Production of heavy isoparaffin hydrocarbons

Abstract

Methods and systems for the production of heavy isoparaffin hydrocarbons include supplying hydrogen and a mixed isoolefin stream including C8-C12 olefins, isoolefins, and oligomers, and C8-C12 + hydrogenated hydrocarbons to a trickle bed reactor system. The hydrogen and the mixed isoolefin are reacted over a hydrogenation catalyst, producing a liquid effluent comprising hydrogenated hydrocarbons and unreacted olefins and oligomers, and a vapor effluent comprising hydrogenated hydrocarbons, hydrogen and unreacted olefins and oligomers. The liquid effluent is fed to a first heat exchanger, producing a cooled liquid effluent stream which, in combination with the vapor effluent, produces a mixed phase effluent. The mixed phase effluent is cooled in a second heat exchanger, producing a partially condensed effluent, which is fed to a drum, producing a discharge stream, a hydrogenation product stream having greater than 95 wt% C8-C12 saturated hydrocarbons, and a hydrogenation recycle stream. The hydrogenation product stream may be provided to a downstream mixing system.

Description

Technical Field

[0001] Embodiments disclosed herein generally relate to methods for hydrogenation of olefin streams.Some embodiments herein relate to methods and apparatus for hydrogenation of isoolefins, such as isooctene or diisopentene, at high conversion. Background Art

[0002] To meet fuel blending requirements, such as octane rating or vapor pressure requirements, smaller molecules can be upgraded to produce longer chain hydrogenated molecules.

[0003] A commonly used method for upgrading smaller olefin molecules (e.g., C2 to C5 olefins) is dimerization, trimerization, or oligomerization. Isobutylene and isopentene are of great commercial importance in many applications. For example, isobutylene is one of the comonomers in butyl rubber. Isobutylene can also be dimerized to generate compounds that can be used as chemical feedstocks for further reactions or in gasoline blending.

[0004] Dimerization involves contacting olefins with a catalyst to produce longer chain molecules. Oligomers can be composed of two or more olefins to form hydrocarbon molecules. For example, dimerization is a type of oligomerization limited to the combination of only two olefin molecules. If the olefin feed contains only one olefin type, a dimer product is formed. If the olefin feed contains two or more different olefins or olefin isomers, a co-dimer product can also be formed.

[0005] Specifically, C4 olefin dimerization is widely used to produce isooctene, an intermediate that can be hydrogenated to produce isooctane, a high-value gasoline blending additive. Similarly, isopentene can be dimerized to produce diisopentene. In either process, a small amount of trimer may also be formed due to secondary trimerization reactions, thereby producing a C12+ olefin product stream.

[0006] In some cases it is desirable to hydrogenate the dimerization product to produce a hydrogenated C8-C12+ stream for product blending.

[0007] Prior art hydrogenation processes are only suitable for the specific feedstocks for which they are designed. The catalysts and operating conditions for a given hydrogenation process are typically tailored for a specific, limited feedstock, and there are significant differences between feedstocks, which means that processes used for the hydrogenation of heavy naphthas cannot be easily used to convert light naphthas.

[0008] Hydrogenation processes developed for pure feed components are generally not applicable to treating fractions containing mixtures of various isomers and long olefin hydrocarbons. This is partly due to the different reactivities of the different hydrocarbons, including differences in the exotherms for C8, C10 and C12. This effectively means that under reaction conditions suitable for complete hydrogenation of C8 olefins, a significant amount of the heavier olefin compounds will remain unsaturated.

[0009] Therefore, most production facilities are designed to separate the oligomerization product into a variety of hydrocarbon streams to be used as light and heavy fuels and solvents and raw materials for petrochemical processes. These streams are then hydrogenated individually using a variety of different hydrogenation units tailored for each specific feed. Using a single unit designed for flexible hydrogenation of different feeds results in poor conversion, catalyst, energy and raw material consumption, poor product quality, etc.

[0010] Therefore, there is a continuing need for improved isoolefin hydrogenation systems and methods. Summary of the invention

[0011] One or more embodiments disclosed herein relate to a method for the hydrogenation of isoolefins. The method may include supplying hydrogenated hydrocarbons and mixed isoolefin streams (including C4 to C12+ isoolefins, such as C4 to C8 or C8 to C12 olefins and oligomers (dimers, trimers, tetramers), and / or C5 to C15+ isoolefins, such as C5 to C10 or C10 to C15 olefins and oligomers) to a trickle bed reactor system comprising one or more beds of a hydrogenation catalyst, and supplying a hydrogen feed stream to the trickle bed reactor system. In certain embodiments, the method may include supplying C8-C12 isoolefins, C8-C12 diisoolefins and C8-C12 hydrogenated hydrocarbons to a trickle bed reactor system comprising one or more beds of a hydrogenation catalyst, and supplying a hydrogen feed stream to the trickle bed reactor system. In other embodiments, the method may include supplying C10-C15 isoolefins, C10-C15 diisoolefins, and C10-C15 hydrogenated hydrocarbons to a trickle bed reactor system comprising one or more beds of a hydrogenation catalyst, and supplying a hydrogen feed stream to the trickle bed reactor system. The hydrogen feed stream and the mixed isoolefin stream are reacted in the presence of one or more beds of a hydrogenation catalyst to produce a liquid effluent comprising hydrogenated hydrocarbons and unreacted olefins and a vapor effluent comprising hydrogenated hydrocarbons, hydrogen, and unreacted olefins. The liquid effluent is supplied to a first heat exchanger, the liquid effluent is cooled, and a cooled liquid effluent stream is produced, which is combined with the vapor effluent to produce a mixed phase effluent. The mixed phase effluent is fed to a second heat exchanger, the mixed phase effluent is cooled, and a partially condensed effluent is produced, which is fed to a drum, producing a vent stream, a hydrogenated product stream containing greater than 95 wt% saturated hydrocarbons (such as C8-C15, C8-C12 or C10-C15 hydrocarbons), and a hydrogenation recycle stream. The method further includes recovering the hydrogenated product stream and sending the hydrogenated product stream to one or more downstream mixing systems.

