CN111440045B - Separation method of carbon-pentaene mixture - Google Patents

Abstract

The invention discloses a method for separating a mixture of carbon pentaolefins, the mixture of carbon pentaolefins contains isoprene; the separation method uses a fluorine-containing anion hybrid porous material with a flexible function as a separation adsorbent, and the The carbon pentaolefin mixture is contacted and adsorbed with the separation adsorbent to realize the separation of isoprene and other carbon pentaolefins; the fluorine-containing anion hybrid porous material has a double interspersed structure, and the general structure formula is A-(C ₁₂ H ₈ N ₂ )-M, wherein: M is a metal ion selected from Cu ²⁺ , Zn ²⁺ , Co ²⁺ or Ni ²⁺ ; A is an inorganic fluorine-containing anion selected from SiF ₆ ^2- , TiF ₆ ^{2 ‑} , GeF ₆ ^2‑ or NbOF ₅ ^2‑ ; C ₁₂ H ₈ N ₂ is the organic ligand 1,2-dipyridylacetylene.

Description

A kind of separation method of carbapentaolefin mixture

technical field

The invention relates to the technical field of chemical engineering, in particular to a method for separating a carbonpentaolefin mixture.

Background technique

The deep separation and purification of carbon five (C5) olefins has important industrial value, and the components with high utilization value and high content include isoprene, cyclopentadiene and piperylene, and the three account for about C5 total. 40%-60% of the components. These dienes have special molecular structures and lively chemical properties, and are valuable basic chemical raw materials. Isoprene (polymerization grade and chemical grade) has a wide range of uses in the production of synthetic rubber, pharmaceutical and pesticide intermediates, synthetic lubricating oil additives, and rubber vulcanizing agents, and its development and utilization prospects are very broad.

The difficulty in the separation and purification of isoprene is that the C5 fraction contains dozens of components such as alkanes, monoolefins, dienes, cycloalkanes, and cycloalkenes. The boiling points of each component are similar, and the relative volatility is small. Azeotropes (such as isoprene and n-pentane) can also be formed between them, and the chemical properties of diolefins are prone to self-polymerization or copolymerization (such as cyclopentadiene), so it is difficult to obtain high-purity products by ordinary distillation methods . The method generally adopted in the industry is to use the thermal dimerization method to first polymerize cyclopentadiene into solid dicyclopentadiene to separate it from the carbon five fraction, and then use the method of thermal depolymerization to separate dicyclopentadiene from dicyclopentadiene. Polymerization-grade cyclopentadiene is separated, and other components are separated by multi-step extraction and rectification, and finally polymerization-grade isoprene is obtained, such as US4570029A, US4438289A, US4147848A, and US3510405A. The method of extractive distillation generally has problems such as high separation energy consumption, high equipment investment, complicated process, solvent recovery and pollution.

With the development and research of adsorption separation materials, adsorption technology is considered to be one of the most potential separation technologies. Traditional materials such as activated carbon, molecular sieves, porous polymers, etc. have been widely studied and made important progress as adsorption materials. However, traditional materials do not have a high degree of recognition of molecules with small differences in size, and the efficiency is low. For example, in patents CN102329179A and CN102351630A, the modified 5A molecular sieve can selectively adsorb normal olefins with smaller molecular sizes, but the 5A molecular sieve has problems such as small adsorption capacity for normal olefins and low separation selectivity.

In recent years, many researchers have investigated the separation performance of metal-organic framework materials in normal isomeric hydrocarbons, and the research generally focuses on the separation of C2-C4 olefins and C5-C8 alkanes. Although there are many materials for the normal isomerization separation of alkanes, there are few materials for the separation of C5 and above liquid olefins. Olefins have a slightly smaller molecular size and more active chemical properties than alkanes because of their double bond structure. Compared with the separation of alkanes, the requirements for the chemical stability and regeneration performance of materials are more stringent. In 2010, Michael Maes et al investigated the separation performance of MIL-96, [Cu ₃ (BTC) ₂ ], chabazite and 5A molecular sieve for C5 mixture. Among them, [Cu ₃ (BTC) ₂ ] has almost the same adsorption capacity for 1-pentene and isoprene, and does not have the separation performance of normal isomerized olefins, and the article does not mention the regeneration of these four materials too much. Performance (Separation of C5-Hydrocarbons on Microporous Materials: Complementary Performance of MOFs and Zeolites[J].J.AM.CHEM.SOC.2010,132,2284–2292). In 2018, Huang Feihe et al. studied the separation of C5 monoolefin isomers by columnar EtP5α materials. This material can identify α and β olefin isomers, and has stable and reproducible chemical properties, but the adsorption capacity is not high (Linear Positional Isomer Sorting in Nonporous AdaptiveCrystals of a Pillar[5]arene[J].J.AM.CHEM.SOC.2018,140-9,3190-3193).

