Membrane separation method and device for separating 1, 3-butadiene from C4 hydrocarbon mixture

Abstract

The invention relates to a membrane separation method and device for separating 1, 3-butadiene from a C4 hydrocarbon mixture. According to the membrane separation method, a C4 hydrocarbon mixture is used as a raw material and is separated through an MOF membrane, and 1, 3-butadiene is obtained on the permeation side of the membrane; the C4 hydrocarbon mixture comprises 1, 3-butadiene, and further comprises one or a combination of more selected from the group consisting of n-butene, isobutene, n-butane, isobutane, cis-2-butene and trans-2-butene; and the MOF film is selected from one or a combination of more of MIL-53, Co-gallate, Al-bttotb, MIL-160, UiO-66, ZIF-7, ZIF-8 and ZIF-90, and the MOF film is selected from one or a combination of more of MIL-53, Co-gallate, Al-bttotb, MIL-160, UiO-66, ZIF-7, ZIF-8 and ZIF-90. The separation is carried out in an MOF membrane separation device, the MOF membrane separation device comprises an MOF membrane separator, and the MOF membrane separator comprises an MOF membrane assembly and the MOF membrane. According to the method, a membrane separation technology is adopted, so that high-purity 1, 3-butadiene can be efficiently obtained in a manner of increasing the productivity.

Description

Technical Field

[0001] The present invention belongs to membrane separation technology, and specifically relates to the field of membrane application in the efficient separation technology of hydrocarbons with the same carbon number, and in particular to a method and device for separating 1,3-butadiene from a C4 hydrocarbon mixture by using membrane separation technology. Background Art

[0002] 1,3-Butadiene is an important component in C4 petroleum fractions. As one of the basic raw materials for petrochemicals, it can be used to produce synthetic rubber, resins and other polymer materials. In the synthetic rubber manufacturing industry, the amount of 1,3-butadiene can account for more than 60% of the total raw material consumption. 1,3-Butadiene is mainly obtained by separating and purifying the C4 fraction mixture in petroleum gas. The C4 mixture is usually composed of 30-60% 1,3-butadiene, 10-20% 1-butene, 10-30% isobutylene, and 3-10% butane and isobutane. In the process of synthetic rubber, the presence of other C4 hydrocarbons will cause structural changes in polybutadiene, affect product quality, and even interrupt the polymerization reaction and reduce 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 processing and production. Since C4 hydrocarbons (especially dienes and monoolefins) have similar boiling points, molecular sizes and physical properties, separating them remains a huge challenge.

[0003] At present, the separation of butadiene from other C4 hydrocarbons in industry is mainly to continuously add a certain highly polar solvent (also known as an extractant, such as acetonitrile, dimethylformamide and N-methylpyrrolidone) into the distillation tower to change the relative volatility between the components in the C4 fraction, so that the liquid mixture that is difficult to separate by ordinary distillation becomes easy to separate. For example, the dimethylformamide DMF method, the production process includes four steps, namely the first extraction distillation step, the second extraction distillation step, the distillation step and the solvent recovery step. After the raw material C4 is vaporized, it enters the first extraction 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, alkynes, etc. are extracted from the bottom of the tower together with the solvent, enter the first desorption tower to be completely desorbed, and enter the second extraction distillation tower for further separation after cooling and compression by a screw compressor. The solvent without C4 components is extracted from the bottom of the desorption tower at high temperature and used as a heat source for extraction distillation, distillation, evaporation and other processes. It is recycled after heat recovery. Harmful impurities such as alkynes, propadiene, sulfides, and carbonyl compounds have high solubility in the solvent. In order to prevent the explosion of vinyl acetylene and ethyl acetylene and further recover the butadiene in the solvent, the rich solvent discharged from the bottom of the second extraction tower is sent to the butadiene recovery tower, and the top of the tower is crude butadiene. The butadiene and a small amount of impurities distilled from the top of the recovery tower are returned to the compressor inlet before the second extraction tower. The solvent containing alkynes in the bottom of the tower is sent to the second desorption tower. Vinyl acetylene and ethyl acetylene are separated from the top of the tower and used as boiler fuel after dilution. The bottom liquid is the solvent and circulated back to the extraction distillation tower. The impurities in the crude butadiene obtained by two-stage extraction distillation are removed by ordinary distillation. C3 and water with higher volatility than butadiene are removed at the top of the light removal tower, and residual 2-butene, 1,2-butadiene, C5 with lower volatility than butadiene and a small amount of butadiene dimers produced during the production process are removed at the bottom of the heavy removal tower. Finally, polymerization-grade butadiene with a purity of more than 99.5% can be obtained at the top of the heavy removal tower. However, extractive distillation usually requires a higher operating temperature (323-393K), a high number of plates exceeding 110, and consumes a large amount of organic solvent. In addition, during the high-temperature distillation process, the polymerization of highly reactive butadiene is inevitable. Therefore, the extractive distillation process is an energy-intensive and environmentally unfriendly process, and it is very important to seek an efficient and low-cost technology for separating butadiene.