[0012] According to one or more embodiments disclosed herein is a system for hydrogenation of isoolefins. The system includes a trickle bed reactor system comprising one or more beds of a hydrogenation catalyst. The trickle bed reactor system is configured to simultaneously: receive a mixed isoolefin stream comprising C8-C15 isoolefins as described above, such as C8-C12+ olefin dimers, trimers and tetramers as described above and C8-C15 hydrogenated hydrocarbons; receive a hydrogen feed stream; react the hydrogen feed stream and the mixed isoolefin stream in the presence of one or more beds of a hydrogenation catalyst; and, produce a liquid effluent comprising hydrogenated hydrocarbons and unreacted olefins and a vapor effluent comprising hydrogenated hydrocarbons, hydrogen and unreacted olefins. The system further includes a first feed line for conveying the liquid effluent to a first heat exchanger configured to cool the liquid effluent to produce a cooled liquid effluent stream. The system further includes a second feed line for conveying a vapor effluent and combining the vapor effluent with a cooled liquid effluent to produce a mixed phase effluent. A second heat exchanger is provided, the second heat exchanger being configured to receive the mixed phase effluent and cool the mixed phase effluent to produce a partially condensed effluent. The third feed line is also configured to convey the partially condensed effluent to the drum. The drum includes: a top exhaust port configured to produce an exhaust stream comprising hydrogen; a hydrogenated product output line configured to produce a hydrogenated product stream comprising greater than 95 wt% C8-C12+ hydrogenated hydrocarbons; and a hydrogenated circulating stream outlet configured to produce a hydrogenated circulating stream. The flow conduit is also configured to deliver the hydrogenated product stream to one or more downstream mixing systems.

[0013] According to one or more embodiments disclosed herein, it is a method for the hydrogenation of isoolefins. The method may include supplying a mixed isoolefin stream (including C8-C15 isoolefins as described above, such as C8-C12+ olefin dimers, trimers and tetramers and C8-C15 hydrogenated hydrocarbons as described above) to a trickle bed reactor system comprising one or more beds of a hydrogenation catalyst. A hydrogen feed stream is also supplied to a trickle bed reactor system. The method also includes reacting a hydrogen feed stream and a mixed isoolefin stream in the presence of one or more beds of a hydrogenation catalyst, producing a liquid effluent comprising hydrogenated hydrocarbons and unreacted olefins and a vapor effluent comprising hydrogenated hydrocarbons, hydrogen and unreacted olefins. The liquid effluent is supplied to a first heat exchanger, cools the liquid effluent, and produces a cooled liquid effluent stream, which is combined with a vapor effluent stream to produce a mixed phase effluent. The mixed phase effluent is fed to a second heat exchanger, the mixed phase effluent is cooled, and a partially condensed effluent is produced, which is fed to a drum, producing a discharge stream, a hydrogenated product stream containing more than 95wt% C8-C12+ saturated hydrocarbons, and a hydrogenated circulating stream. The method further includes recovering the hydrogenated product stream and sending the hydrogenated product stream to one or more downstream mixing systems. The hydrogenated circulating stream is pressurized in a pump to produce a pressurized circulating stream, which is fed to a first heat exchanger. In the first heat exchanger, the pressurized circulating stream and the cooled liquid effluent are heated to produce an intermediate circulating stream. The method also includes heating the intermediate recycle stream in a third heat exchanger to produce a heated recycle stream, combining the heated recycle stream with a fresh isoolefin stream comprising C8-C12 isoolefins and C8-C12 di-isoolefins, and producing a mixed isoolefin stream, wherein the heated recycle stream and the fresh isoolefin stream can be supplied to the trickle bed reactor in a volume ratio of 3:1 to 10:1.

[0014] Other aspects and advantages will be apparent from the following description and appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a simplified process flow diagram of a system for hydrogenation of an isoolefin mixture according to embodiments herein.

[0016] Figure 2 is a simplified process flow diagram of a system for hydrogenation of an isoolefin mixture according to embodiments herein.

