Method and system for extracting methanol from mixed C4 hydrocarbon raw material
By using ionic liquid extractor and microchannel reactor system in methanol production process, the difficulty of azeotropic separation between mixed C4 hydrocarbons and methanol is solved, and efficient refining and separation of methanol is achieved, reducing energy consumption and simplifying the process, realizing the Miniaturized continuous production.
Patent Information
- Application Number
- CN202310834363.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-07-07
- Publication Date
- 2025-01-07
AI Technical Summary
In the methanol production process, the azeotropy phenomenon of mixed C4 hydrocarbons and methanol leads to difficulty in separation, and the water washing process is costly, energy consumption is high, and wastewater is generated, and there are differences in the refining effect.
The ionic liquid extractant is used to extract methanol through the microchannel reactor system, and the imidazole ionic liquid extractant is mixed with the mixed C4 hydrocarbon raw material to achieve phase separation after extraction, and the extraction agent is distilled under reduced pressure to regenerate the extractant.
It realizes efficient refining and separation of methanol, reduces energy consumption, simplifies processes, and miniaturizes the system, and achieves continuous and safe production.
Smart Images
Figure CN119263960A_ABST
Abstract
Description
Technical Field
[0001] This disclosure relates to the technical field of post-etherification purification methods, and more specifically, to a method and system for extracting methanol from a mixed C4 hydrocarbon feedstock. Background Technology
[0002] Methyl tert-butyl ether (MTBE) is an excellent gasoline additive and antiknock agent. Its physical properties are similar to those of gasoline hydrocarbons, and it exhibits good miscibility with gasoline. It can not only improve the octane rating and driving performance of gasoline but also reduce the CO content in exhaust gases, thus lowering gasoline production costs. Typically, the raw materials for MTBE production are methanol and isobutene from an industrial C4 hydrocarbon mixture. The key components of this C4 hydrocarbon mixture are n-butane, isobutane, 1-butene, 2-butene, butadiene, and isobutene. During the reaction, to ensure complete isobutene reaction, an excess of methanol is usually added (a 20% excess results in 100% isobutene conversion). Therefore, after the reaction, methanol needs to be separated from the C4 hydrocarbon mixture for recycling, and the methanol content in the separated C4 hydrocarbons must not exceed 0.05‰. However, during MTBE production, C4 hydrocarbons and raw material methanol easily form an azeotropic mixture (methanol mass fraction 14.3%).
[0003] Industrially, methanol in a mixture is typically absorbed by washing with water, followed by distillation for dehydration. However, this process has drawbacks such as high equipment costs, complex operation, and high energy consumption, and it also generates a large amount of wastewater. Furthermore, the refining effect can vary depending on the arrangement of the process flow. Summary of the Invention
[0004] The purpose of this disclosure is to provide a process for extracting methanol from mixed C4 hydrocarbon feedstocks with good refining effect and low energy consumption.
[0005] To achieve the above objectives, a first aspect of this disclosure provides a method for extracting methanol from a mixed C4 hydrocarbon feedstock, the method comprising:
[0006] S1. A mixture of C4 hydrocarbon raw materials and extractant is obtained by mixing the mixture;
[0007] S2. Extract the mixture in the reactor to obtain the extracted mixture;
[0008] S3. Separate the extracted mixture to obtain a raffinate phase containing C4 hydrocarbons and an extract phase containing methanol;
[0009] The extractant is an ionic liquid extractant.
[0010] Optionally, the ionic liquid extractant is an imidazole-based ionic liquid extractant; preferably, the ionic liquid extractant is 1-butyl-3-methylimidazolium dibutyl phosphate ionic liquid and / or 1-butyl-3-methylimidazolium dinitrile amine salt ionic liquid.
[0011] Optionally, the mixed C4 hydrocarbon feedstock is post-etherified C4; optionally, the methanol content in the mixed C4 hydrocarbon feedstock is 500-4000 μg / g, and the methanol content in the raffinate phase is not higher than 50 μg / g.
