A high-capacity chlorinated hydrocarbon adsorbent and its preparation method and application

Abstract

The present invention relates to the technical field of flue gas treatment, and provides a high-capacity chlorohydrocarbon adsorbent, a preparation method thereof and an application thereof. The structural formula of the adsorbent is Fe x Cu y -MOFs, and the atomic ratio x:y of Fe / Cu is 1:4 to 19. By utilizing the coupling effect of bimetallic ions (Fe 3+ and Cu 2+ ), the acidity of the adsorbent is moderate, and the attraction for chloride ions in chlorohydrocarbons is enhanced, thereby increasing the adsorption capacity for chlorohydrocarbons. Among them, the adsorption capacity for CH3Cl reaches 102.36 mmol / g, the adsorption capacity for CH2Cl2 is 36.43 mmol / g, the adsorption capacity for CHCl3 reaches 15.16 mmol / g, and the adsorption capacity for vinyl chloride is 10.68 mmol / g. The adsorption capacity is greatly improved, and it has high industrial application value.

Description

Technical Field

[0001] The present invention relates to the technical field of flue gas treatment, and in particular to a high-capacity chlorinated hydrocarbon adsorbent, a preparation method thereof and an application thereof. Background Art

[0002] The tail gas from the production process of products such as dimethyl phosphite, silicone, glyphosate, chloromethane and vinyl chloride mainly contains chlorinated hydrocarbons. For example, the current treatment process for chloromethane tail gas is to purify it and then compress, condense and separate it through membranes to recover as much as possible. The condensation method is limited by vapor pressure. The vapor pressure of chlorinated hydrocarbons in the gas phase after condensation is the lowest partial pressure in the gas phase. For example, the vapor pressure of chloromethane at -23.64°C is 0.101MPa. Even at a pressure of 0.8MPa, the content in the gas phase is still higher than 12%. The driving force of membrane separation is the concentration difference. The treated membrane separation tail gas still contains 5% to 10% of chlorinated hydrocarbons. The content of chlorinated hydrocarbons in the tail gas after treatment by these two methods is much higher than the national emission standard GB 39727-20 "Emission Standard of Air Pollutants for Pesticide Manufacturing Industry", which stipulates that the total organic matter emission requirement is less than 150mg / Nm 3 , and with the increasingly stringent environmental protection policies, the emission requirements in some areas are lower than 50mg / Nm 3 Therefore, the current industrial condensation method and membrane separation method cannot meet the accuracy requirements for removing chlorinated hydrocarbons from production tail gas.

[0003] Patents CN101012146A, CN103170214A, and CN106966857A disclose the use of pressure swing adsorption (PSA) processes with adsorbents to adsorb methyl chloride. However, none disclose the adsorption capacity of the adsorbents or whether the residual methyl chloride content in the tail gas meets standards. Prior art also discloses the adsorption of methyl chloride using the metal-organic framework (MOF) material MIL G53. The adsorbent's adsorption capacity for CH2Cl2 is 16.88 mmol / g, and for CHCl3 is 7.11 mmol / g. This low adsorption capacity requires a large adsorbent volume and high cost for the same tail gas treatment volume. To address this issue, a high-capacity adsorbent is needed that can adsorb chlorocarbons in the tail gas with minimal residual chlorocarbons. Summary of the Invention

[0004] In view of this, the present invention proposes a high-capacity chlorinated hydrocarbon adsorbent and its preparation method and application. The adsorbent has a high adsorption capacity and a small amount of residual chlorinated hydrocarbons after adsorbing the chlorinated hydrocarbons in the tail gas.

[0005] The technical solution of the present invention is achieved as follows: In the first aspect, the present invention provides a high-capacity chlorinated hydrocarbon adsorbent, the structural formula of the adsorbent is Fe x Cu y-MOFs, wherein the atomic ratio x:y of Fe / Cu is 1:4-19.

[0006] In a second aspect, the present invention provides a method for preparing a high-capacity chlorinated hydrocarbon adsorbent, comprising the following steps:

[0007] S1, using soluble iron and copper salts as raw materials, trimesic acid as organic ligand, and an organic-inorganic mixed solvent, was synthesized by a hydrothermal method;

[0008] S2, after the reaction is completed, washing with an organic-inorganic mixed solvent and then drying to obtain an adsorbent.

[0009] On the basis of the above technical solution, preferably, the soluble iron salt is FeCl3·6H2O or Fe(NO3)3·9H2O, and the soluble copper salt is Cu(NO3)2·6H2O.

