Trapping agent for C4 mixed hydrocarbon gas separation, preparation method of trapping agent and C4 mixed hydrocarbon gas separation method

Abstract

The invention provides a trapping agent for C4 mixed hydrocarbon gas separation, a preparation method of the trapping agent and a C4 mixed hydrocarbon gas separation method. The trapping agent comprises a solid adsorbent and an organic solvent, the solid adsorbent is CALF-20 (Callidol Alkaline The total mass of the trapping agent is 100%, the content of the solid adsorbent is 15wt%-50wt%, and the content of the organic solvent is 50wt%-85wt%; the organic solvent is prepared from one or a combination of more than two of 1, 3-dimethyl-2-imidazolinone, benzyl alcohol and dimethyl phthalate. The trapping agent is excellent in effect, has the advantages of being large in n-butene adsorption capacity, high in n-isobutene / isobutene selectivity, high in adsorption speed, good in regeneration performance and the like, and provides diversified choices for separating C4 mixed hydrocarbon gas through a slurry method in industrial practical application.

Description

Technical Field

[0001] The invention belongs to the field of hydrocarbon gas separation, and in particular relates to a capture agent for separating C4 mixed hydrocarbon gas, a preparation method thereof, and a C4 mixed hydrocarbon gas separation method. Background Art

[0002] C4 mixed hydrocarbons are important basic chemical raw materials, mainly derived from the by-products of catalytic cracking process in petroleum cracking to produce ethylene, and a small amount from natural gas and oilfield recovery gas. Among them, C4 olefins, as industrial by-products, must be separated and purified before use. However, due to the highly similar structures of components such as n-butene and isobutylene, the molecular size difference is small (0.483 and 0.484nm), and the boiling points are similar (-6 and -6.7℃), which makes it extremely difficult to separate and purify the n- / iso-olefin mixed gas. At present, the separation of n-butene and isobutylene mixtures in industry mainly adopts organic solvent extraction and distillation technology. However, there are problems such as large circulation of organic solvents such as acetonitrile, high energy consumption, and thermal polymerization of olefins. In addition, the number of plates required to obtain high-purity products is large (>200). Therefore, it is urgent to develop new separation technologies.

[0003] In recent years, adsorption separation is considered to be a new generation of separation technology with broad prospects in the field of gas separation. Among them, the most critical thing is to select an adsorbent with considerable adsorption capacity and high adsorption separation selectivity. Commonly used adsorbents include activated carbon, clay, molecular sieves, silica gel, etc. However, due to the uniform internal pore structure of such materials and the difficulty in modifying the pore chemical environment, the adsorption capacity and separation selectivity cannot reach the level of industrial application.

[0004] Absorption-adsorption separation technology (i.e. slurry separation technology) is a highly efficient separation technology developed in recent years. This technical solution is to separate gases by forming porous MOFs materials into a stable slurry suspension, combining the advantages of absorption and adsorption. It can be regarded as a potential application of MOFs materials in addition to membrane technology and fixed bed (PSA or TSA) processes. However, the adsorbent suitable for the efficient separation of C4 mixed hydrocarbons still needs to be studied.

[0005] Therefore, on the basis of ensuring the superior adsorption capacity of solid adsorbents, it is of great significance to significantly increase the separation selectivity and reduce the separation energy consumption through specific porous MOFs materials and organic solvents. Summary of the invention

[0006] In order to solve the above technical problems, the purpose of the present invention is to provide a trapping agent for separating C4 mixed hydrocarbon gas, a preparation method thereof and a method for separating C4 mixed hydrocarbon gas. The trapping agent is prepared by dispersing CALF-20 in an organic solvent to form a porous slurry, which has higher adsorption selectivity and can be used to separate C4 mixed hydrocarbon gas.

[0007] To achieve the above-mentioned object, the present invention provides a trapping agent for separating C4 mixed hydrocarbon gas, wherein the trapping agent comprises a solid adsorbent and an organic solvent; the solid adsorbent is CALF-20; based on the total mass of the trapping agent as 100%, the content of the solid adsorbent is 15wt%-50wt%, and the content of the organic solvent is 50wt%-85wt%; the organic solvent comprises one or a combination of two or more of 1,3-dimethyl-2-imidazolidinone (DMI), benzyl alcohol, and dimethyl phthalate.

