A membrane separation process and apparatus for separating 1,3-butadiene from a C4 hydrocarbon mixture

Abstract

The present application relates to a kind of membrane separation method and device for separating 1,3-butadiene from C4 hydrocarbon mixture.The membrane separation method uses C4 hydrocarbon mixture as raw material, makes it pass through MOF membrane and is separated, and the 1,3-butadiene is obtained in the permeation side of membrane;The C4 hydrocarbon mixture includes 1,3-butadiene, and also includes the combination of one or more selected from normal butene, isobutene, normal butane, isobutane, cis-2-butene, trans-2-butene;The MOF membrane is selected from the combination of one or more of MIL-53, Co-gallate, Al-bttotb, MIL-160, UiO-66, ZIF-7, ZIF-8 and ZIF-90.Separation is carried out in MOF membrane separation device, which includes MOF membrane separator, MOF membrane separator includes MOF membrane assembly and the MOF membrane.The method uses membrane separation technology, and high-purity 1,3-butadiene can be obtained efficiently, and production capacity is increased.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of membrane separation technology, and particularly relates to a method and device for separating 1,3-butadiene from C4 hydrocarbon mixture by using membrane separation technology. BACKGROUND

[0002] 1,3-butadiene is an important component in C4 petroleum distillate, and is one of the basic raw materials for petroleum chemical industry, which can be used to produce synthetic rubber, resin and other polymer materials. In the synthetic rubber manufacturing industry, the consumption of 1,3-butadiene can account for more than 60% of the total raw material consumption. 1,3-butadiene is mainly obtained by separation and purification of C4 fraction mixture in petroleum gas, which usually consists of 30-60% of 1,3-butadiene, 10-20% of 1-butene, 10-30% of isobutene, and 3-10% of butane and isobutane, etc. In the process of synthetic rubber, the presence of other C4 hydrocarbons will cause the structural transformation of polybutadiene, affect the product quality, and even interrupt the polymerization reaction and reduce the polymerization activity. Therefore, the C4 mixed gas must be separated and purified to obtain 1,3-butadiene with a purity of more than 99.5% before it can be put into production. Since C4 hydrocarbons (especially diene and mono-olefin) have similar boiling points, molecular size and physical properties, it is still a great challenge to separate them.

[0003] Currently, the separation of butadiene from other C4 hydrocarbons in industry mainly involves continuously adding a very strong polar solvent (also known as an extractant, such as acetonitrile, dimethylformamide and N-methyl pyrrolidone) into a rectification tower to change the relative volatility between the components in the C4 fraction, so that a liquid mixture that is difficult to separate by ordinary distillation becomes easy to separate. For example, the dimethylformamide DMF method, which includes four processes, namely a first extractive distillation process, a second extractive distillation process, a rectification process and a solvent recovery process. The raw material C4 is vaporized and enters the first extractive distillation tower, and the solvent DMF is added from the upper part of the tower. Butane, butene and C3 with low solubility increase the relative volatility of butadiene, and are separated from the top of the tower, while butadiene and acetylenes are led out from the bottom of the tower together with the solvent, are completely desorbed in the first desorption tower, are cooled and compressed by a screw compressor, and then enter the second extractive distillation tower for further separation. The solvent free of C4 components is taken out from the bottom of the desorption tower at high temperature, and is used as a heat source for extractive distillation, rectification, evaporation and other processes, and is recycled after heat recovery. Acetylenes, propadiene, sulfides and carbonyl compounds have high solubility in the solvent, in order to prevent the explosion of vinyl acetylene and ethyl acetylene, and to further recover butadiene in the solvent, the rich solvent discharged from the bottom of the second extractive tower is sent to a butadiene recovery tower, and the crude butadiene is obtained at the top of the tower. The butadiene and a small amount of impurities distilled from the top of the recovery tower are returned to the inlet of the compressor before the second extractive tower, and the solvent containing acetylenes in the tank is sent to the second desorption tower, from which vinyl acetylene and ethyl acetylene are separated from the top of the tower, are diluted and used as boiler fuel, and the tank liquid is the solvent, which is recycled to the extractive distillation tower. The impurities in the crude butadiene obtained by two-stage extractive distillation are removed by ordinary rectification. C3 and water, which have higher volatility than butadiene, are removed at the top of the light-removing tower, and residual 2-butene, 1,2-butadiene, C5 and a small amount of butadiene dimers generated during production, which have lower volatility than butadiene, are removed at the bottom of the heavy-removing tower, and finally, the polymerization grade butadiene with a purity of more than 99.5% can be obtained at the top of the heavy-removing tower. However, extractive distillation usually requires a high operating temperature (323-393 K), more than 110 plates and a large amount of organic solvent. In addition, the polymerization of butadiene with high reactivity is inevitable during high-temperature distillation. Therefore, the extractive distillation process is energy-intensive and environmentally unfriendly, and it is very important to seek an efficient and low-cost technology for separating butadiene.