It can be seen that the selectivity and adsorption capacity of the existing MOFs materials for the separation of C5 olefins cannot be achieved at the same time, and it is urgent to develop new separation materials and separation methods.

Contents of the invention

Aiming at the deficiencies in this field, the present invention provides a method for separating a mixture of carbopentaolefins, using a fluorine-containing anion hybrid porous material with a flexible structure to achieve efficient separation and purification of isoprene in carbopentaolefins .

A method for separating a mixture of carbon pentaolefins, the mixture of carbon pentaolefins contains isoprene;

The separation method uses a fluorine-containing anion hybrid porous material with a flexible function as a separation adsorbent, and the mixture of carbon pentaolefins is contacted and adsorbed with the separation adsorbent to realize the separation of isoprene from other carbon pentaolefins;

The fluorine-containing anion hybrid porous material has a double interspersed structure, and the general structural formula is A-(C ₁₂ H ₈ N ₂ )-M, wherein:

M is a metal ion, selected from Cu ²⁺ , Zn ²⁺ , Co ²⁺ or Ni ²⁺ ;

其中黑球代表F或O；A is an inorganic fluorine-containing anion, selected from SiF ₆ ^2- , TiF ₆ ^2- , GeF ₆ ^2- or NbOF ₅ ^2- , and the three-dimensional structural formula is:

Among them, the black ball represents F or O;

C ₁₂ H ₈ N ₂ is an organic ligand 1,2-dipyridine acetylene, and its three-dimensional structural formula is:

The fluorine-containing anion hybrid porous material used in the present invention is prepared from metal ions, inorganic anions and organic ligands, and its three-dimensional structure is shown in FIG. 1 . After the material is in contact with the C5 olefin mixture containing isoprene, it has weak adsorption capacity for isoprene and strong adsorption for other components in the mixture, so as to realize the separation of high-purity isoprene from the C5 mixture . The C5 olefin mixture contains isoprene, and may also contain at least one of 1-pentene, trans-2-pentene, cis-2-pentene, piperylene and cyclopentadiene.

框架中的吡啶环具有一定的柔性，可随吸附的过程发生不同程度的偏转。The average pore diameter of the fluorine-containing anion hybrid porous material is

The pyridine ring in the framework is flexible and can be deflected to varying degrees during the adsorption process.

The invention realizes the adjustment of the pore size of the fluorine-containing anion hybrid porous material with flexible functions by selecting different inorganic fluorine-containing anions and metal ions, and modifies the chemical environment in the pores. Appropriate pore size enables the material to achieve different degrees of molecular exclusion for carbon five components of different sizes, and larger olefins are not easy to enter the pores. The anions and gas molecules in the material have different electrostatic interaction strengths, showing different separation selectivities, thereby achieving efficient separation of C5 olefins. Therefore, this type of material exhibits high separation selectivity and adsorption capacity, and has a very promising application prospect as an adsorbent for the separation of C5 olefins and the purification of isoprene.

The fluorine-containing anion hybrid porous material described in the present invention is constructed by a fluorine-containing anion A, a metal ion M and an organic ligand 1,2-dipyridylacetylene (C ₁₂ H ₈ N ₂ ) through a coordination bond. The structural unit is shown in Figure 2.

The synthesis of the fluorine-containing anion hybrid porous material described in the present invention can adopt the existing technology, such as room temperature co-precipitation method, hydrothermal synthesis method, wet mechanical grinding method and slow diffusion interface synthesis method, the synthesis conditions are mild, easy to batch synthesis.

Preferably, the carbon pentaolefin mixture further contains at least one of 1-pentene, trans-2-pentene, cis-2-pentene, piperylene and cyclopentadiene.