[0017] Figure 3 is a simplified process flow diagram of a system for hydrogenation of an isoolefin mixture according to embodiments herein. DETAILED DESCRIPTION

[0018] For the purpose of this description, a single reference numeral will be assigned to a pipeline and a stream carried in the pipeline. The same reference numerals represent similar components. Those skilled in the art will readily appreciate that, although the present disclosure is described with reference to one or more specific combinations of features and measures, many of these features and measures are functionally independent of other features and measures, such that they can be independently applied in other embodiments or combinations equally or similarly.

[0019] Embodiments herein generally relate to the hydrogenation of isoolefins.In certain embodiments, the method and system generally relate to the full hydrogenation of mixed diisoolefin streams.This hydrogenation process may need to control the exothermic reaction caused by the olefin type contained in the feed mixture.The exothermic reaction of C8, C10, C12+ olefins may be very different.In view of the above, known methods will need to separate heavy olefins and hydrogenate each type of olefins respectively subsequently to control the temperature to avoid undesirable side reactions or product degradation.

[0020] Reactors useful in the embodiments disclosed herein may include conventional fixed bed reactors, boiling point reactors, trickle bed reactors, and pulse flow reactors, wherein reactant flow and product flow may be co-current or countercurrent. Boiling point and pulse flow reactors, in addition to capturing at least a portion of the heat of reaction by evaporation, may also provide continuous washing of the catalyst, thereby allowing improved reactor temperature profiles compared to conventional fixed bed reactors. Reactors useful in the embodiments disclosed herein may be used as stand-alone reactors, or may be used in combination with one or more reactors of the same or different types.

[0021] Any type of reactor may be used to carry out the reaction described herein. Examples of reactors suitable for carrying out the reaction related to the hydrogenation of the isoolefin mixture according to the embodiments herein may include a tubular fixed bed reactor, a bubbling bed reactor, a slurry reactor, a pulse flow reactor, a downflow reactor, a trickle bed reactor or any combination of these reactors. Multiple reactor systems that can be used for the embodiments disclosed herein may include a series of multiple reactors or multiple reactors in parallel for the first reaction zone. Those of ordinary skill in the art will recognize that other types of reactors may also be used.

[0022] Reactors that can be used for the embodiments disclosed herein can include any physical device or a combination of two or more devices, including reactors and reactor systems as described above. The reactor can have various internal devices for mixing vapor and liquid components. The reaction zone in the reactor can include a "wettable" structure and / or filler. Wettable structures and fillers that can be used in the embodiments disclosed herein can include various fillers, which can be catalytic or non-catalytic. Suitable wettable structures and fillers can include, for example, random or stacked fillers, which are: catalytically inert stacked fillers containing higher void fractions and maintaining relatively large surface areas, such as Bell saddles (ceramics), Raschig rings (ceramics), Raschig rings (steel), Ball rings (metals), Ball rings (plastics, such as polypropylene), etc. Monoliths are structures containing multiple independent vertical channels and can be made of various materials such as plastics, ceramics or metals, wherein the channels are usually square, which are also suitable wettable structures. Other geometric shapes can also be used.

[0023] Other materials that promote liquid distribution may also be used, including demisters, mist eliminators, or other wire or multifilament type structures. Such multifilament structures may include one or more of fiberglass, steel, Teflon, polypropylene, polyethylene, polyvinylidene fluoride (PVDF), polyester, or other various materials, which may be knitted (or co-knitted, where more than one type of wire or wire structure is used), woven, non-woven, or any other type of multifilament structure. Preferred structures include multifilament wires commonly used in demister service, structures including elements of woven fiberglass cloth, and high surface area stainless steel structured packing.

[0024] Reactors according to embodiments disclosed herein may include one or more reaction zones and one or more beds of catalytic material.

[0025] According to one or more embodiments herein, the hydrocarbon feed to the reactor can include mixed olefin streams, such as the feed stream containing the dimer of isobutylene or isopentene, the co-dimer of isobutylene and isopentene or its mixture.One of the main products from the method according to the embodiment herein can include the hydrogenated product of the mixed diisoolefin stream from the dimerization process.For example, isobutylene can form C8 tertiary olefins through dimerization and subsequently form C8 paraffins through hydrogenation.In certain embodiments, dimer has 8 to 15+ carbon atoms, such as 8 to 12 or 10 to 15 carbon atoms, and corresponds to the dimer prepared by dimerization or oligomerization of C4, C5 or heavier olefins.

[0026] Hydrogenation is a method comprising the steps of: hydrocarbon stream is supplied to hydrogenation unit, the hydrocarbon stream is contacted with hydrogen in the presence of a catalyst so that the olefinic compounds contained therein are hydrogenated to produce saturated products or paraffins, and the saturated products from the hydrogenation unit are recovered. In general, the target may be to saturate all double bonds present, which is called complete hydrogenation. However, those of ordinary skill can recognize that the sufficient conversion of olefinic compounds in the hydrocarbon stream can be between 80% and 99.9%. The conversion may depend on process conditions (temperature, pressure, space velocity), hydrogen flow, catalyst type, catalyst life etc.