[0004] Membrane separation technology, as a green, safe and efficient common platform technology, has the advantages of reduced investment and operating costs, energy saving and consumption reduction, and process intensification due to integration, and is considered as an important prospective technology for realizing the efficient separation of hydrocarbon mixtures with the same carbon number. Theoretical simulation shows that the integration and coupling of membrane separation and distillation technology for the separation of hydrocarbon systems with the same carbon number is expected to save more than 50% of the separation energy consumption.

[0005] However, how to effectively separate 1,3-butadiene by using membrane separation technology to obtain high-purity 1,3-butadiene is rarely reported in the prior art. SUMMARY

[0006] In view of the defects and shortcomings of the prior art, the purpose of the present application is to provide a method for separating 1,3-butadiene from a C4 hydrocarbon mixture, which uses membrane separation technology to efficiently increase production capacity and obtain high-purity 1,3-butadiene.

[0007] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is:

[0008] A membrane separation method for 1,3-butadiene, using a C4 hydrocarbon mixture as raw material, allowing it to pass through a MOF membrane for separation, and obtaining the 1,3-butadiene on the permeation side of the membrane; the C4 hydrocarbon mixture includes 1,3-butadiene and a combination of one or more selected from n-butene, isobutene, n-butane, isobutane, cis-2-butene, and trans-2-butene; the MOF membrane is selected from a combination of one or more of MIL-53, Co-gallate, Al-bttotb, MIL-160, UiO-66, ZIF-7, ZIF-8, and ZIF-90.

[0009] In the present application, the C4 hydrocarbon mixture refers to a mixture of C4 hydrocarbons, which may also include a small amount of C5 component impurities, such as isoamylene, cyclopentane, etc., and the mass percentage content of C5 component is 0.04% or less.

[0010] In the present application, the permeation side refers to the side after the material passes through the membrane, which is the side of the components that can permeate through the membrane; correspondingly, the retentate side refers to the side that cannot pass through the membrane, and these components cannot permeate through the membrane.

[0011] The present application finds that the use of the above-mentioned specific type of MOF membrane can effectively separate 1,3-butadiene.

[0012] In some embodiments, the mass percentage of 1,3-butadiene in the C4 hydrocarbon mixture is 10% to 60%.

[0013] In some embodiments, the mass percentage of n-butene in the C4 hydrocarbon mixture is 10% to 50%.

[0014] In some embodiments, the mass percentage of isobutene in the C4 hydrocarbon mixture is 10% to 50%.

[0015] In some embodiments, the mass percentage of n-butane in the C4 hydrocarbon mixture is 5% to 10%.

[0016] In some embodiments, the mass percentage of the isobutane in the C4 hydrocarbon mixture is 5-10%.

[0017] In some embodiments, the mass percentage of the cis-2-butene in the C4 hydrocarbon mixture is 3.7% or less.

[0018] In some embodiments, the mass percentage of the trans-2-butene in the C4 hydrocarbon mixture is 4.8% or less.

[0019] In some embodiments, the separation factor of the MOF membrane for 1,3-butadiene and other components in the C4 hydrocarbon mixture is 2-7; preferably 6-7.

[0020] In some embodiments, the permeance of the MOF membrane for 1,3-butadiene is 10-100 GPU, preferably 80-100 GPU.

[0021] In some embodiments, the membrane area of the MOF membrane is 0.01-10 m2. 2 .

[0022] In some embodiments, the thickness of the MOF membrane is 500 nm-3 pm, preferably 1.8-2.3 pm.

[0023] In some embodiments, the temperature of the separation is 258-333 K, preferably 298-308 K.

[0024] In some embodiments, the pressure of the separation is 1-7 bar, preferably 1-2 bar.

[0025] Using the above preferred process parameters such as thickness, temperature and pressure, the selectivity of 1,3-butadiene can be further improved, thereby improving the separation effect and obtaining 1,3-butadiene with higher purity.

[0026] In some embodiments, the MOF membrane comprises a support selected from single-channel, multi-channel or flat plate. Correspondingly, the MOF membrane is in the shape of tube or flat plate.

[0027] In some embodiments, the membrane separation method further comprises a step of pretreating the C4 hydrocarbon mixture before the separation; the pretreatment is selected from compression, filtration or heating.