[0010] Based on the above technical solution, preferably, the molar ratio of the iron salt to the copper salt is 1:4-19.

[0011] On the basis of the above technical solution, preferably, the ratio of trimesic acid to the total molar amount of soluble iron salt and copper salt is 2:2-3.

[0012] Based on the above technical solution, preferably, the organic-inorganic mixed solvent is N,N-dimethylformamide, water and ethanol.

[0013] On the basis of the above technical solution, preferably, the volume ratio of N,N-dimethylformamide: water: ethanol is (0.5-2): (0.5-2): (0.5-2).

[0014] Based on the above technical solution, preferably, the hydrothermal reaction temperature is 80-110° C. and the reaction time is 20-24 h.

[0015] In a third aspect, the present invention provides the use of an adsorbent in adsorbing chlorinated hydrocarbons in tail gas.

[0016] On the basis of the above technical solution, preferably, the chlorinated hydrocarbons are monochloromethane, dichloromethane, chloroform and vinyl chloride.

[0017] The high-capacity chlorinated hydrocarbon adsorbent of the present invention, its preparation method and application have the following beneficial effects compared with the prior art:

[0018] (1) The acidity of the bimetallic ion is that the iron ion has a single electron orbit, which enhances the physical attraction of the chlorine atom. The copper ion can be partially reduced to obtain some cuprous ions when used. The presence of some cuprous ions, coupled with the iron ions, significantly enhances the physical attraction of the chlorine atom. 3+ and Cu 2+ ) makes the acidity of the adsorbent moderate, and enhances the attraction of chloride ions in chlorinated hydrocarbons, thereby increasing the adsorption capacity for chlorinated hydrocarbons.

[0019] (2) The adsorbent of the present invention has an adsorption capacity of 102.36 mmol / g for CH3Cl, 36.43 mmol / g for CH2Cl2, 15.16 mmol / g for CHCl3, and 10.68 mmol / g for vinyl chloride. The adsorption capacity is greatly improved, and the adsorbent has high industrial application value.

[0020] (3) The adsorbent of the present invention can achieve an adsorption residual amount that meets emission requirements and meets emission standards; at the same time, under the condition of the same total amount of adsorption required, the amount of adsorbent used can be reduced, thereby reducing the volume of the equipment for loading the adsorbent, that is, the volume of the adsorption tower used, and further reducing the floor space requirement of industrial application equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1 is the infrared spectrum of the adsorbent. DETAILED DESCRIPTION

[0023] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0024] Example 1

[0025] The high capacity chlorinated hydrocarbon adsorbent Fe 0.05 Cu 0.95 -The preparation method of MOFs comprises the following steps:

[0026] 0.1407 g (0.67 mmol) of organic ligand trimesic acid (H3BTC) was dissolved in a solution of 10 mL DMF + 10 mL H2O + 10 mL C2H5OH with a total volume of 30 mL, and the solution was dissolved evenly by ultrasonication for 30 min. 0.0135 g (0.05 mmol) of FeCl3·6H2O and 0.2295 g (0.95 mmol) of Cu(NO3)·6H2O were weighed into the above solution and stirred at room temperature for 1 h until the solution was clarified. The resulting solution was then transferred to a polytetrafluoroethylene autoclave, which was sealed and placed in an oven at 110°C for 24 h before being cooled. The product was exchanged and washed three times with DMF, water, and ethanol, respectively, and dried at 85°C overnight to obtain HKUST-1 (5% Fe), i.e., Fe 0.05 Cu 0.95 -MOFs adsorbent.

[0027] Example 2

[0028] The high capacity chlorinated hydrocarbon adsorbent Fe 0.1 Cu 0.9 -The preparation method of MOFs comprises the following steps:

[0029] 0.1407 g (0.67 mmol) of organic ligand trimesic acid (H3BTC) was dissolved in a solution of 10 mL DMF + 10 mL H2O + 10 mL C2H5OH with a total volume of 30 mL, and the solution was dissolved evenly by ultrasonication for 30 min. 0.027 g (0.1 mmol) of FeCl3·6H2O and 0.2174 g (0.9 mmol) of Cu(NO3)·6H2O were weighed into the above solution and stirred at room temperature for 1 h until the solution was clarified. The resulting solution was then transferred to a polytetrafluoroethylene autoclave, which was sealed and placed in an oven at 110°C for reaction for 24 h before being cooled. The resulting product was exchanged and washed three times with DMF, water, and ethanol, respectively, and dried at 85°C overnight to obtain HKUST-1 (10% Fe), i.e., Fe 0.1 Cu 0.9 -MOFs adsorbent.