Preferably, the mole percentage of isoprene in the carbon pentaolefin mixture is 10%-98%.

According to the separation method of the present invention, the purity of the separated isoprene is greater than 99.9% (mole percentage).

In order to obtain better separation effect, in the separation method of the present invention, the adsorption temperature is preferably -20-70°C, more preferably -5-50°C, and the adsorption pressure is preferably 0-10bar, more preferably 0.5-2bar.

In the separation method of the present invention, after the contact and adsorption between the carbon pentaolefin mixture and the separation adsorbent is completed, the separation adsorbent is desorbed to realize the regeneration of the separation adsorbent.

The desorption can be carried out by purging with inert gas, desorption with desorbent or vacuum desorption. The inert gas is rare gas and/or nitrogen.

The desorption temperature is preferably 0-150°C, more preferably 20-50°C, and the pressure is preferably 0-1 bar, more preferably 0-0.2 bar.

The separation method of the present invention can adopt fixed bed adsorption or simulated moving bed adsorption. The carbon pentaolefin mixture may be in a liquid phase or a gas phase.

In a preferred example, the inorganic fluorine-containing anion A is TiF ₆ ^2- , the organic ligand is 1,2-dipyridylacetylene, the metal ion is Cu ²⁺ , and the flexible fluorine-containing anion hybrid porous material is TIFSIX-2-Cu-i. The adsorption capacities of TIFSIX-2-Cu-i for trans-2-pentene and 1-pentene are as high as 3.1mmol/g and 2.7mmol/g respectively at 45kPa and 298K, and the adsorption capacity for isoprene is only It is 1.7mmol/g; under the conditions of 8.5kPa and 298K, the adsorption capacities of trans-2-pentene and 1-pentene are 2.5mmol/g and 2.0mmol/g respectively, and the adsorption capacity of isoprene is only 0.6mmo/g.

In another preferred example, the inorganic fluorine-containing anion A is NbOF ₅ ^2- , the organic ligand is 1,2-dipyridylacetylene, and the metal ion is Cu ²⁺ , the flexible fluorine-containing anion hybrid porous material is NbOFFIVE-2-Cu-i. The adsorption capacity of NbOFFIVE-2-Cu-i is as high as 2.2mmol/g and 1.6mmol/g for trans-2-pentene and 1-pentene respectively under the conditions of 8.5kPa and 298K, but almost no for isoprene. adsorption. Polymer grade isoprene can be separated from a mixture of C5 olefins.

The invention also provides the application of the fluorine-containing anion hybrid porous material with flexible function in the selective adsorption of carbopentaolefins.

Preferably, the carbon pentaolefin is selected from at least one of isoprene, 1-pentene, trans-2-pentene, cis-2-pentene, piperylene and cyclopentadiene.

Compared with the prior art, the present invention has main advantages including:

(1) The present invention provides a method for the adsorption and separation of C5 olefins by flexible anion hybrid porous materials, by precisely regulating the pore size of the anion hybrid porous materials, the olefins are separated, thereby obtaining high-purity isoprene;

(2) Compared with traditional adsorbents, the flexible anion hybrid porous material used in the present invention has the advantages of adjustable pore structure, large pore volume, and adjustable interaction force with adsorbate molecules, and can realize the shape-selective separation of C5 olefins, and at the same time With high capacity and high selectivity;

(3) The technology adopted in the present invention is a fixed bed single column method or a simulated moving bed technology. Compared with the traditional extractive distillation method, the separation method provided has the advantages of small equipment investment and low energy consumption.

(4) The method provided by the present invention can finally obtain polymer grade isoprene according to industrial requirements, and the purity can reach 99.9% (mol percentage).

(5) Compared with conventional adsorbents, the flexible anionic hybrid porous material used in the present invention has the advantages of mild regeneration conditions, long service life, simple preparation, mild synthesis conditions, easy batch synthesis, and broad industrial application prospects;

(6) Compared with the 5A molecular sieve material, the flexible anionic hybrid porous material used in the present invention has better regeneration performance, and can be regenerated by purging with inert gas at room temperature without heating.

