C4 feed pretreatment for mtbe unit and cracker

Abstract

Systems and processes for processing a C3 and C4 hydrocarbon mixture are disclosed. The C3 and C4 hydrocarbon mixture is separated to remove propane from the C4 hydrocarbons. The resulting C4 hydrocarbons are then processed in an isomerization unit to produce additional isobutane. The isobutane of the isomerization unit effluent is dehydrogenated in a dehydrogenation unit to produce isobutylene. The resulting isobutylene is reacted with an alkanol to produce an alkyl tertiary butyl ether.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to European Patent Application No. 20186356.0, filed on 17 July 2020, the entire contents of which are hereby incorporated by reference. Technical Field

[0003] This invention generally relates to a method for producing alkyl tert-butyl ethers. More specifically, this invention relates to a method for producing alkyl tert-butyl ethers from a mixture of C3 and C4 hydrocarbons. Background Technology

[0004] One of the most common alkyl tert-butyl ethers is methyl tert-butyl ether (MTBE), which is used as an additive in gasoline to increase its octane number. Since around 1970, MTBE has been synthesized by the etherification of isobutylene with methanol in the presence of an acidic catalyst. The isobutylene used in MTBE synthesis can be obtained from C4 hydrocarbons. Typically, isobutylene and methanol are fed into a fixed-bed reactor to produce an effluent containing MTBE. The effluent is then fed into a reaction column, where the remaining isobutylene reacts with additional methanol to produce more MTBE.

[0005] One source of C4 hydrocarbons used in MTBE production is liquefied petroleum gas (LPG), which primarily comprises C4 and C3 hydrocarbons. The LPG is processed in an isomerization unit and then in a dehydrogenation unit to produce isobutylene. The effluent from the dehydrogenation unit then flows to the MTBE synthesis unit, where it reacts with methanol to produce MTBE. However, when using LPG as feedstock, the reaction efficiency in the isomerization and / or dehydrogenation units is relatively low, resulting in high production costs for MTBE.

[0006] Overall, while systems and methods exist for producing MTBE from mixtures of C4 and C3 hydrocarbons (e.g., liquefied petroleum gas), this field still requires improvement due to at least the aforementioned drawbacks of conventional systems and methods. Summary of the Invention

[0007] A solution has been found to the aforementioned problems related to systems and methods for producing alkyl tert-butyl ethers (such as MTBE) from mixtures of C4 and C3 hydrocarbons (e.g., liquefied petroleum gas). The solution lies in a method for processing a hydrocarbon mixture containing C4 and C3 hydrocarbons. This method involves separating the hydrocarbon mixture to generate C3 and C4 feed streams, isomerizing the n-butane in the C4 stream, and dehydrogenating the isobutane in the C4 stream to generate isobutene in a dehydrogenation unit. The effluent from the dehydrogenation unit is further fed into an etherification unit for the production of alkyl tert-butyl ethers. The C3 feed stream can be further processed in a cracker to generate propylene and / or ethylene. This is advantageous for at least reducing the inert portion of the feed stream flowing into the isomerization and / or dehydrogenation units, thereby improving the reaction efficiency of isobutane dehydrogenation. Furthermore, the disclosed method can reduce or eliminate the large amount of propane in the C4 processing step, resulting in a feed stream with a higher concentration of isobutene flowing into the MTBE synthesis unit, thereby improving the reaction efficiency in the etherification unit and reducing the amount of gas recycled back to the dehydrogenation unit. This ultimately helps reduce the production cost of alkyl tert-butyl ethers. Therefore, the system and method of the present invention provide technical solutions to at least some of the problems described above related to conventional systems and methods for producing alkyl tert-butyl ethers.

[0008] Embodiments of the present invention include a method for processing a hydrocarbon mixture. The method includes separating a hydrocarbon mixture comprising propane, n-butane, and / or isobutane to generate (1) a C3 stream primarily comprising propane, and (2) a C4 stream comprising n-butane and / or isobutane. The method includes cracking the propane in the C3 stream under reaction conditions sufficient to generate propylene. The method includes treating at least a portion of the C4 stream under isomerization conditions sufficient to isomerize the n-butane in the C4 stream to generate an isomerization unit effluent comprising isobutane.