[0028] In some embodiments, the membrane separation method is carried out in a MOF membrane separation device, wherein the MOF membrane separation device comprises a MOF membrane separator;

[0029] The MOF membrane separator comprises a MOF membrane assembly and the MOF membrane;

[0030] The MOF membrane assembly is used to fix the MOF membrane;

[0031] The membrane separation method comprises the steps of taking out the 1,3-butadiene from the permeation side of the MOF membrane, and taking out other components in the C4 hydrocarbon mixture from the retentate side of the MOF membrane.

[0032] In some embodiments, the MOF membrane is a sheet-shaped membrane containing a flat carrier, the MOF membrane assembly is provided with a support frame for fixing the MOF membrane, and the support frame can be passed through by gas or liquid; the membrane separation method comprises the steps of passing the C4 hydrocarbon mixture through the MOF membrane in the MOF membrane assembly, and taking out the 1,3-butadiene from the side of the support frame away from the MOF membrane, and taking out other components in the C4 hydrocarbon mixture from the other side of the support frame;

[0033] Alternatively,

[0034] The MOF membrane is a tubular membrane containing a tubular carrier, the MOF membrane assembly is tubular and is arranged outside the MOF membrane, and a cavity is formed between the MOF membrane and the MOF membrane assembly;

[0035] The MOF membrane has a fluid cavity inside for fluid to pass through;

[0036] The membrane separation method comprises the steps of passing the C4 hydrocarbon mixture through the fluid cavity for membrane separation, and taking out the 1,3-butadiene from the cavity, and taking out other components in the C4 hydrocarbon mixture from the fluid cavity.

[0037] The way the MOF membrane assembly fixes the MOF membrane and forms a cavity between them can adopt a conventional structural way in the art, for example, inserting a tubular MOF membrane into a rubber ring made of rubber material, and clamping the rubber ring on the inner wall of the MOF membrane assembly, so that the two are fixed and a cavity is formed in the middle.

[0038] In some embodiments, the C4 hydrocarbon mixture is in gas phase or liquid phase. When the other components in the C4 hydrocarbon mixture are different from the 1,3-butadiene, the state of the mixture may be different, which may be in gas phase or in liquid phase.

[0039] In some embodiments, the MOF membrane separation device comprises a gas phase feed pipe and a liquid phase feed pipe.

[0040] In some embodiments, the C4 hydrocarbon mixture is in gas phase, and the feed flow rate of the gas phase is 0.2-25 L / min.

[0041] In some embodiments, the C4 hydrocarbon mixture is in a liquid phase, and the feed flow rate of the liquid phase is 0.2-25 L / min.

[0042] In some embodiments, the MOF membrane separation device further comprises:

[0043] a pre-treater for pre-treating the C4 hydrocarbon mixture before separation;

[0044] a flow controller for controlling the feed flow rate of the C4 hydrocarbon mixture;

[0045] a pump for extracting the 1,3-butadiene.

[0046] In some embodiments, the flow controller is disposed between the pre-treater and the MOF membrane separator.

[0047] In some embodiments, the C4 hydrocarbon mixture is in a gas phase, and the MOF membrane separation device further comprises a nitrogen purger connected to the outlet of the cavity or the support frame; and the 1,3-butadiene is extracted by the pump or the nitrogen purger.

[0048] In some embodiments, the MOF membrane separation device comprises one or more of the MOF membrane separators.

[0049] Preferably, the plurality of MOF membrane separators are arranged in series.

[0050] In some embodiments, the MOF membrane assembly is made of stainless steel or nylon.

[0051] In some embodiments, the MOF membrane and the MOF membrane assembly are arranged in concentric circles, and the cavity is in the shape of a circular ring.

[0052] Preferably, the radius of the circular ring is 1-5 mm.

[0053] In some embodiments, if the feed is a gas phase mixture, the gas phase product on the permeation side of the MOF membrane separation device is extracted by N2 purging or a pump, and the gas phase product on the retentate side is extracted by a back pressure valve. The back pressure valve can provide negative pressure, which is beneficial for the extraction of the retentate components. If the feed is a liquid phase mixture, the liquid phase product on the permeation side of the MOF membrane separation device is extracted by a pump, and the liquid phase product on the retentate side is extracted by a back pressure valve.

[0054] In some embodiments, the purity of 1,3-butadiene in the extracted components on the permeation side is controlled to be above 95.0%, preferably 95.0%-99.5%. The purity is very high.