[0004] Membrane separation technology is a green, safe and efficient common platform technology. Since separation is not limited by thermodynamic equilibrium, it has the advantages of reduced investment and operating costs, energy saving and consumption reduction, and process intensification brought about by the integration effect. It is considered to be an important prospective technology that can potentially achieve efficient separation of hydrocarbon mixtures with the same carbon number. Theoretical simulations show 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 separation energy consumption.

[0005] However, there are few reports on the existing technology on how to use membrane separation technology to effectively separate 1,3-butadiene and efficiently obtain high-purity 1,3-butadiene. Summary of the invention

[0006] In view of the shortcomings and deficiencies of the prior art, the object of the present invention is to provide a method for separating 1,3-butadiene from a C4 hydrocarbon mixture, which adopts membrane separation technology and can obtain high-purity 1,3-butadiene with high efficiency and increased production capacity.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is:

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

[0009] In the present invention, the C4 hydrocarbon mixture refers to a mixture in which the majority of components are C4 hydrocarbons, which may also include a small amount of C5 component impurities, such as isopentene, cyclopentane, etc., and the mass percentage content of the C5 component is less than 0.04%.

[0010] In the present invention, the permeate 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; in contrast, the retentate side refers to the side that cannot pass through the membrane, and these components cannot permeate through the membrane.

[0011] The present invention finds that 1,3-butadiene can be effectively separated by using the above-mentioned specific type of MOF membrane.

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

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

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

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

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

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

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

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

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

[0021] In some embodiments, the MOF membrane has a membrane area of ​​0.01 to 10 m 2 .

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

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

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

[0025] By adopting the above-mentioned 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, and the support is selected from a single-channel type, a multi-channel type, or a flat plate type. Correspondingly, the MOF membrane is in a tubular or flat plate shape.

[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 performed in a MOF membrane separation device, and the MOF membrane separation device includes 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 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 retentate side of the MOF membrane.

[0032] In some embodiments, the MOF membrane is a sheet membrane containing a flat carrier, and a support frame for fixing the MOF membrane is provided in the MOF membrane assembly, and the support frame can allow gas or liquid to pass through; the membrane separation method comprises the steps of allowing the C4 hydrocarbon mixture to pass through the MOF membrane in the MOF membrane assembly, and 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;

[0033] or,

[0034] The MOF membrane is a tubular membrane, which contains a tubular carrier, the MOF membrane assembly is tubular and 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 allowing the C4 hydrocarbon mixture to pass through the fluid cavity for membrane separation, producing the 1,3-butadiene from the cavity, and producing other components in the C4 hydrocarbon mixture from the fluid cavity.

[0037] The method of fixing the MOF membrane in the MOF membrane assembly and forming a cavity between the two can adopt a conventional structural method in the field, for example, the tubular MOF membrane is inserted into a rubber ring made of rubber material, and the rubber ring is clamped on the inner wall of the MOF membrane assembly, so that the two can be fixed and a cavity is formed in the middle.

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

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

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

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

[0043] a pre-processor for pre-treating the C4 hydrocarbon mixture prior to separation;

[0044] A flow controller is used to control the feed flow rate of the C4 hydrocarbon mixture;

[0045] A pump for producing the 1,3-butadiene.

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

[0047] In some embodiments, the C4 hydrocarbon mixture is in gas phase, and the MOF membrane separation device further includes a nitrogen purge, which is connected to the outlet of the cavity or the support frame; the membrane separation method extracts the 1,3-butadiene through the pump or the nitrogen purge.

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

[0049] Preferably, the multiple 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 annular.

[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 permeate side of the MOF membrane separation device is purged with N2 or connected to a pump for control of extraction, and the gas phase product on the retentate side is connected to a back pressure valve for control of extraction, and the back pressure valve can provide negative pressure to facilitate the extraction of the retentate component. If the feed is a liquid phase mixture, the liquid phase product on the permeate side of the MOF membrane separation device is extracted by a pump, and the liquid phase product on the retentate side is connected to a back pressure valve for control of extraction.