[0009] Embodiments of the present invention include a method for processing a hydrocarbon mixture. The method includes separating a hydrocarbon mixture comprising propane, n-butane, and / or isobutane to generate (1) a C3 stream primarily comprising propane, and (2) a C4 stream comprising n-butane and / or isobutane. The method includes cracking the propane in the C3 stream under reaction conditions sufficient to generate propylene. The method includes treating at least a portion of the C4 stream under isomerization conditions sufficient to isomerize the n-butane in the C4 stream to generate an isomerization unit effluent comprising isobutane. The method includes dehydrogenating the isobutane in the isomerization unit effluent in a dehydrogenation unit to generate isobutene in the dehydrogenation unit effluent. The method further includes reacting the isobutene in the dehydrogenation unit effluent with an alkynyl alcohol in the presence of a catalyst in an etherification unit under reaction conditions sufficient to generate alkyl tert-butyl ethers in the etherification unit effluent.

[0010] Embodiments of the present invention include a method for processing a hydrocarbon mixture. The method includes separating a hydrocarbon mixture comprising propane, n-butane, and / or isobutane to generate (1) a first C3 stream primarily comprising propane, and (2) a first C4 stream comprising n-butane and / or isobutane. The method includes separating a second hydrocarbon mixture comprising propane, n-butane, and / or isobutane to generate (a) a second C3 stream primarily comprising propane, and (b) a second C4 stream comprising n-butane and / or isobutane. The method includes cracking the propane in the first and second C3 streams under reaction conditions sufficient to generate propylene. The method further includes cracking the n-butane and / or isobutane in the second C4 stream to generate propylene, ethylene, and / or benzene. The method includes treating at least a portion of the first C4 stream under isomerization conditions sufficient to isomerize the n-butane in the C4 stream to generate an isomerization unit effluent comprising isobutane. The method includes dehydrogenating isobutane in an isomerization unit effluent to generate isobutene in the dehydrogenation unit effluent. The method also includes reacting isobutene in an etherification unit effluent with an alkynyl alcohol in the presence of a catalyst under reaction conditions sufficient to generate alkyl tert-butyl ethers in the etherification unit effluent.

[0011] The following includes definitions of various terms and expressions used in this specification.

[0012] The terms “about” or “approximately” are defined as close to what a person skilled in the art would understand. In one non-limiting embodiment, these terms are defined as less than 10%, preferably less than 5%, more preferably less than 1%, and most preferably less than 0.5%.

[0013] The terms "weight%", "volume%", or "molar%" refer to the weight, volume, or mole percentage of a component, based on the total weight, total volume, or total number of moles of the material containing that component. In a non-limiting example, 10 moles of component in 100 moles of material is 10 moles of the component.

[0014] The term “basically” and its variations are defined as including ranges of up to 10%, up to 5%, up to 1%, or up to 0.5%.

[0015] When used in the claims and / or description, the terms “suppress” or “reduce” or “prevent” or “avoid” or any variation thereof include any measurable reduction or complete suppression to achieve the desired result.

[0016] The term “effective” as used in this specification and / or claims means sufficient to achieve the desired, anticipated, or anticipated result.

[0017] When used with the terms “comprising,” “including,” “containing,” or “having” in the claims or specification, the use of “a” or “a type” may mean “a type,” but it is also consistent with the meaning of “a type or more types,” “at least one type,” and “a type or more than one type.”

[0018] The words “contain,” “have,” “include,” or “contain” are inclusive or open-ended and do not exclude additional, unmentioned elements or methods or steps.

[0019] The method of the present invention may "comprise", "consistently constitute" or "consistent with" specific ingredients, components, compositions, etc. disclosed throughout the specification.

[0020] The term "major" as used in this specification and / or claims means greater than any one of 50 wt%, 50 mol%, and 50 vol%. For example, "major" can include all values ​​and ranges from 50.1 wt% to 100 wt%, 50.1 mol% to 100 mol%, or 50.1 vol% to 100 vol%.

[0021] Other objects, features, and advantages of the present invention will become apparent from the following drawings, detailed description, and embodiments. However, it should be understood that while the drawings, detailed description, and embodiments are given by way of illustration only, they are not intended to be limiting. Furthermore, it is conceivable that changes and modifications within the spirit and scope of the invention will be clearly apparent to those skilled in the art from this detailed description. In further embodiments, features from a particular embodiment may be combined with features from other embodiments. For example, a feature from one embodiment may be combined with features from any other embodiment. In further embodiments, additional features may be added to the specific embodiments described herein. Attached Figure Description

[0022] For a more complete understanding, please now refer to the following description in conjunction with the accompanying drawings, wherein:

[0023] Figure 1A-1C A schematic diagram of a system for producing MTBE according to an embodiment of the present invention is shown; Figure 1A A schematic diagram of a system for producing MTBE from a mixture of C3 and C4 propane and butane is shown. Figure 1B A schematic diagram of a system for producing MTBE from a mixture of propane and butane for integration with a second propane and butane processing unit is shown. Figure 1C A schematic diagram of a system for producing MTBE from a mixture of propane and butane is shown, in which a portion of the C4 is processed in a butane cracker; and

