Co-generation of high-purity isobutylene and high-purity isooctene

Abstract

A system and process for the production of high-purity isobutylene streams, high-purity isooctene streams, or co-production of high-purity isobutylene and high-purity isooctene. This system and process favorably processes mixed C4 hydrocarbon streams through etherification, decomposition, isomerization, and / or dimerization, as well as various separation systems, to produce desired high-purity streams.

Description

Technical Field

[0001] Embodiments of the present disclosure generally relate to systems and processes for the co-production of high purity isooctene and high purity isobutylene.

Background Art

[0002] High purity isobutylene is used as a raw material for the production of butyl rubber, PIB (polyisobutylene), and MMA (methyl methacrylate), and is usually produced from a commercially proven MTBE decomposition process. High purity isooctene is used to produce octylphenol resins used as tackifiers in radial tires, octylated diphenylamine stabilizers for lubricants and rubbers, isononyl derivatives used to produce polymerization initiators and compressor fluids, and comonomers in the production of elastomers and hydrocarbon resins, or as a raw material for the production of chain terminators for polycarbonate resins.

Summary of the Invention

Means for Solving the Problems

[0003] Embodiments described herein relate to the production of high purity isobutylene and high purity diisobutylene (also known as isooctene or a mixture of 2,4,4-trimethyl-1-pentene and 2,4,4-trimethyl-2-pentene) that includes an olefin dimerization step, etherification, ether decomposition, or a combination of butene isomerization and hydrogenation. Embodiments described herein also contemplate the use of several dimerization reaction regulators such as C1-C4 alcohols, other oxygen-containing compounds such as ETBE, ESBE, MTBE, MSBE, water and / or ethylene glycol. This method can be flexible in producing both high purity isobutylene and high purity isooctene, or only high purity isooctene.

[0004] In one embodiment, the embodiments disclosed herein relate to a process for the co-production of high-purity isobutylene and high-purity isooctene. This process involves supplying ethanol and mixed C4 hydrocarbons to an ETBE converter, the mixed C4 feed stream containing a mixture of hydrocarbons including 1-butene, 2-butene, n-butane, isobutane, and isobutylene. Within the ETBE converter, isobutylene reacts with ethanol catalyzed to form ethyl tert-butyl ether, generating an ETBE reaction effluent stream, which is recovered from the reactor and separated to recover a first fraction containing ethyl tert-butyl ether and a second fraction containing 1-butene, 2-butene, isobutane, and n-butane. The first fraction containing ethyl tert-butyl ether is then supplied to an ETBE decomposition unit. In the ETBE decomposition unit, ethyl tert-butyl ether is decomposed to form a decomposition reaction effluent containing isobutylene, ethanol, and unreacted ethyl tert-butyl ether, which is then separated to recover an isobutylene fraction containing 95% or more by weight of isobutylene and a first oxygen-containing compound fraction containing ethanol and unreacted ethyl tert-butyl ether. The first portion of the isobutylene fraction is recovered as a high-purity isobutylene product fraction. The second portion of the isobutylene fraction is supplied to the isobutylene dimerizer. Part of the first fraction containing ethyl tert-butyl ether, part of the first oxygen-containing compound fraction, or both are also supplied to the isobutylene dimerizer as reaction modifiers. In the isobutylene dimerizer, isobutylene is dimerized to form a dimerization reaction effluent containing isooctene, a reaction modifier, and by-products isobutylene trimer and oligomer. This effluent is then separated to recover a heavy fraction containing isooctene, by-products isobutylene trimer and oligomer, ethyl tert-butyl ether, and ethanol, and a light fraction containing isobutylene and ethanol. The heavy fraction is fed into an oxygen-containing compound separator to separate the heavy fraction, recovering a first dimerization product fraction containing isooctene and by-products isobutylene trimer and oligomer, and a second dimerization product fraction containing the reaction modifier.The first dimerization product fraction is supplied to a DIB purifier, where it is separated to recover an isooctene fraction containing 95% or more by weight of isooctene, and a by-product fraction containing isobutylene trimers and oligomers.

[0005] In another embodiment, embodiments disclosed herein relate to a process for the co-production of high-purity isobutylene and high-purity isooctene. This process involves supplying methanol and mixed C4 hydrocarbons to an MTBE converter, the mixed C4 feed stream containing a mixture of hydrocarbons including 1-butene, 2-butene, n-butane, isobutane, and isobutylene. Within the MTBE converter, isobutylene reacts with methanol catalyzed to form methyl tert-butyl ether, the MTBE reaction effluent is collected and separated to recover a first fraction containing methyl tert-butyl ether and a second fraction containing 1-butene, 2-butene, isobutane, and n-butane. The first fraction containing methyl tert-butyl ether is then supplied to an MTBE decomposition unit. In the MTBE decomposition unit, methyl tert-butyl ether is decomposed, forming a decomposition reaction effluent containing isobutylene, methanol, and unreacted methyl tert-butyl ether. This effluent is then separated to recover an isobutylene fraction containing 95% or more by weight of isobutylene, and a first oxygen-containing compound fraction containing methanol and unreacted methyl tert-butyl ether. The first portion of the isobutylene fraction is recovered as a high-purity isobutylene product fraction, and the second portion of the isobutylene fraction is supplied to the isobutylene dimerizer. A portion of the first fraction containing methyl tert-butyl ether, a portion of the first oxygen-containing compound fraction, or both are also supplied to the isobutylene dimerizer as reaction modifiers. In the isobutylene dimerizer, isobutylene is dimerized to form a dimerization reaction effluent containing isooctene, a reaction modifier, and by-products isobutylene trimer and oligomer. This effluent is then separated to recover a heavy fraction containing isooctene, by-products isobutylene trimer and oligomer, methyl tert-butyl ether, and methanol, and a light fraction containing isobutylene and methanol. Next, in the oxygen-containing compound separator, the heavy fraction is separated to recover a first dimerization product fraction containing isooctene and by-products isobutylene trimer and oligomer, and a second dimerization product fraction containing a reaction modifier.The first dimerization product fraction is supplied to a DIB purifier, where it is separated to recover an isooctene fraction containing 95% or more by weight of isooctene, and a by-product fraction containing isobutylene trimers and oligomers.

[0006] In another embodiment, embodiments disclosed herein relate to a process for the co-production of high-purity isobutylene and high-purity isooctene. This process involves feeding a mixed C4 stream containing a mixture of hydrocarbons including 1-butene, 2-butene, n-butane, isobutane, and isobutylene into a catalytic separator. Within the catalytic separator, a portion of the 1-butene is converted to 2-butene, and the hydrocarbon mixture is separated to recover a first top fraction containing 1-butene, isobutane, and isobutene, and a bottom fraction containing n-butane and 2-butene. A portion of the first top fraction is recovered as a high-purity isobutylene product fraction containing at least 95% by weight of isobutylene. This process also involves feeding an alcohol selected from ethanol or methanol and a second portion of the first top fraction into an etherification converter. In the etherification unit, the alcohol and isobutylene react to form alkyl tert-butyl ether, and the etherification reaction effluent containing the alkyl tert-butyl ether and alcohol is recovered. The etherification reaction effluent is supplied to the isobutylene dimerizer as a reaction modifier. The second portion of the first top fraction is also supplied to the isobutylene dimerizer. In the isobutylene dimerizer, isobutylene is dimerized to form a dimerization reaction effluent containing isooctene, the reaction modifier, and by-products isobutylene trimer and oligomer. This dimerization reaction effluent is separated to recover a heavy fraction containing isooctene, by-products isobutylene trimer and oligomer, alkyl tert-butyl ether, and alcohol, and a light fraction containing isobutylene and alcohol. The heavy fraction is fed into an oxygen-containing compound separator, where a first dimerization product fraction containing isooctene and by-products isobutylene trimer and oligomer is recovered, and a second dimerization product fraction containing reaction modifiers is recovered. Furthermore, the first dimerization product fraction is fed into a DIB purifier, where it is separated, and an isooctene fraction containing 95% by weight or more isooctene and a by-product fraction containing isobutylene trimer and oligomer are recovered.

[0007] In another embodiment, embodiments disclosed herein relate to a system for the co-production of high-purity isobutylene and high-purity isooctene. This system includes an etherification unit (ETBE or MTBE converter), a decomposition unit, an isobutylene dimerizer, an oxygen-containing compound separator, and a DIB purifier.

[0008] In the system of the embodiment utilizing ethanol, the system may include one or more fluid conduits for supplying ethanol and mixed C4 hydrocarbons to an ETBE converter, the mixed C4 feedstream containing a mixture of hydrocarbons including 1-butene, 2-butene, n-butane, isobutane, and isobutylene. The ETBE converter includes one or more reactors configured to react isobutylene with ethanol using a catalyst to form ethyl tert-butyl ether and to recover the ETBE reaction effluent, and a separation system configured to separate the ETBE reaction effluent and recover a first fraction containing ethyl tert-butyl ether and a second fraction containing 1-butene, 2-butene, isobutane, and n-butane. A channel is provided for supplying the first fraction containing ethyl tert-butyl ether to an ETBE decomposition unit. The ETBE decomposition apparatus includes one or more reactors configured to decompose ethyl tert-butyl ether to form a decomposition reaction effluent containing isobutylene, ethanol, and unreacted ethyl tert-butyl ether, and a separation system configured to separate the reaction effluent and recover an isobutylene fraction containing 95% by weight or more isobutylene and a first oxygen-containing compound fraction containing ethanol and unreacted ethyl tert-butyl ether. A channel is provided for recovering the first portion of the isobutylene fraction as a high-purity isobutylene product fraction, and a channel is also provided for supplying the second portion of the isobutylene fraction to an isobutylene dimerizer. Furthermore, a channel is provided for supplying a portion of the first fraction containing ethyl tert-butyl ether, a portion of the first oxygen-containing compound fraction, or both, to the isobutylene dimerizer as a reaction modifier.The isobutylene dimerizer includes one or more reactors configured to dimerize isobutylene to form a dimerization reaction effluent containing isooctene, a reaction modifier, and by-products isobutylene trimers and oligomers; and a separation system for separating the dimerization reaction effluent to recover a heavy fraction containing isooctene, a reaction modifier, by-products isobutylene trimers and oligomers, ethyl tert-butyl ether, and ethanol, and a light fraction containing isobutylene and ethanol. The oxygen-containing compound separator is configured to separate the heavy fraction to recover a first dimerization product fraction containing isooctene and by-products isobutylene trimers and oligomers, and a second dimerization product fraction containing the reaction modifier. The flow path is fluidly connected to supply the first dimerization product fraction to a DIB purifier. The DIB purification apparatus also includes a separation system for separating the first dimerization product fraction and recovering an isooctene fraction containing 95% or more by weight of isooctene, and a by-product fraction containing isobutylene trimers and oligomers.

