Application of hetero[3]arene crystalline materials as o-chlorotoluene adsorbents

Abstract

The present invention discloses an application of a hetero[3]aromatic hydrocarbon crystal material as an o-chlorotoluene adsorbent, and utilizes the hetero[3]aromatic hydrocarbon crystal material to adsorb and separate a mixture of chlorotoluene isomers. The chemical structure of the hetero[3]aromatic hydrocarbon crystal material is as follows: The separation process of the present invention is simple to operate and has low equipment requirements; the separation process does not require distillation operation, has low energy consumption, saves energy, and reduces the production cost of o-chlorotoluene; the crystal material used is highly stable and can be recycled without reducing the separation effect.

Description

Technical Field

[0001] The present invention relates to the field of adsorption separation technology, and in particular to the application of a hetero[3]arene crystal material as an o-chlorotoluene adsorbent. Background Art

[0002] o-Chlorotoluene plays a vital role in the field of fine chemicals. In recent years, new intermediates including pharmaceuticals, pesticides and dyes have been developed using o-chlorotoluene as a starting material, and its application areas are constantly expanding. Specifically, o-chlorotoluene is used as a raw material for synthesizing dyes in the dye industry; in the pesticide industry, it can be used as an active ingredient in herbicides and insecticides; in the pharmaceutical field, it can be used to manufacture antibiotics, analgesics and drugs for preventing and treating heart disease; and in the spice industry, it can be used to manufacture products such as artificial musk. In addition, o-chlorotoluene can also be used as a raw material for solvents, inks, coatings and resins, and has important industrial significance. o-Chlorotoluene is usually obtained through alkylation or chlorination reactions, but due to the electron-donating effect of the methyl group, a certain amount of m-chlorotoluene and p-chlorotoluene will also be produced during the production process. Therefore, the separation and purification of p-chlorotoluene isomers to obtain o-chlorotoluene is a key step in obtaining high-purity o-chlorotoluene. Industrially, obtaining high-purity o-chlorotoluene primarily relies on methods such as distillation and rectification. However, these methods consume significant amounts of energy because the three chlorotoluene isomers have similar boiling points (o-chlorotoluene: 43.15K, m-chlorotoluene: 434.15K, and p-chlorotoluene: 435.15K). Furthermore, utilizing the differences in molecular size and geometry of chlorotoluene isomers, porous materials (such as zeolites, metal-organic frameworks, and covalent organic frameworks) have been reported to offer promising applications in separating chlorotoluene isomers. However, these porous materials are relatively chemically unstable, and their structures are likely to be destroyed by exposure to high temperatures, acids, bases, and even aqueous solutions.

[0003] Patent specification CN 105693465 A discloses a technology for separating chlorotoluene isomers using differential pressure thermal coupling distillation. The technology divides the chlorotoluene isomer distillation system into two separation systems: an o-chlorotoluene separation system and a p-chlorotoluene separation system. A conventional distillation tower is divided into a low-pressure tower and a high-pressure tower, with the high-pressure tower overhead gas serving as the heat source for the low-pressure tower kettle reboiler. This achieves heat coupling and matching, achieving both effective separation of chlorotoluene isomers and energy conservation and consumption reduction. However, the distillation process still consumes a lot of energy and has low separation efficiency.

[0004] Patent publication number CN 114436766 A discloses a method for producing high-purity o-chlorotoluene by adsorption separation. The method provides selective adsorption of p-chlorotoluene contained in o-chlorotoluene to produce high-purity o-chlorotoluene. The method can reduce the mass fraction of p-chlorotoluene in the o-chlorotoluene to below 0.05 wt%. After the adsorbent is saturated with adsorption, it is washed with toluene, filtered, and dried at atmospheric pressure to achieve recycling. The adsorbent can be recycled more than 50 times. While it has the advantages of low energy consumption and high purity of the o-chlorotoluene produced, the method is complex and still a chemical separation method, resulting in high energy consumption. Summary of the Invention

[0005] In view of the shortcomings existing in the art and the defects existing in the technology for separating chlorotoluene isomers, such as high energy consumption, complicated process and the need for high-purity desorbent, the present invention provides a method for separating chlorotoluene isomers, which uses hetero[3]aromatic crystal materials as o-chlorotoluene adsorbents and utilizes hetero[3]aromatic crystal materials to adsorb and separate chlorotoluene isomer mixtures, with low energy consumption and simple process.