[0024] Figure 2 A schematic flowchart of a method for producing MTBE according to an embodiment of the present invention is shown. Detailed Implementation

[0025] Currently, MTBE can be produced by sequentially processing a mixture of C3 and C4 hydrocarbons in an isomerization unit and a dehydrogenation unit. The effluent from the dehydrogenation unit, which contains isobutene, is then fed into an MTBE synthesis unit to produce MTBE. However, the C3 hydrocarbons and light hydrocarbons (e.g., methane and C2 hydrocarbons) in the hydrocarbon mixture are inert components, diluting the C4 hydrocarbon reactants in each reaction unit, thereby reducing reaction efficiency and increasing energy consumption for MTBE production. This invention provides a solution to this problem. The solution presupposes a system and method for processing hydrocarbons, which includes separating C3 and / or C1 to C2 hydrocarbons from the hydrocarbon mixture prior to processing in the isomerization and / or dehydrogenation units, resulting in a higher concentration of isobutane in the feed stream compared to conventional methods, thereby achieving higher reaction efficiency in the feed stream of the dehydrogenation unit. Furthermore, the separated C3 and / or C1 to C2 hydrocarbons can be processed in a steam cracking unit to generate light olefins and / or aromatics, thereby improving the utilization and overall value of the C3 and C4 hydrocarbon mixture. These and other non-limiting aspects of the invention will be discussed in further detail in the following sections.

[0026] A. Systems for processing mixtures of C3 and C4 hydrocarbons

[0027] In embodiments of the present invention, the system for processing hydrocarbon mixtures containing C3 and C4 hydrocarbons includes a separation unit, an isomerization unit, a dehydrogenation unit, a steam cracking unit, and an etherification unit. Notably, compared to conventional systems, this system can reduce energy consumption and improve the production efficiency of alkyl tert-butyl ethers. (Refer to...) Figure 1A The diagram shows a schematic of a system 100 for producing MTBE using a mixture of C3 and C4 as raw materials.

[0028] According to an embodiment of the invention, system 100 includes a first separation device 101 configured to separate a feed stream 11 containing C3 and C4 hydrocarbons to form a first C3 feed stream 12 primarily containing propane and a first C4 feed stream 13 primarily containing n-butane and isobutane. In an embodiment of the invention, the first separation device 101 may include a distillation column. The distillation column may include a propane stripper. In an embodiment of the invention, feed stream 11 may contain 0 to 7 wt% propane, 60 to 80 wt% n-butane, and 20 to 30 wt% isobutane. In an embodiment of the invention, feed stream 11 may include liquefied petroleum gas and may be referred to herein as the first feed stream. In an embodiment of the invention, the first C3 feed stream 12 also contains methane and / or C2 hydrocarbons. According to an embodiment of the invention, the top outlet of the first separation device 101 is in fluid communication with the inlet of a cracking unit 102, such that the first C3 feed stream 12 flows from the first separation device 101 to the cracking unit 102. The cracking unit 102 can be configured to first crack the hydrocarbons of the first C3 feed stream 12 to produce (1) light olefins comprising propylene and / or ethylene, and / or (2) aromatics comprising benzene. In an embodiment of the invention, the cracking unit 102 includes a propane steam cracker.

[0029] According to an embodiment of the invention, the bottom outlet of the first separation device 101 is in fluid communication with the isomerization device 103, such that the first C4 feed stream 13 flows from the first separation device 101 to the isomerization device 103. The isomerization device 103 can be configured to isomerize the n-butane in the first C4 stream 13 to generate an isomerization device effluent stream 14 containing isobutane. The isomerization device 103 may include a fixed-bed reactor, a continuous catalytic converter, and / or an adiabatic or cooled isothermal conversion reactor. In an embodiment of the invention, the isomerization device 103 includes a catalyst, which includes Pt / AlCl3 / Al2O3, Pt / AlCl3 / zeolite, or Pt / SO4. 2- -ZrO2, SO4 2- / ZrO2-Al2O3, or any combination thereof. In an embodiment of the invention, additional n-butane may be added to the first C4 feed stream 13.