[0008] According to a specific embodiment of the present invention, preferably, the organic solvent is 1,3-dimethyl-2-imidazolidinone.

[0009] In some specific embodiments, preferably, based on the total mass of the collector as 100%, the content of the solid adsorbent is 20wt%-40wt%, specifically 15wt%, 20wt%, 30wt%, 35wt%, 40wt%, 50wt% and the like.

[0010] In some specific embodiments, preferably, based on the total mass of the capture agent as 100%, the content of the organic solvent is 60wt%-80wt%, specifically 50wt%, 60wt%, 75wt%, 80wt%, 85wt% and the like.

[0011] In some specific embodiments, preferably, the collector does not contain water.

[0012] In some specific embodiments, preferably, the collector consists of a solid adsorbent and an organic solvent.

[0013] The inventors of the present invention have found that the metal organic framework material CALF-20 is a hydrophilic material. Once compounded with water, water will occupy the pores of CALF-20 and reduce its adsorption effect. Therefore, the present invention uses an organic solvent to compound with CALF-20 to obtain a MOF slurry. In the present invention, the organic solvent and CALF-20 can produce a synergistic effect, so that the absorption rate and adsorption amount of the capture agent for n-butene are significantly improved. Compared with MOF slurries of other metal organic framework materials, within approximately the same adsorption time, the capture agent containing CALF-20 of the present invention has a larger adsorption capacity for n-butene and a higher adsorption selectivity.

[0014] The present invention also provides a method for preparing the above-mentioned C4 mixed hydrocarbon gas separation collector, wherein the preparation method comprises: mixing a solid adsorbent and an organic solvent, stirring evenly until a dispersed and stable MOF slurry is formed, and obtaining the C4 mixed hydrocarbon gas separation collector.

[0015] The present invention also provides a method for separating C4 mixed hydrocarbon gas, wherein the method utilizes the above-mentioned collector for separating C4 mixed hydrocarbon gas to separate the C4 mixed hydrocarbon gas.

[0016] According to a specific embodiment of the present invention, preferably, the volume ratio (initial gas-liquid ratio) of the C4 mixed hydrocarbon gas to the capture agent is (5-30): 1. The volume of the C4 mixed hydrocarbon gas refers to the volume under standard conditions.

[0017] According to a specific embodiment of the present invention, preferably, the C4 mixed hydrocarbon gas includes one or a combination of two or more of n-butene, isobutene, trans-butene, cis-butene, butadiene, n-butane, isobutane, etc.

[0018] According to a specific embodiment of the present invention, preferably, the C4 mixed hydrocarbon gas is n-butene and isobutene.

[0019] According to a specific embodiment of the present invention, preferably, the molar fraction of isobutylene in the C4 mixed hydrocarbon gas before separation is 20 mol% to 60 mol%.

[0020] According to a specific embodiment of the present invention, preferably, the separation temperature of the C4 mixed hydrocarbon gas is 293.15K-323.15K; and the separation time of the C4 mixed hydrocarbon gas is 20-50min.

[0021] According to a specific embodiment of the present invention, preferably, the separation method further comprises the step of desorbing the captured gas under vacuum and heating conditions, and then regenerating it for recycling.

[0022] According to a specific embodiment of the present invention, preferably, the heating temperature is 323.15K-353.15K.

[0023] According to a specific embodiment of the present invention, preferably, the vacuum pressure is below 1 kPa.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) The MOF slurry trap provided by the present invention has excellent gas separation effects, and has the advantages of high n-butene adsorption capacity, high n / isobutene selectivity, short equilibrium time, fast desorption speed, high regeneration performance, etc.; at the same time, it can achieve continuous operation and heat integration, and provides a variety of choices for the separation of C4 mixed hydrocarbon gas by slurry method in practical industrial applications. In addition, the trap for separating C4 mixed hydrocarbon gas can be applied to the multi-stage separation of C4 mixed hydrocarbon gas, and can achieve good separation effects for C4 mixed olefins and C4 mixed hydrocarbon gas containing alkanes.