[0006] A method for separating chlorotoluene isomers, using hetero[3]arene crystal materials as o-chlorotoluene adsorbents, and utilizing the hetero[3]arene crystal materials to adsorb and separate chlorotoluene isomer mixtures, wherein the chemical structure of the hetero[3]arene crystal materials is as follows:

[0007]

[0008] The chlorotoluene isomer mixture is contacted with hetero[3]aromatic crystal material for adsorption to achieve the separation of o-chlorotoluene. The chlorotoluene isomer mixture is o-chlorotoluene and m-chlorotoluene, or o-chlorotoluene and p-chlorotoluene, or a mixture of o-chlorotoluene, m-chlorotoluene and p-chlorotoluene. The chlorotoluene isomer mixture is a mixed vapor or mixed solution of chlorotoluene. The volume ratio of o-chlorotoluene to m-chlorotoluene in the mixture of o-chlorotoluene and m-chlorotoluene is 1:1; the volume ratio of o-chlorotoluene to p-chlorotoluene in the mixture of o-chlorotoluene and p-chlorotoluene is 1:1; the volume ratio of o-chlorotoluene to p-chlorotoluene in the mixture of o-chlorotoluene, m-chlorotoluene and p-chlorotoluene is 1:1:1.

[0009] The hetero[3]arene crystalline material is an existing material, as disclosed by Jiong Zhou et al. in Chemical Communications, Vol. 52, 2016, pp. 1622-1624. Preferably, the hetero[3]arene crystalline material is activated after recrystallization in a poor solvent before use. The poor solvent may be acetone. The hetero[3]arene crystalline material obtained by recrystallization may be activated by heating to remove solvent molecules. Preferably, the activation temperature is not less than 150° C. and the activation time is not less than 2 hours. The activated hetero[3]arene crystalline material can be directly used for the adsorption separation of a mixture of chlorotoluene isomers.

[0010] The specific steps of using hetero[3]aromatic hydrocarbon crystal material to absorb and separate chlorotoluene mixture are as follows: placing the hetero[3]aromatic hydrocarbon crystal material in a mixed steam of o-chlorotoluene and m-chlorotoluene, or o-chlorotoluene and p-chlorotoluene, or o-chlorotoluene, m-chlorotoluene and p-chlorotoluene, at a temperature less than 80°C.

[0011] The adsorption time can be changed with the change of factors such as the sample amount and the ratio of o-chlorotoluene in the mixture. During the adsorption process, the hetero[3]arene crystalline material will undergo a change in crystal form. Due to multiple non-covalent bond interactions, 1 H NMR results showed that o-chlorotoluene in the mixture formed a host-guest complex with hetero[3]arene, and the stoichiometric ratio of the host-guest complex was 1:1.

[0012] After the hetero[3]arene crystalline material is completely adsorbed in the mixed vapor or mixed solution of chlorotoluene, the hetero[3]arene crystalline material is removed and vacuum heating or reduced pressure heating is used to remove the chlorotoluene mixture adsorbed on the surface of the hetero[3]arene crystalline material. Preferably, the temperature of the vacuum heating or reduced pressure heating is less than 80°C. The heating time can be adjusted according to the sample amount. Under conditions below 80°C, the host-guest complex still exists stably, while the chlorotoluene mixture adsorbed on the surface can be gradually removed. By removing the mixed vapor adsorbed on the surface, the purity of the o-chlorotoluene separated by adsorption can be further improved.

[0013] Heating desorption can be used to remove the o-chlorotoluene adsorbed and complexed by the hetero[3]arene crystalline material, while regenerating the hetero[3]arene crystalline material. The desorption time can be adjusted according to the sample amount. Preferably, the heating temperature is 80 to 100°C. At this temperature, the host-guest complex is unstable, and the adsorbed o-chlorotoluene molecules will gradually be released, while the hetero[3]arene crystalline material is stable. The PXRD pattern shows that only the crystal form changes during the desorption process. After desorption is completed, the regenerated hetero[3]arene crystalline material is obtained, which can be used to adsorb and separate the chlorotoluene isomers for the next cycle.