[0012] Optionally, in the mixture, the mass ratio of the extractant to the mixed C4 hydrocarbon feedstock is 1:2 to 1:50, preferably 1:10 to 1:30.
[0013] Optionally, the reactor is a microchannel reactor; optionally, the extraction reaction temperature is 20–100°C, preferably 30–70°C; the outlet pressure of the microchannel reactor is 200–800 kPa, preferably 300–450 Pa; optionally, the residence time of the mixture in the microchannel reactor is 5–70 min, preferably 10–40 min.
[0014] Optionally, the method further includes: preheating the mixed C4 hydrocarbon feedstock and the extractant to the extraction temperature respectively, and then mixing them in a micro mixer to obtain the mixture.
[0015] Optionally, the flow rate of the preheated mixed C4 hydrocarbon feedstock into the micromixer is 0-2000 μL / min; the flow rate of the preheated extractant into the micromixer is 0-200 μL / min.
[0016] Optionally, the microchannel structure in the micromixer is a T-shaped channel structure or a Y-shaped channel structure. Optionally, the cross-section of the microchannel is rectangular, with a width of 0.2–1.2 mm, preferably 0.5–0.8 mm; a height of 1–15 mm, preferably 3–10 mm; and a length of 200–1200 mm, preferably 400–800 mm.
[0017] Optionally, the method further includes: subjecting the extract phase to vacuum distillation, and using the resulting distillate as a regenerated extractant.
[0018] A second aspect of this disclosure provides a system suitable for a method of extracting methanol from a mixed C4 hydrocarbon feedstock, the system comprising: a micromixer, a microchannel reactor, a back pressure valve, and a product separation device; the micromixer and the microchannel reactor are housed in a temperature control device, the product separation device is housed in a cooling device; the product separation device includes a raffinate outlet located at the upper part of the device and an extractant outlet located at the bottom of the device;
[0019] The micromixer includes a C4 hydrocarbon feed inlet, an extractant inlet, and a mixture outlet. The mixture outlet is connected to the feed inlet of the microchannel reactor, the discharge outlet of the microchannel reactor is connected to the feed inlet of the back pressure valve, and the discharge outlet of the back pressure valve is connected to the feed inlet of the product separation device.
[0020] Optionally, the system further includes a vacuum distillation apparatus, the inlet of which is connected to the extract phase outlet of the product separation apparatus;
[0021] Optionally, the system further includes a mixed C4 hydrocarbon feed tank, an extractant feed tank, a mixed C4 hydrocarbon feed pump, and an extractant feed pump; the mixed C4 hydrocarbon feed tank is connected to the mixed C4 hydrocarbon feed inlet of the micro mixer via the mixed C4 hydrocarbon feed pump, and the extractant feed tank is connected to the extractant feed inlet of the micro mixer via the extractant feed pump.
[0022] Through the above technical solution, the method disclosed herein uses an ionic liquid extractant to extract methanol from mixed C4 hydrocarbon feedstocks through the efficient mass transfer and mixing characteristics of a microreactor system. This method has a short residence time, low extractant dosage, high extraction rate, small system size, and simple process, and can continuously and safely extract methanol from mixed C4 hydrocarbon feedstocks.
[0023] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Attached Figure Description
[0024] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the drawings:
[0025] Figure 1 This is a schematic diagram of the process for extracting methanol from a mixed C4 hydrocarbon feedstock as disclosed in this publication.
[0026] Explanation of reference numerals in the attached figures
[0027] 1. Mixed C4 hydrocarbon feed tank; 2. Extractant feed tank
[0028] 3. Mixed C4 hydrocarbon feed pump; 4. Extractant feed pump
[0029] 5. Micromixer 6. Microchannel reactor
[0030] 7. Back pressure valve 8. Product separation device
[0031] 9. Raffinate containing C4 hydrocarbons 10. Vacuum distillation apparatus Detailed Implementation
[0032] The following provides a detailed description of specific embodiments of this disclosure. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit this disclosure.