[0009] Similarly, in the case of a methanol-based system, the system may involve similar apparatus operations as described above for ethanol, although with a slightly different configuration to account for the differences in methanol use and recovery compared to ethanol and its associated by-products.

[0010] The system of such an embodiment includes one or more fluid conduits for supplying methanol and mixed C4 hydrocarbons to an MTBE converter, the mixed C4 feedstream containing a mixture of hydrocarbons including 1-butene, 2-butene, n-butane, isobutane, and isobutylene. The MTBE converter includes one or more reactors configured to react isobutylene with methanol catalyzed to form methyl tert-butyl ether and to recover the MTBE reaction effluent, and a separation system for separating the MTBE reaction effluent to recover a first fraction containing methyl tert-butyl ether and a second fraction containing 1-butene, 2-butene, isobutane, and n-butane. A channel is provided for supplying the first fraction containing methyl tert-butyl ether to an MTBE decomposition unit. The MTBE decomposition apparatus includes one or more reactors for decomposing methyl tert-butyl ether to form a decomposition reaction effluent containing isobutylene, methanol, and unreacted methyl tert-butyl ether, and a separation system configured to separate the reaction effluent and recover an isobutylene fraction containing 95% by weight or more isobutylene and a first oxygen-containing compound fraction containing methanol and unreacted methyl tert-butyl ether. A channel is provided for recovering the first portion of the isobutylene fraction as a high-purity isobutylene product fraction, and another channel is provided for supplying the second portion of the isobutylene fraction to an isobutylene dimerizer. Furthermore, a channel is provided for supplying a portion of the first fraction containing methyl tert-butyl ether, a portion of the first oxygen-containing compound fraction, or both, to the isobutylene dimerizer as a reaction modifier. An isobutylene dimerizer includes one or more reactors for dimerizing isobutylene to form a dimerization reaction effluent containing isooctene, a reaction modifier, and by-products isobutylene trimers and oligomers; and a separation system for separating the dimerization reaction effluent to recover a heavy fraction containing isooctene, by-products isobutylene trimers and oligomers, methyl tert-butyl ether, and methanol, and a light fraction containing isobutylene and methanol.The oxygen-containing compound separator is configured to separate the heavy fraction and recover a first dimerization product fraction containing isooctene and by-products isobutylene trimers and oligomers, and a second dimerization product fraction containing reaction modifiers. A channel is provided for supplying the first dimerization product fraction to a DIB purifier, which includes a separation system for separating the first dimerization product fraction and recovering an isooctene fraction containing 95% by weight or more isooctene and a by-product fraction containing isobutylene trimers and oligomers.

[0011] In another embodiment, embodiments disclosed herein relate to a system for co-producing high-purity isobutylene and high-purity isooctene. The system includes one or more channels for supplying a mixed C4 stream containing a mixture of hydrocarbons including 1-butene, 2-butene, n-butane, isobutane, and isobutylene to a catalytic separator. The catalytic separator includes a catalytic distillation column configured to separate the hydrocarbon mixture while converting a portion of the 1-butene to 2-butene, in order to recover a first top fraction containing 1-butene, isobutane, and isobutene, and a bottom fraction containing n-butane and 2-butene. A channel is provided for recovering a portion of the first top fraction as a high-purity isobutylene product fraction containing at least 95% by weight of isobutylene. One or more channels are provided for supplying an alcohol selected from ethanol or methanol and a second portion of the first top fraction to an etherification converter. The etherification conversion apparatus includes one or more reactors for reacting an alcohol with isobutylene to form an alkyl tert-butyl ether and recovering an etherification reaction effluent containing the alkyl tert-butyl ether and the alcohol. A channel is provided for supplying the etherification reaction effluent as a reaction modifier to an isobutylene dimerizer, and a channel is also provided for supplying a second portion of the first top fraction to the isobutylene dimerizer. The isobutylene dimerizer includes one or more reactors for dimerizing isobutylene to form a dimerization reaction effluent containing isooctene, a reaction modifier, and by-products isobutylene trimers and oligomers, and a separation system for separating the dimerization reaction effluent to recover a heavy fraction containing isooctene, by-products isobutylene trimers and oligomers, alkyl tert-butyl ether, and alcohol, and a light fraction containing isobutylene and alcohol. The oxygen-containing compound separator is configured to separate the heavy fraction and recover a first dimerization product fraction containing isooctene and by-products isobutylene trimer and oligomer, and a second dimerization product fraction containing reaction modifiers. Furthermore, a channel is provided for supplying the first dimerization product fraction to the DIB purification apparatus.The DIB purification apparatus includes a separation system for separating the first dimerization product fraction and recovering an isooctene fraction containing 95% or more by weight of isooctene, and a by-product fraction containing isobutylene trimers and oligomers.

[0012] As outlined above, the co-production of high-purity isooctene and high-purity isobutylene is intended to supply most or all of the high-purity isobutylene for the production of high-purity isooctene, as outlined above and as will be further described later herein.

[0013] Other aspects and advantages will become apparent from the following description and the attached claims. [Brief explanation of the drawing]

[0014] [Figure 1] A simplified process flow diagram of a system for co-producing high-purity isobutene and high-purity isooctene according to one or more embodiments disclosed herein is shown. [Figure 2] A simplified process flow diagram of a system for co-producing high-purity isobutene and high-purity isooctene according to one or more embodiments disclosed herein is shown. [Figure 3] A simplified process flow diagram of a system for co-producing high-purity isobutene and high-purity isooctene according to one or more embodiments disclosed herein is shown. [Figure 4] A catalytic deisobutene apparatus useful in the embodiments described herein is illustrated. [Figure 5] A general process block flow diagram of an isobutylene dimerizer according to one or more embodiments disclosed herein is shown. [Figure 6] A simplified block flow diagram of an etherification apparatus according to one or more embodiments disclosed herein is shown. [Modes for carrying out the invention]

[0015] Embodiments of this disclosure generally relate to systems and processes for the co-production of high-purity isooctene and high-purity isobutylene. More specifically, embodiments described herein are directed toward the production of high-purity isobutylene and high-purity isooctene from mixed C4 streams.

[0016] In the embodiments described herein, useful alcohol feed streams include methanol or ethanol. In other embodiments, alcohol feed streams may include propanol or butanol, as well as other C3 and C4 alcohols.

[0017] To generate a C4 flow, various upstream production processes can be used, including fluid catalytic cracking (FCC) units, residual oil fluid catalytic cracking (RFCC) units, steam cracking units, pyrolysis units (pyrolysis using steam or pyrolysis without steam), and various other methods for producing mixed C4. The mixed C4 flow produced from these units may contain isobutene, isobutane, 1-butene, 2-butene, n-butane, and butadiene, as well as other components.

[0018] Such upstream C4 production systems produce similar chemical compounds, but result in flows with different compositional mixtures of various C4 compounds. For example, a mixed C4 from an FCC or RFCC may have a much higher concentration of isobutane (e.g., over 20% or 25% by weight) than raffinate-1 recovered from the butadiene production process of a vapor cracker (e.g., less than 5% or 3% by weight of isobutane). At the same time, the isobutylene concentration in the C4 of the FCC / RFCC is much lower than that of the C4 from the vapor cracker (e.g., less than 25% or 30% by weight in the RFCC, compared to over 35% or 40% by weight in the vapor cracker C4). Similarly, there may also be differences in the 1-butene concentrations of each (FCC / RFCC vs. vapor cracker) (e.g., less than 20% or 15% by weight vs. over 35% or 40% by weight). Furthermore, the diene content of the FCC / RFCC mixed C4 is much higher than that of Raffinate-1 from a vapor cracking unit (e.g., 0.3 wt% or 3,000 ppmw vs. 40 ppmw). The embodiments described herein can produce high-purity isobutylene and high-purity isooctene from any of these various flows or from a mixture of two or more of these flows.

[0019] Generally, the embodiments described herein first convert a C4 mixture with isobutylene into an oxygenated compound via etherification, and then decompose this oxygenated compound into a high-purity isobutylene (HPIB) stream and C1-C2 alcohols. The HPIB is then diluted with C4 paraffin to control the exothermic reaction in dimerization. The oxygenated compound from the decomposition step, along with the oxygenated compound recovered from a downstream separator, is used as a reaction modifier to control the oligomerization reaction and enhance selectivity to high-purity isooctene (HPDIB). A variation of the HPIB preparation is carried out via hydrogen isomerization.

[0020] In the first embodiment, for example, mixed C4 reacts with ethanol to produce ETBE, which is then decomposed (reverse decomposition) to produce high-purity isobutylene as part of the preparation of the feed for the high-purity isooctene production step. In the fully integrated configuration, all of the HPIB produced is diluted with C4 paraffin, which is assumed to be a semi-closed circulating system, depending on the amount of HPIB produced. The recirculated paraffin forms an azeotrope with ethanol (for example, when using ETBE) and is returned to the dimerization as a feed stream, and it is expected that the diluent will decrease (only replenishment will occur) during normal operation. The ethanol associated with the diluent will also act as an additional modifier in the dimerization process. From the reverse decomposition step, an oxygen-containing compound purge containing ETBE, some ESBE (depending on the reacted n-butene), TBA, ethanol, DEE, and water is also sent to the dimerization step as a reaction modifier. A slipstream of the ETBE product from the etherification step may be required depending on the oxygen-containing compound purge from the reverse decomposition step. In the dimerization step, HPIB is diluted with C4 paraffin and an oxygenated compound. Since the resulting HPIB contains very little linear butene, the dimerization step is expected to selectively produce 2,4,4-trimethyl-1-pentene / 2-pentene (244TM1P and 244TM2P), with C8 codimers such as dimethylhexene present at less than 1% by weight. The C8, C12+, and oxygenated compound are then sent to a purification compartment where the oxygenated compound, C12+, and the main product DIB are separated. The oxygenated compound is then recycled back to the dimerization step as a modifier. Depending on the control and closure of the oxygenated compound required for the dimerization reaction, purging of the oxygenated compound in the dimerization step may or may not be necessary. A similar embodiment is envisioned where methanol is used as the alcohol, resulting in the production of methyl tert-butyl ether (MTBE) along with the other reaction and separation steps, and the decomposition of MTBE to form high-purity isobutylene.