[0054] In some embodiments, the purity of 1,3-butadiene in the component produced from the permeate side is controlled to be above 95.0%, preferably 95.0%-99.5%, which is very high.

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

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

[0057] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0058] The membrane separation method of 1,3-butadiene of the present invention has high separation selectivity when separating 1,3-butadiene and other low-carbon hydrocarbon mixtures, can achieve effective separation and concentration of 1,3-butadiene, has excellent separation effect, low device investment, energy saving and environmental protection, and can generate huge economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

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

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

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

[0064] Figure 6 This is a graph showing the effect of impurity gases on the separation performance of the MIL-160 membrane separation device.

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

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

[0067] Among them, 1-preprocessor, 2-pump, 3-flow controller, 4-MOF membrane separator, 5-MOF membrane assembly, 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 DESCRIPTION

[0068] Figure 1 Taking a tubular membrane separation device (i.e., the MOF membrane 6 therein is tubular and uses a tubular carrier) as an example, the raw gas or raw 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 pretreatment device 1, so that the feed meets the corresponding requirements. The specific structure of the pretreatment device 1 used in the present invention is not particularly limited, and may include a compression device, a drying device, a filtering device or a heating device, which can pretreat the C4 hydrocarbon mixture before the raw material enters the MOF membrane separator to achieve the required feed state. The treated raw material enters the MOF membrane separator 4 through the flow controller 3 for separation.

[0069] The mixed hydrocarbons pretreated by the preprocessor 1 enter the MOF membrane separator 4, which mainly includes a MOF membrane assembly 5 and a MOF membrane 6, wherein the MOF membrane assembly 5 is made of stainless steel or nylon. The mixed hydrocarbon components pass through the fluid cavity 10 and are separated by the MOF membrane 6, wherein the part that passes through the membrane layer is called the permeate component, which passes through the membrane layer and enters the permeate side, i.e., the cavity 9 area, and the component that does not pass through the membrane layer is called the retentate component and enters the retentate side. Subsequently, each component is tested for extraction in a corresponding manner.

[0070] The specific operations are as follows:

[0071] First, the entire system is in a closed state, the feed is controlled to be liquid phase, and the partial valve 8 is opened. The partial valve 8 is adjusted according to the back pressure requirement, the partial pump 2 is started and the flow controller 3 corresponding to the liquid phase feed pipe 12 is adjusted to make the mixed hydrocarbon (C4 hydrocarbon mixture) feed meet the required feed requirements, and then enter the MOF membrane separator 4 for separation. Since the permeate side component is only produced by the pump during liquid phase feeding, at this time, it is necessary to open the corresponding partial valve 8 and start the partial pump 2 to produce the permeate component, and the retentate side component is produced through another partial valve 8.

[0072] Alternatively, the entire system is first closed, the feed is controlled to be gas phase, the partial valve 8 is opened, the partial valve 8 is adjusted according to the back pressure requirement, and the flow controller 3 corresponding to the gas phase feed pipe 11 is adjusted to make the mixed hydrocarbon feed meet the required feed requirements, and then enter the MOF membrane separator 4 for separation, the retentate side component is controlled by the partial valve 8 to be produced, and the permeate side component can be extracted by pumping or nitrogen purging. If the pump is used for extraction, the corresponding partial valve 8 is opened and the corresponding pump 2 is started to produce the product. If nitrogen purging is used, the corresponding flow controller 3 and partial valve 8 are opened, and the permeate component is produced at one end of the valve 8.

[0073] When the above-mentioned MOF membrane separation device is used, the main feature is that under gas phase feed conditions, the permeate side is produced by pump or N2 purge, and the retentate side is produced by back pressure valve control. When liquid phase feed is used, the permeate side is produced by pump, and the retentate side is produced by back pressure valve control. When the hydrocarbon mixture enters the separation device, the 1,3-butadiene component enters the permeate side. If the concentration of 1,3-butadiene on the retentate side is not reduced to the target value, the back pressure valve can be used to control the retentate hydrocarbon mixture to flow back to the MOF membrane assembly or enter the next MOF membrane assembly (for example, in series) for separation. When the permeate component 1,3-butadiene cannot reach a sufficient purity, the gas phase feed can use a pump or N2 purge to provide power to send the permeate gas 1,3-butadiene to the next MOF membrane assembly for separation. When liquid feed is used, the operation method is the same as that of gas feed. The purity of the final produced product 1,3-butadiene is 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 line can be added at the outlet of the retentate side to reduce the impact of high-concentration feed on the membrane separation of the target system.