[0027] Total conversion also may depend on the selection of hydrogenation process.Under the present invention, when this method was carried out by downflow trickle bed reactor, the conversion in one or more catalyst zones can be 80% to 95%, and wherein at least part of olefinic compounds is hydrogenated.Remaining olefinic compounds is further hydrogenated in lower catalyst bed, or as a part for circulation, or both have, causing required total conversion, such as from 95% to 99.9%.

[0028] In existing olefin hydrogenation processes, the mixed olefin stream must be separated into discrete hydrocarbon stream fractions, such as C8 stream, C10 stream and C12 stream, for example, and each fraction recovered is hydrogenated separately. This is usually necessary to control the exothermic reaction, avoid catalyst degradation and produce consistent high-quality products. The inventors have found that by appropriate conditions and the appropriate use of heat exchangers and circulation, the need for upstream separation systems can be eliminated while still achieving high conversion.

[0029] The operating conditions within the trickle bed reactor system for hydrogenation of mixed diisoolefins may include temperatures and pressures sufficient to fully hydrogenate the C8-C12 diisoolefins, C8-C15 diisoolefins, or C10-C15 diisoolefins. Thus, the temperature within the reaction zone may be closely related to the pressure, the combination of which provides boiling of the diisoolefins, thereby maintaining contact between the non-hydrogenated components and the catalyst bed or beds.

[0030] Typical conditions for the hydrogenation reaction include a catalyst bed temperature of about 50°C to 300°C, a hydrogen partial pressure of about 5 barg to 75 barg in some embodiments, 20 barg to 40 barg in other embodiments, or 28 barg to 35 barg in other embodiments, and an equivalent liquid hourly space velocity of about 1.0 hour hr to 2.0 hour hr. -1. The temperature within the column is determined by the inlet temperature of the liquid feed. By using a hydrogenation recycle stream, the temperature of the liquid feed can be controlled between 30°C and 100°C; for example, embodiments herein may include heating an intermediate recycle stream in a third heat exchanger to a temperature sufficient to heat the mixed isoolefin stream to a temperature in the range of 30°C to 100°C. Under standard operating conditions, the temperature in the column may experience an exotherm of 50°C to 100°C throughout the reactor and may be further controlled by high recycle flow rates to avoid a gradual increase in temperature. Even if a trickle bed reactor is used, some isoolefins may still remain unconverted and leave the column with the bottoms product.

[0031] Hydrogenated product is removed from the trickle bed reactor together with a small amount of unconverted olefin as bottoms product. The middle distillate vapor stream of hydrogenated product and unconverted olefin can be taken out below the bottom of one or more catalyst beds. The middle distillate vapor stream can also be included in the hydrogen and light hydrocarbons evaporated during the hydrogenation reaction. This middle distillate can be used for controlling the exothermic reaction, thereby producing stable hydrogenation reaction product by mixed olefinic feedstock.

[0032] Many hydrogenation catalysts are known in the art. The catalyst may be provided on an oxide support. The shape of the catalyst may vary and may be spherical or extruded cylinder or leaf-shaped. Known hydrogenation catalysts typically comprise a metal selected from platinum, palladium, iron and nickel.

[0033] For the hydrogenation reaction in one or more catalyst zones, the hydrogen provided in excess is generally 1.05 to 10 times the stoichiometric amount required for complete hydrogenation of olefins in the feed stream; in other embodiments, 1.5 to 10 times the stoichiometric amount required. The hydrogen feed may include fresh hydrogen and recycled hydrogen. Fresh hydrogen may be supplied by a dedicated hydrogen generation unit. Circulated hydrogen may be obtained from many known hydrogen circulation systems. In addition, depending on the configuration, desired conversion, and diluent flow rate, hydrogen may be supplied to the hydrogenation reaction system at multiple different locations.

[0034] Reference now Figure 1 , shows a simplified process flow diagram of a system for hydrogenation of an isoolefin mixture according to a disclosed embodiment. Although primarily described for C4 oligomers, the system can operate similarly for C5 oligomers or a mixture of C4 and C5 oligomers.

[0035] Olefin feed, such as the dimerization product stream comprising C8-C12+ diisoolefins, can be supplied to reactor 100 via flow line 12. In one or more embodiments, olefin feed can include 80wt%-90wt%C8 olefins, 10wt%-15wt%C12 olefins, 0.1wt%-5wt%C16+ olefins, and trace ethers depending on upstream processing. Reactor 100 can be a downflow liquid phase catalytic reaction system comprising one or more hydrogenation catalyst beds, such as a trickle bed reactor. Olefin feed 12 can be combined with heated hydrogenation circulating stream 34 to form a mixed feed stream 14, and is supplied to the inlet at the top of reactor 100.