[0021] In a second embodiment, for example, the mixed C4 is sent to a catalytic deisobutanizer. In the catalyst section of this column, the 1-butene component in the feed stream is isomerized to 2-butene to facilitate the separation of isobutylene and isobutane in the mixed feed stream. A small amount of hydrogen is supplied into this distillation column to control the hydrogen isomerization reaction in the catalyst section. The top of the column is assumed to consist of isobutane, isobutylene, and a small amount of 1-butene. The bottom of the column consists of n-butane and the remaining 2-butene, as well as any heavy components that may be present in the mixed C4 feedstock. The top of the column is then split into two streams. One stream is the main feed stream to the dimerization step, and the other stream is for the production of oxygenates, in this case, ETBE from the reaction of ethanol. The ETBE reaction step can be carried out in a dimerizer. Another variation of this dimerization step consists of an ETBE reactor (etherification only) followed by a dimerizer. The etherification step depends on the requirements in the dimerization. Similar to the first embodiment described above, the dimerization step involves dilution with an external C4 paraffin stream and a splitting section and a purification section for producing an oxygenate stream and the main product, high purity DIB. Similarly, a similar reaction / separation scheme using methanol as the alcohol can be employed.

[0022] In one or more embodiments of the present disclosure, the purity of the produced high purity isobutylene is from any lower limit of 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, or 98% by weight to any upper limit of 90%, 91%, 92%, 93%, 94%, 95%, 98%, 98.5, 99.0, 99.5, 99.8, or 99.9% by weight, and any lower value can be combined with a mathematically compatible upper value. For example, the purity of the produced isobutylene can be at least 95%, at least 98%, at least 99%, or at least 99.5% by weight.

[0023] In one or more embodiments of the present disclosure, the purity of the high purity isooctene produced is from any lower limit of 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, or 98% by weight to 90%, 91%, 92%, 93%, 94%, 95%, 98%, 98.5, 99.0, 99.5, 99.8, or 99.9% by weight, and any lower limit can be combined with a mathematically compatible upper limit. For example, the purity of the isooctene produced can be at least 95%, at least 98%, at least 99%, or at least 99.5% by weight.

[0024] Referring now to FIG. 1, a simplified process flow diagram of a system 100 for producing high purity isobutylene and high purity isooctene according to an embodiment described herein is illustrated. System 100 includes a MTBE conversion unit 102, a MTBE decomposition unit 104, an isobutylene dimerization unit 106, an oxygenated compound separator 108, a diisobutylene purification zone 110, and optionally a C4 separation zone 112, and may include major equipment operations. Each of these devices may include pre-treatment equipment (filters, adsorption beds, etc.) for the feed stream, storage tanks, one or more reactors in series and / or in parallel, separation devices (distillation columns, extractive distillation columns, flash drums, and / or knockout drums may be included), and other components, as well as one or more of other components such as valves, pumps, controllers, overhead condensation systems (condensers, heat exchangers, drums, etc.), reboilers, etc. These devices do not all include these equipment respectively. Further, although these components are not shown in the simplified process flow diagram, those skilled in the art will be able to easily understand and grasp how the process flow and such equipment can be incorporated as outlined in the following description.

[0025] Methanol 120 and a mixed C4 hydrocarbon stream 122 are fed into an MTBE converter which includes one or more reactors or catalytic distillation columns containing an etherification catalyst. The mixed C4 feed stream may contain a mixture of hydrocarbons, for example, 1-butene, 2-butene, n-butane, isobutane, and isobutylene. Within the MTBE converter, the feed stream is brought into contact with the etherification catalyst under appropriate conditions, and isobutylene is reacted with methanol and the catalyst to form methyl tert-butyl ether. The MTBE reaction effluent is recovered from the reaction area(s), and then separated to recover a first fraction 124 containing methyl tert-butyl ether and a second fraction 126 containing 1-butene, 2-butene, isobutane, and n-butane. In addition to recovering MTBE and C4 products, the MTBE conversion area 102 may further include a water wash column, an extraction distillation column, and / or other separators for separating unreacted methanol from the MTBE product, in which case this methanol may be returned to the reactor for continuous use in the production of MTBE.

[0026] If it is desired to further process and separate any remaining C4 components in the second fraction, such as recovering 2-butene or isobutane, the second fraction 126 may be fed to a C4 separation section 112. The C4 separation section 112 may include, for example, a distillation column or fractionator for separating a heavy C4 fraction 128 containing n-butane and 2-butene from a light C4 fraction 130 containing 1-butene, isobutane, and any unreacted isobutylene from the etherification reactor. In other embodiments, the C4 separation section 112 may include a catalytic deisobutene generator that may include a regioisomerization catalyst section for converting 1-butene to 2-butene, and a distillation structure or number of stages for separating the light C4 fraction 130 containing isobutane and any unreacted isobutylene from the heavy C4 fraction containing 2-butene and n-butane.

[0027] The first fraction 124 contains methyl tert-butyl ether produced in the etherification reactor and is then supplied to the MTBE decomposition unit 104. As a starter or supplemental oxygen-containing compound reaction modifier (selectivator), a portion 132 of the first fraction may be sent to the isobutylene dimerizer 106.

[0028] In the MTBE decomposition unit, methyl tert-butyl ether is decomposed (reverse decomposition) to form a decomposition reaction effluent containing isobutylene, methanol, and unreacted methyl tert-butyl ether. The reaction effluent is then separated to recover an isobutylene fraction 134, which may be a high-purity isobutylene stream containing 95% by weight or more isobutylene, and a first oxygen-containing compound fraction 136, which may contain methanol obtained as a result of reverse decomposition and any unreacted methyl tert-butyl ether. If desired as a reaction product, a portion of the isobutylene fraction 140 may be recovered as a high-purity isobutylene product fraction.

[0029] The oxygenated compound fraction 136 contains methanol and methyl tert-butyl ether, and if desired, the oxygenated compounds may be separated and recovered. The first portion of the oxygenated compound fraction 136, which may be methanol, or a mixture of methanol and methyl tert-butyl ether, other oxygenation reaction byproducts such as MSBE, and others as described above, may be returned to the etherification reaction area 102 via the oxygenated compound fraction channel 136. Additionally or alternatively, the second portion 138 of the oxygenated compound fraction may be used as a start-up or replenishment selector in the isobutylene dimerizer 106, together with or in addition to any reaction modifier supplied from either the etherification unit 102 or the oxygenated compound separator 108.

[0030] The isobutylene fraction 134, i.e., the portion not recovered as a high-purity isobutylene product, is then mixed with a diluent 142 and supplied to the isobutylene dimerizer 106. The diluent 142 may include, for example, a mixture of n-butane, isobutane, or C4 paraffin.

[0031] In an isobutylene dimerizer, isobutylene can be dimerized on a dimerization catalyst and in the presence of a diluent and reaction modifier under appropriate reaction conditions to form a dimerization effluent containing isooctene, the reaction modifier, and by-products isobutylene trimers and oligomers. The dimerization effluent can then be separated to recover a heavy fraction 144 containing isooctene, by-products isobutylene trimers and oligomers, methyl tert-butyl ether, and methanol, and a light fraction 146 containing isobutylene, methanol, and a diluent n-butane or isobutane. If desired, the light fraction 146 can be further processed to separate methanol and diluent and recycled to a suitable reactor.

[0032] The heavy fraction 144 is fed to an oxygen-containing compound separator to recover a first dimerization product fraction 148 containing isooctene and by-products isobutylene trimer and oligomer, and a second dimerization product fraction 150 containing a reaction modifier. In some embodiments, the reaction modifier can be recycled to the dimerization reaction area 106.

[0033] The first dimerization product fraction 148 is supplied to the DIB purifier 110. Inside the DIB purifier 110, the first dimerization product fraction 148 is separated, and an isooctene fraction 152, which may be a high-purity isooctene fraction containing 95% by weight or more isooctene, and a by-product fraction 154 containing isobutylene trimers and oligomers are recovered.

[0034] As described above, the reaction zones in this specification may generate reaction byproducts. For example, one or both of the MTBE reaction effluent and the decomposition reaction effluent may further contain one or more byproducts, such as diisobutylene, methyl sec-butyl ether, tertiary butyl alcohol, or dimethyl ether, and others. Such components may move along with their respective boiling fractions, which are recovered and processed as described above.

[0035] Referring here to Figure 2, a simplified process flow diagram of System 200 for producing high-purity isobutylene and high-purity isooctene according to embodiments described herein is illustrated. System 200 may include major apparatus operations, including an ETBE converter 202, an ETBE decomposition unit 204, an isobutylene dimerizer 206, an oxygen-containing compound separator 208, a diisobutylene purification area 210, and optionally a C4 separation area 212. Each of these apparatuses may include feed stream pretreatment equipment (filters, adsorption beds, etc.), storage tanks, one or more reactors in series and / or parallel, separation equipment (distillation columns, extractive distillation columns, flash drums, and / or removers), and other components, as well as one or more other components such as valves, pumps, controllers, top-of-column condensation systems (condensers, heat exchangers, drums, etc.), and reboilers. Not all apparatuses include each of these components. Furthermore, although these components are not shown in the simplified process flow diagram, those skilled in the art will readily understand and grasp how the process flow and such equipment can be incorporated, as outlined in the following description.