[0055] In some embodiments, the content of 1,3-butadiene in the retentate side produced component is controlled in the range of 5.0% or less, for example, 1.0%-5.0%.

[0056] The present application also provides a MOF membrane separation device used in the foregoing method. The MOF membrane separation device can effectively separate 1,3-butadiene.

[0057] Thanks to the above technical solutions, the present application has the following advantages compared with the prior art:

[0058] The membrane separation method of 1,3-butadiene of the present application has high separation selectivity when separating 1,3-butadiene and other low-carbon hydrocarbon mixtures, can effectively separate and enrich 1,3-butadiene, has excellent separation effect, has low device investment, is energy-saving and environment-friendly, and can produce huge economic benefits. BRIEF DESCRIPTION OF DRAWINGS

[0059] Figure 1 is a structural schematic diagram of the MOF membrane separation device of the present application.

[0060] Figure 2 is another structural schematic diagram of the MOF membrane separator of the present application.

[0061] Figure 3 is a result graph of the influence of feed temperature on the separation performance of the MIL-53 membrane separation device.

[0062] Figure 4 is a result graph of the influence of feed pressure on the separation performance of the ZIF-90 membrane separation device.

[0063] Figure 5 is a result graph of the influence of feed membrane thickness on the separation performance of the Al-bttotb membrane separation device.

[0064] Figure 6 is a result graph of the influence of impurity gas on the separation performance of the MIL-160 membrane separation device.

[0065] Figure 7 is a result graph of the influence of feed composition on the separation performance of the ZIF-8 membrane separation device.

[0066] Figure 8 is a result graph of the influence of mixed liquid phase feed on the stability of the UiO-66 membrane separation device.

[0067] Wherein, 1-preprocessor, 2-pump, 3-flow controller, 4-MOF membrane separator, 5-MOF membrane module, 6-MOF membrane, 7-pressure gauge, 8-valve, 9-cavity, 10-fluid cavity, 11-gas phase feed pipe, 12-liquid phase feed pipe, 13-support frame, a-permeate component, b-retentate component, c-nitrogen, d-feed. Detailed Implementation

[0068] Figure 1 Taking a tubular membrane separation device (i.e., the MOF membrane 6 is tubular, using a tubular carrier) as an example, the feed gas or feed liquid (C4 hydrocarbon mixture) enters the device from the gas phase feed pipe 11 or the liquid phase feed pipe 12, respectively, and then undergoes pretreatment (compression, filtration, or heating, etc.) by the preprocessor 1 to ensure that the feed meets the corresponding requirements. The specific structure of the preprocessor 1 used in this invention is not particularly limited; it can include a compression device, a drying device, a filtration device, or a heating device. This pretreatment of the C4 hydrocarbon mixture before the feed enters the MOF membrane separator ensures the required feed state. The treated feed enters the MOF membrane separator 4 for separation via the flow controller 3.

[0069] The mixed hydrocarbons, pretreated by preprocessor 1, enter MOF membrane separator 4, which mainly consists of MOF membrane module 5 and MOF membrane 6. MOF membrane module 5 is made of stainless steel or nylon. The mixed hydrocarbon components pass through fluid chamber 10 and are separated by MOF membrane 6. The portion that permeates through the membrane layer is called the permeate component and enters the permeate side, i.e., cavity 9 region. The component that does not permeate through the membrane layer is called the residual component and enters the residual side. Subsequently, each component is sampled and tested using appropriate methods.

[0070] The specific steps are as follows:

[0071] First, the entire system is shut down, the feed is controlled as liquid phase, partial valve 8 is opened, partial valve 8 is adjusted according to the back pressure requirements, partial pump 2 is started and the flow controller 3 corresponding to the liquid phase feed pipe 12 is adjusted so that the mixed hydrocarbon (C4 hydrocarbon mixture) feed meets the required feed requirements, and then enters the MOF membrane separator 4 for separation. Since the permeate side component is only collected by the pump when the liquid phase feed is used, at this time, the corresponding partial valve 8 needs to be opened and partial pump 2 needs to be started to collect the permeate component, and the residual component is collected through another partial valve 8.

[0072] Alternatively, the entire system can be shut down first, with the feed controlled in the gas phase. Partial valve 8 can be opened, and its adjustment based on back pressure requirements can be made. The flow controller 3 corresponding to the gas phase feed pipe 11 can also be adjusted to ensure the mixed hydrocarbon feed meets the required feed conditions. The mixture then enters the MOF membrane separator 4 for separation. The permeate-side component is collected via partial valve 8, while the permeate-side component can be collected by pump extraction or nitrogen purging. If pump extraction is used, the corresponding partial valve 8 is opened, and the corresponding pump 2 is started to collect the product. If nitrogen purging is used, the corresponding flow controller 3 and partial valve 8 are opened, and the permeate component is collected at one end of valve 8.