[0033] A first aspect of this disclosure provides a method for extracting methanol from a mixed C4 hydrocarbon feedstock, the method comprising:
[0034] S1. A mixture of C4 hydrocarbon raw materials and extractant is obtained by mixing the mixture;
[0035] S2. Extract the mixture in the reactor to obtain the extracted mixture;
[0036] S3. Separate the extracted mixture to obtain a raffinate phase containing C4 hydrocarbons and an extract phase containing methanol;
[0037] The extractant is an ionic liquid extractant.
[0038] The method disclosed herein has low energy consumption, can completely refine and separate methanol from mixed C4 hydrocarbon feedstock, achieves enhanced refining process and miniaturized equipment, and is simple and can be used for continuous production.
[0039] The inventors of this disclosure unexpectedly discovered that ionic liquid catalysts exhibit significant advantages in extracting methanol from mixed C4 hydrocarbon feedstocks due to their excellent thermal stability, chemical stability, and structural designability. In this disclosure, the ionic liquid extractant can be an imidazole-based ionic liquid extractant; preferably, when the ionic liquid extractant used in this disclosure is 1-butyl-3-methylimidazolium dibutyl phosphate ionic liquid and / or 1-butyl-3-methylimidazolium dinitrile amine salt ionic liquid, the extraction effect is significantly improved.
[0040] Preferably, the mixed C4 hydrocarbon feedstock is post-etherified C4; in an exemplary embodiment of this disclosure, the methanol content in the post-etherified C4 is 500-4000 μg / g, and the methanol content in the extracted post-etherified C4 is not higher than 50 μg / g.
[0041] According to this disclosure, in the mixture, the mass ratio of the extractant to the mixed C4 hydrocarbon feedstock can be 1:2 to 1:50, preferably 1:10 to 1:30.
[0042] According to this disclosure, the reactor is preferably a microchannel reactor. The microchannel reactor used in this disclosure has the advantages of good mass transfer performance and easily adjustable residence time, enabling effective matching of material residence time, reaction time, and mass transfer time, thereby improving the efficiency of methanol extraction. The extraction reaction temperature can be 20–100℃, preferably 30–70℃; the outlet pressure of the microchannel reactor can be 200–800 kPa, preferably 300–450 Pa; the residence time of the mixture in the microchannel reactor can be 5–70 min, preferably 10–40 min.
[0043] According to this disclosure, the method may further include: preheating the mixed C4 hydrocarbon feedstock and the extractant to their respective extraction temperatures, and then mixing them via a micromixer to obtain the mixture. This disclosure utilizes the uniform liquid-liquid mixing characteristic of the micromixer to disperse the mixed C4 hydrocarbon feedstock and extractant into small, uniform, and controllable droplets, and significantly shortens the material mixing time.
[0044] According to this disclosure, the flow rate of the preheated mixed C4 hydrocarbon feedstock into the micromixer can be 0-2000 μL / min; the flow rate of the preheated extractant into the micromixer can be 0-200 μL / min.
[0045] The microchannel structure in the micromixer described in this disclosure is a T-shaped channel structure or a Y-shaped channel structure. Optionally, the cross-section of the microchannel is rectangular, with a width of 0.2–1.2 mm, preferably 0.5–0.8 mm; a height of 1–15 mm, preferably 3–10 mm; and a length of 200–1200 mm, preferably 400–800 mm.
[0046] The method for extracting methanol from a mixed C4 hydrocarbon feedstock in a microreactor system disclosed herein involves mixing the mixed C4 hydrocarbon feedstock and an ionic liquid extractant in a micromixer. In the micromixing channel, most of the methanol is extracted from the mixed C4 hydrocarbon feedstock into the ionic liquid extractant. The extracted material is then sent to a product receiver in a cooling device for cooling and stratification. The upper liquid phase is the extracted mixed C4 hydrocarbon feedstock, in which most of the methanol has been removed, and the lower liquid phase is the ionic liquid extractant containing most of the methanol.