[0036] Ethanol 220 and a mixed C4 hydrocarbon stream 222 are supplied to an ETBE converter, which includes one or more reactors or catalytic distillation columns containing an etherification catalyst. The mixed C4 feed stream may contain, for example, a mixture of hydrocarbons including 1-butene, 2-butene, n-butane, isobutane, and isobutylene. Within the ETBE converter, the feed stream is brought into contact with the etherification catalyst under appropriate conditions, and isobutylene is reacted with ethanol by the catalyst to form ethyl tert-butyl ether. The ETBE reaction effluent is recovered from the reaction area(s), and then separated to recover a first fraction 224 containing ethyl tert-butyl ether and a second fraction 226 containing 1-butene, 2-butene, isobutane, and n-butane. In addition to recovering ETBE and C4 products, the ETBE conversion area 202 may further include a water wash column, an extraction distillation column, and / or other separators for separating unreacted ethanol from the ETBE product, in which case this ethanol may be returned to the reactor for continuous use in the production of ETBE.

[0037] If it is desired to further process and separate any C4 components remaining in the second fraction, such as recovering 2-butene or isobutane, the second fraction 226 may be fed to a C4 separation area 212. The C4 separation area 212 may include, for example, a distillation column or fractionator for separating a heavy C4 fraction 228 containing n-butane and 2-butene from a light C4 fraction 230 containing 1-butene, isobutane, and any unreacted isobutylene from the etherification reactor. In other embodiments, the C4 separation area 212 may include a catalytic deisobutene generator that may include a regioisomerization catalyst area for converting 1-butene to 2-butene and a distillation structure or number of stages for separating the light C4 fraction 230 containing isobutane and any unreacted isobutylene from the heavy C4 fraction containing 2-butene and n-butane.

[0038] The first fraction 224 contains ethyl tert-butyl ether produced in the etherification reactor and is then supplied to the ETBE decomposition unit 204. As a reaction modifier for oxygen-containing compounds during startup or as a replenishment, a portion of the first fraction may be sent to the isobutylene dimerizer 206 via the flow path 232.

[0039] In the ETBE decomposition unit, ethyl tert-butyl ether is decomposed (reverse decomposition) to form a decomposition reaction effluent containing isobutylene, ethanol, and unreacted ethyl tert-butyl ether. The reaction effluent is then separated, and the isobutylene fraction 234 is recovered, which may be a high-purity isobutylene stream containing 95% by weight or more isobutylene, and the first oxygen-containing compound fraction 236 may contain ethanol obtained as a result of reverse decomposition and any unreacted ethyl tert-butyl ether. If desired as a reaction product, a portion 240 of the isobutylene fraction can be recovered as a high-purity isobutylene product fraction.

[0040] The oxygenated compound fraction 236 contains ethanol and ethyl tert-butyl ether, and this oxygenated compound fraction 236 may be separated and the oxygenated compounds recovered if desired. The first portion of the oxygenated compound fraction 236, which may be ethanol, or a mixture of ethanol and ethyl tert-butyl ether, other oxygenation reaction byproducts such as ESBE and DEE, and others as described above, may be returned to the etherification reaction area 202 via the oxygenated compound fraction channel 236. Additionally or alternatively, the second portion 238 of the oxygenated compound fraction may be used as a start-up or replenishment selector in the isobutylene dimerizer 206, together with or in addition to any reaction modifier supplied from either the etherification unit 202 (via channel 232) or the oxygenated compound separator 208 (via channel 250).

[0041] The isobutylene fraction 234, i.e., the portion not recovered as a high-purity isobutylene product, is then mixed with a diluent 242 and supplied to the isobutylene dimerizer 206. The diluent 242 may include, for example, a mixture of n-butane, isobutane, or C4 paraffin.

[0042] In an isobutylene dimerizer, isobutylene can be dimerized on a dimerization catalyst and in the presence of a diluent and reaction modifier under appropriate reaction conditions to form a dimerization effluent containing isooctene, the reaction modifier, and by-products isobutylene trimers and oligomers. The dimerization effluent can then be separated to recover a heavy fraction 244 containing isooctene, by-products isobutylene trimers and oligomers, ethyl tert-butyl ether, and ethanol, and a light fraction 246 containing isobutylene, ethanol, and a diluent n-butane or isobutane. If desired, the light fraction 246 can be further processed to separate ethanol and diluent and recycled to a suitable reactor.

[0043] The heavy fraction 244 is fed to an oxygen-containing compound separator to recover a first dimerization product fraction 248 containing isooctene and by-products isobutylene trimers and oligomers, and a second dimerization product fraction 250 containing a reaction modifier (oxygen-containing compound). In some embodiments, this reaction modifier can be recycled to the dimerization reaction area 206.

[0044] The first dimerization product fraction 248 is supplied to the DIB purifier 210. Inside the DIB purifier 210, the first dimerization product fraction 248 is separated, and an isooctene fraction 252, which may be a high-purity isooctene fraction containing 95% by weight or more isooctene, and a by-product fraction 254 containing isobutylene trimers and oligomers are recovered.

[0045] As described above, the reaction area in this specification may generate reaction byproducts. For example, one or both of the ETBE reaction effluent and the decomposition reaction effluent may further contain one or more byproducts, such as diisobutylene, ethyl sec butyl ether, tertiary butyl alcohol, or dimethyl ether, and others. Such components may move along with their respective boiling fractions, which are recovered and processed as described above.

[0046] Referring here to Figure 3, a simplified process flow diagram of System 300 for producing high-purity isobutylene and high-purity isooctene according to embodiments described herein is illustrated. System 300 may include major apparatus operations including a C4 separation area (deisobutene removal unit) 302, an etherification unit 304, an isobutylene dimerizer 306, an oxygen-containing compound separator 308, and a diisobutylene purification area 310. Each of these apparatuses may include feed stream pretreatment equipment (filters, adsorption beds, etc.), storage tanks, one or more reactors in series and / or parallel, separation equipment (distillation columns, extraction distillation columns, flash drums, and / or removers), and other components, as well as one or more other components such as valves, pumps, controllers, top-of-column condensation systems (condensers, heat exchangers, drums, etc.), and reboilers. Not all apparatuses include each of these components. Furthermore, although these components are not shown in the simplified process flow diagram, those skilled in the art will readily understand and grasp how the process flow and such equipment can be incorporated, as outlined in the following description.

[0047] A mixed C4 stream 320 containing hydrogen 318 and a mixture of hydrocarbons including 1-butene, 2-butene, n-butane, isobutane, and isobutylene is fed to a catalytic separator. The catalytic separator 302 may include a deisobutene unit and optionally a top separator (not shown) or a side draw, each of which may be used to recover an isobutylene fraction or to further separate isobutane from isobutylene. For example, the hydrocarbon mixture in the catalytic separator may be separated to recover a first top fraction containing at least 95% by weight of isobutylene and a side draw fraction containing 1-butene, isobutane, and isobutylene, where the side draw fraction is supplied as an isobutylene fraction to an etherification unit. Similarly, a top separator may be used to further separate isobutylene from isobutane to recover a high-purity isobutylene product and an isobutylene-containing fraction to be supplied to an etherification unit. The catalytic separation apparatus may also include a reaction distillation section containing a positional hydrogenation isomerization catalyst for converting 1-butene to 2-butene, which facilitates the separation of the C4 component with a similar boiling point to produce a high-purity isobutylene fraction.

[0048] Within the catalytic separator 302, a portion of 1-butene is converted to 2-butene, and the hydrocarbon mixture is separated to recover a first top fraction 322 containing isobutane, isobutylene, and any residual 1-butene, and a bottom fraction 324 containing n-butane and 2-butene. If desired, a portion 326 of the first top fraction 322 may be recovered as a high-purity isobutylene product fraction, such as a stream containing at least 95% by weight of isobutylene.

[0049] An alcohol stream 328, such as ethanol or methanol, and a second portion 330 of the first top fraction are supplied to the etherification converter 304. The second portion 330 of the isobutylene product is a small portion of isobutylene, which is used to generate an ether reaction modifier for use in the isobutylene dimerizer 306, which receives the majority of the isobutylene in the first top fraction 322.

[0050] Inside the etherification converter 304, an alcohol and isobutylene are reacted to form an alkyl tert-butyl ether, and an etherification reaction effluent 332 is recovered containing the alkyl tert-butyl ether, unreacted alcohol, and various reaction byproducts such as DEE, DME, TBA, ESBE, MSBE, or others as described above.

[0051] The diluent 334, such as isobutane or n-butane, and the isobutylene in the first top fraction 322 are fed to the isobutylene dimerizer along with the etherification reaction effluent 332, which is then fed to the isobutylene dimerizer 306 as a reaction modifier. In the isobutylene dimerizer 306, the isobutylene is dimerized to form a dimerization reaction effluent containing isooctene, the diluent, the reaction modifier, and by-products isobutylene trimers and oligomers. The dimerization reaction effluent is then separated to recover a heavy fraction 336 containing isooctene, by-products isobutylene trimers and oligomers, alkyl tert-butyl ether, and alcohol, and a light fraction 338 containing the diluent (e.g., isobutane or n-butane), any unreacted isobutylene, and a light reaction modifier such as methanol or ethanol. If desired, the light fraction 338 may be further processed to separate the alcohol and diluent and recycled to a suitable reactor.

[0052] The heavy fraction 336 is fed to the oxygen-containing compound separator 308, where a first dimerization product fraction 340 containing isooctene and by-products isobutylene trimers and oligomers is recovered, and a second dimerization product fraction 342 containing reaction modifiers is recovered. Part or all of the second product fraction 342 may be returned to the isobutylene dimerizer 306 for use as reaction modifiers.

[0053] The first dimerization product fraction 340 is supplied to the DIB purifier 310. In the DIB purifier 310, the first dimerization product fraction 340 is separated, and an isooctene fraction 344, which may be a high-purity isooctene fraction containing 95% by weight or more isooctene, and a by-product fraction 346 containing isobutylene trimers and oligomers are recovered.

[0054] As outlined above, the embodiments described herein include various apparatus operations for producing and recovering high-purity isooctene and high-purity isobutylene. Such embodiments may include, for example, etherification apparatuses (MTBE or ETBE production apparatuses), catalytic separation apparatuses (catalytic deisobutene deconjugates), ether decomposition apparatuses (MTBE or ETBE decomposition apparatuses), isobutylene dimerizers, oxygen-containing compound separators, and diisobutylene purification apparatuses. Each of these apparatuses will be described in further detail below.