Description of drawings

Figure 1 shows the fluorine-containing anion hybrid porous structure with flexible functions constructed by inorganic fluorine-containing anion A, metal ion M and organic ligand 1,2-dipyridylacetylene (C ₁₂ H ₈ N ₂ ) through coordination bonds. Schematic diagram of the three-dimensional structure of the material;

Figure 2 shows the fluorine-containing anion hybrid porous structure with flexible functions constructed by inorganic fluorine-containing anion A, metal ion M and organic ligand 1,2-dipyridylacetylene (C ₁₂ H ₈ N ₂ ) through coordination bonds. Schematic diagram of the structural unit of the material;

Fig. 3 is the adsorption isotherm of the anion hybrid porous material TIFSIX-2-Ni-i material obtained in Example 1 to 1-pentene, trans-2-pentene and isoprene at 298K;

Fig. 4 is the adsorption isotherm of the anionic hybrid porous material GeFSIX-2-Cu-i material obtained in Example 2 to 1-pentene, trans-2-pentene and isoprene at 298K;

Fig. 5 is the adsorption isotherm of the anionic hybrid porous material SIFSIX-2-Cu-i material obtained in Example 3 to 1-pentene, trans-2-pentene and isoprene at 298K;

Fig. 6 is the adsorption isotherm of the anionic hybrid porous material TIFSIX-2-Cu-i material obtained in Example 4 to 1-pentene, trans-2-pentene and isoprene at 298K;

Fig. 7 is the adsorption isotherm of the anionic hybrid porous material NbOFFIVE-2-Cu-i material obtained in Example 5 to 1-pentene, trans-2-pentene and isoprene at 298K;

Fig. 8 is the adsorption isotherm of the anionic hybrid porous material NbOFFIVE-2-Zn-i material obtained in Example 6 to 1-pentene and isoprene at 298K;

Fig. 9 is the breakthrough curve of the anionic hybrid porous material TIFSIX-2-Cu-i material of Example 7 to 1-pentene and isoprene mixed gas at 298K;

Fig. 10 is the penetration curve of the anionic hybrid porous material TIFSIX-2-Cu-i material of Example 7 to 1-pentene, trans-2-pentene and isoprene mixed gas at 298K;

Fig. 11 is the breakthrough curve of the anionic hybrid porous material NbOFFIVE-2-Cu-i material of Example 8 to 1-pentene and isoprene mixed gas at 298K;

Fig. 12 is the breakthrough curve of the anionic hybrid porous material NbOFFIVE-2-Cu-i material of Example 8 to 1-pentene, trans-2-pentene and isoprene mixed gas at 298K;

Figure 13 is a graph of the cycle adsorption performance of TIFSIX-2-Cu-i and NbOFFIVE-2-Cu-i on 1-pentene in Example 9.

detailed description

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. It should be understood that these examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention. The operating methods not indicated in the following examples are generally in accordance with conventional conditions, or in accordance with the conditions suggested by the manufacturer.

Example 1

Dissolve 1.0mmol Ni(BF ₄ ) ₂ , 1.0mmol (NH4) ₂ TiF ₆ in 10mL of anhydrous methanol, dissolve 1.5mmol of 1,2-dipyridylacetylene in 10mL of methanol, and mix the two solutions at 20～85℃ Stir. After the reaction is completed, the product is obtained by suction filtration. The product is washed with methanol for 3 to 4 times and then soaked in methanol for activation for 1 day. Vacuum activation at 85°C for 24 hours yielded a fluorine-containing anion hybrid porous material TIFSIX-2-Ni-i with flexible functions.

The single-component adsorption isotherm of TIFSIX-2-Ni-i was measured at 298K for 1-pentene, trans-2-pentene, and isoprene. The results are shown in Figure 3, showing that the material can achieve the above C5 Separation of olefin components.

Example 2

Dissolve 1.0mmol Cu(BF ₄ ) ₂ H2O, 1.0mmol (NH ₄ ) ₂ GeF ₆ in 10mL water, and 1.5mmol 1,2-dipyridylacetylene in 10mL methanol, mix and stir at 65°C After 24 hours, the obtained material was suction-filtered, washed with methanol for 3 to 4 times, and vacuum activated at room temperature for 24 hours to obtain a fluorine-containing anion hybrid porous material GeFSIX-2-Cu-i with flexible functions.

