Molding preparation method and application of cyclodextrin-based adsorbent

Abstract

The invention belongs to the technical field of clean oil product functional materials and polycyclic aromatic hydrocarbon adsorption, and discloses a molding preparation method and application of a cyclodextrin-based adsorbent. The cyclodextrin forming adsorbent is obtained by carbonizing a cyclodextrin self-crosslinked organic porous material by taking p-phenylene diisocyanate as a cross-linking agent; the preparation method comprises the following specific steps: polymerizing cyclodextrin and p-phenylene diisocyanate in a DMF (Dimethyl Formamide) solvent, freeze-drying, and finally carbonizing to obtain the cyclodextrin forming adsorbent. The prepared material can be applied to adsorption of polycyclic aromatic hydrocarbon organic pollutants, and is mainly used for removing polycyclic aromatic hydrocarbon anthracene or acenaphthene in simulated catalytic cracking diesel oil; the result shows that the adsorption capacities of the adsorbent on polycyclic aromatic hydrocarbon anthracene and acenaphthene can reach 62.04 mg / g and 35.25 mg / g (the concentration of anthracene and acenaphthene is 200ppm) at most. The prepared cyclodextrin forming adsorbent has the advantages of being easy and convenient to operate, high in adsorption efficiency, good in cycling stability, low in cost and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of clean oil functional materials and new polycyclic aromatic hydrocarbon adsorption technologies, and particularly relates to a forming preparation method and application of a cyclodextrin-based adsorbent. Background Art

[0002] Fluid catalytic cracking (FCC) diesel is an important component of vehicle diesel. However, its aromatic hydrocarbon content is usually as high as over 60%, which results in a low cetane number, poor combustion performance, and is prone to forming PM2.5 particulate matter during combustion. Therefore, it is of great significance to extract polycyclic aromatic hydrocarbons (especially bicyclic aromatic hydrocarbons) from FCC diesel before hydrofining. This process can not only effectively reduce the hydrogen consumption in the subsequent hydrofining process but also use the separated aromatic hydrocarbon components in chemical fields such as pharmaceuticals and rubber, realizing the efficient utilization of resources. Therefore, developing suitable oil de-aromatization technologies is crucial for improving diesel quality, reducing environmental pollution, and enhancing resource utilization efficiency.

[0003] Traditional de-aromatization technologies usually adopt hydrofining, which reduces the diesel density through selective ring-opening reactions and saturates the aromatic hydrocarbons to improve the cetane number of diesel. However, hydrofining has many deficiencies, such as high investment costs, complex processes, and large energy consumption. In addition to hydrofining, there are also extraction methods and adsorption separation methods. The extraction method has a relatively mature process, mild operating conditions, and simple technical requirements. However, the organic extractants (such as sulfolane) used in its operation are highly harmful to the environment and can corrode equipment. In contrast, the adsorption separation method has gradually become a more promising aromatic hydrocarbon removal method due to its advantages of low cost, simple operation, and easy recovery.

[0004] Organic porous polymers (POPs) exhibit excellent performance in the fields of adsorption and separation due to their high specific surface area and adjustable pore structure, especially having significant advantages in removing organic pollutants, heavy metal ions, and gas adsorption in water bodies. However, most current POPs adsorbent materials exist in powder form, which is difficult to meet the requirements of large-scale industrial applications and recycling. Therefore, developing formed adsorbent materials has important research value and practical significance. Summary of the Invention

[0005] The technical problem to be solved by the present invention is: in view of the current situation where polycyclic aromatic hydrocarbons degrade FCC diesel, to research a formed adsorbent that is simple, efficient, low-cost, easy to separate, and recyclable for adsorbing polycyclic aromatic hydrocarbons in FCC diesel.

[0006] The present invention proposes a method for preparing an adsorbent molding based on a cyclodextrin (CD) polymer, which uses cyclodextrin as a building unit and p-phenylene diisocyanate as a cross-linking agent to obtain an organic porous polymer, and then obtains a porous carbon material through a direct carbonization method. The porous carbon material has a high specific surface area, microporosity, and nitrogen and oxygen heteroatom doping content, and exhibits a high adsorption capacity for polycyclic aromatic hydrocarbons.

[0007] In order to achieve the above objectives, the present invention adopts the following technical solutions:

[0008] A molding preparation method based on cyclodextrin adsorbent, the steps are as follows:

[0009] (1) First, cyclodextrin (CD) is dissolved in N,N-dimethylformamide (DMF) solution, and then p-phenylene diisocyanate is added and mixed evenly;

[0010] (2) placing the mixed solution obtained in step (1) in an oil bath and allowing to stand to obtain a milky white gel-like solid, collecting the milky white gel-like solid, washing it with anhydrous ethanol and deionized water in sequence, and freezing it in a refrigerator after washing;

[0011] (3) After being frozen in the refrigerator, the mixture was placed in a freeze dryer and freeze-dried to obtain a white solid block;

[0012] (4) calcining the white block solid obtained in step (3), and cooling to room temperature after calcination to obtain a cyclodextrin shaped adsorbent.