[0030] Example 3

[0031] The high capacity chlorinated hydrocarbon adsorbent Fe 0.2 Cu 0.8 -The preparation method of MOFs comprises the following steps:

[0032] 0.1407 g (0.67 mmol) of organic ligand trimesic acid (H3BTC) was dissolved in a solution of 10 mL DMF + 10 mL H2O + 10 mL C2H5OH with a total volume of 30 mL, and the solution was dissolved evenly by ultrasonication for 30 min. 0.054 g (0.2 mmol) of FeCl3·6H2O and 0.1932 g (0.8 mmol) of Cu(NO3)·6H2O were weighed into the above solution and stirred at room temperature for 1 h until the solution was clarified. The resulting solution was then transferred to a polytetrafluoroethylene autoclave, which was sealed and placed in an oven at 110°C for reaction for 24 h before being cooled. The resulting product was exchanged and washed three times with DMF, water, and ethanol, respectively, and dried at 85°C overnight to obtain HKUST-1 (20% Fe), i.e., Fe 0.2 Cu 0.8 -MOFs adsorbent.

[0033] Example 4

[0034] The high capacity chlorinated hydrocarbon adsorbent Fe 0.1 Cu 0.9 -The preparation method of MOFs comprises the following steps:

[0035] 0.2102 g (1 mmoL) of organic ligand trimesic acid (H3BTC) was dissolved in a solution of DMF 3.75 mL + H2O 11.25 mL + C2H5OH 15 mL with a total volume of 30 mL, and the solution was dissolved evenly by ultrasonication for 30 min. 0.0404 g (0.1 mmoL) of Fe(NO3)3·9H2O and 0.2174 g (0.9 mmoL) of Cu(NO3)·6H2O were weighed into the above solution and stirred at room temperature for 1 h until the solution was clarified. The resulting solution was then transferred to a polytetrafluoroethylene high-pressure reactor, sealed, and placed in an oven at 80°C for reaction for 22 h, then cooled. The resulting product was exchanged and washed three times with DMF, water, and ethanol, respectively, and dried at 85°C overnight to finally obtain HKUST-1 (10% Fe), i.e., Fe 0.1 Cu 0.9 -MOFs adsorbent.

[0036] Example 5

[0037] The high capacity chlorinated hydrocarbon adsorbent Fe 0.1 Cu 0.9 -The preparation method of MOFs comprises the following steps:

[0038] 0.1681 g (0.8 mmol) of organic ligand trimesic acid (H3BTC) was dissolved in a solution of DMF 11.25 mL + H2O 15 mL + C2H5OH 3.75 mL with a total volume of 30 mL, and the solution was dissolved evenly by ultrasonication for 30 min. Then 0.0404 g (0.1 mmol) of Fe(NO3)3·9H2O and 0.2174 g (0.9 mmol) of Cu(NO3)·6H2O were weighed into the above solution and stirred at room temperature for 1 h until the solution was clarified. The resulting solution was then transferred to a polytetrafluoroethylene autoclave, sealed, and placed in an oven at 100°C for reaction for 20 h, then cooled. The resulting product was exchanged and washed three times with DMF, water, and ethanol, respectively, and dried at 85°C overnight to finally obtain HKUST-1 (10% Fe), i.e., Fe 0.1 Cu 0.9 -MOFs adsorbent.

[0039] Comparative Example 1

[0040] The preparation method of the chlorinated hydrocarbon adsorbent of Comparative Example 1 comprises the following steps:

[0041] 0.1407 g (0.67 mmol) of the organic ligand H3BTC was dissolved in a 30 mL solution of 10 ml DMF, 10 ml H2O, and 10 ml C2H5OH, and sonicated for 30 min to achieve uniform dissolution. 0.2416 g (1 mmol) of Cu(NO3)·6H2O was then added to the solution and stirred at room temperature for 1 h until the solution clarified. The resulting solution was then transferred to a polytetrafluoroethylene autoclave, sealed, and placed in an oven at 110°C for 24 h before cooling. The resulting product was then washed three times with DMF, water, and ethanol, respectively, and dried at 85°C overnight to obtain HKUST-1.