[0030] According to an embodiment of the invention, the outlet of the isomerization unit 103 is in fluid communication with the inlet of the dehydrogenation unit 104, such that the isomerization unit effluent stream 14 flows from the isomerization unit 103 to the dehydrogenation unit 104. In an embodiment of the invention, the dehydrogenation unit 104 is configured to dehydrogenate the isobutane in the isomerization unit effluent stream 14 to generate a dehydrogenation unit effluent stream 15 comprising isobutene and / or unreacted isobutane. In an embodiment of the invention, the dehydrogenation unit 104 includes one or more fixed-bed reactors, one or more fluidized-bed reactors, or one or more continuous catalytic converters. The dehydrogenation unit 104 may include a dehydrogenation catalyst comprising chromium oxide / alumina, Pt / alumina, or a combination thereof.

[0031] According to an embodiment of the invention, the outlet of the dehydrogenation unit 104 can be in fluid communication with the inlet of the etherification unit 105, such that the effluent stream from the dehydrogenation unit flows from the dehydrogenation unit 104 to the etherification unit 105. In an embodiment of the invention, the etherification unit 105 is configured to react the effluent stream 15 from the dehydrogenation unit with an alkanol under reaction conditions sufficient to generate a product stream 16 containing alkyl tert-butyl ethers and a recycle stream 17 containing unreacted isobutane. In an embodiment of the invention, the alkyl tert-butyl ethers include MTBE and / or ethyl tert-butyl ether (ETBE). The etherification unit 105 may include an MTBE and / or ETBE synthesis reactor, and an effluent separator configured to separate the effluent from the MTBE and / or ETBE synthesis reactor to form a product stream 16 containing MTBE and / or ETBE and a recycle stream 17 containing isobutane. The MTBE and / or ETBE synthesis reactor may contain a catalyst for catalyzing the MTBE and / or ETBE synthesis reaction, the catalyst comprising a cation exchange resin, sulfonated styrene-divinylbenzene, a cation exchange resin packed with a polystyrene polymer, or a combination thereof. In an embodiment of the invention, the outlet of the etherification unit 105 is in fluid communication with the inlet of the dehydrogenation unit 104, such that the recirculated feed stream 17 flows from the etherification unit 105 back to the dehydrogenation unit 104.

[0032] like Figure 1B As shown, system 200 includes all the feed streams and devices of system 100. According to an embodiment of the invention, system 200 further includes a second separation device 106 configured to receive and separate a second feed stream 18 containing C3 and C4 hydrocarbons to form a second C3 feed stream 19 and a second C4 feed stream 20. In an embodiment of the invention, the second feed stream 18 also contains methane and C2 hydrocarbons. The second C3 feed stream 19 may primarily contain propane. The second C4 feed stream 20 may primarily contain n-butane and isobutane. In an embodiment of the invention, the second feed stream 18 may include liquefied petroleum gas. The second separation device 106 may include a propane stripper.

[0033] According to an embodiment of the invention, the top outlet of the second separation unit 106 may be in fluid communication with the inlet of the cracking unit 102, such that a second C3 feed stream flows from the second separation unit 106 to the cracking unit 102. In an embodiment of the invention, the second C3 feed stream 19 may be merged with the first C3 feed stream 12 to form a merged C3 feed stream 21. The merged C3 feed stream 21 may flow to the cracking unit 102. According to an embodiment of the invention, the bottom outlet of the second separation unit 106 may be in fluid communication with the inlet of a mixed butane cracking unit 107, such that a second C4 feed stream 20 flows from the second separation unit 106 to the mixed butane cracking unit 107. The mixed butane cracking unit 107 may be configured to crack the n-butane and / or isobutane of the second C4 feed stream 20 to produce light olefins and / or aromatics. Light olefins may include ethylene and propylene. Aromatics may include benzene. In an embodiment of the invention, the second separation unit 106 and the mixed butane cracking unit 107 may be in a separate chemical production unit outside of system 100.

[0034] like Figure 1C As shown, system 300 includes all the feed streams and devices of system 100. According to an embodiment of the invention, system 300 further includes a second mixed butane cracking unit 108. The outlet of the first separation unit 101 may be in fluid communication with the second mixed butane cracking unit 108, such that at least a portion of the first C4 feed stream 13 forming the cracker feed stream 22 flows from the first separation unit 101 to the second mixed butane cracking unit 108. The second mixed butane cracking unit 108 may be configured to crack the n-butane and / or isobutane of the cracker feed stream 22 to produce light olefin hydrocarbons and / or aromatics. In embodiments of the invention, the light olefins may include ethylene and / or propylene. The aromatics may include benzene.