[0047] According to this disclosure, the method may further include: subjecting the extract phase to vacuum distillation, and using the resulting distillate as a regenerated extractant.
[0048] A second aspect of this disclosure provides a system suitable for a method of extracting methanol from a mixed C4 hydrocarbon feedstock, the system comprising: a micromixer, a microchannel reactor, a back pressure valve, and a product separation device; the micromixer and the microchannel reactor are housed in a temperature control device, the product separation device is housed in a cooling device; the product separation device includes a raffinate outlet located at the upper part of the device and an extractant outlet located at the bottom of the device;
[0049] The micromixer includes a C4 hydrocarbon feed inlet, an extractant inlet, and a mixture outlet; the mixture outlet is connected to the inlet of the microchannel reactor, the outlet of the microchannel reactor is connected to the inlet of the back pressure valve, and the outlet of the back pressure valve is connected to the inlet of the product separation device.
[0050] Optionally, the system further includes a vacuum distillation unit, the inlet of which is connected to the outlet of the extract phase. This disclosure facilitates the separation of methanol from the extract phase by using a vacuum distillation unit, thereby obtaining a distillate residue that can be recycled as a regenerated extractant.
[0051] Optionally, the system further includes a mixed C4 hydrocarbon feed tank, an extractant feed tank, a mixed C4 hydrocarbon feed pump, and an extractant feed pump; the mixed C4 hydrocarbon feed tank is connected to the mixed C4 hydrocarbon feed inlet of the micromixer via the mixed C4 hydrocarbon feed pump, and the extractant feed tank is connected to the extractant feed inlet of the micromixer via the extractant feed pump. The system of this disclosure facilitates feed control by including the C4 hydrocarbon feed tank, the extractant feed tank, the mixed C4 hydrocarbon feed pump, and the extractant feed pump.
[0052] An exemplary implementation of this disclosure, such as Figure 1 As shown, the mixed C4 hydrocarbon feed tank 1 is connected to the first inlet of the micromixer 5 via a pipeline through the mixed C4 hydrocarbon feed pump 3. The extractant feed tank 2 is connected to the second inlet of the micromixer 5 via a pipeline through the ion extractant feed pump 4. The outlet of the micromixer 5 is connected to the inlet of the microchannel reactor 6. The outlet of the microchannel reactor 6 is connected to the inlet of the back pressure valve 7. The outlet of the back pressure valve 7 is connected to the product separation device. The micromixer 5 and the microchannel reactor 6 are placed in a temperature control device. The product separation device 8 is placed in a cooling device. The product separation device 8 is, for example, a receiving tank.
[0053] After the ionic liquid extractant in the extractant raw material tank 2 and the regenerated ionic liquid extractant 10 are mixed, they are mixed with mixed C4 hydrocarbons in a certain proportion in a micro mixer 5 via a mixed C4 hydrocarbon feed pump and an extractant feed pump. The mixture then enters a microchannel reactor 8 and completes methanol extraction under preset reaction conditions. After extraction, the mixture enters a product separation device 8 located in a cooling device after passing through a back pressure valve 7. The upper liquid phase is the raffinate containing C4 hydrocarbons, and the lower liquid phase is the extract phase containing methanol. The extract phase containing methanol is then recycled after vacuum distillation.
[0054] The present disclosure is further described in detail below through examples. All raw materials used in the examples are commercially available.
[0055] Example 1
[0056] The raw material used in this embodiment is a C4 ether (a mixture of methanol and n-hexane) with a methanol content of 1000 ppm. 1-Butyl-3-methylimidazolium dibutyl phosphate ionic liquid is used as the extractant. Figure 1 The process flow shown illustrates methanol extraction experiments on C4 after etherification. The micromixer employs a T-type mixing method, with a micromixing channel cross-section width of 0.5 mm, a height of 8 mm, and a length of 600 mm.