[0013] In step (1), the cyclodextrin includes any one of α-CD, β-CD and γ-CD.

[0014] In step (1), the usage ratio of cyclodextrin, p-phenylene diisocyanate and DMF is 0.1 g:0.23 g:1 mL.

[0015] In step (2), the temperature of the oil bath is 70-90° C. and the time is 5-15 min.

[0016] In step (2), the freezing temperature of the refrigerator is -10 to -20°C, and the freezing time is 12 to 24 hours.

[0017] In step (3), the freeze-drying temperature is -30 to -50°C and the time is 12 to 24 hours.

[0018] In step (4), the calcination is carried out under a nitrogen atmosphere at a heating rate of 5°C min -1 The calcination temperature is 900-1000°C and the time is 2-3 hours.

[0019] The cyclodextrin shaped adsorbent prepared by the present invention is applied to the adsorption of polycyclic aromatic hydrocarbon organic pollutants;

[0020] Furthermore, the use of the cyclodextrin shaped adsorbent prepared by the present invention for adsorbing and removing polycyclic aromatic hydrocarbons such as anthracene or acenaphthylene in catalytic cracking diesel oil.

[0021] Taking the described cyclodextrin shaped adsorbent as an example of polycyclic aromatic hydrocarbons in simulated catalytic cracking diesel oil for adsorption treatment. The adsorption process adopts a static adsorption process, that is, the simulated catalytic cracking diesel oil is adsorbed in a closed adsorption container. The ratio of the adsorbent to the simulated catalytic cracking diesel oil is 1 g / L, the initial concentration of the simulated catalytic cracking diesel oil is 200 mg / L, the adsorption capacity increases with the increase of adsorption time and basically reaches equilibrium after 3 hours, and the highest adsorption capacities for anthracene and acenaphthylene are 62.04 mg / g and 35.25 mg / g respectively.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] (1) The main raw material for synthesizing the cyclodextrin shaped adsorbent of the present invention is cyclodextrin, which is easy to obtain and has low cost.

[0024] (2) The preparation process and operation of synthesizing the cyclodextrin shaped adsorbent of the present invention are very simple, the preparation period is short, the product is non-toxic, environmentally friendly, does not require special chemical equipment, and is easy to realize industrial production.

[0025] (3) The cyclodextrin shaped adsorbent of the present invention has a relatively high adsorption capacity for polycyclic aromatic hydrocarbon organic pollutants; by further studying the influence of its carbonization temperature on the performance of the adsorbent, the optimal carbonization temperature is determined, and its adsorption effect on polycyclic aromatic hydrocarbon organic pollutants is significantly increased. For example, for anthracene, it is increased from 12.50 mg / g to 62.04 mg / g, and the increase rate is 79.85%. Specific embodiments

[0026] It should be understood that the terms described in the present invention are only for describing specific embodiments and are not used to limit the present invention. In addition, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each intermediate value within any stated value or stated range and each smaller range between any other stated value or intermediate value within the stated range are also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded from the range.

[0027] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Although this invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of this invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the said documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0028] Without departing from the scope or spirit of the present invention, various modifications and variations can be made to the specific embodiments of the description of the present invention, which will be obvious to those skilled in the art.

[0029] Regarding the terms "comprising", "including", "having", "containing", etc. used herein, they are all open-ended terms, meaning including but not limited to.

[0030] Example 1:

[0031] First, 0.1 g of α-CD was dissolved in 1 ml of DMF solution, and then 0.23 g of p-phenylene diisocyanate was added and mixed evenly. The mixed solution was placed in an oil bath at 80 °C and left standing for 5 minutes to obtain a milky white gel-like solid. The solid was collected and washed successively with absolute ethanol and deionized water, and then placed in a refrigerator at -16 °C for freezing for 12 hours. The frozen solid was put into a freeze dryer and dried at -45 °C for 12 hours to obtain a white solid, named α-CD-PPDI.

[0032] α-CD-PPDI was placed in a porcelain boat and put into a tubular furnace. N2 was passed through for half an hour before heating. The heating program of the tubular furnace was set as follows: under a nitrogen atmosphere, it was heated from room temperature to the set temperature at a heating rate of 5 °C / min, maintained for 2 hours, and finally cooled naturally to room temperature. Finally, the product was collected to obtain a porous carbon material;

[0033] A series of porous carbon materials (denoted as α-CD-PPDI-900 and α-CD-PPDI-1000 respectively) were prepared at different carbonization temperatures (900 °C, 1000 °C).