[0042] Comparative Example 2

[0043] The preparation method of the chlorinated hydrocarbon adsorbent of Comparative Example 2 comprises the following steps:

[0044] 0.1407 g (0.67 mmol) of organic ligand H3BTC was dissolved in a solution of DMF 10 ml + H2O 10 ml + C2H5OH 10 ml with a total volume of 30 mL, and the solution was dissolved evenly by ultrasonication for 30 min. Then, 0.2702 g (1 mmol) of FeCl3·6H2O was weighed into the above solution and stirred at room temperature for 1 h until the solution became clear. The resulting solution was then transferred to a polytetrafluoroethylene high-pressure reactor, sealed, and placed in an oven for reaction at 110°C for 24 h, then cooled. The resulting product was exchanged and washed three times with DMF, water, and ethanol, respectively, and dried at 85°C overnight to finally obtain MIL-100(Fe).

[0045] Comparative Example 3

[0046] Comparative Example 3 Compared with Example 2 (HKUST-1 (25% Fe)), the molar ratio of iron salt to copper salt is 1:3. The specific method is as follows:

[0047] 0.1407 g (0.67 mmol) of organic ligand trimesic acid (H3BTC) was dissolved in a solution of 10 mL DMF + 10 mL H2O + 10 mL C2H5OH with a total volume of 30 mL, and the solution was dissolved evenly by ultrasonication for 30 min. 0.06758 g (0.25 mmol) of FeCl3·6H2O and 0.1813 g (0.75 mmol) of Cu(NO3)·6H2O were weighed into the above solution and stirred at room temperature for 1 h until the solution was clarified. The resulting solution was then transferred to a polytetrafluoroethylene autoclave, which was sealed and placed in an oven at 110°C for 24 h before being cooled. The product was exchanged and washed three times with DMF, water, and ethanol, respectively, and dried at 85°C overnight to obtain HKUST-1 (25% Fe), i.e., Fe 0.25 Cu 0.75 -MOFs adsorbent.

[0048] Comparative Example 4

[0049] Comparative Example 4 Compared with Example 2 (HKUST-1 (4% Fe)), the molar ratio of iron salt to copper salt is 1:24. The specific method is as follows:

[0050] 0.1407 g (0.67 mmol) of organic ligand trimesic acid (H3BTC) was dissolved in a solution of 10 mL DMF + 10 mL H2O + 10 mL C2H5OH with a total volume of 30 mL, and the solution was dissolved evenly by ultrasonication for 30 min. 0.0108 g (0.04 mmol) of FeCl3·6H2O and 0.2310 g (0.96 mmol) of Cu(NO3)·6H2O were weighed into the above solution and stirred at room temperature for 1 h until the solution was clarified. The resulting solution was then transferred to a polytetrafluoroethylene autoclave, which was sealed and placed in an oven at 110°C for 24 h before being cooled. The product was exchanged and washed three times with DMF, water, and ethanol, respectively, and dried at 85°C overnight to obtain HKUST-1 (4% Fe), i.e., Fe 0.04 Cu 0.96 -MOFs adsorbent.

[0051] Comparative Example 5

[0052] Compared with Example 2 (HKUST-1 (10% Fe)), in Comparative Example 5, the oven temperature exceeded the specified range, specifically, the reaction was performed at 120° C. for 24 h. The rest of the contents were the same.

[0053] Comparative Example 6

[0054] Compared with Example 2 (HKUST-1 (10% Fe)), the reaction time of Comparative Example 6 exceeds the specified range, specifically, the reaction time is 26 h at 110°C.

[0055] from Figure 1 From the comparison of the absorption peaks, it can be seen that the relevant groups of the absorbents of Examples 1-3 of the present invention are successfully connected to the metal ions, which makes the acidity of the metal ions moderate and improves the adsorption capacity of the adsorbent for chlorinated hydrocarbons.

[0056] The adsorption capacity of the adsorbent is tested by filling the adsorbent into the adsorption tower with the adsorbent bed evenly distributed. A gas containing 20% ​​chlorinated hydrocarbons is introduced into the adsorption tower from one end and passes through the adsorbent bed. The adsorbed tail gas is discharged from the other end. When the chlorinated hydrocarbon content in the tail gas exceeds 50mg / Nm 3 , the experiment was stopped and the content of chlorinated hydrocarbons adsorbed by the adsorbent was measured. Adsorption conditions: adsorption pressure 0.5-0.8 MPa, adsorption temperature 25°C. The results are shown in Table 1.