[0026] (2) After the C4 mixed hydrocarbon gas separation trap provided by the present invention is saturated with absorbed gas, the gas can be desorbed by heating and vacuuming to achieve slurry regeneration and reuse. The regeneration temperature of the trap is mild, the energy consumption is low, the slurry reuse performance is excellent, and the regeneration performance is good. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is the adsorption curve of n-butylene / isobutylene in solid CALF-20 in Test Example 1 of the present invention.

[0028] Figure 2 This is the adsorption kinetic curve of n-butylene / isobutylene in CALF-20 slurry in Test Example 2 of the present invention.

[0029] Figure 3 The kinetic curves of isobutylene in different solvents. DETAILED DESCRIPTION

[0030] In order to have a clearer understanding of the technical features, purposes and beneficial effects of the present invention, the technical solution of the present invention is now described in detail below, but it should not be construed as limiting the applicable scope of the present invention.

[0031] The small-scale experimental devices of the present invention are all devices described in paragraphs 23 and 24 of the specification of CN102389686A (ZL201110284360.5), which are used for thermodynamic and kinetic experiments of pure gas and mixed gas.

[0032] The gas composition in the adsorption phase is obtained by material balance calculation of the components during the adsorption process. The data processing and calculation process of the relevant gas solubility experiment and separation experiment are as follows:

[0033] In the following calculation results, z1 refers to the mole fraction of n-butene in the feed gas before separation; y1 refers to the mole fraction of n-butene in the mixed gas phase when the adsorption time is reached; x1 refers to the mole fraction of n-butene adsorbed by the adsorbent; similarly, z2, y2, and x2 refer to the mole fractions of isobutylene in the feed gas before separation, in the mixed gas phase when the adsorption time is reached, and adsorbed by the adsorbent, respectively. T refers to the system temperature; P E Refers to the equilibrium pressure in the sapphire kettle; P1 and P2 refer to the initial pressure of the equilibrium kettle and the pressure after gas intake respectively; R is the gas constant;

[0034] Initial gas inlet mole number n of sapphire reactor t Calculated by the following formula:

[0035]

[0036] Where V tis the total effective volume of the equilibrium kettle and the connecting pipeline; the compression factors Z1 and Z2 corresponding to the initial pressure of the equilibrium kettle and the pressure after air intake are calculated by the BWRS state equation (Benedict-Webb-Rubin-Starling).

[0037] The total amount of gas phase in the sapphire reactor is n E Calculated by the following formula:

[0038]

[0039] Where V g is the gas volume in the sapphire reactor after adsorption equilibrium; Z E It is the compression factor corresponding to the temperature and pressure in the sapphire kettle.

[0040] t refers to the adsorption time for n-butylene / isobutylene separation; when the specified adsorption time reaches t, the total amount of gas phase substances in the sapphire reactor is n t1 Calculated by the following formula:

[0041]

[0042] Where P t1 is the pressure in the sapphire reactor when the specified adsorption time t is reached; Z t1 is the compression factor of the sapphire kettle at the temperature and pressure at this time; V g is the gas volume in the sapphire kettle; n t1 It is the total amount of gas phase substances in the sapphire kettle when the specified adsorption time t is reached.

[0043] The total amount of gas moles of n-butene (n1) and isobutene (n2) adsorbed by the adsorbent is calculated by the following formula:

[0044] n1=n t ×z1-n t1 ×y1;n2=n t ×z2-n t1 ×y2;

[0045] The mole fraction of n-butene (x1) and isobutene (x2) adsorbed by the adsorbent were calculated by the following formulas:

[0046]

[0047] S V Refers to solubility, the solubility of n-butene S V1 Defined as:

[0048]

[0049] Where V Sis the volume of the adsorbent, which is calculated by the height h of the adsorbent in the sapphire kettle; r is the inner diameter of the sapphire kettle; h is the height of the adsorbent in the sapphire kettle;

[0050] Solubility coefficient S of gas component i in slurry Ci (mol·L -1 bar -1 ) is defined as:

[0051]

[0052] φ refers to the initial gas-liquid ratio, which is calculated by the following formula;

[0053]

[0054] The separation efficiency of slurry to mixed gas can be evaluated by the separation factor β, which is calculated by the following formula:

[0055]

[0056] Gas recovery rate R i The calculation is as follows:

[0057]

[0058] Gas composition analysis was performed using HP7890B chromatograph.