[0036] Fresh or recycled hydrogen can be supplied to the reactor 100 via flow line 10. Hydrogen gas stream 10 can be split into a first hydrogen feed 10A upstream of the reactor 100, which can be supplied to an inlet near the top of the reactor 100. In one or more embodiments in which two catalyst zones are located in the reactor 100, a second hydrogen feed 10B can be supplied to the reactor 100 at an inlet in the middle of the catalyst zone to provide additional hydrogen in the lower catalyst bed, thereby making up for the hydrogen consumed by the hydrogenation process in the upper catalyst bed. Although generally described herein as two catalyst beds, any number of catalyst beds can be used according to feedstock and desired conversion. In one or more embodiments, 1 to 10 catalyst beds can be used. In one or more embodiments, if desired, additional hydrogen can also be supplied to an inlet below the catalyst bed to achieve complete or substantially complete conversion of olefins.

[0037] In reactor 100, diolefins are reacted in the presence of hydrogen and a hydrogenation catalyst contained in the reaction zone to convert at least a portion of the diolefins to paraffins. The components flowing downward through the reaction zone of the liquid phase trickle bed reactor may then exit the reaction zone into a decanting section of the reactor or into a separate decanter, thereby allowing unreacted hydrogen and any vaporized hydrocarbons or byproducts to be decanted and recovered as vapor effluent 20, and the remaining liquid products to be recovered as liquid effluent 16.

[0038] Liquid effluent 16 can be taken from the bottom of reactor 100. The liquid effluent can be a substantially hydrogenated product, such as a hydrogenated product greater than 80 wt% in some embodiments, and a hydrogenated product of 95 wt%+ in other embodiments, with some residual olefinic hydrocarbons. Liquid effluent 16 can be supplied to a first heat exchanger 102, where the temperature is reduced to 40°C to 120°C. The cooled liquid effluent 18 can be combined with a vapor effluent 20 from reactor 100, such as in a mixed tee downstream of the first heat exchanger 102. The vapor effluent 20 can be discharged from a side draw in the reactor 100 located below one or more catalyst beds / upper end of the decanting zone. The combined vapor / liquid effluent 19 can be supplied to a second heat exchanger 104, where the combined vapor / liquid effluent is further cooled to 30°C to 80°C, condensing and / or absorbing hydrocarbons contained in the vapor effluent.

[0039] The partially condensed stream 22 may then be fed to the drum 108. The drum 108 may be operated at a temperature and pressure suitable for separating the remaining vapor component into a gaseous portion and a liquid portion. In one or more embodiments, the drum may be operated at a temperature of 30° C. to 80° C. and a pressure of 10 bar gauge to 40 bar gauge.

[0040] Drum 108 may produce a gaseous component stream via effluent stream 24, which may consist primarily of hydrogen, a hydrogenation product stream 26, and a hydrocarbon recycle stream 28. The hydrogen in effluent stream 24 may optionally be returned to hydrogen feed 10 as part of the recycled hydrogen.

[0041] Hydrogenated product stream 26 can be a substantially hydrogenated product of C8-C12+ paraffins. In one or more embodiments, the hydrogenated product can be 95wt% paraffins or more, such as at least 98wt%, 99wt%, 99.5wt%, 99.8wt% or 99.9wt% paraffins. In one or more embodiments, the olefins in product stream 26 can be limited to 5wt% olefins or less. In one or more embodiments, the olefins in product stream 26 can be limited to at most 2wt%, 1wt%, 0.5wt%, 0.2wt% or 0.1wt%. For example, such a product stream can be suitable for direct mixing in a gasoline pool.

[0042] The hydrocarbon recycle stream 28 may have a composition similar to the product stream 26, and therefore in one or more embodiments, may also be removed as an additional product with the product stream 26. However, in one or more embodiments, the hydrocarbon recycle stream 28 may be used as a feed diluent to help control the exothermic reaction in the reactor 100, thereby allowing the mixed olefinic feed to be hydrogenated without upstream separation. This may be achieved by pressurizing the hydrocarbon recycle stream 28 in the pump 110. The pump 110 may increase the pressure of the stream to 15 bar gauge to 45 bar gauge, producing a pressurized recycle stream 30. The pressurized recycle stream may be supplied to the first heat exchanger 102 (recycle / effluent exchanger), wherein the temperature of the pressurized recycle stream 30 is increased to about 40°C to 100°C, producing an intermediate recycle stream 32. The intermediate recycle stream 32 may be further heated in the third heat exchanger 106 to produce a heated recycle stream 34, which may be combined with the olefinic hydrocarbon feed 12 such as in a mixing tee, and supplied to the reactor 100.

[0043] Combining the heated recycle stream 34 with the olefin feed 12 can be done for several reasons. The heated recycle stream 34, which is primarily hydrogenated hydrocarbons, can be used as a reaction diluent in the reactor 100. In one or more embodiments, the volume ratio of the recycle to fresh feed can be 3:1 to 10:1, or 4:1 to 8:1, such as about 5:1. Relatively large amounts of hydrogenated, recycled hydrocarbons can help control the exothermic reaction within the reactor 100, controlling vaporization and temperature rise within the reactor, thereby preventing the olefins from undergoing additional oligomerization reactions to produce larger hydrocarbons.