[0035] B. Methods for treating mixtures of C3 and C4 hydrocarbons

[0036] Methods for processing mixtures of C3 and C4 hydrocarbons have been discovered. For example... Figure 2 As shown, embodiments of the present invention include a method 400 for processing a mixture of C3 and C4 hydrocarbons to produce alkyl tert-butyl ethers, which improves efficiency and reduces energy consumption compared to conventional methods. Method 400 can be implemented by systems 100, 200, and / or 300, such as... Figure 1A-1C As shown, as described above.

[0037] According to an embodiment of the invention, as shown in block 401, method 400 includes separating a hydrocarbon mixture comprising propane, n-butane, and / or isobutane in a first separation unit 101 to produce (1) a first C3 stream 12 primarily comprising propane, and (2) a first C4 stream 13 comprising n-butane and / or isobutane. The first feed stream 11 may contain 20 to 30 wt% isobutane, 60 to 80 wt% n-butane, and 0 to 7 wt% propane. The first feed stream 11 may also contain methane and / or C2 hydrocarbons, and the first C3 stream 12 may also contain methane and / or C2 hydrocarbons from the first feed stream 11. In an embodiment of the invention, at block 401, the first separation unit 101 operates in a top condensation temperature range of 30 to 40°C and a bottom temperature range of 60 to 120°C. The first separation device 101, located at frame 401, can operate at operating pressures ranging from 15 to 18 bar and in all ranges and values ​​therebetween, including the ranges of 15 to 16 bar, 16 to 17 bar, and 17 to 18 bar. In an embodiment of the invention, the first C3 feed stream 12 comprises 95 to 99.9% by weight propane. The first C4 feed stream 13 may comprise 60 to 75% by weight n-butane and 20 to 40% by weight isobutane.

[0038] According to an embodiment of the invention, as shown in block 402, method 400 includes separating a second hydrocarbon mixture comprising propane, n-butane, and / or isobutane in a second separation unit 106 to produce (a) a second C3 stream 19 primarily comprising propane, and (b) a second C4 stream 20 comprising n-butane and / or isobutane. In an embodiment of the invention, the second feed stream 18 comprises 20 to 30 wt% isobutane, 60 to 80 wt% n-butane, and 0 to 7 wt% propane. The second feed stream 18 may also comprise methane and / or C2 hydrocarbons. According to an embodiment of the invention, the second feed stream 18 comprises liquefied petroleum gas. In an embodiment of the invention, the second separation unit 106 may comprise a distillation column. At block 402, the distillation column may operate in a top condensation range of 30°C to 40°C, a bottom temperature range of 60°C to 120°C, and an operating pressure range of 15 bar to 18 bar. The second C3 stream 19 may contain 95 to 99.9% by weight propane. The second C4 stream 20 may contain 60 to 80% by weight n-butane and 20 to 30% by weight isobutane. In an embodiment of the invention, the second C3 stream 19 may be combined with the first C3 stream 12 to form a combined C3 stream 21.

[0039] According to an embodiment of the invention, as shown in block 403, method 400 includes cracking propane in a first C3 feed stream 12 and / or a second C3 feed stream 19 in a cracking apparatus 102 under reaction conditions sufficient to produce propylene and / or ethylene. Cracking at block 403 may further produce benzene. In an embodiment of the invention, the cracking apparatus 102 includes a steam cracker. The steam cracker can operate at an operating temperature of 750°C to 890°C and a residence time of 0.1 seconds to 0.5 seconds.

[0040] According to an embodiment of the invention, as shown in block 404, method 400 includes cracking n-butane and / or isobutane in a second C4 feed stream 20 in a mixed butane cracking unit 107 to produce propylene, ethylene, benzene, or combinations thereof. The mixed butane cracking unit 107 may include a steam cracker. In an embodiment of the invention, the cracking at block 404 can be carried out at a cracking temperature of 750°C to 890°C and a residence time of 0.1 seconds to 0.5 seconds.

[0041] According to an embodiment of the invention, as shown in block 405, method 400 includes treating at least a portion of the first C4 feed stream 13 in an isomerization apparatus 103 under isomerization conditions sufficient to isomerize the n-butane in the first C4 feed stream 13 to generate an isomerization apparatus effluent stream 14 containing isobutane. In an embodiment of the invention, the isomerization apparatus effluent stream 14 may contain 95 to 99.5 wt% isobutane and all ranges and values ​​therebetween, including 95 to 95.5 wt%, 95.5 to 96 wt%, 96 to 96.5 wt%, 97 to 97 wt%, 97 to 97.5 wt%, 97.5 to 98 wt%, 98 to 98.5 wt%, 98.5 to 99 wt%, and 99 to 99.5 wt%. At block 405, the reaction conditions in the isomerization apparatus 103 may include a reaction temperature of 125°C to 175°C and all ranges and values ​​therebetween. The reaction conditions in the isomerization unit 103 at frame 405 may also include a reaction pressure of 20 to 30 bar, and all ranges and values ​​therebetween. The reaction conditions in the isomerization unit 101 at frame 405 may also include 4 to 6 hours. -1 The heavy space velocity within the range, and all ranges and values ​​in between.