[0075] The MOF membrane 6 can also be a sheet-like membrane, such as Figure 2 As shown, at this time, a support frame 13 for fixing the MOF membrane 6 is provided in the MOF membrane assembly 5, and the support frame 13 can allow gas or liquid to pass through; the membrane separation method includes the steps of allowing the C4 hydrocarbon mixture to pass through the MOF membrane 6 in the MOF membrane assembly 5, and 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 the method corresponding to the tubular membrane.

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

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

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

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

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

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

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

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

[0084] The present invention will be further described in detail below by specific embodiments. However, it should be understood by those skilled in the art that the following examples are only used to illustrate the present invention and should not be considered as limiting the scope of the present invention. The specific techniques and conditions not indicated in the examples should be based on the techniques or conditions described in the literature in this area. The reagents or instruments used without indicating the manufacturer are all conventional products that can be obtained commercially.

[0085] Example 1

[0086] This embodiment provides a membrane separation method for 1,3-butadiene, which is as follows:

[0087] A sheet-like MIL-53 membrane with a thickness of 1 μm was selected as the separation membrane material, and a mixed gas of 50% n-butene and 50% 1,3-butadiene by mass was introduced into the preprocessor 1 to remove moisture and other solid particles in the mixed gas, and the feed pressure was controlled at 1 bar, and the temperature was set to 298 K. The pretreated raw gas was passed through the feed port of the membrane assembly through a flow controller at a flow rate of 0.25 L / min and entered the MOF membrane separator 4 for separation. The permeate side component 1,3-butadiene was produced through the outlet of the membrane assembly by pump or N2 purge, and the retentate component was produced through the outlet of the membrane assembly through the back pressure valve control.

[0088] The separation temperature was changed to 298K, 303K, 308K, 313K, 318K, and 323K, and the permeability of 1,3-butadiene and n-butene was tested and the separation selectivity was calculated. The results are shown in Figure 3 As shown in the figure, it can be seen that the separation selectivity of the MOF membrane separation device for 1,3-butadiene / n-butene is as high as 7 8, and the permeability of 1,3-butadiene is as high as 6.9×10 -9 mol / m 2 s Pa. As the feed temperature increases from 298K to 323K, the separation selectivity decreases by 29.7%. The purity of 1,3-butadiene in the first gas component produced from the permeate side is as high as over 95%, and the concentration of n-butene in the second gas component produced from the retentate side is 60%, which can be connected to the next membrane module for further separation.

[0089] Example 2

[0090] This embodiment provides a membrane separation method for 1,3-butadiene, which is as follows:

[0091] A 1 μm thick sheet ZIF-90 membrane was selected as the separation membrane material, and a mixed gas of 50% isobutylene and 50% 1,3-butadiene by mass was introduced into the preprocessor 1 to remove moisture and other solid particles in the mixed gas, and the feed temperature was controlled at 348K, and the pressure was set to 1 bar (gauge pressure). The pretreated raw gas was passed through the feed port of the membrane assembly through a flow controller at a flow rate of 0.4 L / min and entered the ZIF-90 membrane separator 4 for separation. The outlet of the permeate side membrane assembly was pumped or N2 purged to extract the permeate gas component, and the residual component entered the back pressure valve through the outlet of the membrane assembly to control the extraction.

[0092] The separation pressure was changed 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 and the separation selectivity was calculated. The results are shown in Figure 4 As shown in Figure 2, the separation selectivity of the ZIF-90 membrane separation device for 1,3-butadiene / isobutylene is as high as 15.3, and the permeability of 1,3-butadiene is as high as 1.08×10 -8 mol / m 2 s Pa. As the feed pressure increases, the permeability of 1,3-butadiene decreases by 14.8% and the separation selectivity decreases by 28.9%. The purity of 1,3-butadiene in the first gas component produced from the permeate side is as high as over 90%, and the concentration of isobutylene in the second gas component produced from the retentate side is higher than 60%, which can be connected to the next membrane module for further separation.