[0044] Additionally, by using the first heat exchanger 102 and the third heat exchanger 106, the temperature of the recycle stream can be raised to a point where, by mixing directly with the olefin feed 12, the temperature of the mixed feed stream 14 can be 10°C to 20°C higher than the temperature of the olefin feed 12. This can ensure that the olefin feed is hot enough to initiate hydrogenation while not being hot enough to cause a runaway reaction within the reactor 100. For example, the first heat exchanger 102 and the third heat exchanger 106 can be configured to heat the hydrogenation recycle stream to a sufficiently high temperature such that, after mixing with the olefin feed 12, the mixed hydrocarbon feed 14, in one or more embodiments, is at a feed temperature of 30°C to 100°C, or in other embodiments, at a feed temperature of 45°C to 80°C.

[0045] As described above, the exothermic reaction may result in a temperature increase of, for example, 60° C. to 70° C. In yet another embodiment, the liquid effluent 16 may be at a sufficiently high temperature to heat the pressurized recycle stream 30 to the necessary temperature to ensure that the mixed hydrocarbon feed 14 is at the desired feed temperature. In such an embodiment, the third heat exchanger 106 may be configured with a bypass to avoid overheating of the feed stream. Thus, the third heat exchanger 106 may be used primarily during startup operations when additional heating is required, or during operating conditions that require less or greater amounts of diluent hydrocarbons.

[0046] In one or more embodiments, a first portion of the intermediate recycle stream 32 may bypass the third heat exchanger 106 while a second portion of the intermediate recycle stream 32 passes through the third heat exchanger 106. In this way, the final temperature of the mixed hydrocarbon feed 14 may be controlled. In one or more embodiments, the third heat exchanger 106 may be used only during startup. In such embodiments, during "normal" operation, the entire intermediate recycle stream 32 may bypass the third heat exchanger 106.

[0047] The overall composition of the mixed olefin stream 12 may vary, for example, based on upstream processing (such as in an oligomerization reactor). Due to changes in the oligomerization reactor over time, such as increasing the reactor temperature due to catalyst deactivation, coking / polymer accumulation or poisoning, or changes in the starting olefin mixture supplied to the oligomerization reaction, the composition of the C8+ olefin stream 12 supplied to the hydrogenation reactor 100 may vary. As a result, the exotherm generated by the hydrogenation in the reactor 100 may vary. By appropriately controlling the circulation to feed volume ratio, the temperature of the mixed feed stream 14 (via one or more of the exchangers 102, 104, 106), the hydrogen partial pressure, and the above-mentioned other factors, the exotherm in the reactor 100 can be appropriately controlled. Feedforward control based on component analysis of stream 12, feedback control based on the temperature of stream 16, and other control schemes or combinations of control schemes can be used.

[0048] Reference now Figure 2 , the reactor 100 can be supplemented with a small adjustment reactor 101, as shown, to provide additional isoolefin conversion, or to ensure complete or near complete conversion. This adjustment reactor 101 can be another trickle bed reactor, a fixed bed reactor, or other reactor types that a person of ordinary skill in the art can select. The hydrogenation product stream 16 can be supplied to the adjustment reactor 101 before the first heat exchanger 102. The additional hydrogenation reaction in the adjustment reactor 101 can also further increase the temperature of the effluent stream 17.

[0049] In one or more embodiments, when an additional trim reactor 101 is used between the reactor 100 and the first heat exchanger 102, the additional heat generated by the hydrogenation reaction can increase the temperature of the effluent stream 17. Therefore, this heat will increase the temperature of the intermediate recycle stream 32 from the first heat exchanger 102. In such embodiments, more of the recycle stream can bypass the third heat exchanger 106, or the third heat exchanger 106 can be completely offline. Completely bypassing or nearly completely bypassing the third heat exchanger 106 can ensure that the feed temperature of the mixed iso-olefin stream 14 does not exceed the desired temperature.

[0050] Reference now Figure 3 , liquid effluent 16 can be drawn from the bottom of reactor 100 and pressurized using pump 111. The liquid effluent can be a substantially hydrogenated product, such as a hydrogenated product greater than 80 wt% in some embodiments, and 95 wt%+ hydrogenated product in other embodiments, with some residual olefinic hydrocarbons. The liquid effluent 16 can be fed to heat exchangers 105 and 107 operating in parallel. Heat exchanger 107 can be used to heat liquid effluent 16, while heat exchanger 105 can be used to cool liquid effluent 16. By using heat exchangers 105 and 107, the temperature of product stream 31 and heated circulating stream 34 can be controlled so that the catalyst in reactor 100 can be efficiently operated.

[0051] Thus, a system is disclosed herein that can flexibly produce hydrogenated products without having to separate mixed olefin streams upstream of multiple hydrogenation units. This can be achieved by taking a liquid product from the bottom of the reactor, taking a gaseous effluent from the middle of the reactor, and preheating the olefin feed by mixing it directly with a relatively large amount of recycled hydrogenated products.

[0052] Unless defined otherwise, all technical and scientific terms used have the same meaning as commonly understood by one of ordinary skill in the art to which these systems, apparatuses, methods, processes, and compositions belong.

[0053] The singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.

[0054] As used herein and in the appended claims, the words "comprising," "having," and "including" and all grammatical variations thereof are each intended to have an open, non-limiting meaning that does not exclude additional elements or steps.