[0042] According to an embodiment of the invention, as shown in block 406, method 400 includes dehydrogenating isobutane in isomerization unit effluent 14 in the presence of a dehydrogenation catalyst within a dehydrogenation unit 104, under reaction conditions sufficient to generate isobutene in the dehydrogenation unit effluent 15. In an embodiment of the invention, the reaction conditions at block 406 include a reaction temperature of 520°C to 640°C, a reaction pressure of 0.36 bar to 1.2 bar, and / or 0.2 to 1.2 h. -1The range of weight hourly space velocity. The dehydrogenation unit effluent stream 15 may contain 35 to 65 wt% isobutylene and all ranges and values ​​therebetween, including the ranges of 35 to 40 wt%, 40 to 45 wt%, 45 to 50 wt%, 50 to 55 wt%, 55 to 60 wt%, and 60 to 65 wt%.

[0043] According to an embodiment of the invention, as shown in block 407, method 400 includes reacting isobutylene from dehydrogenation unit effluent 15 with an alkanol in an etherification unit 105 under reaction conditions sufficient to generate an alkyl tert-butyl ether in the etherification unit effluent stream, in the presence of a catalyst. In embodiments of the invention, non-limiting examples of alkanols include methanol and ethanol. Non-limiting examples of alkyl tert-butyl ethers may include methyl tert-butyl ether (MTBE) and ethyl tert-butyl ether (ETBE). The etherification catalyst may include a cation exchange resin, an ion exchange resin packed with divinyl polystyrene, an ion exchange resin packed with a polymer support, or a combination thereof. The reaction conditions in the etherification unit 105 at block 407 may include an etherification temperature of 40°C to 55°C, an etherification pressure of 5 to 8 bar, and a reaction time of 2 to 4 hours. -1 The liquid hourly space velocity. In an embodiment of the invention, at block 407, the etherification unit effluent stream is further separated to generate a product stream 16 primarily comprising alkyl tert-butyl ethers and a recycle stream 17 primarily comprising isobutane. In an embodiment of the invention, the alkyl tert-butyl ether is MTBE, and product stream 16 comprises 98 to 99.5% by weight MTBE.

[0044] According to an embodiment of the invention, as shown in block 408, method 400 includes diverting recycle stream 17 from etherification unit 105 to dehydrogenation unit 104. In an embodiment of the invention, as shown in block 409, method 400 includes cracking a portion of the first C4 stream 13 in a second mixed butane cracking unit 108 under reaction conditions sufficient to generate light olefins including propylene and / or ethylene. Cracking at block 409 may further generate benzene. In an embodiment of the invention, cracking at block 409 is carried out at a cracking temperature of 750°C to 890°C and a residence time of 0.1 seconds to 0.5 seconds.

[0045] Although embodiments of the present invention have been referenced Figure 2 The boxes have been described, but it should be understood that the operation of the present invention is not limited to... Figure 2 The specific boxes and / or the specific order of the boxes shown. Therefore, embodiments of the present invention can use different... Figure 2 Various boxes in a specific order are used to provide the functionality described in this article.

[0046] The systems and processes described herein may also include various devices not shown and known to those skilled in the art of chemical processing. For example, some controllers, pipes, computers, valves, pumps, heaters, thermocouples, pressure indicators, mixers, heat exchangers, etc., may not be shown.

[0047] As part of this disclosure, specific embodiments are included below. These embodiments are for illustrative purposes only and are not intended to limit the invention. Those skilled in the art will readily recognize that parameters can be changed or modified to produce substantially the same results.

[0048] Example 1

[0049] (Propane Production Simulation)

[0050] The feeds used in the following examples were obtained through statistical analysis of two years of actual operating data from a liquefied petroleum gas (LPG) feed unit (all results are shown in Tables 1 through 3). Bottom and distillate compositions were obtained by simulating a tower suitable for this service. Tables 1 and 3 differ in propane product specifications. The results in Table 3 are matched to commercially available cracker feedstock propane purity. Table 2 shows the maximum propane content in the LPG feed.