[0093] Example 3

[0094] This embodiment provides a membrane separation method for 1,3-butadiene, which is as follows:

[0095] The sheet-like Al-bttotb membranes with different membrane thicknesses (thicknesses are 0.8μm, 1.3μm, 1.8μm, 2.3μm, and 2.8μm, respectively) were selected as separation membrane materials, and n-butene and 1,3-butadiene were mixed in a mass ratio of 1:1 and passed into the preprocessor 1 to remove moisture and other solid particles in the mixed gas, and the feed temperature was controlled at 298K and the pressure was controlled at 1bar. The pretreated raw gas was passed through the flow controller at a flow rate of 0.15L / min through the feed port of the membrane assembly into the Al-bttotb membrane separation device for separation, and the permeate side components were extracted through the outlet of the membrane assembly by pump or N2 purge, and the residual components were extracted through the outlet of the membrane assembly into the back pressure valve to control the extraction.

[0096] The effect of membrane thickness on separation effect is shown in the following table. Figure 5 As shown in Figure 2, the separation selectivity of the Al-bttotb membrane separation device for 1,3-butadiene / n-butene is as high as 6, and the permeability of 1,3-butadiene is as high as 9.2×10 -9mol / m 2 s Pa. As the membrane thickness increases, the permeability of 1,3-butadiene decreases by 55.43% and the separation selectivity increases by 57.3%. The purity of 1,3-butadiene in the first gas component produced from the permeate side is as high as over 95%, and the concentration of n-butene in the second gas component produced from the retentate side is higher than 60%, which can be connected to the next membrane module for further separation.

[0097] Example 4

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

[0099] A sheet-like MIL-160 membrane with a thickness of 1.5 μm was selected as the separation membrane material, and a mixed gas of 50% by mass of isobutylene and 50% by mass of 1,3-butadiene was introduced into the preprocessor 1 to remove moisture 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 pretreated raw gas was passed through the flow controller at a flow rate of 0.3 L / min through the inlet of the membrane assembly into the MIL-160 membrane separator 4 for separation, and the first gas component was extracted from the permeate side through the outlet of the membrane assembly by pump or N2 purge, and the retentate side component was extracted through the outlet of the membrane assembly into the back pressure valve controlled extraction.

[0100] The composition of the mixed gas is adjusted to contain other impurity gases in addition to isobutylene and 1,3-butadiene. The specific composition is: a mixed gas of 5% by mass of normal butane, 5% by mass of isobutane, 20% by mass of isobutylene, 20% by mass of normal butene and 50% by mass of 1,3-butadiene.

[0101] The results are as follows Figure 6 As shown in the figure, when the MIL-160 membrane separation device separates a mixture containing only isobutylene and 1,3-butadiene (without impurity gas), as the separation time increases, the separation selectivity of isobutylene / 1,3-butadiene is maintained at about 6, and the permeability of 1,3-butadiene is maintained at 9.6×10 -9 mol / m 2 s Pa. When separating mixed gases containing impurities, the separation selectivity of 1,3-butadiene / isobutylene and the permeability of 1,3-butadiene slightly decreased, and the permeability of 1,3-butadiene slightly fluctuated with the increase of separation time, but remained unchanged overall, and the separation selectivity of isobutylene / 1,3-butadiene remained basically unchanged. This shows that the method of the present invention can effectively separate raw mixed gases containing impurity gases. The purity of 1,3-butadiene in the gas components extracted from the permeation side is as high as over 92%.

[0102] Example 5

[0103] This embodiment provides a membrane separation method for 1,3-butadiene, which is as follows:

[0104] A ZIF-8 membrane with a thickness of 2 μm (the carrier is an alumina ceramic tube, single channel) is selected as the separation membrane material to separate the gas phase mixture of n-butene and 1,3-butadiene, wherein the 1,3-butadiene composition of the feed is controlled from 10% to 90% (mass percentage, 10%, 30%, 50%, 70%, 90% respectively). First, the mixed gas is passed into the preprocessor 1 to remove moisture and other solid particles in the mixed gas, so that the temperature of the treated gas is controlled at 313K and the pressure is controlled at 1 bar. The pretreated raw gas is passed through the flow controller at a flow rate of 0.2 L / min through the inlet of the membrane assembly into the ZIF-8 membrane separator 4 for separation. The first gas component is extracted from the permeate side through the outlet of the membrane assembly by a pump or N2 purge, and the residual side component enters the back pressure valve through the outlet of the membrane assembly to control the extraction. Figure 7 As shown in the figure, with the increase of 1,3-butadiene feed ratio, the permeability of n-butene increased slightly, and the permeability of 1,3-butadiene was generally stable at 3.4×10 -8 mol / m 2 s Pa, the overall selectivity of the separation membrane shows a downward trend. It can be seen that the present invention can effectively separate the raw material mixture with a wide range of 1,3-butadiene composition.