The single-component adsorption isotherms of GeFSIX-2-Cu-i at 298K for 1-pentene, trans-2-pentene, and isoprene were measured, and the results are shown in Figure 4, showing that this material can achieve the above C5 Separation of olefin components.

Example 3

Dissolve 1.0mmol Cu(BF ₄ ) ₂ H2O, 1.0mmol (NH ₄ ) ₂ SiF ₆ in 10mL water, and 1.5mmol 1,2-dipyridylacetylene in 10mL methanol, mix and stir at 85°C After 12 hours, the obtained material was suction-filtered, washed with methanol for 3-4 times, and vacuum activated at 65°C for 24 hours to obtain the fluorine-containing anion hybrid porous material SIFSIX-2-Cu-i with flexible functions.

The single-component adsorption isotherm of SIFSIX-2-Cu-i was measured at 298K for 1-pentene, trans-2-pentene, and isoprene. The results are shown in Figure 5, showing that the material can achieve the above C5 Separation of olefin components.

Example 4

Dissolve 1.0mmol Cu(BF ₄ ) ₂ ·H2O, 1.0mmol (NH4) ₂ TiF ₆ in 10mL water, dissolve 1.5mmol 1,2-dipyridineacetylene in 10mL methanol, mix and stir at 85°C for 12h , the resulting slurry was activated under vacuum at 80°C for 24 hours after suction filtration, and a fluorine-containing anion hybrid porous material TIFSIX-2-Cu-i with flexible functions was obtained.

The single-component adsorption isotherm of TIFSIX-2-Cu-i was measured at 298K for 1-pentene, trans-2-pentene, and isoprene. The results are shown in Figure 6, showing that this material can achieve the above C5 Separation of olefin components.

Example 5

Dissolve 1.0mmol CuNbOF ₅ in 10mL water, dissolve 1.5mmol 1,2-dipyridylacetylene in 10mL methanol, add the ligand solution dropwise to the magnetically stirred inorganic salt solution, then heat the reaction at 80°C for 24h, and the product is extracted Filter and wash with methanol for 3 to 4 times, and activate at room temperature for 24 hours to obtain the fluorine-containing anion hybrid porous material NbOFFIVE-2-Cu-i with flexible functions.

The single-component adsorption isotherm of NbOFFIVE-2-Cu-i was measured at 298K for 1-pentene, trans-2-pentene, and isoprene. The results are shown in Figure 7, showing that this material can achieve the above C5 Separation of olefin components.

Example 6

Dissolve 1.0mmol ZnNbOF ₅ in 10mL water, dissolve 1.5mmol 1,2-dipyridylacetylene in 10mL methanol, add the ligand solution dropwise to the magnetically stirred inorganic salt solution, then heat the reaction at 80°C for 24h, and the product is pumped out. Filter and wash with methanol for 3 to 4 times, and activate at room temperature for 24 hours to obtain the fluorine-containing anion hybrid porous material NbOFFIVE-2-Zn-i with flexible functions.

The single-component adsorption isotherm of NbOFFIVE-2-Zn-i at 298K for 1-pentene and isoprene was measured, and the results are shown in Figure 8, showing that this material can achieve the separation of the above-mentioned C5 olefin components.

Example 7

Pack the TIFSIX-2-Cu-i of Example 4 into a 5cm adsorption column, and pass 0.1MPa of 1-pentene and isoprene (molar ratio 1:1) mixed steam at 1mL/min at 25°C. into the adsorption column, the breakthrough curve is shown in Figure 9, high-purity isoprene can be obtained in the effluent gas, and the adsorption stops when 1-pentene breaks through. Afterwards, switch to nitrogen to purge the adsorption column at room temperature, and the adsorption column can be recycled.

The TIFSIX-2-Cu-i of Example 4 was packed into a 5cm adsorption column, and 0.1MPa of 1-pentene, trans-2-pentene, isoprene (molar ratio 1:1: 1) The mixed steam is passed into the adsorption column at 1mL/min, the breakthrough curve is shown in Figure 10, high-purity isoprene can be obtained in the outflow gas, and the adsorption stops when trans-2-pentene breaks through. Afterwards, switch to nitrogen to purge the adsorption column at room temperature, and the adsorption column can be recycled.