[0051] Table 1 Results obtained using low propane feed

[0052]

[0053] Table 2 Results obtained using the maximum propane feed

[0054]

[0055] Table 3 Results obtained using commercially pure propane specifications

[0056]

[0057] In the context of this invention, at least 15 embodiments are described below. Embodiment 1 is a method for processing a hydrocarbon mixture. The method includes separating a hydrocarbon mixture containing propane, n-butane, and / or isobutane to generate (1) a C3 stream mainly containing propane and (2) a C4 stream containing n-butane and / or isobutane. The method further includes cracking the propane in the C3 stream under reaction conditions sufficient to generate propylene and / or ethylene. The method further includes treating at least a portion of the C4 stream under isomerization conditions sufficient to isomerize the n-butane in the C4 stream to generate an isomerization unit effluent containing isobutane. Embodiment 2 is the method of Example 1, further including dehydrogenating the isobutane in the isomerization unit effluent in a dehydrogenation unit to generate isobutene in the dehydrogenation unit effluent. The method further includes reacting the isobutene in the dehydrogenation unit effluent with an alkanol in the presence of a catalyst in an etherification unit under reaction conditions sufficient to generate alkyl tert-butyl ethers in the etherification unit effluent. Embodiment 3 is the method of Embodiment 2, wherein the effluent from the dehydrogenation unit contains 35-60% by weight isobutene. Embodiment 4 is the method of any one of Embodiments 2 or 3, wherein the effluent from the etherification unit contains at least some isobutane, and the method further includes recycling at least some isobutane from the etherification unit effluent to the dehydrogenation unit. Embodiment 5 is the method of any one of Embodiments 2 to 4, wherein the dehydrogenation unit comprises a dehydrogenation catalyst containing chromium oxide / alumina, Pt / alumina, or a combination thereof. Embodiment 6 is the method of any one of Embodiments 2 to 5, wherein alkanols include methanol and / or ethanol. Embodiment 7 is the method of any one of Embodiments 2 to 6, wherein alkyl tert-butyl ethers include methyl tert-butyl ether and / or ethyl tert-butyl ether. Embodiment 8 is the method of any one of Embodiments 1 to 7, further comprising cracking at least a portion of the C4 feed stream in a mixed butane cracker to produce propylene, ethylene, and / or benzene. Embodiment 9 is the method of any one of Embodiments 1 to 8, wherein the C4 feed stream contains 60-75% by weight n-butane and 20-40% by weight isobutane. Embodiment 10 is the method of any one of Embodiments 1 to 9, wherein the C3 feed stream contains 95 to 99.9% by weight propane. Embodiment 11 is the method of any one of Embodiments 1 to 10, wherein the isomerization unit effluent contains 95 to 99.9% by weight isobutane. Embodiment 12 is the method of any one of Embodiments 1 to 11, wherein the hydrocarbon mixture comprises liquefied petroleum gas. Embodiment 13 is the method of any one of Embodiments 1 to 12, wherein the cracking of propane is carried out in a steam cracker at a temperature of 750°C to 900°C and a steam cracker residence time of 0.1 seconds to 0.5 seconds. Embodiment 14 is the method of any one of Embodiments 1 to 13, wherein the isomerization unit comprises Pt / AlCl3 / Al2O3, Pt / AlCl3 / zeolite, or Pt / SO4. 2--ZrO2, SO4 2- Isomerization catalysts of ZrO2-Al2O3 or combinations thereof.

[0058] Implementation Scheme 15 is a method for processing a hydrocarbon mixture. The method includes separating a first hydrocarbon mixture containing propane, n-butane, and / or isobutane to generate (1) a first C3 stream primarily containing propane, and (2) a first C4 stream containing n-butane and / or isobutane. The method further includes separating a second hydrocarbon mixture containing propane, n-butane, and / or isobutane to generate (a) a second C3 stream primarily containing propane, and (b) a second C4 stream containing n-butane and / or isobutane. The method further includes cracking the propane in the first and second C3 streams under reaction conditions sufficient to generate propylene, and cracking the n-butane and / or isobutane in the second C4 stream to generate propylene, ethylene, and / or benzene. The method further includes treating at least a portion of the C4 stream under isomerization conditions sufficient to isomerize the n-butane in the first C4 stream to generate an isomerization unit effluent containing isobutane. In addition, the method includes dehydrogenating isobutane in the isomerization unit effluent to generate isobutene in the dehydrogenation unit effluent, and reacting isobutene in the dehydrogenation unit effluent with alkynol in the presence of a catalyst in the etherification unit under reaction conditions sufficient to generate alkyl tert-butyl ether in the etherification unit effluent.