[0055] Etherification apparatus and decomposition apparatus

[0056] The method of performing reverse decomposition and separation after etherification generates a high-purity isobutylene product stream by selectively converting isobutylene in the mixed C4 feed stream to one or more of methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE), tertiary butyl alcohol (TBA), and other possible oxygenated intermediates, which allows for easy separation of the resulting ether or alcohol from the lighter C4 n-olefin and paraffin. The ether or alcohol is reverse-decomposed to form its constituent isobutene and water or alcohol, and the isobutene is then easily separated from the water or alcohol and recovered as a high-purity isobutylene product stream. The recovered alcohol or water can then be fed back into the reactor for selective conversion of isobutene.

[0057] The reaction system may include one or more reactors and catalytic distillation reactors suitable for the etherification of isobutene with one or more alcohols, and may form one or more C4 ethers such as MTBE and / or ETBE. Alternatively, water may be used to convert isobutene to an alcohol such as TBA.

[0058] C4 isoolefins can be treated according to the embodiments described herein to etherify them. Catalysts used in reactors and distillation column reactors according to the embodiments described herein may have the function of selectively hydrogenating butadiene, regioisomerizing olefins, and / or etherifying isoolefins.

[0059] Typical conditions for oxygen-containing compound reactions include catalyst bed temperatures above approximately 60°C. For catalytic distillation reactors, this includes top pressures above approximately 5.5 barg and a reaction time of approximately 1.0–2.0 hours. -1 The equivalent liquid space-time velocity can be used. The temperature inside this column is determined by the boiling point of the liquid mixture present at any given pressure. The temperature at the bottom of the column will reflect the composition of the materials in that part of the column and will be higher than that at the top. That is, at a constant pressure, a change in temperature indicates a change in composition within the column. To change the temperature, the pressure inside the column must be changed. Therefore, temperature control in the reaction area is controlled by pressure, and the addition of heat (since the reaction is exothermic) will only cause more boiling. Increasing the pressure will increase the temperature, and vice versa. Even when a distillation column reactor is used, some isoolefin may remain unconverted and may flow out of the column along with the top.

[0060] The ether product, being the material with the highest boiling point, is removed from the distillation column reactor as a bottom distillate. The top distillate may contain isoolefins along with unreacted light alcohols such as methanol or ethanol used as reactants in the upstream reactor, and light inert substances such as n-butene and butane.

[0061] The catalyst for etherification may be any known etherification catalyst, such as an acidic cation exchange resin like AMBERLYST 15 supplied by DuPont Chemical Company. In this specification, a catalyst structure suitable for arranging cation exchange resin particles on the bed of a fixed-bed reactor may be used. Furthermore, the temperature and pressure may be similar to those known in the art for carrying out the specified reaction.

[0062] In some embodiments, the etherification system may include an unreacted n-butene effluent. An effluent containing unreacted n-butene from the oxygen-containing compound reactor may be fed into a C4 separation system. The C4 separation system may be used to produce an isobutane product stream that may contain isobutylene and / or 1-butene, as well as a product stream of normal butane and 2-butene. In some embodiments, these streams may be used as diluents or hydrogenated to form a diluent paraffin stream. In some embodiments, the etherification system may produce an ETBE product stream. In other embodiments, the etherification system may produce an MTBE product stream.

[0063] The oxygenated (ether or alcohol) effluent from the etherification reaction system is then supplied to the reverse decomposition unit.

[0064] This reverse decomposition system produces high-purity isobutene along with unreacted feed components and reaction byproducts such as n-butene, tert-butyl alcohol (TBA), methanol or ethanol, unconverted MTBE or ETBE, methyl sec-butyl ether (MSBE) or ethyl sec-butyl ether (ESBE), diethyl ether (DEE) or dimethyl ether (DME), or diisobutene (DIB). The reverse decomposition unit includes a distillation unit that separates components from the reaction effluent to yield high-purity isobutylene. The recovered alcohol can be fed back to the etherification reaction system. In some embodiments, such as when the oxygen-containing compound is ethanol, the recovered ethanol can be fed back to the etherification reaction system to reduce the amount of ethanol supplied. In some embodiments, no additional external ethanol supply stream is required.

[0065] Contact of the catalyst described herein with an ether feed stream under decomposition conditions may result in the formation of desired olefins and alcohols, as well as by-products, which may include oligomers such as dimers or trimers of the by-product ether, alcohol, and desired olefin product. In some embodiments, contact of the ether feed stream with the catalyst described herein may result in the conversion of at least 90% by weight of the ether, at least 85% by weight in other embodiments, at least 80% by weight in other embodiments, at least 75% by weight in other embodiments, and at least 70% by weight in other embodiments.

[0066] Referring here to Figure 6, a simplified block flow diagram of the etherification apparatus (102, 202) and reverse decomposition apparatus (104, 204) according to the embodiments described herein is illustrated. Mixed C4 stream 701 containing isobutylene among the other components described above, and stream 703 containing oxygenated compound reactants such as methanol, ethanol, isobutanol, water, or mixtures thereof, may be supplied to the etherification reaction system 702. The etherification reaction system 702 may include one or more reactors for selectively reacting isobutylene with water, methanol, ethanol, or other oxygenated reactants on a suitable catalyst, for example, to form one or more of MTBE, ETBE, or TBA. The reaction effluent stream 704 may then be fed to a separation system 706, which may include, for example, one or more distillation columns or extractive distillation columns, to separate MTBE, ETBE, or TBA from the unreacted C4 component in the mixed feed stream 701, recover the MTBE, ETBE, or TBA as an effluent stream 708, and recover the lighter C4 component via one or more flow streams 714. Unreacted water or alcohol and other etherification reaction byproducts may be recovered by one or more flow streams 715.

[0067] The effluent 708 may then be fed to a reverse decomposition reaction system 710, where it is converted back to its constituent molecules isobutylene and oxygen-containing compound reactants such as water, methanol, or ethanol. The reverse decomposition reaction system 710 may include one or more reactors containing a suitable reverse decomposition catalyst. The decomposed effluent 712 may then be recovered from the reactor and fed to a separation system 720, which may include one or more distillation columns or extractive distillation columns for recovering a high-purity isobutylene product 716, any heavy reaction by-products 717, and an alcohol or water reactant 718. The alcohol or water reactant 718 may, if desired, be recycled upstream to the reaction system 702. Although not illustrated, embodiments described herein aim to recover 1-butene, 2-butene, MTBE, ETBE, or other components as separate product streams from the various reaction effluents and separation schemes described above. Since the formation of alcohols or ethers provides efficient separation of isobutylene from n-butene and isobutane that may be present in the C4 feedstream, the use of reverse decomposition following etherification can be used to produce high-purity isobutene products.

[0068] Although the embodiment shown in Figure 3 does not include a decomposition apparatus, the above description of the etherification apparatus applies to the embodiment shown in Figure 3.

[0069] dimerization device Various catalysts and reactor configurations can be used to selectively dimerize isobutylene to form isooctene. One example is an isobutylene dimerization process, which selectively dimerizes isobutylene to isooctene, with a reaction modifier providing the selective formation of isooctene in a preferred ratio to the dimer and trimer of isobutylene. Other known processes can also be used to dimerize isobutylene to form isooctene according to the embodiments described herein. By-products containing C9 and heavier components, such as trimers, tetramers, or other oligomers, as well as by-products resulting from the reaction of isobutylene with present reaction modifiers, can result in a variety of heavier hydrocarbon species. After dimerizing isobutylene to form isooctene, the reaction effluent can be fed into a separation system to separate the desired C8 olefin product stream from the C9 and heavier olefin by-products.

[0070] A general process block flow diagram of an isobutylene dimerizer (106, 206, 306) according to embodiments described herein is shown in Figure 5. An isobutylene-containing stream 601 may be fed into an isobutylene dimerizer 602. The isobutylene dimerizer 302 may contain a selective dimerization catalyst and may be operated under conditions suitable for dimerizing isobutylene (contained in stream 601) to produce isooctene and various by-products. The isobutylene dimerizer effluent stream may be recovered from the isobutylene dimerizer via a flow stream 604, and this recovered effluent stream may be fed into a separator 606 for separating the unrefined isooctene product stream 608 from lighter component streams 613 such as unreacted isobutylene, diluent isobutane or n-butane, and any light reaction modifiers. In some embodiments, such as when the conversion of isobutylene is incomplete, isobutylene may be removed from the resulting isooctene and purged to continue the conversion, or recycled to the dimerization reactor via flow path 623. Similarly, oxygen-containing compounds, such as those recovered in flow path 613, may be recycled to the dimerization reactor as reaction modifiers. The separation apparatus 606 may include, for example, one or more distillation columns or extractive distillation columns for carrying out the desired separation.

[0071] Oxygen-containing compound separator and diisobutylene purification apparatus Each of the oxygen-containing compound separator and diisobutylene purification apparatus may include one or more distillation columns and / or extraction distillation columns for the separation of the various components described above. Although no further details are provided here, it should be noted that in embodiments forming TBA as a byproduct, TBA forms an azeotropic mixture with C8 olefins, and control of TBA is necessary in the design of the oxygen-containing compound separator using a purge flow to meet the DIB purity requirements.

[0072] C4 separation device / CDDeIB device As described in the embodiments above, the mixed C4 feedstream can be separated to recover a light C4 stream containing isobutylene, isobutane, and / or 1-butene, and a heavy C4 stream containing n-butane and 2-butene. In some embodiments, the C4 separation apparatus is or includes a catalytic deisobutene unit for separating light (low boiling point) C4 from heavy (high boiling point) C4.

[0073] Referring here to Figure 4, a simplified process flow diagram of a catalytic deisobutene apparatus 400 according to an embodiment described herein is illustrated. The first step is to feed a mixed C4 stream 402, for example, a mixed C4 reaction effluent or mixed C4 feed stream (320 in Figure 3) from an etherification apparatus (102 and 202 in Figures 1 and 2, respectively) into a deisobutene apparatus (catalytic distillation column) 510. A mixed C4 stream containing 1-butene, 2-butene, isobutene, and n-butane, among other possible C4 components, as well as other possible C4 components, is fed into the catalytic distillation column 510 near the bottom of the catalytic distillation section 512 (catalyst section 512), which contains a hydrogen isomerization catalyst supported in the form of a catalytic distillation structure. Hydrogen may be supplied via a channel 520 and may also be introduced below the catalyst section 512.