[0073] The main features of the MOF membrane separation unit described above are as follows: under gas-phase feed conditions, the permeate side is pumped or purged with N2 for extraction, while the residual side is controlled by a back pressure valve. Under liquid-phase feed conditions, the permeate side is pumped out, and the residual side is controlled by a back pressure valve. When the hydrocarbon mixture enters the separation unit, the 1,3-butadiene component enters the permeate side. If the 1,3-butadiene concentration on the residual side does not decrease to the target value, the residual hydrocarbon mixture can be controlled by a back pressure valve to be returned to the MOF membrane module or fed into the next MOF membrane module (e.g., in series) for separation. When the permeate component 1,3-butadiene cannot achieve sufficient purity, the gas-phase feed can use a pump or N2 purging to power the permeate gas 1,3-butadiene to the next stage MOF membrane module for separation. The operation method is the same for liquid feed as for gas feed. The final extracted product, 1,3-butadiene, has a purity greater than 95%.

[0074] In addition, when the system to be separated contains impurities and the impurities are enriched to a high concentration after separation, a branch can be added at the permeate outlet to reduce the impact of high-concentration feed on the membrane separation of the target system.

[0075] MOF membrane 6 can also be a sheet-like membrane, such as Figure 2 As shown, the MOF membrane module 5 is equipped with a support frame 13 for fixing the MOF membrane 6, and the support frame 13 allows gas or liquid to pass through. The membrane separation method includes the steps of passing a C4 hydrocarbon mixture through the MOF membrane 6 in the MOF membrane module 5, the steps of extracting 1,3-butadiene from the side of the support frame 13 away from the MOF membrane 6, and the steps of extracting other components in the C4 hydrocarbon mixture from the other side of the support frame 13. The extraction method is basically the same as that corresponding to the tubular membrane method.

[0076] The feed pressure range of the above MOF membrane separation equipment is controlled between 1 and 7 bar.

[0077] The feed temperature range of the above-mentioned MOF membrane separation equipment is controlled between 258 and 333 K.

[0078] The feed flow rate of the above-mentioned MOF membrane separation equipment is controlled within the range of 0.2 to 25 L / min.

[0079] The 1,3-butadiene feed composition of the above-mentioned MOF membrane separation equipment is controlled within the range of 10% to 90%.

[0080] The separation factor in the above-mentioned MOF membrane separation equipment is controlled within the range of 2-40.

[0081] The permeability of 1,3-butadiene in the above-mentioned MOF membrane separation device is controlled within the range of 10 to 100 GPU.

[0082] The membrane thickness in the above MOF membrane separation equipment is controlled between 500 nm and 3 μm.

[0083] The purity of 1,3-butadiene in the permeate side of the MOF membrane separation device is controlled in the range of 95.0%-99.5%.

[0084] The application will be further described in detail through specific embodiments. However, those skilled in the art should understand that the following examples are only used to illustrate the application and should not be regarded as limiting the scope of the application. The specific techniques and conditions not mentioned in the examples should be based on the techniques or conditions described in the literature in the art. The reagents or instruments not mentioned by the manufacturer are all conventional products that can be obtained by market.

[0085] Example 1

[0086] This example provides a membrane separation method of 1,3-butadiene, which is specifically as follows:

[0087] A sheet-shaped MIL-53 membrane with a thickness of 1 μm is selected as the separation membrane material. A mixed gas with a mass percentage of 50% n-butene and 50% 1,3-butadiene is introduced into a pre-treater 1 to remove water and other solid particles in the mixed gas. The feed pressure is controlled at 1 bar, and the temperature is set at 298 K. The pre-treated raw gas is introduced into a MOF membrane separator 4 through a flow controller at a flow rate of 0.25 L / min through the feed port of the membrane module for separation. The permeate component 1,3-butadiene is collected through the membrane module outlet by a pump or N2purging, and the retentate component is collected through the membrane module outlet by a back pressure valve.