[0105] Example 6

[0106] This embodiment provides a membrane separation method for 1,3-butadiene, which is as follows:

[0107] A sheet-like UiO-66 membrane with a thickness of 1.5 μm was selected as the separation membrane material, and a mixture of 5% n-butane, 5% isobutane, 20% isobutylene, 20% n-butene and 50% 1,3-butadiene by mass percentage was passed into the preprocessor 1 to remove water and other solid particles in the mixture, and the feed temperature was controlled at 263 K and the pressure was controlled at 1 bar. The pretreated raw material was passed through the flow controller at a flow rate of 0.4 L / min through the feed port of the membrane assembly into the UiO-66 membrane separator 4 for separation, and the liquid phase component was extracted through the pump at the outlet of the permeate side membrane assembly, and the retentate component was controlled by the back pressure valve through the outlet of the membrane assembly.

[0108] The separation effect changes with time. Figure 8 As shown in Figure 2, with the increase of separation time, the separation selectivity of the UiO-66 membrane separation device for 1,3-butadiene / other C4 hydrocarbons is about 3.1, and the permeability of 1,3-butadiene is 8.5×10 -9 mol / m 2s Pa. This shows that the stability of the UiO-66 membrane fluctuates slightly under liquid conditions, but is generally stable. The purity of 1,3-butadiene in the first liquid component produced from the permeate side is as high as over 90%, and the purity of other C4 hydrocarbon components in the second liquid component produced from the retentate side is higher than 80%, which can be connected to the next membrane module for further separation.

[0109] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A membrane separation method for 1,3-butadiene, characterized in that: A C4 hydrocarbon mixture is used as a raw material and is separated through a MOF membrane to obtain the 1,3-butadiene on the permeation side of the membrane; the C4 hydrocarbon mixture includes 1,3-butadiene and also includes a combination of one or more selected from n-butene, isobutylene, n-butane, isobutane, cis-2-butene and trans-2-butene; the MOF membrane is selected from a combination of one or more selected from MIL-53, Co-gallate, Al-bttotb, MIL-160, UiO-66, ZIF-7, ZIF-8 and ZIF-90.

2. The membrane separation method of 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 2-40; and / or the permeability of the MOF membrane to 1,3-butadiene is 10-100 GPU.

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

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

5. The membrane separation method of 1,3-butadiene according to any one of claims 1 to 4, characterized in that: The membrane separation method is carried out in a MOF membrane separation device, and the MOF membrane separation device comprises a MOF membrane separator; The MOF membrane separator comprises a MOF membrane assembly and the MOF membrane; The MOF membrane assembly is used to fix the MOF membrane; The membrane separation method comprises 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 retentate side of the MOF membrane.

6. The membrane separation method of 1,3-butadiene according to claim 5, characterized in that: The MOF membrane is a sheet-like membrane, which contains a flat carrier. The MOF membrane assembly is provided with a support frame for fixing the MOF membrane, and the support frame can allow gas or liquid to pass through. The membrane separation method comprises the steps of allowing the C4 hydrocarbon mixture to pass through the MOF membrane in the MOF membrane assembly, and 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, which contains a tubular carrier, the MOF membrane assembly is tubular and arranged outside the MOF membrane, and 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 comprises the steps of allowing the C4 hydrocarbon mixture to pass through the fluid cavity for membrane separation, producing the 1,3-butadiene from the cavity, and producing other components in the C4 hydrocarbon mixture from the fluid cavity.

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

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

9. The membrane separation method of 1,3-butadiene according to claim 6, characterized in that: The MOF membrane separation device also includes: a pre-processor for pre-treating the C4 hydrocarbon mixture prior to separation; A flow controller for controlling the feed flow of the C4 hydrocarbon mixture; A pump for producing the 1,3-butadiene.

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

11. The membrane separation method of 1,3-butadiene according to claim 6, characterized in that: The MOF membrane separation device comprises one or more MOF membrane separators; preferably, the multiple MOF membrane separators are arranged in series; and / or the material of the MOF membrane assembly is stainless steel or nylon.

12. A MOF membrane separation device as claimed in any one of claims 5 to 11.

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