[0014] Due to the differences in the molecular structures of chlorotoluene isomers, the hetero[3]arene crystalline material can form a host-guest complex with o-chlorotoluene in a stoichiometric ratio of 1:1. The host-guest complex gradually decomplexes upon heating, releasing the adsorbed o-chlorotoluene. The hetero[3]arene crystalline material is stable at the desorption temperature and can be reused after the desorption process is completed without loss of selectivity.

[0015] Compared with the prior art, the present invention has the following main advantages: the separation process is simple to operate and has low equipment requirements; the separation process does not require distillation operation, has low energy consumption, saves energy, and reduces the production cost of o-chlorotoluene; the crystal material used is highly stable and can be recycled without reducing the separation effect.

[0016] The present invention utilizes hetero[3]arene to separate o-chlorotoluene from a gaseous chlorotoluene mixture with a purity exceeding 98%. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 These are the X-ray diffraction (PXRD) data of hetero[3]arene p-chlorotoluene isomers after vapor adsorption.

[0018] Figure 2 Headspace gas chromatography of mixed vapors of o-chlorotoluene and m-chlorotoluene after adsorption of hetero[3]aromatic hydrocarbons.

[0019] Figure 3 Headspace gas chromatography of hetero[3]aromatic hydrocarbons after adsorption of mixed vapors of o-chlorotoluene and p-chlorotoluene.

[0020] Figure 4 This is the headspace gas chromatography after adsorption of the three-component mixed vapor of hetero[3]aromatic parachlorotoluene.

[0021] Figure 5 This is the cyclic performance diagram of the adsorption of three-component mixed vapor of hetero[3]aromatic hydrocarbon p-chlorotoluene. DETAILED DESCRIPTION

[0022] The following non-limiting examples are provided to enable those skilled in the art to more fully understand the present invention, but are not intended to limit the present invention in any way. The operating methods in the following examples where specific conditions are not specified are generally performed under conventional conditions or conditions recommended by the manufacturer.

[0023] Example 1

[0024] Preparation of hetero[3]arene crystalline material: Weigh 2 g of hetero[3]arene and place it in 20 mL of acetone. Heat to boiling, add acetone dropwise until it is completely dissolved, store the solution at 0°C overnight, collect the precipitated crystals by filtration, dry the obtained crystals in a vacuum at 50°C, and activate at 150°C for 2 hours to obtain a white powder, which is recorded as H.

[0025] The product characterization data prepared in this example are as follows:

[0026] H, 1 H NMR (600MHz, CDCl3, 293K, ppm) δ7.11 (d, J = 6Hz, 2H), 6.66 (d, J = 6Hz, 2H),

[0027] 6.28(s,2H),6.22(s,2H),4.11–3.97(m,8H),3.83(s,6H),3.64(s,6H),3.57(s,6H),3.40(d,J=18Hz,2H),1.39(t,J=6Hz,6H).

[0028] The PXRD test results are as follows Figure 1 As shown, the obtained hetero[3]arene crystalline material has good crystallinity.

[0029] Example 2

[0030] Adsorption of individual chlorotoluene isomers by hetero[3]arene crystalline materials: Take three 20 mL inoculum bottles, add 1 mL of o-chlorotoluene, m-chlorotoluene and p-chlorotoluene respectively, and name them H-oCT, H-mCT and H-pCT respectively. Take 20 mg of the hetero[3]arene crystalline materials prepared in Example 1 and place them in three 5 mL open inoculum bottles respectively. Place the three open 5 mL inoculum bottles in three 20 mL inoculum bottles respectively. Seal the 20 mL inoculum bottles and place them in a 25°C water bath for 8 hours.