[0088] The separation temperature is changed to 298 K, 303 K, 308 K, 313 K, 318 K, and 323 K, respectively, and the permeation rates of 1,3-butadiene and n-butene are tested, and the separation selectivity is calculated. The results are shown in Table 1. Figure 3 As shown in Table 1, the separation selectivity of the MOF membrane separation device for 1,3-butadiene / n-butene is as high as 7.8, and the permeation rate of 1,3-butadiene is as high as 6.9 x 10 -9 mol / m 2 s Pa. With the increase of the feed temperature from 298 K to 323 K, the separation selectivity decreases by 29.7%. The purity of 1,3-butadiene in the first gas component collected on the permeate side is as high as 95% or more, and the concentration of n-butene in the second gas component collected on the retentate side is 60%, which can be introduced into the next membrane module for further separation.

[0089] Example 2

[0090] This example provides a membrane separation method of 1,3-butadiene, which is specifically as follows:

[0091] A sheet-like ZIF-90 membrane with a thickness of 1 μm was selected as the separation membrane material. A mixed gas containing 50% isobutylene and 50% 1,3-butadiene by mass percentage was introduced into the pre-processor 1 to remove moisture and other solid particles from the mixed gas. The feed temperature was controlled at 348 K and the pressure was set to 1 bar (gauge pressure). The pretreated feed gas was then introduced into the ZIF-90 membrane separator 4 through the feed inlet of the membrane module at a flow rate of 0.4 L / min via a flow controller. The permeate gas component was collected from the outlet of the permeate membrane module by a pump or N2 purging, while the residual component was collected through the outlet of the membrane module via a back pressure valve.

[0092] The separation pressure was varied to 1 bar, 1.5 bar, 2 bar, 2.5 bar, and 3 bar, and the permeability of 1,3-butadiene and n-butene was tested. The separation selectivity was calculated. The results are as follows: Figure 4 As shown, the ZIF-90 membrane separation unit exhibits a high separation selectivity of 15.3 for 1,3-butadiene / isobutene, and a high permeability of 1.08 × 10⁻⁶ for 1,3-butadiene. -8 mol / m 2 As the feed pressure increased, the permeability of 1,3-butadiene decreased by 14.8%, and the separation selectivity decreased by 28.9%. The purity of 1,3-butadiene in the first gas component collected from the permeate side was over 90%, and the concentration of isobutene in the second gas component collected from the permeate side was over 60%, which can be fed into the next membrane module for further separation.

[0093] Example 3

[0094] This embodiment provides a membrane separation method for 1,3-butadiene, as detailed below:

[0095] Sheet-like Al-bttotb membranes of varying thicknesses (0.8 μm, 1.3 μm, 1.8 μm, 2.3 μm, and 2.8 μm) were selected as the separation membrane material. Butene and 1,3-butadiene were mixed at a 1:1 mass ratio and fed into pre-processor 1 to remove moisture and other solid particles from the mixed gas. The feed temperature was controlled at 298 K and the pressure at 1 bar. The pretreated feed gas was then fed into the Al-bttotb membrane separator at a flow rate of 0.15 L / min through the membrane module inlet via a flow controller. The permeate was collected through the membrane module outlet by a pump or N2 purging, while the residual component was collected through the membrane module outlet via a back pressure valve.

[0096] The effect of membrane thickness on separation efficiency is as follows: Figure 5 As shown, the Al-bttotb membrane separation device exhibits a high selectivity of 6 for separating 1,3-butadiene / n-butene, and a high permeability of 9.2 × 10⁻⁶ for 1,3-butadiene. -9mol / m 2 s Pa. With the increase of membrane thickness, the permeation rate of 1,3-butadiene decreased by 55.43%, and the separation selectivity increased by 57.3%. The purity of 1,3-butadiene in the first gas component collected from the permeation side was as high as more than 95%, and the concentration of n-butene in the second gas component collected from the retentate side was higher than 60%, which could be further separated by the next membrane module.

[0097] Example 4

[0098] The present embodiment provides a membrane separation method for 1,3-butadiene, which is specifically as follows:

[0099] A sheet-shaped MIL-160 membrane with a thickness of 1.5 μm was selected as the separation membrane material. A mixed gas with a mass percentage of 50% isobutene and 50% 1,3-butadiene was introduced into a pre-treater 1 to remove water and other solid particles in the mixed gas, so that the temperature of the treated gas was controlled at 323 K and the pressure was controlled at 2 bar. The pre-treated raw gas was introduced into the MIL-160 membrane separator 4 through the inlet of the membrane module at a flow rate of 0.3 L / min by a flow controller, and the first gas component was collected from the permeation side through the outlet of the membrane module by a pump or N2purging, and the retentate side component was collected through the outlet of the membrane module by a back pressure valve.

[0100] The composition of the mixed gas was adjusted, which contained other impurity gases in addition to isobutene and 1,3-butadiene, and the specific composition was as follows: a mixed gas with a mass percentage of 5% n-butane, 5% isobutane, 20% isobutene, 20% n-butene and 50% 1,3-butadiene.