[0034] Adsorption capacity comparison experiment of adsorbents:

[0035] Prepare 5 mL of simulated cracked diesel (n-hexadecane) containing anthracene / acenaphthylene with an initial concentration of 200 mg / L in a glass bottle. Add 5 mg of the α-CD-PPDI, α-CD-PPDI-900, and α-CD-PPDI-1000 adsorbents prepared in Example 1 respectively. Use a water bath shaker to shake at a speed of 130 rpm / min at room temperature for 3 hours. After reaching the adsorption equilibrium, use gas chromatography to measure the concentration of polycyclic aromatic hydrocarbons and calculate the adsorption capacity. The results are shown in Table 1.

[0036] Table 1 Adsorption capacity data of different adsorbents under the condition that the initial concentration of polycyclic aromatic hydrocarbons is 200 mg / L

[0037] Adsorbent Anthracene adsorption capacity (mg / g) Acenaphthylene adsorption capacity (mg / g) α-CD-PPDI 13.46 2.17 α-CD-PPDI-900 30.58 19.73 α-CD-PPDI-1000 58.79 33.63

[0038] As can be seen from Table 1, after carbonizing α-CD-PPDI, its adsorption effect on polycyclic aromatic hydrocarbons anthracene and acenaphthylene increased significantly, from 13.46 mg / g and 2.17 mg / g to 58.79 mg / g and 33.63 mg / g respectively.

[0039] Example 2:

[0040] First, dissolve 0.1 g of β-CD in 1 ml of DMF solution, and then add 0.23 g of p-phenylene diisocyanate and mix evenly. Place the mixed solution in an oil bath at 80 °C and let it stand for 5 minutes to obtain a milky white gel-like solid. Collect the solid and wash it successively with absolute ethanol and deionized water. After washing, place it in a refrigerator at -16 °C and freeze for 12 hours. Place the frozen solid in a freeze dryer and dry it at -45 °C for 12 hours to obtain a white solid, named β-CD-PPDI.

[0041] Place β-CD-PPDI in a porcelain boat and put it into a tube furnace. Before heating, pass N2 for half an hour. The heating program of the tube furnace is set as follows: under a nitrogen atmosphere, heat from room temperature at a heating rate of 5 °C / min to the set temperature respectively, hold for 2 hours, and finally cool naturally to room temperature. Finally, collect the product to obtain a porous carbon material; a series of porous carbon materials (denoted as β-CD-PPDI-900 and β-CD-PPDI-1000 respectively) were prepared at different carbonization temperatures (900 °C, 1000 °C).

[0042] Adsorption capacity comparison experiment of three adsorbents:

[0043] Prepare 5 mL of simulated cracked diesel (n-hexadecane) containing anthracene / acenaphthylene with an initial concentration of 200 mg / L in a glass bottle. Add 5 mg of the β-CD-PPDI, β-CD-PPDI-900, and β-CD-PPDI-1000 adsorbents prepared in Example 1 respectively. Use a water bath shaker to shake at a speed of 130 rpm / min at room temperature for 3 hours. After reaching the adsorption equilibrium, use gas chromatography to measure the concentration of polycyclic aromatic hydrocarbons and calculate the adsorption capacity. The results are shown in Table 2.

[0044] Table 2 Adsorption capacity data of different adsorbents under the condition of an initial concentration of 200 mg / L of polycyclic aromatic hydrocarbons

[0045] Adsorbent Anthracene adsorption capacity (mg / g) Acenaphthylene adsorption capacity (mg / g) β-CD-PPDI 12.50 1.09 β-CD-PPDI-900 29.96 24.07 β-CD-PPDI-1000 62.04 35.25

[0046] As can be seen from Table 2, after carbonizing β-CD-PPDI, its adsorption effect on polycyclic aromatic hydrocarbons anthracene and acenaphthylene increased significantly, from 12.50 mg / g and 1.09 mg / g to 62.04 mg / g and 35.25 mg / g respectively.

[0047] Example 3:

[0048] First, dissolve 0.1 g of γ-CD in 1 ml of DMF solution, and then add 0.23 g of p-phenylene diisocyanate and mix evenly. Place the mixed solution in an oil bath at 80 °C and let it stand for 5 minutes to obtain a milky white gel-like solid. Collect the solid and wash it successively with absolute ethanol and deionized water. After washing, put it in a refrigerator at -16 °C and freeze it for 12 hours. Place the frozen solid in a freeze dryer and dry it at -45 °C for 12 hours to obtain a white solid, named γ-CD-PPDI.