[0074] When the reactant feed stream comes into contact with the catalyst, any butadiene in the feed stream is hydrogenated to butene, and equilibrium amounts of 1-butene and 2-butene are produced in the catalyst. 2-butene is distilled and removed as a bottom fraction, directing the reaction at the catalytic site toward the production of 2-butene.

[0075] The removal section of the column may include conventional distillation structures such as bubble caps, sieve trays, or inert packing materials, enabling the complete separation of the 2-butene product from the lower boiling point isobutene and isobutane. The present normal butane will also be removed as a bottom fraction. The 2-butene and normal butane can then be recovered from the catalytic distillation column 510 via channel 525.

[0076] The top flow 516, containing isobutane, as well as optional isobutylene and 1-butene, is condensed in the condenser 518. The condensed top is collected in the receiver separator 530, where the liquid isobutane and isobutylene are separated from the hydrogen and light material discharged through the channel 536. If desired, the hydrogen can be recycled to the catalytic distillation column 510 (hydrogen recovery and recycling are not shown). A portion of the condensed top product is recycled as reflux to the catalytic distillation column 510 via the channel 524. The isobutane and isobutylene are removed as top products via the channel 546.

[0077] The top product stream 546 may contain isobutane and isobutylene, which may result from by-product hydrogenation in the catalytic distillation column 510 or as reaction by-products elsewhere in the system (100, 200). In some embodiments, if a higher purity isobutylene product is desired, for example, the top product stream 546 may be fed to a separator (not shown) for separating isobutylene from isobutane. For example, a small separator may be required for the removal of trace amounts of isobutane. In some embodiments, the deisobutene separator may be such as those described in U.S. Patent No. 6,242,661 or U.S. Patent No. 7,982,086. In other embodiments, an integrated isobutylene (IB) separator, such as that described in U.S. Patent No. 1,105,3177, may be used to remove isobutane from isobutylene to produce a higher purity isobutylene product.

[0078] The catalyst material used for the isomerization reaction is preferably in the form of a distillation packing, such as conventional distillation packing shapes such as Raschig rings, pole rings, or saddles, or as other structures such as balls, irregular shapes, sheets, tubes, spirals, bags, or other structures (e.g., those described in U.S. Patents 4,242,530, 4,443,559, 5,189,001, 5,348,710, and 5,431,890), plated on a grill or screen, or a mesh polymer foam (the foam's cellular structure must be large enough not to cause a large pressure loss through the column, otherwise it must be arranged like chunks or condensing tubes to allow vapor flow). Similarly, the catalyst may be palladium, platinum, or nickel supported on an 1 / 8-inch alumina extruded body, either bagged or loosely packed into the column. In some embodiments, the catalyst may be contained in structures disclosed in U.S. Patent No. 5,730,843, U.S. Patent No. 5,266,546, U.S. Patent No. 4,731,229, and U.S. Patent No. 5,073,236.

[0079] The catalyst contained within the reaction zone of the catalytic distillation column can be any catalyst suitable for the isomerization of 1-butene to 2-butene or hydrogen isomerization. In some embodiments, the catalyst may contain palladium, platinum, or nickel, and may be in the form of an extruded body, for example. For hydrogen isomerization, since hydrogen is lost from the catalyst by hydrogenation when butadiene is contained in the feed stream, the hydrogen supply rate to the distillation column reactor should be sufficient to maintain the catalyst in the active (hydride) form. The hydrogen supply rate can be adjusted so that there is enough hydrogen to support the hydrogenation reaction of butadiene and replenish the hydrogen lost from the catalyst, but can be kept below the amount required for the hydrogenation reaction of butene or the amount that would cause flooding of the column. Generally, the molar ratio of hydrogen to C4 hydrocarbons supplied to the floor of the catalytic distillation column is in the range of about 0.01:1 to 0.60:1, preferably 0.01:1 to 0.10:1.

[0080] Embodiments described herein may carry out the catalytic distillation step in a catalyst-packed column, which is understood to contain a gas phase and some liquid phase in any distillation. Since the reaction occurs simultaneously with the distillation, the initial reaction products are removed from the reaction area as quickly as possible. Furthermore, since all components are boiling, the reaction temperature is controlled by the boiling point of the mixture at the system pressure, which may vary from stage to stage. The heat in the reaction simply causes boiling and does not raise the temperature. In addition, the reaction driving force is increased because the reaction products are removed and cannot contribute to the reverse reaction. As a result, considerable control over the reaction rate and product distribution can be achieved by adjusting the system pressure. Also, throughput (residence time = liquid time-space velocity) -1 By adjusting the following, the product distribution and the degree of conversion from 1-butene to 2-butene can be further controlled.

[0081] The temperature inside a distillation column reactor is determined by the boiling point of the liquid mixture present at any given pressure. The temperature at the bottom of the column will reflect the composition of the materials in that part of the column and will be higher than the temperature at the top. That is, at a constant pressure, a change in the system's temperature indicates a change in the composition within the column. To change the temperature, the pressure is changed. Therefore, temperature control in the reaction zone is achieved by changing the pressure. Increasing the pressure raises the temperature in the system, and vice versa.

[0082] The catalytic distillation columns according to the embodiments described herein may be operated with a top temperature in the range of 32°C to 138°C and a pressure in the range of 3 bara to 20 bara, taking into account the effect of pressure on temperature as described above. In other embodiments, the catalytic distillation columns according to the embodiments described herein may be operated with a top temperature in the range of 85°C or 90°C to 130°C or 135°C and a pressure in the range of 9 bara, 10 bara, or 11 bara to 16 bara, 18 bara, or 20 bara, where any lower limit may be combined with any upper limit. In other embodiments, the top temperature of the catalytic distillation column may be in the range of 32°C to about 80°C, for example, in the range of about 47°C to about 68°C or about 60°C to about 65°C. In yet another embodiment, the top temperature is from the lower limit of 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 85, or 90°C. The range can be up to an upper limit of 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 85, 90, 100, 110, 120, 130, or 138°C, where any lower limit can be combined with any upper limit. In some embodiments, the top pressure of the catalytic distillation column can be in the range of about 3 bara to about 12 bara, for example, in the range of about 7 bara to about 10 bara. In yet another embodiment, the top pressure of the catalytic distillation column can range from a lower limit of about 9, 10, 11, 12, 13, 14, or 15 bara to an upper limit of about 14, 15, 16, 17, 18, 19, or 20 bara. The bottom temperature of the catalytic distillation column corresponds to the boiling point of higher boiling point components under operating conditions and in various embodiments can range from about 60°C to about 180°C, for example, from about 60°C to about 100°C or from about 65°C to about 88°C, but can be higher based on the desired top temperature and pressure.The operating temperature may also take into account the catalyst activity required to facilitate the desired 1-butene to 2-butene reaction.

[0083] In the embodiments described herein, the catalytic distillation column is operated under conditions such as temperature and pressure, which tend to keep 1-butene in contact with the catalyst while 2-butene is excluded from contact with the catalyst. Thus, once 1-butene isomerized to 2-butene, it detaches from the catalyst and descends through the column, where it is removed as a bottom fraction. The column may include reflux, in which case the reflux ratio can be, for example, in the range of 0.5:1 to 33:1.

[0084] As described above, the mixed C4 is supplied to a catalytic distillation column. Within the catalytic distillation column, the C4 stream is further processed along with the hydrogen feed stream using a positional isomerization catalyst and a hydrogenation catalyst to convert 1-butene to 2-butene and selectively hydrogenate any butadiene present from the upstream process. Simultaneous fractional distillation results in two C4 product streams, in some embodiments, containing 2-butene and n-butane bottom distillation products as well as a high-purity isobutene top product. A hydrogen-containing vent gas may also be recovered.

[0085] With respect to Figure 3, the isobutylene product stream produced by processing the C4 feed stream through the catalytic distillation column may have an isobutylene content of at least 80% by weight. The high-purity isobutylene product stream may be produced with a purity of at least 85% by weight, at least 90% by weight, at least 95% by weight, at least 98% by weight, at least 99% by weight, at least 99.5% by weight, or at least 99.9% by weight in various embodiments. With respect to Figures 1 and 2, the C4 fraction fed into the C4 separation area may be deficient in isobutylene that has been reacted and consumed in the etherification reaction area, in which case the top product from catalytic distillation may be a high-purity isobutane product, which may have a purity of at least 85% by weight, at least 90% by weight, at least 95% by weight, at least 98% by weight, at least 99% by weight, at least 99.5% by weight, or at least 99.9% by weight in various embodiments.

[0086] In further embodiments, a catalytic distillation column for processing the mixed C4 stream described herein may result in three C4 product streams containing 2-butene and n-butane bottom-flow products, isobutane top-flow products, and high-purity isobutylene products. The high-purity isobutylene products can be recovered, for example, as a bottom-flow draw from a separator as described above, or, in some embodiments, as a side-draw fraction 530 from the catalytic distillation column. This side-draw may be located in a column of appropriate height and may recover an isobutane / isobutene stream having an isobutane to isobutene ratio in the range of 0.001:1 to 2:1, e.g., 0.01:1 to 1:1.5, or 0.1:1 to 1:1. This side draw may be located above the catalytic distillation reaction area, and the feed flow may be located below the catalytic distillation reaction area, providing a side draw containing a relatively low amount of n-butene so that a flow containing more than 80%, more than 95%, more than 98%, or more than 99%, or more than 99.9%, of isobutylene can be recovered. A sufficient number of stages and height to the column may be provided to result in an isobutane top flow that is primarily isobutane-containing, for example, more than 95% or more than 98% isobutane (both by weight %).

[0087] In some embodiments, the isobutylene product stream produced by isomerization of 1-butene to 2-butene in a catalytic distillation column, as described herein, may have an isobutylene purity of at least 99.9% by weight, 99.95% by weight, or 99.99% by weight, based on the total amount of isobutylene and 1-butene contained in the high-purity isobutylene product stream, whether it is a top draw or a side draw from the catalytic distillation column.

[0088] Diluent It has been found that the operation of the isobutylene dimerizer can be improved by the addition of a diluent. n-butane produced in the catalytic distillation column (Figure 3), or n-butane recovered in the etherification unit of the C4 separation unit (Figures 1 and 2), can be supplied to the dimerizer, where the n-butane can act as a diluent to help control the reaction in the skeleton isomerization unit. Alternatively, fresh butane or supplemental butane can be supplied to the dimerizer. In some embodiments, for example, where the feed stream concentration or the formation of n-butane byproducts is low, the resulting diluent feed stream to the dimerizer will also have a small amount of n-butane. In such embodiments, a saturated (hydrogenation) reactor can be used to react n-butane with hydrogen to form a desired amount of n-butane for use as a diluent during skeleton isomerization.