[0101] The results are shown in Table 1. Figure 6 As shown in Table 1, when the MIL-160 membrane separation device was used to separate the mixture containing only isobutene and 1,3-butadiene (without impurity gas), the separation selectivity of isobutene / 1,3-butadiene was maintained at about 6, and the permeation rate of 1,3-butadiene was maintained at about 9.6 x 10 -9 mol / m 2 s Pa. When the mixed gas containing impurities was separated, the separation selectivity of 1,3-butadiene / isobutene and the permeation rate of 1,3-butadiene decreased slightly, and the permeation rate of 1,3-butadiene fluctuated slightly with the increase of separation time, but remained unchanged overall, and the separation selectivity of isobutene / 1,3-butadiene remained basically unchanged. This indicates that the method of the present application can effectively separate the raw mixed gas containing impurity gases. The purity of 1,3-butadiene in the gas component collected from the permeation side was as high as more than 92%.

[0102] Example 5

[0103] The embodiment provides a membrane separation method of 1,3-butadiene, and specifically as follows.

[0104] ZIF-8 membranes (alumina ceramic tube as a carrier, single channel) with a membrane thickness of 2 μm are selected as separation membrane materials, and a gaseous mixture of n-butene and 1,3-butadiene is separated, wherein the 1,3-butadiene composition of the feed is controlled from 10% to 90% (mass percentage, 10%, 30%, 50%, 70%, and 90% respectively). The mixed gas is first introduced into a pre-treater 1 to remove water and other solid particles in the mixed gas, so that the temperature of the treated gas is controlled at 313 K and the pressure is controlled at 1 bar. The pre-treated raw gas is introduced into a ZIF-8 membrane separator 4 through the inlet of a membrane module at a flow rate of 0.2 L / min, the first gas component is collected on the permeation side through the outlet of the membrane module by pumping or N2purging, and the retentate side component is collected through the outlet of the membrane module by a back pressure valve. Figure 7 As shown in the figure, with the increase of the 1,3-butadiene feed ratio, the permeation rate of n-butene slightly rises, the permeation rate of 1,3-butadiene is generally stable and maintained at about 3.4 x 10 -8 mol / m 2 s Pa, and the selectivity of the separation membrane as a whole shows a downward trend. It can be seen that the raw mixture with a wide range of 1,3-butadiene composition can be effectively separated by the method.

[0105] Embodiment 6

[0106] The embodiment provides a membrane separation method of 1,3-butadiene, and specifically as follows.

[0107] A sheet-shaped UiO-66 membrane with a membrane thickness of 1.5 μm is selected as a separation membrane material, and a mixed solution with 5% n-butane, 5% iso-butane, 20% iso-butene, 20% n-butene, and 50% 1,3-butadiene is introduced into a pre-treater 1 to remove water and other solid particles in the mixed solution, the temperature of the feed is controlled at 263 K, and the pressure is controlled at 1 bar. The pre-treated raw material is introduced into a UiO-66 membrane separator 4 through the inlet of a membrane module at a flow rate of 0.4 L / min, the liquid phase component is collected on the permeation side through the outlet of the membrane module by pumping, and the retentate component is collected through the outlet of the membrane module by a back pressure valve.

[0108] The change of the separation effect with time is shown in the figure. Figure 8 As shown in the figure, with the increase of the separation time, the separation selectivity of the UiO-66 membrane separation device for 1,3-butadiene / other C4hydrocarbons is about 3.1, and the permeation rate of 1,3-butadiene is about 8.5 x 10 -9 mol / m 2s Pa. This indicates that the stability of UiO-66 membrane slightly fluctuates under liquid phase conditions, but is generally stable. The purity of 1,3-butadiene in the first liquid component collected from the permeate side is as high as more than 90%, and the purity of other C4 hydrocarbon components in the second liquid component collected from the retentate side is higher than 80%, which can be further separated by the next membrane module.

[0109] The above examples are only for illustrating the technical concept and characteristics of the present application, and the purpose is to enable those skilled in the art to understand the content of the present application and to implement it, and cannot limit the protection scope of the present application. Any equivalent changes or modifications made according to the spirit and essence of the present application shall be covered within the protection scope of the present application.