[0057] When conducting the methanol extraction experiment, the reaction temperature was set to 70℃, the outlet pressure of the microchannel reactor was set to 400kPa, the mass ratio of 1-butyl-3-methylimidazolium phosphate dibutyl ionic liquid to C4 after etherification was set to 1:30, the flow rate of C4 after etherification was adjusted to 300μL / min, and the flow rate of 1-butyl-3-methylimidazolium phosphate dibutyl ionic liquid was adjusted to 10μL / min, so that the residence time of the mixture in the micro-reaction channel was 10min.
[0058] Gas chromatography analysis of the raffinate containing C4 hydrocarbons revealed that the methanol content in the C4 ether after methanol extraction was 26.7 ppm, and the methanol extraction rate was 97.3%, meeting industrial-grade requirements. The pressure drop in the microchannel reactor was 0.3 kPa, which met the process design requirements.
[0059] Example 2
[0060] The reaction process in this embodiment is the same as that described in Example 1. The difference is that the extraction reaction temperature is set to 55°C, the outlet pressure of the microchannel reactor is set to 400 kPa, the mass ratio of 1-butyl-3-methylimidazolium phosphate dibutyl ionic liquid to C4 after etherification is set to 1:30, the flow rate of C4 after etherification is adjusted to 360 μL / min, and the flow rate of 1-butyl-3-methylimidazolium phosphate dibutyl ionic liquid is adjusted to 12 μL / min, so that the residence time of the mixture in the micro-reaction channel is 40 min.
[0061] Gas chromatography analysis of the raffinate containing C4 hydrocarbons revealed that the methanol content in the C4 ether after methanol extraction was 38.1 ppm, and the methanol extraction rate was 96.2%, meeting industrial-grade requirements. The pressure drop in the microchannel reactor was 0.4 kPa, which met the process design requirements.
[0062] Example 3
[0063] The reaction process in this embodiment is the same as that described in Example 1. The difference is that the extraction reaction temperature is set to 55°C, the outlet pressure of the microchannel reactor is set to 400 kPa, the mass ratio of 1-butyl-3-methylimidazolium phosphate dibutyl ionic liquid to C4 after etherification is set to 1:10, the flow rate of C4 after etherification is adjusted to 120 μL / min, the flow rate of 1-butyl-3-methylimidazolium phosphate dibutyl ionic liquid is adjusted to 12 μL / min, and the residence time of the mixture in the microreaction channel is set to 10 min.
[0064] Gas chromatography analysis of the raffinate containing C4 hydrocarbons revealed that the methanol content in the C4 ether after methanol extraction was 20.4 ppm, and the methanol extraction rate was 98.0%, meeting industrial-grade requirements. The pressure drop in the microchannel reactor was 0.4 kPa, which met the process design requirements.
[0065] Example 4
[0066] The reaction process in this embodiment is the same as that described in Example 1. The difference is that the extraction reaction temperature is set to 60°C, the microchannel reactor outlet pressure is 400 kPa, and 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid is used as the extractant. Figure 1 The process flow shown is used to perform methanol extraction experiments on C4 after etherification.
[0067] Gas chromatography analysis of the raffinate containing C4 hydrocarbons revealed that the methanol content in the C4 ether after methanol extraction was 48 ppm, and the methanol extraction rate was 95.2%, meeting industrial-grade requirements. The pressure drop in the microchannel reactor was 0.4 kPa, which met the process design requirements.
[0068] As can be seen from Examples 1-4, the method disclosed herein extracts methanol from post-etherification C4 using the highly efficient mass transfer and mixing characteristics of a microreactor system. This method features short residence time, low extractant dosage, and high extraction rate. In particular, when an imidazole-based ionic liquid extractant is used, the extraction efficiency of methanol from post-etherification C4 is significantly improved.
[0069] The preferred embodiments of this disclosure have been described in detail above. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.
[0070] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.
[0071] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.