[0059] The synthesis process of the solid adsorbent CALF-20 used in the embodiments and comparative examples of the present invention is as follows:

[0060] A mixed solution was prepared by mixing water and methanol in a mass ratio of 1:4, and then basic zinc carbonate, anhydrous oxalic acid and 1,2,4-triazole were dissolved in the mixed solution in a mass ratio of 12:7:60, and reacted in a high-pressure hydrothermal autoclave at 453 K for 48 hours. After the reaction was completed, the mixture was cooled to room temperature; the obtained white precipitate was washed with water and methanol, and dried in air to obtain a solid adsorbent CALF-20.

[0061] Example 1

[0062] This embodiment provides a trapping agent for separating carbon four (C4) mixed hydrocarbon gas, and the preparation method of the trapping agent is as follows:

[0063] CALF-20 and DMI are mixed and stirred evenly until a dispersed and stable MOF slurry is formed, wherein the content of CALF-20 is 40wt% based on the total mass of the collector as 100%, and a collector for separation of C4 mixed hydrocarbon gas is obtained, which is recorded as CALF-20 (40wt%) / DMI slurry.

[0064] Example 2

[0065] This embodiment provides a C4 mixed hydrocarbon gas separation capture agent, the difference between the capture agent and Example 1 is: based on the total mass of the capture agent as 100%, the content of the CALF-20 is 30wt%, and the other parameters are the same as those in Example 1, and the C4 mixed hydrocarbon gas separation capture agent is obtained, which is recorded as CALF-20 (30wt%) / DMI slurry.

[0066] Example 3

[0067] This embodiment provides a C4 mixed hydrocarbon gas separation capture agent, the difference between the capture agent and Example 1 is: based on the total mass of the capture agent as 100%, the content of the CALF-20 is 20wt%, and the other parameters are the same as those in Example 1, and the C4 mixed hydrocarbon gas separation capture agent is obtained, which is recorded as CALF-20 (20wt%) / DMI slurry.

[0068] Example 4

[0069] This embodiment provides a C4 mixed hydrocarbon gas separation capture agent, the difference between the capture agent and Example 1 is: based on the total mass of the capture agent as 100%, the content of the CALF-20 is 50wt%, and the other parameters are the same as those in Example 1, and the C4 mixed hydrocarbon gas separation capture agent is obtained, which is recorded as CALF-20 (50wt%) / DMI slurry.

[0070] Comparative Example 1

[0071] This comparative example provides a C4 mixed hydrocarbon gas separation collector. The difference between the collector and Example 1 is that only solid CALF-20 is used as the collector, and no organic solvent is added to form the MOF slurry.

[0072] Comparative Example 2

[0073] This comparative example provides a C4 mixed hydrocarbon gas separation collector. The difference between the collector and Example 1 is that the organic solvent is replaced with N-methylpyrrolidone (NMP), and the other parameters are the same as those in Example 1. A propylene propane mixed gas separation collector is obtained, which is recorded as CALF-20 (40wt%) / NMP slurry.

[0074] Comparative Example 3

[0075] This comparative example provides a C4 mixed hydrocarbon gas separation collector. The difference between the collector and Example 1 is that the organic solvent is replaced with N,N-dimethylpropylene urea (DMPU), and the other parameters are the same as those in Example 1. A propylene propane mixed gas separation collector is obtained, which is recorded as CALF-20 (40wt%) / DMPU slurry.