[0057] Table 1 Comparison of adsorption capacity of the adsorbents of the embodiment and the comparative example

[0058]

[0059]

[0060] As shown in Table 1, the adsorbents prepared by the present invention have a high adsorption capacity for chlorinated hydrocarbons. Among them, the adsorbent of Example 2 has the best effect, with an adsorption capacity of 102.36 mmol / g for CH3Cl, 36.43 mmol / g for CH2Cl2, 15.16 mmol / g for CHCl3, and 10.68 mmol / g for vinyl chloride, showing high industrial application value. Reducing (Example 1) or increasing (Example 3) the iron content will reduce the adsorption capacity for chlorinated hydrocarbons. The adsorbents prepared with a single copper salt (Comparative Example 1) or iron salt (Comparative Example 2) have a significantly weakened attraction to chlorine atoms.

[0061] Comparative Examples 3-4 show that when the molar ratio of iron salt to copper salt exceeds the limited range of 1:4-19, the coupling effect of the two ions is weakened, the ability to attract chlorine atoms decreases, and the adsorption capacity for different types of chlorinated hydrocarbons is significantly reduced.

[0062] The hydrothermal reaction temperature is 80-110°C. A suitable reaction temperature promotes the coordination reaction. Too low a temperature prevents the reaction from proceeding, while too high a temperature causes the organic ligand H3BTC to decompose, significantly reducing adsorption capacity. For example, in Comparative Example 5, the hydrothermal reaction temperature was 120°C, but no adsorption material was synthesized due to the decomposition of H3BTC.

[0063] During the hydrothermal reaction, if the reaction time is too short, the coordination reaction is incomplete, while if the reaction time is too long, the specific surface area of ​​the resulting adsorbent is reduced, affecting the adsorption capacity for chlorinated hydrocarbons. The reaction time in Comparative Example 6 was too long, and after the adsorption of methyl chloride, the adsorption capacity was relatively low. Since this adsorbent was intended for industrial applications, it did not meet the adsorption requirements, and subsequent adsorption of CH2Cl2, CHCl3, and CH2CHCl was not performed.

[0064] Table 2 Tail gas emission data of the industrial pilot of the adsorbent HKUST-1 (10% Fe) of the present invention

[0065]

[0066] The adsorbent of the present invention is used in a pressure swing adsorption process. From the operating results of an industrial pilot, it can be seen that under the condition that the chlorinated hydrocarbon content in the raw gas is between 20% and 25%, after three months of continuous and stable operation, the adsorbent has a good purification effect on chlorinated hydrocarbon tail gas, and the tail gas emissions are better than the national emission standards, which has significant industrial application value.

[0067] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. Application of a high-capacity chlorinated hydrocarbon adsorbent in adsorbing chlorinated hydrocarbons in tail gas, characterized in that: The structural formula of the adsorbent is Fe x Cu y -MOFs, wherein the atomic ratio x:y of Fe / Cu is 1:4 to 19; Preparation method of the chlorinated hydrocarbon adsorbent The following steps are involved: S1, using soluble iron salt and copper salt as raw materials, trimesic acid as organic ligand, adding organic-inorganic mixed solvent, and synthesized by hydrothermal method; S2, after the reaction is completed, washing with an organic-inorganic mixed solvent and then drying to obtain an adsorbent; In step S1, the reaction temperature of the hydrothermal method is 80-110° C., and the reaction time is 20-24 h.

2. The use according to claim 1, characterized in that: The soluble iron salt is FeCl3·6H2O or Fe(NO3)3·9H2O, and the soluble copper salt is Cu(NO3)2·6H2O.

3. The use according to claim 1, characterized in that: The molar ratio of the iron salt to the copper salt is 1:4-19.

4. The use according to claim 1, characterized in that: The molar ratio of the trimesic acid to the total amount of soluble iron salt and copper salt is 2:2-3.

5. The use according to claim 1, characterized in that: The organic-inorganic mixed solvent is N,N-dimethylformamide, water and ethanol.

6. The use according to claim 5, characterized in that: The volume ratio of the N,N-dimethylformamide: water: ethanol is (0.5-2): (0.5-2): (0.5-2).

7. The use according to claim 1, characterized in that: The chlorinated hydrocarbons are methyl chloride, dichloromethane, chloroform and vinyl chloride.

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