Claims
1. A method for extracting methanol from a mixed C4 hydrocarbon feedstock, characterized in that: include: S1, mixing a mixed C4 hydrocarbon raw material and an extractant to obtain a mixed material; S2, extracting the mixed material in a reactor to obtain an extracted mixed material; S3, separating the mixed material after extraction to obtain a raffinate phase containing C4 hydrocarbons and an extract phase containing methanol; Wherein, the extractant is an ionic liquid extractant.
2. The method according to claim 1, wherein: The ionic liquid extractant is an imidazole ionic liquid extractant; preferably, the ionic liquid extractant is 1-butyl-3-methylimidazole dibutyl phosphate ionic liquid and / or 1-butyl-3-methylimidazole dinitrile amine salt ionic liquid.
3. The method according to claim 1, wherein: The mixed C4 hydrocarbon feedstock is etherified C4; optionally, the methanol content in the mixed C4 hydrocarbon feedstock is 500-4000 μg / g, and the methanol content in the raffinate phase is not higher than 50 μg / g.
4. The method according to claim 1 or 3, wherein: In the mixed material, the mass ratio of the extractant to the mixed C4 hydrocarbon raw material is 1:2 to 1:50, preferably 1:10 to 1:
30.
5. The method according to claim 1, wherein: The reactor is a microchannel reactor; Optionally, the reaction temperature of the extraction is 20 to 100°C, preferably 30 to 70°C; Optionally, the outlet pressure of the microchannel reactor is 200-800 kPa, preferably 300-450 Pa; the residence time of the mixed material in the microchannel reactor is 5-70 min, preferably 10-40 min.
6. The method according to claim 1, wherein: The method further comprises: preheating the mixed C4 hydrocarbon feedstock and the extractant to extraction temperature respectively, and mixing them in a micro mixer to obtain the mixed material; Optionally, the flow rate of the preheated mixed C4 hydrocarbon feedstock into the micromixer is 0-200 μL / min; the flow rate of the preheated extractant into the micromixer is 0-2000 μL / min.
7. The method according to claim 6, wherein: The microchannel structure in the micromixer is a T-shaped channel structure or a Y-shaped channel structure; Optionally, the cross-section of the microchannel is rectangular, with a width of 0.2 to 1.2 mm, preferably 0.5 to 0.8 mm; a height of 1 to 15 mm, preferably 3 to 10 mm; and a length of 200 to 1200 mm, preferably 400 to 800 mm.
8. The method according to claim 1, wherein: The method further comprises: performing reduced pressure distillation on the extraction phase, and continuously using the obtained residual material as a regenerated extraction agent.
9. A system suitable for the method for extracting methanol from a mixed C4 hydrocarbon feedstock according to any one of claims 1 to 8, characterized in that: The system comprises: a micro mixer, a microchannel reactor, a back pressure valve and a product separation device; the micro mixer and the microchannel reactor are placed in a temperature control device, the product separation device and the cooling device; the product separation device comprises a raffinate phase outlet located in the upper middle part of the device and an extraction phase outlet located in the bottom of the device; Wherein, the micro-mixer includes a mixed C4 hydrocarbon raw material feed port, an extractant feed port and a mixed material discharge port, the mixed material discharge port is connected to the feed port of the microchannel reactor, the discharge port of the microchannel reactor is connected to the feed port of the back pressure valve, and the discharge port of the back pressure valve is connected to the feed port of the product separation device.
10. The system according to claim 9, wherein: The system further comprises a vacuum distillation device, wherein a feed inlet of the vacuum distillation device is connected to an extraction phase outlet of the product separation device; Optionally, the system further comprises a mixed C4 hydrocarbon feedstock tank, an extractant feedstock tank, a mixed C4 hydrocarbon feedstock feed pump and an extractant feed pump; the mixed C4 hydrocarbon feedstock tank is connected to the mixed C4 hydrocarbon feedstock feed port of the micromixer via the mixed C4 hydrocarbon feedstock feed pump, and the extractant feedstock tank is connected to the extractant feed port of the micromixer via the extractant feed pump.