[0031] The product characterization data prepared in this example are as follows:

[0032] H-oCT, 1 H NMR (600MHz, CDCl3, 293K, ppm) δ7.11 (d, J = 6Hz, 2H), 7.05-7.00 (m, 4H),

[0033] 6.07–6.02(m,4H),6.66(d,J=6Hz,2H),6.28(s,2H),6.22(s,2H),4.11–3.97(m,8H),3.83 (s, 6H), 3.64 (s, 6H), 3.57 (s, 6H), 3.40 (d, J = 18Hz, 2H), 2.41 (s, 3H), 1.39 (t, J = 6Hz, 6H).

[0034] H-mCT, 1H NMR (600MHz, CDCl3, 293K, ppm) δ7.11 (d, J = 6Hz, 2H), 6.93 (s, 1H), 6.66

[0035] (d,J=6Hz,2H),6.28(s,2H),6.22(s,2H),4.11–3.97(m,8H),3.83(s,6H),3.6 4(s,6H),3.57(s,6H),3.40(d,J=18Hz,2H),2.36(s,2H),1.39(t,J=6Hz,6H).

[0036] H-pCT, 1 H NMR (600MHz, CDCl3, 293K, ppm) δ7.11 (d, J = 6Hz, 2H), 7.06 (d, J = 12Hz,

[0037] 2H),6.66(d,J=6Hz,2H),6.28(s,2H),6.22(s,2H),4.11–3.97(m,8H),3.83(s,6H) ,3.64(s,6H),3.57(s,6H),3.40(d,J=18Hz,2H),2.35(s,2H),1.39(t,J=6Hz,6H).

[0038] 1 H NMR results showed that hetero[3]arene crystalline materials had different degrees of adsorption effects on the three chlorotoluene isomers.

[0039] The PXRD test results are as follows Figure 1 As shown in the figure, compared with the PXRD spectrum of the initially activated hetero[3]arene crystal material, the PXRD spectrum of the hetero[3]arene crystal material after being placed in the vapor of o-chlorotoluene, m-chlorotoluene and p-chlorotoluene for a period of time has changed, which indicates that its unit cell parameters have changed, meaning that o-chlorotoluene, m-chlorotoluene and p-chlorotoluene have been adsorbed into the hetero[3]arene crystal material respectively. This proves that hetero[3]arene has an adsorption effect on the three chlorotoluene isomers.

[0040] Example 3

[0041] Adsorption of hetero[3]aromatic hydrocarbon crystal material on a 1:1 (v:v) mixture of o-chlorotoluene and m-chlorotoluene: Take a 20 mL inoculum bottle, add 1 mL of o-chlorotoluene and 1 mL of m-chlorotoluene, and name it H-omCT. Take 20 mg of the hetero[3]aromatic hydrocarbon crystal material prepared in Example 1 and place it in a 5 mL open inoculum bottle. Place the open 5 mL inoculum bottle in the above 20 mL inoculum bottle, and seal the 20 mL inoculum bottle. Place it in a 25°C water bath for 32 hours. The resulting powder is placed in a 50°C vacuum oven for 30 minutes.

[0042] The product characterization data prepared in this example are as follows:

[0043] H-omCT, 1 H NMR (600MHz, CDCl3, 293K, ppm) δ7.11 (d, J = 6Hz, 2H), 7.05 (m, 4H),

[0044] 6.07–6.02(m,4H),6.66(d,J=6Hz,2H),6.28(s,2H),6.22(s,2H),4.11–3.97(m,8H),3.83 (s, 6H), 3.64 (s, 6H), 3.57 (s, 6H), 3.40 (d, J = 18Hz, 2H), 2.41 (s, 3H), 1.39 (t, J = 6Hz, 6H).

[0045] exist 1 Only the signal of hydrogen atoms corresponding to o-chlorotoluene was found in the H NMR spectrum, which indicates that hetero[3]arene crystal materials can selectively adsorb o-chlorotoluene.

[0046] The PXRD test results are as follows Figure 1 As shown, compared with the PXRD spectrum of the initially activated hetero[3]aromatic hydrocarbon crystal material, the PXRD spectrum of the hetero[3]aromatic hydrocarbon crystal material after being placed in the mixed vapor of o-chlorotoluene and m-chlorotoluene for a period of time changes, and the spectrum change is the same as that of H-oCT, which indicates that the hetero[3]aromatic hydrocarbon crystal material can selectively adsorb o-chlorotoluene.