[0089] dehydrogenation If a sufficient amount of isobutane product is recovered, this recovered isobutane product may be dehydrogenated, if desired, to form additional isobutene and hydrogen. The hydrogen may be recovered and used as a feed stream to a catalytic deisobutene or hydrogenation reactor to generate an n-butane diluent, while the C4 dehydrogenated effluent may be fed to a catalytic deisobutene, etherification reactor, or otherwise processed using the apparatus described herein to recover additional isobutylene.

[0090] As described above, embodiments described herein include the production of MTBE or ETBE for use as a dimerization reaction modifier for producing isooctene and isobutylene in high purity via ether reverse decomposition. Based on enthalpy calculations between ETBE decomposition and MTBE decomposition, the enthalpy from ETBE decomposition is lower than that from MTBE, hypothetically meaning that less energy is required. Hypothetically, the same reactor conditions in the MTBE decomposition mode can also be applied to ETBE decomposition based on enthalpy data from in-house models for the compound. For the decomposition rate between ETBE and MTBE, a decomposition rate lower than 5% is estimated. If the decomposition rate of MTBE is 88%, it is assumed that ETBE is 95% of 88%, i.e., about 84%. The components expected at the outlet of the isobutylene reactor in an ETBE environment are isobutylene, n-butene, TBA, ethanol, unconverted ETBE and ESBE, DEE (heavier than DME), and DIB. These components can be separated by distillation, and the isobutylene product can be purified. The ethanol recovered from the decomposition process can be supplied back to the upstream etherification unit to reduce ethanol replenishment from the feed source. Components such as ETBE, ESBE, TBA, DIB, DEE, water, and additional ethanol obtained from the ETBE reaction process can be used as modifiers for the subsequent dimerization step to produce isooctene. The purity of this isooctene will depend on the amount of n-butene present in the feed stream, which is less than 1% by weight in some embodiments. The less n-butene present in the C4 feed stream, the higher the purity of the final isooctene (DIB) product. Variations of the dimerization selector can also be used, and oxygen-containing compounds derived from ethanol, as well as C1-C4 alcohols and / or glycols, can be used.

[0091] The methods illustrated and described herein can be used to modify existing MTBE equipment for gasoline blending (for example), thereby modifying such equipment to produce isooctene for petrochemical applications. This method can also be used for the co-production of HPIB and HPDIB. The advantages of the methods described herein are the possibility of reusing existing MTBE platforms for the isooctene process and the semi-closed-loop system in the use of external diluents.

[0092] Useful reactors in the embodiments disclosed herein may include conventional fixed-bed reactors, boiling reactors, and pulsed-flow reactors, in which the reaction flow and product flow may be parallel or counter-flow. Boiling reactors and pulsed-flow reactors may also provide continuous cleaning of the catalyst in addition to capturing at least some of the heat in the reaction through evaporation, enabling an improved reactor temperature profile compared to conventional fixed-bed reactors. Useful reactors in the embodiments disclosed herein may be used as standalone reactors or in combination with one or more reactors of the same or different types.

[0093] Any type of reactor may be used to carry out the reactions described herein. Examples of reactors suitable for carrying out the reactions of the embodiments described herein may include distillation column reactors, split-wall distillation column reactors, conventional tubular fixed-bed reactors, bubble column reactors, slurry reactors with or without a distillation column, pulse-flow reactors, catalytic distillation columns in which a slurry solid catalyst flows down the column, conventional fixed-bed reactors, or any combination of these reactors. A multi-reactor system useful in the embodiments disclosed herein may include, for each reaction area, reactors of the same type arranged in series or in parallel, or reactors of different types arranged in series. Those skilled in the art will recognize that other types of reactors may also be used.

[0094] Unless otherwise defined, all technical and scientific terms used have the same meaning as those generally understood by those skilled in the art in which these systems, apparatus, methods, processes, and compositions belong.

[0095] Unless the context explicitly indicates otherwise, the singular forms "a," "an," and "the" refer to multiple objects.

[0096] As used herein and in the appended claims, the words “comprise,” “has,” and “include,” as well as all their grammatical variations, are intended to have an open, non-restrictive meaning that does not exclude any additional elements or processes.

[0097] When the terms "approximately" or "about" are used, these terms 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%.

[0098] A range can be expressed in a form that includes approximately "one specific value" to approximately "another specific value." When such a range is expressed, another embodiment should be understood as being from one specific value to another specific value, and including all specific values ​​and their combinations within that range.

[0099] While this disclosure includes a limited number of embodiments, those skilled in the art who are interested in this disclosure will understand that other embodiments can be devised that do not deviate from the scope of this disclosure. Therefore, the scope should be limited only by the appended claims.

Claims

1. A process for the co-production of high-purity isobutylene and high-purity isooctene, wherein the process comprises The process involves supplying ethanol and mixed C4 hydrocarbons to an ETBE converter, wherein the mixed C4 supply stream contains a mixture of hydrocarbons including 1-butene, 2-butene, n-butane, isobutane, and isobutylene. Within the ETBE conversion apparatus, the isobutylene is reacted with ethanol using a catalyst to form ethyl tert butyl ether; the ETBE reaction effluent is recovered; and the ETBE reaction effluent is separated to recover a first fraction containing the ethyl tert butyl ether and a second fraction containing 1-butene, 2-butene, isobutane, and n-butane. The first fraction containing ethyl tert butyl ether is supplied to the ETBE decomposition apparatus, In the ETBE decomposition apparatus, ethyl tert butyl ether is decomposed to form a decomposition reaction effluent containing isobutylene, ethanol, and unreacted ethyl tert butyl ether; and the reaction effluent is separated to recover an isobutylene fraction containing 95% by weight or more of isobutylene and a first oxygen-containing compound fraction containing the ethanol and unreacted ethyl tert butyl ether. The first portion of the isobutylene fraction is recovered as a high-purity isobutylene product fraction, The second portion of the isobutylene fraction is supplied to an isobutylene dimerizer, A portion of the first fraction containing ethyl tert butyl ether, a portion of the first oxygen-containing compound fraction, or both, is supplied to the isobutylene dimerizer as a reaction modifier. In the isobutylene dimerizer, the isobutylene is dimerized to form a dimerization reaction effluent containing isooctene, a reaction modifier, and by-products isobutylene trimer and oligomer; and the dimerization reaction effluent is separated to recover a heavy fraction containing isooctene, the by-products isobutylene trimer and oligomer, ethyl tert butyl ether, and ethanol, and a light fraction containing isobutylene and ethanol. The heavy fraction is supplied to an oxygen-containing compound separator to recover a first dimerization product fraction containing isooctene and the by-products isobutylene trimer and oligomer, and a second dimerization product fraction containing a reaction modifier. The first dimerization product fraction is supplied to the DIB purification apparatus, In the DIB purification apparatus, the first dimerization product fraction is separated to recover an isooctene fraction containing 95% by weight or more isooctene and a by-product fraction containing the isobutylene trimer and oligomer. A process that includes this.

2. The process according to claim 1, further comprising supplying a portion of the second dimerization product fraction containing the reaction modifier to the isobutylene dimerizer as an additional reaction modifier.

3. The process according to claim 1, further comprising supplying the second fraction to a C4 separator, separating the second fraction in the C4 separator to recover a light C4 fraction containing 1-butene and isobutane and a heavy C4 fraction containing 2-butene and n-butane.

4. The process according to claim 1, wherein one or both of the ETBE reaction effluent and the decomposition reaction effluent further comprise one or more of the by-products diisobutene, ethylsec butyl ether, tertiary butyl alcohol, or diethyl ether.

5. The process according to claim 1, further comprising supplying a portion of the first oxygen-containing compound fraction to the ETBE converter.

6. A process for the co-production of high-purity isobutylene and high-purity isooctene, wherein the process comprises The method involves supplying methanol and mixed C4 hydrocarbons to an MTBE converter, wherein the mixed C4 supply stream contains a mixture of hydrocarbons including 1-butene, 2-butene, n-butane, isobutane, and isobutylene. Within the MTBE conversion apparatus, isobutylene is reacted with ethanol using a catalyst to form methyl tert-butyl ether; the MTBE reaction effluent is recovered; and the MTBE reaction effluent is separated to recover a first fraction containing the methyl tert-butyl ether and a second fraction containing 1-butene, 2-butene, isobutane, and n-butane. The first fraction containing the methyl tert butyl ether is supplied to the MTBE decomposition apparatus. In the MTBE decomposition apparatus, methyl tert-butyl ether is decomposed to form a decomposition reaction effluent containing isobutylene, methanol, and unreacted methyl tert-butyl ether; and the reaction effluent is separated to recover an isobutylene fraction containing 95% by weight or more of isobutylene and a first oxygen-containing compound fraction containing methanol and unreacted methyl tert-butyl ether. The first portion of the isobutylene fraction is recovered as a high-purity isobutylene product fraction, The second portion of the isobutylene fraction is supplied to an isobutylene dimerizer, A portion of the first fraction containing methyl tert butyl ether, a portion of the first oxygen-containing compound fraction, or both, is supplied to the isobutylene dimerizer as a reaction modifier. In the isobutylene dimerizer, the isobutylene is dimerized to form a dimerization reaction effluent containing isooctene, a reaction modifier, and by-products isobutylene trimer and oligomer; and the dimerization reaction effluent is separated to recover a heavy fraction containing isooctene, the by-products isobutylene trimer and oligomer, methyl tert butyl ether, and methanol, and a light fraction containing isobutylene and methanol. The heavy fraction is supplied to an oxygen-containing compound separator to recover a first dimerization product fraction containing isooctene and the by-products isobutylene trimer and oligomer, and a second dimerization product fraction containing a reaction modifier. The first dimerization product fraction is supplied to the DIB purification apparatus, In the DIB purification apparatus, the first dimerization product fraction is separated to recover an isooctene fraction containing 95% by weight or more isooctene and a by-product fraction containing the isobutylene trimer and oligomer. A process that includes this.