[0076] Test Example 1

[0077] This test example uses the solid CALF-20 collector prepared in Comparative Example 1 to test the adsorption performance of pure n-butene and pure isobutylene. The specific results are as follows:

[0078] At 298.15K, the adsorption performance of n-butylene and isobutylene was tested. Figure 1 As shown. Figure 1 It can be observed that in the entire equilibrium pressure range, there is a significant difference in the adsorption of n-butene and isobutene by CALF-20 dry material, that is, the adsorption of isobutene always remains at a low level, while the adsorption of n-butene continues to increase with the increase of relative pressure. Specifically, when the relative pressure reaches 0.4 bar, the solubility of n-butene is as high as 57.83 cm 3 / g, while the solubility of isobutylene is only 1.03cm 3 / g. This obvious difference in adsorption capacity fully demonstrates the excellent molecular sieve adsorption performance of CALF-20 for n-butene, and has certain potential in achieving efficient and selective adsorption of n-butene.

[0079] However, the MOF dry material itself is a powdered solid with fine particles, which is easily blown away when in contact with gas, resulting in large losses, low utilization rate, and difficulty in molding. Therefore, it cannot be directly used for gas capture, and the dry material is not conducive to heat integration. In addition, the solid CALF-20 collector is hydrophilic and easily absorbs moisture in the air, causing its structure to be destroyed. Therefore, due to its own limitations, the MOF dry material cannot be directly used for the efficient separation of n- / isobutylene mixed gas, and needs to be prepared into a slurry to protect the solid CALF-20.

[0080] Test Example 2

[0081] This test example uses the small-scale experimental device of the present invention and takes the collector in Example 2 as the test object to measure the kinetic curves of pure n-butene and pure isobutene. The specific process and results are as follows:

[0082] Using the CALF-20 (30 wt%) / DMI slurry prepared in Example 2 as a collector, the kinetic curves of pure n-butene and pure isobutylene in the CALF-20 (30 wt%) / DMI slurry were measured at an adsorption temperature of 293.15 K and an inlet pressure of 50 kPa. The results are as follows: Figure 2 As shown. Figure 2It can be seen that the initial difference in the adsorption rate of the two is not obvious, indicating that both n-butene and isobutene were adsorbed into the liquid phase relatively quickly at the beginning. As time goes by, the dissolution amount of the two begins to show a significant difference, which means that isobutene is only partially absorbed by the solvent. After the solvent reaches saturation for isobutene, the amount of isobutene no longer decreases, while n-butene can enter the pores of CALF-20 and is almost completely adsorbed by the slurry (the pressure of n-butene drops from 50.4kPa to 2.5kPa). Therefore, the above significant thermodynamic and kinetic differences provide feasibility for the further use of the collector in the separation of n- / isobutene mixed gas.

[0083] Test Example 3

[0084] This test example uses the small-scale experimental device of the present invention, takes the collector prepared in Examples 1-4 as the test object, and measures the experimental results of the separation of normal / isobutylene mixed gas by CALF-20 / DMI slurry at different solid contents. The specific process is as follows:

[0085] Separation conditions: adsorption temperature is room temperature 293.15K, initial gas-liquid ratio Ф is fixed at about 12.5, separation time is 40min, n-butene / isobutylene concentration in feed gas is 49.49% / 50.51% (z1 / z2), separation results are shown in Table 1, R1 is n-butene recovery rate. It can be seen from Table 1 that CALF-20 slurry with different solid contents shows excellent separation effect on n-butene / isobutylene mixed gas, among which isobutylene in gas phase can be concentrated to more than 95.62mol%; and with the increase of solid content, the separation factor of slurry also shows an upward trend, and the separation effect is significantly enhanced.

[0086] Therefore, the collector prepared in Examples 1-4 can achieve efficient separation of n-butylene / isobutylene mixed gas by preparing CALF-20 slurry, solving the problem that solid collectors cannot be actually applied to gas separation; further, by selecting a suitable organic solvent, a better separation effect is achieved.