[0055] "Optionally" means that the subsequently described event or circumstance may or may not occur. The description includes instances where the event or circumstance occurs and instances where the event or circumstance does not occur.

[0056] When the word "about" or "approximately" is used, the term may mean that the value may vary by up to ±10%, up to 5%, up to 2%, up to 1%, up to 0.5%, up to 0.1%, or up to 0.01%.

[0057] Ranges can be expressed as from about one particular value to about another particular value, inclusive. When such a range is expressed, it should be understood that another embodiment is from the one particular value to the other particular value, as well as all the particular values ​​within the range and combinations thereof.

[0058] Although only a few exemplary embodiments have been described in detail above, those skilled in the art will readily appreciate that many modifications may be made to the exemplary embodiments without substantially departing from the present invention. Therefore, all such modifications are intended to be included within the scope of the present disclosure as defined by the following claims.

Claims

1. A method for the hydrogenation of isoolefins, the method comprising: feeding a mixed isoolefin stream comprising C8-C12 olefins including isoolefins and oligomers and C8-C12 hydrogenated hydrocarbons to a trickle bed reactor system comprising one or more beds of a hydrogenation catalyst; supplying a hydrogen feed stream to the trickle bed reactor system; reacting the hydrogen feed stream and the mixed isoolefin stream in the one or more beds of a hydrogenation catalyst to produce a liquid effluent comprising hydrogenated hydrocarbons and unreacted olefins and a vapor effluent comprising hydrogenated hydrocarbons, hydrogen, and unreacted olefins; supplying the liquid effluent to a first heat exchanger, cooling the liquid effluent, and producing a cooled liquid effluent stream; combining the vapor effluent and the cooled liquid effluent stream to produce a mixed phase effluent; feeding the mixed phase effluent to a second heat exchanger, cooling the mixed phase effluent, and producing a partially condensed effluent; feeding the partially condensed effluent to a drum to produce a vent stream, a hydrogenation product stream comprising greater than 95 wt% C8-C12 saturated hydrocarbons, and a hydrogenation recycle stream; and The hydrogenated product stream is recovered and sent to one or more downstream mixing systems.

2. The method according to claim 1, further comprising: pressurizing the hydrogenated recycle stream in a pump to produce a pressurized recycle stream; feeding the pressurized recycle stream to the first heat exchanger, wherein the first heat exchanger is configured to heat the pressurized recycle stream and cool the liquid effluent to produce an intermediate recycle stream; and The intermediate recycle stream is combined with a fresh iso-olefin stream comprising C8-C12 olefins including iso-olefins and oligomers to produce the mixed iso-olefin stream.

3. The process of claim 1 or claim 2, further comprising recovering the vapor effluent from a side draw located near the bottom of the one or more beds of the hydrogenation catalyst.

4. The process according to any one of claims 1 to 3, further comprising supplying the hydrogen feed stream at a first hydrogen feed inlet located near the top of the trickle bed reactor system or at a second hydrogen feed inlet located intermediate the first bed of hydrogenation catalyst and the second bed of hydrogenation catalyst, or both.

5. The process according to claim 4, wherein said supplying said hydrogen feed stream occurs at a hydrogen partial pressure of 20 barg to 40 barg.

6. The process of claim 4, wherein the hydrogen in the hydrogen feed stream is supplied at 1.5 to 10 times the stoichiometric amount required for the hydrogenation of the C8-C12 isoolefins and C8-C12 oligomers in the mixed isoolefin stream.

7. The process of claim 2, further comprising heating the intermediate recycle stream in a third heat exchanger prior to combining the intermediate recycle stream with the fresh iso-olefin stream.

8. The process of claim 7, further comprising heating the intermediate recycle stream in the third heat exchanger to a temperature sufficient to heat the mixed iso-olefin stream to a temperature in the range of 30°C to 100°C.

9. The process according to any one of claims 1 to 8, wherein the effluent stream comprises hydrogen, the process further comprising recycling a portion of the effluent stream to the hydrogen feed stream.

10. The process according to any one of claims 1 to 9, wherein the mixed iso-olefin stream is recovered from an upstream C4 / C5 oligomerization process.

11. A system for hydrogenation of isoolefins, the system comprising: A trickle bed reactor system comprising one or more beds of a hydrogenation catalyst, the trickle bed reactor system being configured to simultaneously: receiving a mixed isoolefin stream comprising C8-C12 olefins including isoolefins and oligomers and C8-C12 hydrogenated hydrocarbons, receiving a hydrogen feed stream, reacting the hydrogen feed stream and the mixed isoolefin stream in the one or more beds of hydrogenation catalyst, and producing a liquid effluent comprising hydrogenated hydrocarbons, hydrogen, and unreacted olefins and a vapor effluent comprising hydrogenated hydrocarbons, hydrogen, and unreacted olefins; a first feed line for conveying the liquid effluent to a first heat exchanger configured to cool the liquid effluent and produce a cooled liquid effluent stream; a second feed line for conveying the vapor effluent and combining the vapor effluent with the cooled liquid effluent to produce a mixed phase effluent; a second heat exchanger configured to receive the mixed phase effluent and cool the mixed phase effluent to produce a partially condensed effluent; as well as a third feed line for conveying the partially condensed effluent to a drum, the drum further comprising: a top exhaust port configured to produce an exhaust stream comprising hydrogen, a hydrogenated product output line configured to produce a hydrogenated product stream comprising greater than 95 wt% C8-C12 hydrogenated hydrocarbons, and a hydrogenated circulating stream outlet configured to produce a hydrogenated circulating stream; as well as A flow conduit is provided for conveying the hydrogenated product stream to one or more downstream mixing systems.