Claims

1. A membrane separation method for 1,3-butadiene, characterized in that: A C4 hydrocarbon mixture is used as a raw material and separated by passing it through a MOF membrane to obtain the 1,3-butadiene on the permeate side of the membrane. The C4 hydrocarbon mixture includes 1,3-butadiene and also includes one or more combinations selected from n-butene, isobutene, n-butane, isobutane, cis-2-butene, and trans-2-butene. The MOF membrane is selected from one or more combinations selected from ZIF-8 and ZIF-90.

2. The membrane separation method for 1,3-butadiene according to claim 1, characterized in that: In the C4 hydrocarbon mixture, the mass percentage of 1,3-butadiene is 10% to 90%; and / or, the separation factor of the MOF membrane for 1,3-butadiene and other components in the C4 hydrocarbon mixture is 2 to 40; and / or, the permeability of the MOF membrane for 1,3-butadiene is 10 to 100 GPU.

3. The membrane separation method for 1,3-butadiene according to claim 1, characterized in that: The MOF membrane has a membrane area of ​​0.01~10 m². 2 ; and / or, the thickness of the MOF membrane is 500 nm-3 µm; and / or, the separation temperature is 258 ~333 K; and / or, the separation pressure is 1-7 bar.

4. The membrane separation method for 1,3-butadiene according to claim 1, characterized in that: The MOF membrane includes a support selected from single-channel, multi-channel, or flat-plate types; and / or, the membrane separation method further includes a pretreatment step of the C4 hydrocarbon mixture prior to the separation; the pretreatment is selected from compression, filtration, or heating.

5. The membrane separation method for 1,3-butadiene according to any one of claims 1-4, characterized in that: The membrane separation method is carried out in an MOF membrane separation device, which includes an MOF membrane separator. The MOF membrane separator includes an MOF membrane module and the MOF membrane; The MOF membrane assembly is used to fix the MOF membrane; The membrane separation method includes the steps of extracting the 1,3-butadiene from the permeate side of the MOF membrane and the steps of extracting other components in the C4 hydrocarbon mixture from the effluent side of the MOF membrane.

6. The membrane separation method for 1,3-butadiene according to claim 5, characterized in that: The MOF membrane is a sheet-like membrane containing a flat-plate carrier. The MOF membrane assembly is provided with a support frame for fixing the MOF membrane, and the support frame allows gas or liquid to pass through. The membrane separation method includes the steps of passing the C4 hydrocarbon mixture through the MOF membrane in the MOF membrane assembly, the steps of extracting the 1,3-butadiene from the side of the support frame away from the MOF membrane, and the steps of extracting other components in the C4 hydrocarbon mixture from the other side of the support frame. or, The MOF membrane is a tubular membrane containing a tubular carrier. The MOF membrane assembly is tubular and disposed outside the MOF membrane. A cavity is formed between the MOF membrane and the MOF membrane assembly. The MOF membrane has a fluid cavity inside for fluid to pass through; The membrane separation method includes the steps of passing the C4 hydrocarbon mixture through the fluid cavity for membrane separation, the steps of extracting the 1,3-butadiene from the cavity, and the steps of extracting other components of the C4 hydrocarbon mixture from the fluid cavity.

7. The membrane separation method for 1,3-butadiene according to claim 6, characterized in that: The C4 hydrocarbon mixture is in the gas phase or liquid phase; and / or, the MOF membrane separation device includes a gas phase feed pipe and a liquid phase feed pipe.

8. The membrane separation method for 1,3-butadiene according to claim 7, characterized in that: The C4 hydrocarbon mixture is in the gas phase, and the feed flow rate of the gas phase is 0.2~25 L / min; or, the C4 hydrocarbon mixture is in the liquid phase, and the feed flow rate of the liquid phase is 0.2~25 L / min.

9. The membrane separation method for 1,3-butadiene according to claim 6, characterized in that: The MOF membrane separation device further includes: A preprocessor for pretreating the C4 hydrocarbon mixture prior to separation; A flow controller for controlling the feed flow rate of the C4 hydrocarbon mixture; Pumps used to extract the 1,3-butadiene.

10. The membrane separation method for 1,3-butadiene according to claim 9, characterized in that: The C4 hydrocarbon mixture is in the gas phase, and the MOF membrane separation device further includes a nitrogen purger, which is connected to the outlet or support frame of the cavity; the membrane separation method extracts the 1,3-butadiene through the pump or the nitrogen purger.

11. The membrane separation method for 1,3-butadiene according to claim 6, characterized in that: The MOF membrane separation device includes one or more of the MOF membrane separators.

12. The membrane separation method for 1,3-butadiene according to claim 11, characterized in that: The plurality of MOF membrane separators are arranged in series; and / or, the MOF membrane assembly is made of stainless steel or nylon.

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