[0047] The results of headspace gas chromatography are as follows Figure 2 As shown, the results indicate that hetero[3]arene crystal materials can selectively adsorb o-chlorotoluene with a selectivity of 98.26%.

[0048] Example 4

[0049] Adsorption of hetero[3]arene crystalline material on a 1:1 (v:v) mixture of o-chlorotoluene and p-chlorotoluene: Take a 20 mL inoculum bottle, add 1 mL of o-chlorotoluene and 1 mL of p-chlorotoluene, and name it H-opCT. Take 20 mg of the hetero[3]arene crystalline material prepared in Example 1 and place it in a 5 mL open inoculum bottle. Place the open 5 mL inoculum bottle in the above 20 mL inoculum bottle. Seal the 20 mL inoculum bottle and place it in a 25°C water bath for 24 hours. The resulting powder is placed in a 50°C vacuum oven for 30 minutes.

[0050] The product characterization data prepared in this example are as follows:

[0051] H-opCT, 1 H NMR (600MHz, CDCl3, 293K, ppm) δ7.11 (d, J = 6Hz, 2H), 7.05 (m, 4H),

[0052] 6.07–6.02(m,4H),6.66(d,J=6Hz,2H),6.28(s,2H),6.22(s,2H),4.11–3.97(m,8H),3.83 (s, 6H), 3.64 (s, 6H), 3.57 (s, 6H), 3.40 (d, J = 18Hz, 2H), 2.41 (s, 3H), 1.39 (t, J = 6Hz, 6H).

[0053] exist 1 Only the signal of hydrogen atoms corresponding to o-chlorotoluene was found in the H NMR spectrum, which indicates that hetero[3]arene crystal materials can selectively adsorb o-chlorotoluene.

[0054] The PXRD test results are as follows Figure 1 As shown, compared with the PXRD spectrum of the initially activated hetero[3]aromatic hydrocarbon crystal material, the PXRD spectrum of the hetero[3]aromatic hydrocarbon crystal material after being placed in the mixed vapor of o-chlorotoluene and p-chlorotoluene for a period of time changes, and the spectrum change is the same as that of H-oCT, which indicates that the hetero[3]aromatic hydrocarbon crystal material can selectively adsorb o-chlorotoluene.

[0055] The results of headspace gas chromatography are as follows Figure 2 As shown, the results indicate that hetero[3]arene crystal materials can selectively adsorb o-chlorotoluene with a selectivity of 99.24%.

[0056] Example 5

[0057] Adsorption of a 1:1:1 (v:v:v) mixed vapor of o-chlorotoluene, m-chlorotoluene and p-chlorotoluene by hetero[3]aromatic crystalline material: Take a 20 mL inoculum bottle, add 1 mL of o-chlorotoluene, 1 mL of m-chlorotoluene and 1 mL of p-chlorotoluene, and name it H-ompCT. Take 20 mg of the hetero[3]aromatic crystalline material prepared in Example 1 and place it in a 5 mL open inoculum bottle. Place the open 5 mL inoculum bottle in the above 20 mL inoculum bottle. Seal the 20 mL inoculum bottle and place it in a 25°C water bath for 14 hours. The resulting powder is placed in a 50°C vacuum oven for 30 minutes.

[0058] The product characterization data prepared in this example are as follows:

[0059] H-ompCT, 1 H NMR (600MHz, CDCl3, 293K, ppm) δ7.11 (d, J = 6Hz, 2H), 7.05 (m, 4H),

[0060] 6.07–6.02(m,4H),6.66(d,J=6Hz,2H),6.28(s,2H),6.22(s,2H),4.11–3.97(m,8H),3.83 (s, 6H), 3.64 (s, 6H), 3.57 (s, 6H), 3.40 (d, J = 18Hz, 2H), 2.41 (s, 3H), 1.39 (t, J = 6Hz, 6H).

[0061] exist 1 Only the signal of hydrogen atoms corresponding to o-chlorotoluene was found in the H NMR spectrum, which indicates that hetero[3]arene crystal materials can selectively adsorb o-chlorotoluene.