7. The process according to claim 6, further comprising supplying a portion of the second dimerization product fraction containing the reaction modifier to the isobutylene dimerizer as an additional reaction modifier.

8. The process according to claim 6, further comprising supplying the second fraction to a C4 separator, separating the second fraction in the C4 separator to recover a light C4 fraction containing 1-butene and isobutane and a heavy C4 fraction containing 2-butene and n-butane.

9. The process according to claim 6, wherein one or both of the MTBE reaction effluent and the decomposition reaction effluent further comprise one or more by-products: diisobutene, methylsec butyl ether, tertiary butyl alcohol, or dimethyl ether.

10. The process according to claim 6, further comprising supplying a portion of the first oxygen-containing compound fraction to the MTBE converter.

11. A process for the co-production of high-purity isobutylene and high-purity isooctene, wherein the process comprises A mixed C4 stream containing a mixture of hydrocarbons including 1-butene, 2-butene, n-butane, isobutane, and isobutylene is supplied to the catalytic separator. Within the catalyst separation apparatus, a portion of 1-butene is converted to 2-butene, and the hydrocarbon mixture is separated to recover a first top fraction containing 1-butene, isobutane, and isobutene, and a bottom fraction containing n-butane and 2-butene. A portion of the first top fraction is recovered as a high-purity isobutylene product fraction containing at least 95% by weight of isobutylene, A second portion of the first top fraction is supplied to an etherification device, and an alcohol selected from ethanol or methanol is supplied to the etherification device. Within the etherification conversion apparatus, the process involves reacting an alcohol with isobutylene to form an alkyl tert butyl ether, and recovering the etherification reaction effluent containing the alkyl tert butyl ether and the alcohol. The aforementioned etherification reaction effluent is supplied to the isobutylene dimerizer as a reaction modifier, The second portion of the first top fraction is supplied to the isobutylene dimerizer, In the isobutylene dimerizer, the isobutylene is dimerized to form a dimerization reaction effluent containing isooctene, a reaction modifier, and by-products isobutylene trimer and oligomer; and the dimerization reaction effluent is separated to recover a heavy fraction containing isooctene, the by-products isobutylene trimer and oligomer, alkyl tert butyl ether, and alcohol, and a light fraction containing isobutylene and alcohol. The heavy fraction is supplied to an oxygen-containing compound separator to recover a first dimerization product fraction containing isooctene and the by-products isobutylene trimer and oligomer, and a second dimerization product fraction containing a reaction modifier. The first dimerization product fraction is supplied to the DIB purification apparatus, In the DIB purification apparatus, the first dimerization product fraction is separated to recover an isooctene fraction containing 95% by weight or more isooctene and a by-product fraction containing the isobutylene trimer and oligomer. A process that includes this.

12. The process according to claim 11, wherein separating the mixture in the catalyst separation apparatus includes recovering a first top fraction containing at least 95% by weight of isobutylene and a side draw fraction containing 1-butene, isobutane, and isobutylene, the side draw fraction being supplied as a second fraction to the etherification conversion apparatus.

13. The process according to claim 11, further comprising supplying a portion of the second dimerization product fraction to the isobutylene dimerizer.

14. The process according to claim 11, wherein the alcohol is ethanol.

15. The process according to claim 11, wherein the alcohol is methanol.

16. A system for the co-production of high-purity isobutylene and high-purity isooctene, wherein the system is One or more fluid conduits for supplying ethanol and mixed C4 hydrocarbons to an ETBE converter, wherein the mixed C4 hydrocarbons contain a mixture of hydrocarbons including 1-butene, 2-butene, n-butane, isobutane, and isobutylene, The ETBE conversion apparatus includes one or more reactors configured to react isobutylene with ethanol using a catalyst to form ethyl tert butyl ether and to recover the ETBE reaction effluent, and a separation system configured to separate the ETBE reaction effluent and recover a first fraction containing the ethyl tert butyl ether and a second fraction containing 1-butene, 2-butene, isobutane, and n-butane, A channel for supplying the first fraction containing ethyl tert butyl ether to an ETBE decomposition apparatus, The ETBE decomposition apparatus includes one or more reactors configured to decompose ethyl tert butyl ether to form a decomposition reaction effluent containing isobutylene, ethanol, and unreacted ethyl tert butyl ether, and a separation system configured to separate the reaction effluent and recover an isobutylene fraction containing 95% by weight or more isobutylene and a first oxygen-containing compound fraction containing the ethanol and unreacted ethyl tert butyl ether, A channel for recovering the first portion of the isobutylene fraction as a high-purity isobutylene product fraction, A flow path for supplying the second portion of the isobutylene fraction to an isobutylene dimerizer, A flow path for supplying a portion of the first fraction containing ethyl tert butyl ether, a portion of the first oxygen-containing compound fraction, or both, to the isobutylene dimerizer as a reaction modifier, The isobutylene dimerizer includes one or more reactors configured to dimerize the isobutylene to form a dimerization reaction effluent containing isooctene, a reaction modifier, and by-products isobutylene trimer and oligomer; and a separation system for separating the dimerization reaction effluent to recover a heavy fraction containing isooctene, the by-products isobutylene trimer and oligomer, ethyl tert butyl ether, and ethanol, and a light fraction containing isobutylene and ethanol. A separator for oxygen-containing compounds for separating the heavy fraction and recovering a first dimerization product fraction containing isooctene and the by-products isobutylene trimer and oligomer, and a second dimerization product fraction containing a reaction modifier, A flow path for supplying the first dimerization product fraction to the DIB purification apparatus, The DIB purification apparatus includes a separation system for separating the first dimerization product fraction and recovering an isooctene fraction containing 95% by weight or more isooctene and a by-product fraction containing the isobutylene trimer and oligomer, A system that includes these features.

17. A system for the co-production of high-purity isobutylene and high-purity isooctene, wherein the system is One or more fluid conduits for supplying methanol and the mixed C4 hydrocarbon to an MTBE converter, wherein the mixed C4 hydrocarbon contains a mixture of hydrocarbons including 1-butene, 2-butene, n-butane, isobutane, and isobutylene, The MTBE conversion apparatus includes one or more reactors configured to react isobutylene with ethanol using a catalyst to form methyl tert butyl ether and to recover the MTBE reaction effluent, and a separation system for separating the MTBE reaction effluent to recover a first fraction containing the methyl tert butyl ether and a second fraction containing 1-butene, 2-butene, isobutane, and n-butane, A channel for supplying the first fraction containing the methyl tert butyl ether to an MTBE decomposition apparatus, The MTBE decomposition apparatus includes one or more reactors for decomposing methyl tert-butyl ether to form a decomposition reaction effluent containing isobutylene, methanol, and unreacted methyl tert-butyl ether, and a separation system configured to separate the reaction effluent and recover an isobutylene fraction containing 95% by weight or more isobutylene and a first oxygen-containing compound fraction containing the methanol and unreacted methyl tert-butyl ether, A channel for recovering the first portion of the isobutylene fraction as a high-purity isobutylene product fraction, A flow path for supplying the second portion of the isobutylene fraction to an isobutylene dimerizer, A flow path for supplying a portion of the first fraction containing methyl tert butyl ether, a portion of the first oxygen-containing compound fraction, or both, to the isobutylene dimerizer as a reaction modifier, The isobutylene dimerizer includes one or more reactors for dimerizing the isobutylene to form a dimerization reaction effluent containing isooctene, a reaction modifier, and by-products isobutylene trimer and oligomer, and a separation system for separating the dimerization reaction effluent to recover a heavy fraction containing isooctene, the by-products isobutylene trimer and oligomer, methyl tert butyl ether, and methanol, and a light fraction containing isobutylene and methanol. A separator for oxygen-containing compounds for separating the heavy fraction and recovering a first dimerization product fraction containing isooctene and the by-products isobutylene trimer and oligomer, and a second dimerization product fraction containing a reaction modifier, A flow path for supplying the first dimerization product fraction to the DIB purification apparatus, The DIB purification apparatus includes a separation system for separating the first dimerization product fraction and recovering an isooctene fraction containing 95% by weight or more isooctene and a by-product fraction containing the isobutylene trimer and oligomer, A system that includes these features.

18. A system for the co-production of high-purity isobutylene and high-purity isooctene, wherein the system is One or more channels for supplying a mixed C4 stream containing a mixture of hydrocarbons including 1-butene, 2-butene, n-butane, isobutane, and isobutylene to a catalytic separator, The catalyst separation apparatus includes a catalytic distillation column configured to convert a portion of the 1-butene to 2-butene and simultaneously separate the hydrocarbon mixture to recover a first top fraction containing 1-butene, isobutane, and isobutene, and a bottom fraction containing n-butane and 2-butene, A channel for recovering a portion of the first top fraction as a high-purity isobutylene product fraction containing at least 95% by weight of isobutylene, One or more channels for supplying an alcohol selected from ethanol or methanol and a second portion of the first top fraction to an etherification conversion device, The etherification conversion apparatus includes one or more reactors for reacting an alcohol with isobutylene to form an alkyl tert butyl ether and recovering an etherification reaction effluent containing the alkyl tert butyl ether and the alcohol, A channel for supplying the etherification reaction outflow to an isobutylene dimerizer as a reaction modifier, A flow path for supplying the second portion of the first top fraction to the isobutylene dimerizer, The isobutylene dimerizer includes one or more reactors for dimerizing the isobutylene to form a dimerization reaction effluent containing isooctene, a reaction modifier, and by-products isobutylene trimer and oligomer, and a separation system for separating the dimerization reaction effluent to recover a heavy fraction containing isooctene, the by-products isobutylene trimer and oligomer, alkyl tert butyl ether, and alcohol, and a light fraction containing isobutylene and alcohol. A separator for oxygen-containing compounds for separating the heavy fraction and recovering a first dimerization product fraction containing isooctene and the by-products isobutylene trimer and oligomer, and a second dimerization product fraction containing a reaction modifier, A flow path for supplying the first dimerization product fraction to the DIB purification apparatus, The DIB purification apparatus includes a separation system for separating the first dimerization product fraction and recovering an isooctene fraction containing 95% by weight or more isooctene and a by-product fraction containing the isobutylene trimer and oligomer, A system that includes these features.

Images