Example 8

Pack the NbOFFIVE-2-Cu-i of Example 5 into a 5cm adsorption column, and pass 0.1MPa of 1-pentene and isoprene (molar ratio 1:1) mixed steam at 1mL/min at 25°C into the adsorption column, the breakthrough curve is as shown in Figure 11, and high-purity isoprene (hollow circle in Figure 11) can be obtained in the effluent gas, and the adsorption stops when 1-pentene (solid circle in Figure 11) breaks through. Afterwards, switch to nitrogen to purge the adsorption column at room temperature, and the adsorption column can be recycled.

The NbOFFIVE-2-Cu-i of Example 5 was packed into a 5cm adsorption column, and 0.1MPa of 1-pentene, trans-2-pentene, isoprene (molar ratio 1:1: 1) The mixed steam is passed into the adsorption column at 1mL/min. The breakthrough curve is shown in Figure 12. High-purity isoprene can be obtained in the effluent gas, and the adsorption stops when trans-2-pentene breaks through. Afterwards, switch to nitrogen to purge the adsorption column at room temperature, and the adsorption column can be recycled.

Example 9

The materials prepared in Examples 4 and 5 were tested for 1-pentene adsorption cycle regeneration performance at room temperature, and the results obtained are shown in Figure 13, which proves that the materials have excellent cycle regeneration stability.

In addition, it should be understood that after reading the above description of the present invention, those skilled in the art may make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of the present application.

Claims (10)

1. a separation method of a carbopentaene mixture, characterized in that, the carbopentaene mixture contains isoprene; The separation method uses a fluorine-containing anion hybrid porous material with a flexible function as a separation adsorbent, and the mixture of carbon pentaolefins is contacted and adsorbed with the separation adsorbent to realize the separation of isoprene from other carbon pentaolefins; The fluorine-containing anion hybrid porous material has a double interspersed structure, and the general structural formula is A-(C ₁₂ H ₈ N ₂ )-M, wherein: M is a metal ion, selected from Cu ²⁺ , Zn ²⁺ , Co ²⁺ or Ni ²⁺ ; A is an inorganic fluorine-containing anion, selected from SiF ₆ ^2- , TiF ₆ ^2- , GeF ₆ ^2- or NbOF ₅ ^2- ; C ₁₂ H ₈ N ₂ is the organic ligand 1,2-dipyridylacetylene. 2. separation method according to claim 1, is characterized in that, described carbon pentaolefin mixture also contains 1-pentene, trans-2-pentene, cis-2-pentene, piperylene, cyclopentene at least one of the dienes. 3. The separation method according to claim 1 or 2, characterized in that, the mole percentage of isoprene in the carbon pentaolefin mixture is 10% to 98%. 4. The separation method according to claim 1, characterized in that the purity of the isolated isoprene is greater than 99.9%. 5. The separation method according to claim 1, characterized in that, the adsorption temperature is -20-70° C., and the adsorption pressure is 0-10 bar. 6. separation method according to claim 1, is characterized in that, after the contact adsorption of described carbon pentaolefin mixture and described separation adsorbent finishes, described separation adsorbent is desorbed, realizes the desorption of described separation adsorbent. regeneration. 7. The separation method according to claim 6, characterized in that, the desorption adopts inert gas purging, desorbent desorption or vacuum desorption. 8. The separation method according to claim 6, characterized in that, the desorption temperature is 0-150° C., and the pressure is 0-1 bar. 9. The separation method according to any one of claims 5 to 8, characterized in that fixed bed adsorption or simulated moving bed adsorption is used. 10. An application of a fluorine-containing anion hybrid porous material with flexible functions in the selective adsorption of carbon pentaolefins, characterized in that the fluorine-containing anion hybrid porous material with flexible functions is used for isoprene and Separation of other carbon pentaolefins; The fluorine-containing anion hybrid porous material with flexible function has a double interspersed structure, and the general structural formula is A-(C ₁₂ H ₈ N ₂ )-M, wherein: M is a metal ion, selected from Cu ²⁺ , Zn ²⁺ , Co ²⁺ or Ni ²⁺ ; A is an inorganic fluorine-containing anion, selected from SiF ₆ ^2- , TiF ₆ ^2- , GeF ₆ ^2- or NbOF ₅ ^2- ; C ₁₂ H ₈ N ₂ is the organic ligand 1,2-dipyridylacetylene.

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