[0062] The PXRD test results are as follows Figure 1 As shown, compared with the PXRD spectrum of the initially activated hetero[3]aromatic hydrocarbon crystal material, the PXRD spectrum of the hetero[3]aromatic hydrocarbon crystal material after being placed in the mixed vapor of o-chlorotoluene, m-chlorotoluene and p-chlorotoluene for a period of time changes, and the spectrum change is the same as that of H-oCT, which indicates that the hetero[3]aromatic hydrocarbon crystal material can selectively adsorb o-chlorotoluene.

[0063] The results of headspace gas chromatography are as follows Figure 4 As shown, the results indicate that hetero[3]arene crystal materials can selectively adsorb o-chlorotoluene with a selectivity of 98.04%.

[0064] Example 6

[0065] Regeneration of hetero[3]arene crystalline material: 20 mg of hetero[3]arene crystalline material saturated with o-chlorotoluene was heated in a vacuum oven at 100°C for 2 hours. The sample was recorded as HD.

[0066] The product characterization data prepared in this embodiment are as follows:

[0067] HD, 1 H NMR (600MHz, CDCl3, 293K, ppm) δ7.11 (d, J = 6Hz, 2H), 6.66 (d, J = 6Hz,

[0068] 2H), 6.28 (s, 2H), 6.22 (s, 2H), 4.11–3.97 (m, 8H), 3.83 (s, 6H), 3.64 (s, 6H), 3.57 (s, 6H), 3.40 (d, J = 18Hz, 2H), 1.39 (t, J = 6Hz, 6H).

[0069] exist 1 It was found in the H NMR spectrum that the signal of the hydrogen atom corresponding to o-chlorotoluene had disappeared, which indicated that the hetero[3]arene crystal material had completed desorption and regeneration, and all o-chlorotoluene molecules had been released.

[0070] The PXRD test results are as follows Figure 1 As shown in FIG, compared with the PXRD spectrum of the initially activated hetero[3]arene crystal material, the PXRD spectrum of the hetero[3]arene crystal material after complete desorption changes very little, which indicates that the hetero[3]arene crystal material has completed the desorption process and can be used for the next adsorption separation of chlorotoluene isomers.

[0071] Example 7

[0072] Reuse of hetero[3]arene crystal material: 20 mg of hetero[3]arene crystal material regenerated in Example 5 was used to repeat Example 5. The results are shown in FIG. Figure 5 As shown, the selectivity of the hetero[3]arene crystalline material did not decrease after being reused 5 times.

Claims

1. Application of hetero[3]arene crystalline material as o-chlorotoluene adsorbent, characterized in that: A mixture of chlorotoluene isomers is separated by adsorption using hetero[3]arene crystalline materials, wherein the chemical structure of the hetero[3]arene crystalline materials is as follows: The chlorotoluene isomer mixture is contacted with a hetero[3]arene crystal material for adsorption to achieve separation of o-chlorotoluene; the chlorotoluene isomer mixture is a mixture of o-chlorotoluene and m-chlorotoluene, or o-chlorotoluene and p-chlorotoluene, or o-chlorotoluene, m-chlorotoluene and p-chlorotoluene; The adsorption temperature is less than 80°C.

2. The use according to claim 1, characterized in that After the adsorption is completed, vacuum heating or reduced pressure heating is used to remove the chlorotoluene isomer mixture adsorbed on the surface of the hetero[3]arene crystal material, and the temperature of the vacuum heating or reduced pressure heating is less than 80°C.

3. The use according to claim 1 or 2, characterized in that The o-chlorotoluene adsorbed and complexed by the hetero[3] aromatic hydrocarbon crystal material is removed by heating and desorption, thereby achieving the regeneration of the hetero[3] aromatic hydrocarbon crystal material; the heating temperature is 80-100°C.

4. The use according to claim 1, characterized in that The hetero[3]arene crystalline material is first recrystallized in a poor solvent and then activated before use.

5. The use according to claim 4, characterized in that The poor solvent is acetone.

6. The use according to claim 4, characterized in that The activation temperature is not lower than 150° C. and the activation time is not less than 2 hours.

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