exchange unit configured to recover heat from at least one line from the distillation column.

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