[0059] Although the embodiments and advantages of this application have been described in detail, it should be understood that various changes, substitutions, and modifications can be made therein without departing from the spirit and scope of the embodiments as defined in the appended claims. Furthermore, the scope of this application is not intended to be limited to the specific embodiments of the processes, machines, manufactures, compositions, tools, methods, and steps described in the specification. Those skilled in the art will readily understand from the foregoing disclosure that processes, machines, manufactures, compositions, tools, methods, or steps that are currently existing or have been developed thereafter can be utilized to perform substantially the same function or achieve substantially the same results as the corresponding embodiments described herein. Therefore, the appended claims are intended to include such processes, machines, manufactures, compositions, tools, methods, or steps within their scope.

Claims

1. A method for processing a hydrocarbon mixture, the method comprising: Separate a hydrocarbon mixture containing propane, n-butane and / or isobutane to produce (1) a C3 stream mainly containing propane and (2) a C4 stream containing n-butane and / or isobutane; The propane vapor of the C3 feed stream is cracked under reaction conditions sufficient to produce at least one olefin selected from propylene or ethylene. At least a portion of the C4 feed stream is treated under isomerization conditions sufficient to isomerize the n-butane in the C4 feed stream to produce an isomerization device effluent containing isobutane. The isobutane in the isomerization unit effluent is dehydrogenated in a dehydrogenation unit to generate isobutene in the dehydrogenation unit effluent; wherein the dehydrogenation unit effluent contains 35 to 60% by weight of isobutene. as well as At least a portion of the C4 feed stream is cracked in a mixed butane cracker to produce propylene, ethylene, and / or benzene.

2. The method according to claim 1, further comprising: In the etherification unit, isobutylene from the dehydrogenation unit effluent is reacted with an alkanol under reaction conditions sufficient to generate alkyl tert-butyl ether in the etherification unit effluent.

3. The method of claim 2, wherein the effluent from the etherification apparatus comprises at least some isobutane, the method further comprising: At least some of the isobutane is recycled from the effluent of the etherification unit back to the dehydrogenation unit.

4. The method according to any one of claims 1 to 2, wherein the dehydrogenation device comprises a dehydrogenation catalyst containing chromium oxide / aluminum oxide, Pt / aluminum oxide, or a combination thereof.

5. The method according to claim 2, wherein the alkanol comprises methanol and / or ethanol.

6. The method of claim 2, wherein the alkyl tert-butyl ether comprises methyl tert-butyl ether and / or ethyl tert-butyl ether.

7. The method according to any one of claims 1 to 2, wherein the C4 feed stream comprises 60 to 75% by weight of n-butane and 20 to 40% by weight of isobutane.

8. The method according to any one of claims 1 to 2, wherein the C3 feed stream comprises 95 to 99.9% by weight of propane.

9. The method according to any one of claims 1 to 2, wherein the effluent from the isomerization device comprises 95 to 99.9% by weight of isobutane.

10. The method according to any one of claims 1 to 2, wherein the hydrocarbon mixture comprises liquefied petroleum gas.

11. The method according to any one of claims 1 to 2, wherein the cracking of propane is carried out in a steam cracker at a temperature of 750°C to 900°C and a steam cracker residence time of 0.1 seconds to 0.5 seconds.

12. The method according to any one of claims 1 to 2, wherein the isomerization apparatus comprises Pt / AlCl3 / Al2O3, Pt / AlCl3 / zeolite, or Pt / SO4. 2- -ZrO2, SO4 2- Isomerization catalysts of ZrO2-Al2O3 or combinations thereof.

13. A method for processing a hydrocarbon mixture, the method comprising: Separate a first hydrocarbon mixture containing propane, n-butane and / or isobutane to generate (1) a first C3 stream mainly containing propane and (2) a first C4 stream containing n-butane and / or isobutane; Separate a second hydrocarbon mixture containing propane, n-butane and / or isobutane to generate (a) a second C3 stream mainly containing propane and (b) a second C4 stream containing n-butane and / or isobutane; The propane vapors of the first C3 feed stream and the second C3 feed stream are cracked under reaction conditions sufficient to generate propylene; The second C4 feed stream is cracked to produce propylene, ethylene and / or benzene; At least a portion of the first C4 feed stream is treated under isomerization conditions sufficient to isomerize the n-butane in the first C4 feed stream to generate an isomerization device effluent containing isobutane. In the dehydrogenation unit, isobutane in the isomerization unit effluent is dehydrogenated to generate isobutene in the dehydrogenation unit effluent; as well as In the etherification unit, isobutylene from the dehydrogenation unit effluent is reacted with alkynols under reaction conditions sufficient to generate alkyl tert-butyl ethers in the etherification unit effluent, in the presence of a catalyst.

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