[0087] Table 1. Separation results of n-butene (1) / isobutene (2) mixed gas by slurries with different solid contents

[0088]

[0089] Test Example 4

[0090] In practical applications, the regeneration performance of the adsorbent is one of the key factors to measure its performance. Therefore, in order to further verify whether the collector of the present invention has good regeneration performance, this test example uses the small-scale experimental device of the present invention to test the regeneration performance of the CALF-20 (40wt%) / DMI slurry collector prepared in Example 1, and conducts multiple absorption-desorption cycle experiments. The specific process and results are as follows:

[0091] This test example mainly examines the separation performance and regeneration performance of the collector through separation experiments and cyclic regeneration experiments. Among them, the adsorption temperature is 293.15K, the initial gas-liquid ratio Φ is fixed at about 12, the separation time is 50min, and the concentration of n- / isobutylene in the raw gas is 49.49% / 50.51% (z1 / z2). The regeneration conditions are heating and vacuum desorption at a temperature of 343.15K for 40min. This treatment method is intended to remove the gas molecules adsorbed in the slurry to the greatest extent possible so as to restore its adsorption capacity in the next experiment. The results of regeneration are shown in Table 2. It can be seen from Table 2 that at an adsorption temperature of 293.15K, as the number of regeneration experiments gradually increases, the separation factor β always remains above 50, indicating that the performance of the collector prepared in Example 1 can still be maintained at a very high level after multiple uses.

[0092] Table 2. Repeated experimental results of separation of n-butene (1) / isobutene (2) mixed gas by slurry collector prepared in Example 1

[0093]

[0094] Test Example 5

[0095] This test example adopts the small-scale experimental device of the present invention, takes the collectors prepared in Example 1 and Comparative Examples 2-3 as test objects, and explores the effect of using different organic solvents to prepare CALF-20 (40wt%) slurry on the separation effect of normal / isobutylene mixed gas. The specific process and results are as follows:

[0096] Separation conditions: adsorption temperature is 293.15K, separation time is 50min, the concentration of n-butene / isobutylene in the raw gas is 49.49% / 50.51% (z1 / z2), and the separation results are shown in Table 3, where Sc1 is the solubility coefficient of n-butene. It can be seen from Table 3 that, compared with slurries prepared with different organic solvents, under the same conditions, the separation effect of the collector prepared using DMI solvent in Example 1 is the best, and the separation factor β reaches 33.2; in contrast, the separation effects of the collectors prepared in Comparative Examples 2-3 are all weaker than those in Example 1, and the separation factor β of Comparative Example 2 (NMP) is 19.4, and the separation factor β of Comparative Example 3 (DMPU) is 17.6.

[0097] Table 3. Effect of CALF-20 slurry in different solvents on the separation of n-butene (1) / isobutene (2) mixed gas

[0098]

[0099] In addition, the kinetic curves of isobutylene in different solvents are as follows Figure 3 As shown, from Figure 3 It can be seen that after the adsorption process of the nine solvents reaches equilibrium, DMI and benzyl alcohol are the solvents with relatively small adsorption of isobutylene among the nine solvents (manifested in relatively small pressure drop), while the solubility of n-butene in these conventional organic solvents is relatively high and there is no obvious difference. Therefore, the selection of solvents with less adsorption of isobutylene will be more conducive to the separation of n- / isobutylene. In contrast, the adsorption of isobutylene by NMP and dimethyl phthalate is almost the same, both higher than DMI and benzyl alcohol, resulting in weaker separation effect than DMI and benzyl alcohol, and NMP is highly corrosive and easily affects the stability of slurry properties. Therefore, although the adsorption of isobutylene by the two is similar, the separation effect of NMP in actual application is not as good as that of dimethyl phthalate; while solvents such as dimethyl sulfoxide, cyclopentane and o-xylene have higher adsorption of isobutylene and weaker separation effect. In addition, when selecting organic solvents, in addition to the adsorption amount, the boiling point of the solvent itself is also a key evaluation indicator. DMI has a relatively high boiling point, which makes it more advantageous in applications where solvent evaporation needs to be prevented.

[0100] Test Example 6

[0101] This test example adopts the small-scale experimental device of the present invention, takes the CALF-20 (40wt%) / DMI slurry collector prepared in Example 1 as the test object, and performs separation experiments on two different multi-component C4 mixed hydrocarbon gases under the conditions of an adsorption temperature of 293.15K and a separation time of 40min. The separation results are shown in Tables 4 and 5, wherein the initial gas-liquid ratio in Table 4 is fixed at about 8.2, and the initial gas-liquid ratio in Table 5 is fixed at about 10.6.