[0049] Place γ-CD-PPDI in a porcelain boat and put it into a tube furnace. Before heating, pass N2 for half an hour. The heating program of the tube furnace is set as follows: under a nitrogen atmosphere, heat from room temperature to the set temperature at a heating rate of 5 °C / min, hold for 2 hours, and finally cool naturally to room temperature. Finally, collect the product to obtain a porous carbon material; a series of porous carbon materials (denoted as γ-CD-PPDI-900 and γ-CD-PPDI-1000 respectively) were prepared at different carbonization temperatures (900 °C, 1000 °C).

[0050] Adsorption capacity comparison experiment of three adsorbents:

[0051] Prepare 5 mL of simulated cracked diesel (n - hexadecane) containing anthracene / acenaphthylene with an initial concentration of 200 mg / L in a glass bottle. Add 5 mg of the γ - CD - PPDI, γ - CD - PPDI - 900, and γ - CD - PPDI - 1000 adsorbents prepared in Example 1 respectively. Use a water bath shaker to shake at a speed of 130 rpm / min for 3 hours at room temperature. After reaching the adsorption equilibrium, use gas chromatography to measure the concentration of polycyclic aromatic hydrocarbons and calculate the adsorption capacity. The results are shown in Table 3.

[0052] Table 3: Adsorption capacity data of different adsorbents under the condition that the initial concentration of polycyclic aromatic hydrocarbons is 200 mg / L

[0053] Adsorbent Anthracene adsorption capacity (mg / g) Acenaphthylene adsorption capacity (mg / g) γ-CD-PPDI 8.63 3.26 γ-CD-PPDI-900 26.42 17.92 γ-CD-PPDI-1000 59.23 29.31

[0054] As can be seen from Table 3, after carbonizing γ - CD - PPDI, its adsorption effect on polycyclic aromatic hydrocarbons anthracene and acenaphthylene increases significantly, from 8.63 mg / g and 3.26 mg / g to 59.23 mg / g and 29.31 mg / g respectively.

[0055] Note: The above embodiments are only used to illustrate the present invention and do not limit the technical solutions described in the present invention; therefore, although this specification has elaborated on the present invention with reference to the above - mentioned various embodiments, those skilled in the art should understand that the present invention can be modified or equivalently replaced; and all technical solutions and their improvements that do not deviate from the spirit and scope of the present invention should be covered within the scope of the claims of the present invention.

Claims

1. A molding preparation method based on cyclodextrin adsorbent, characterized in that: The following steps are involved: (1) First, cyclodextrin is dissolved in N,N-dimethylformamide (DMF) solution, and then p-phenylene diisocyanate is added and mixed evenly; (2) placing the mixed solution obtained in step (1) in an oil bath and allowing to stand to obtain a milky white gel-like solid, collecting the milky white gel-like solid, washing it with anhydrous ethanol and deionized water in sequence, and freezing it in a refrigerator after washing; (3) After being frozen in the refrigerator, the mixture was placed in a freeze dryer and freeze-dried to obtain a white solid block; (4) calcining the white block solid obtained in step (3), and cooling to room temperature after calcination to obtain a cyclodextrin shaped adsorbent.

2. The molding preparation method based on cyclodextrin adsorbent according to claim 1, characterized in that: In step (1), the cyclodextrin includes any one of α-CD, β-CD, and γ-CD.

3. The molding preparation method based on cyclodextrin adsorbent according to claim 1, characterized in that: In step (1), the usage ratio of cyclodextrin, p-phenylene diisocyanate and DMF is 0.1 g:0.23 g:1 mL.

4. The molding preparation method based on cyclodextrin adsorbent according to claim 1, characterized in that: In step (2), the temperature of the oil bath is 70-90° C. and the time is 5-15 min.

5. The molding preparation method based on cyclodextrin adsorbent according to claim 1, characterized in that: In step (2), the freezing temperature of the refrigerator is -10 to -20°C, and the freezing time is 12 to 24 hours.

6. The molding preparation method based on cyclodextrin adsorbent according to claim 1, characterized in that: In step (3), the freeze-drying temperature is -30 to -50°C and the time is 12 to 24 hours.

7. The molding preparation method based on cyclodextrin adsorbent according to claim 1, characterized in that: In step (4), the calcination is carried out under a nitrogen atmosphere at a heating rate of 5°C min -1 The calcination temperature is 900-1000°C and the time is 2-3 hours.

8. Use of the cyclodextrin shaped adsorbent prepared by the method according to any one of claims 1 to 7 for adsorbing polycyclic aromatic hydrocarbon organic pollutants.

9. The use according to claim 8, characterized in that The cyclodextrin shaped adsorbent is used for adsorbing and removing polycyclic aromatic hydrocarbons anthracene or acenaphthylene from catalytic cracking diesel.