12. The system of claim 11, further comprising: a pump configured to pressurize the hydrogenated recycle stream and produce a pressurized recycle stream; a fourth feed line for conveying the pressurized recycle stream to the first heat exchanger, wherein the first heat exchanger is configured to heat the pressurized recycle stream and cool the liquid effluent to produce an intermediate recycle stream; as well as A mixing tee configured to combine the intermediate recycle stream with a fresh iso-olefin stream comprising C8-C12 olefins including iso-olefins and oligomers to produce the mixed iso-olefin stream.

13. The system of claim 11 or claim 12, wherein the hydrogenation catalyst comprises a metal selected from the group consisting of platinum, palladium, iron, and nickel.

14. The system of any one of claims 11 to 13, wherein the trickle bed reactor system further comprises a side draw configured to recover the vapor effluent, the side draw being located near the bottom of the one or more beds of the hydrogenation catalyst.

15. The system of any one of claims 11 to 14, wherein the trickle bed reactor system further comprises a first hydrogen feed inlet located near the top of the liquid phase trickle bed reactor system, or a second hydrogen feed inlet located intermediate the first bed of hydrogenation catalyst and the second bed of hydrogenation catalyst, or both.

16. The system of claim 15, wherein the trickle bed reactor system is operated at a hydrogen partial pressure of 20 barg to 40 barg.

17. The system of claim 12, further comprising a third heat exchanger located intermediate the mixing tee of the first heat exchanger, the third heat exchanger configured to heat the intermediate recycle stream to a temperature sufficient to heat the mixed iso-olefin stream to a temperature in the range of 30°C to 100°C.

18. The system of any one of claims 11 to 17, further comprising a recycle line configured to recycle a portion of the exhaust stream to the hydrogen feed stream.

19. The system of any one of claims 11 to 18, wherein the mixed iso-olefin stream is recovered from an upstream C4 / C5 oligomerization process.

20. A process for the hydrogenation of isoolefins, the process comprising: feeding a mixed isoolefin stream comprising C8-C12 olefins including isoolefins and oligomers and C8-C12 hydrogenated hydrocarbons to a trickle bed reactor system comprising one or more beds of a hydrogenation catalyst; supplying a hydrogen feed stream to the trickle bed reactor system; reacting the hydrogen feed stream and the mixed isoolefin stream in the presence of the one or more beds of a hydrogenation catalyst to produce a liquid effluent comprising hydrogenated hydrocarbons and unreacted olefins and a vapor effluent comprising hydrogenated hydrocarbons, hydrogen, and unreacted olefins; supplying the liquid effluent to a first heat exchanger, cooling the liquid effluent, and producing a cooled liquid effluent stream; combining the vapor effluent and the cooled liquid effluent stream to produce a mixed phase effluent; feeding the mixed phase effluent to a second heat exchanger, cooling the mixed phase effluent, and producing a partially condensed effluent; feeding the partially condensed effluent to a drum to produce a vent stream, a hydrogenation product stream comprising greater than 95 wt % C8-C12 saturated hydrocarbons, and a hydrogenation recycle stream; recovering the hydrogenated product stream and sending the hydrogenated product stream to one or more downstream mixing systems; pressurizing the hydrogenated recycle stream in a pump to produce a pressurized recycle stream; feeding the pressurized recycle stream to the first heat exchanger, wherein the first heat exchanger is configured to heat the pressurized recycle stream and cool the liquid effluent to produce an intermediate recycle stream; heating the intermediate recycle stream in a third heat exchanger to produce a heated recycle stream; and The heated recycle stream is combined with a fresh isoolefin stream comprising C8-C12 olefins including isoolefins and oligomers to produce the mixed isoolefin stream, wherein the heated recycle stream and the fresh isoolefin stream are fed to the trickle bed reactor in a volume ratio of 3:1 to 10:

1.

21. A process according to claim 20 comprising supplying the hydrogen feed stream at a hydrogen partial pressure of from 20 barg to 40 barg.

22. The process of claim 21 wherein the hydrogen in the hydrogen feed stream is supplied at 1.5 to 10 times the stoichiometric amount required for the hydrogenation of the C8-C12 isoolefins and C8-C12 olefins in the mixed isoolefin stream.

23. The process of any one of claims 20 to 22, further comprising heating the intermediate recycle stream in the third heat exchanger to a temperature sufficient to heat the mixed iso-olefin stream to a temperature in the range of 30°C to 100°C.

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