[0102] Table 4. Test results of the slurry collector prepared in Example 1 for separating multi-component C4 mixed hydrocarbon gas 1

[0103]

[0104] Note: The calculation method of the separation factor of the two components is

[0105] From the separation results of C4 mixed hydrocarbon gas 1 (a mixture of trans-butene (1), normal-butene (2), iso-butene (3), cis-butene (4) and butadiene (5)) in Table 4, it can be seen that iso-butene exhibits a significant separation selectivity advantage in the separation process with other C4 olefin components; the separation factors of iso-butene from trans-butene, normal-butene, cis-butene and butadiene are as high as 78.49, 59.26, 42.12 and 147.04. Therefore, in the separation experiment of C4 olefin mixed gas, the concentration of iso-butene was greatly increased from 26.3 mol% to 93.1 mol%. The above results show that CALF-20 / DMI slurry collector has great application potential in the multi-stage separation of C4 mixed olefin gas.

[0106] Table 5. Test results of the slurry collector prepared in Example 1 for separating multi-component C4 mixed hydrocarbon gas 2

[0107]

[0108]

[0109] As can be seen from Table 5, when n-butane and isobutane exist in the mixed hydrocarbon gas 2, the separation selectivity of isobutene relative to other C4 hydrocarbons is challenged. However, the concentration of isobutane increased from 24.07 mol% to 47.60 mol%, showing a separation selectivity advantage; among them, the separation selectivity of butadiene / isobutane was more significant, and its separation factor reached the highest 82.33. At the same time, the separation factors of butadiene / n-butane and butadiene / isobutene were also at a high level, with specific values ​​of 26.06 and 19.92, respectively. In addition, butadiene / n-butene and n-butene / isobutane also achieved a certain degree of separation effect, and their separation factors were 8.64 and 9.52, respectively. The above results show that CALF-20 / DMI slurry collector also has broad application prospects for the separation of C4 mixed hydrocarbon gases containing alkanes.

Claims

1. A collector for separating C4 mixed hydrocarbon gas, wherein: The collector comprises a solid adsorbent and an organic solvent; The solid adsorbent is CALF-20; Based on the total mass of the trapping agent as 100%, the content of the solid adsorbent is 15wt%-50wt%, and the content of the organic solvent is 50wt%-85wt%; The organic solvent includes one or a combination of two or more of 1,3-dimethyl-2-imidazolidinone, benzyl alcohol, and dimethyl phthalate.

2. The collector according to claim 1, wherein The organic solvent is 1,3-dimethyl-2-imidazolidinone.

3. The method for preparing a capture agent for separating C4 mixed hydrocarbon gas according to claim 1 or 2, wherein: The preparation method comprises: mixing a solid adsorbent and an organic solvent, and stirring them evenly until a dispersed and stable MOF slurry is formed, so as to obtain a capture agent for separating C4 mixed hydrocarbon gas.

4. A method for separating C4 mixed hydrocarbon gas, wherein: The method comprises utilizing the trapping agent for separating C4 mixed hydrocarbon gas as claimed in claim 1 or 2 to separate C4 mixed hydrocarbon gas.

5. The separation method according to claim 4, wherein: The volume ratio of the C4 mixed hydrocarbon gas to the capture agent is (5-30):

1.

6. The separation method according to claim 4, wherein: The C4 mixed hydrocarbon gas includes one or a combination of two or more of n-butene, isobutene, trans-butene, cis-butene, butadiene, n-butane and isobutane; Preferably, the C4 mixed hydrocarbon gas is n-butene and isobutene.

7. The separation method according to claim 6, wherein: Before separation, the molar fraction of isobutylene in the C4 mixed hydrocarbon gas is 20 mol% to 60 mol%.

8. The separation method according to claim 4, wherein: The separation temperature of the C4 mixed hydrocarbon gas is 293.15K-323.15K; the separation time of the C4 mixed hydrocarbon gas is 20-50min.

9. The separation method according to claim 4, wherein: The separation method also includes the steps of: desorbing the captured gas under vacuum and heating conditions, and then regenerating it for recycling.

10. The separation method according to claim 9, wherein: The heating temperature is 323.15K-353.15K; preferably, the vacuum pressure is below 1 kPa.

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