CN107312181B

CN107312181B - Method for rapidly preparing Cu-BTC

Info

Publication number: CN107312181B
Application number: CN201710504661.1A
Authority: CN
Inventors: 冯光; 夏潇潇; 王少颖; 李松
Original assignee: Huazhong University of Science and Technology
Current assignee: Huazhong University of Science and Technology
Priority date: 2017-06-28
Filing date: 2017-06-28
Publication date: 2020-05-19
Anticipated expiration: 2037-06-28
Also published as: CN107312181A

Abstract

The invention belongs to the technical field of organic metal framework materials and ionic liquid, and particularly relates to a method for quickly preparing Cu-BTC, which comprises the following steps: s1, adding ionic liquid into the copper ion solution, and dropwise adding the trimesate solution while stirring until the mixture is uniformly mixed; s2 centrifuging the product of step S1 to separate layers, and only leaving a precipitate; s3, adding an organic solvent into the precipitate, fully stirring and standing; s4, centrifugal drying treatment is carried out on the product after standing to prepare the required Cu-BTC. The invention greatly accelerates the speed of the whole production process, shortens dozens of hours to dozens of hours in the prior art, simultaneously improves the quality and the yield of the Cu-BTC, reduces the energy consumption in the reaction process, and finally reduces the cost of the Cu-BTC, thereby being particularly suitable for the mass production of the Cu-BTC.

Description

Method for rapidly preparing Cu-BTC

Technical Field

The invention belongs to the technical field of organic metal framework materials and ionic liquids, and particularly relates to a method for quickly preparing Cu-BTC.

Background

The metal organic framework material is a crystal material with an ordered structure formed by self-assembling metal ions and organic ligands. Due to their high porosity, large surface area, low density and good mechanical and chemical stability, metal organic framework materials are considered to be in CO₂One of the most promising nanomaterials in the field of adsorption.

Cu-BTC is the most common metal organic framework material, and has the characteristics of unsaturated metal sites, a paddle structure and the like. At present, the main synthesis method of Cu-BTC is a solvothermal method, but the method has the following defects: (1) the method is time-consuming, the reaction time is often dozens of hours or even longer, the yield of the Cu-BTC is greatly influenced, and (2) the energy consumption in the production process is high, and the cost is increased. Therefore, although commercialization of Cu-BTC has been achieved, it is very expensive.

The ionic liquid is a substance which consists of anions and cations and is liquid at normal temperature, has good thermal stability and chemical stability, and can be widely applied to the fields of electrochemistry, organic synthesis, catalysis, separation and the like. The ionic liquid has good intersolubility with organic matters and inorganic matters and exists in an ionic state, so that the ionic liquid serving as an organic solvent has good application prospect in preparing the nano material. However, in the prior art, no precedent for using the ionic solution for preparing the metal organic framework material is found.

Aiming at the technical problems, further improvement and improvement are urgently needed in the field, and a preparation method of the Cu-BTC is designed, so that the problems of long time consumption, high energy consumption and the like in the production process can be avoided, and the requirement of rapidly preparing the Cu-BTC in a large scale is met.

Disclosure of Invention

Aiming at the defects or the improvement requirements of the prior art, the invention provides a method for quickly preparing Cu-BTC, wherein the principle that ionic liquid can play the roles of a solvent and a catalyst simultaneously in hydrogenation reaction is provided and fully utilized by designing the types and the proportions of reactants as key participators, and the ionic liquid is added into a reaction solution to accelerate the reaction rate of a copper ion solution and trimesic acid; in addition, important process parameters in the preparation process are designed in a targeted manner, so that the reaction rate and the yield of the whole preparation process can be controlled better, the speed of the whole production process is greatly increased, dozens of hours to dozens of hours in the prior art are shortened, the quality and the yield of the Cu-BTC are improved, the energy consumption in the reaction process is reduced, and the cost of the Cu-BTC is finally reduced, so that the method is particularly suitable for large-scale production of the Cu-BTC.

In order to achieve the purpose, the invention provides a method for quickly preparing Cu-BTC, which is characterized by comprising the following steps:

s1, adding ionic liquid into the copper ion solution, stirring to mix the ionic liquid and the copper ion solution uniformly, and then dropwise adding trimesic acid salt solution while stirring until the ionic liquid and the copper ion solution are mixed uniformly;

s2 centrifuging the product obtained in step S1 to separate layers, and then pouring out the supernatant to leave only the precipitate;

s3 adding an organic solvent to the precipitate obtained in step S2, stirring the mixture sufficiently, and then standing the mixture;

s4, the product after standing in the step S3 is centrifuged and dried to obtain the required Cu-BTC.

Further preferably, the ionic liquid is 1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium trifluoromethanesulfonate or 1-butyl-3-methylimidazolium bistrifluoromethylsulfonimide in a purity of 97 to 99% in step S1. Tests prove that the ionic liquid can play the roles of a solvent and a catalyst at the same time, can accelerate the reaction rate of a copper ion solution and trimesic acid, greatly shortens the reaction time, and improves the quality and yield of Cu-BTC.

Preferably, the copper ion solution is copper nitrate, copper chloride or copper acetate, and the concentration of the copper ion solution is 0.1mol/L-0.3 mol/L.

Preferably, in step S1, the concentration of the trimesate solution is 0.05mol/L-0.2 mol/L. The comparative test proves that the trimesic acid salt solution is adopted to provide the organic ligand, the solubility of the organic ligand in water is increased, the reaction rate of the copper ion solution and the trimesic acid is accelerated, and the yield of Cu-BTC is improved.

Preferably, in step S1, the ratio of the amounts of the ionic liquid, the copper ions and the trimesate is 1 (1-2) to (1-5).

Preferably, in step S2, the time of the centrifugal treatment is 2min-10min, and the rotation speed is 4000r/min-7000 r/min.

Preferably, in step S3, the organic solution added may be absolute ethanol, acetone, chloroform, etc., or deionized water; the standing temperature is 20-30 ℃, and the standing time is 1-3 h.

Preferably, in step S4, the time of the centrifugal treatment is 2min-10min, and the rotation speed is 4000r/min-7000 r/min; the drying temperature is 60-80 ℃, and the drying time is 12-24 h.

Tests prove that the concentration and the ratio of each solution are controlled within the range, and parameters such as the time and the temperature of centrifugal treatment and drying treatment during reaction are controlled within the range, so that the reaction rate of the copper ion solution and the trimesic acid can be further improved, the reaction time of Cu-BTC can be controlled, and the yield of the Cu-BTC can be improved.

Generally, compared with the prior art, the technical scheme of the invention has the following advantages and beneficial effects:

(1) the method of the invention utilizes the principle that the ionic liquid can play the role of a solvent and a catalyst simultaneously in the hydrogenation reaction, and adds the ionic liquid into the reaction solution to accelerate the reaction rate of the copper ion solution and the trimesic acid; the speed of the whole production process is greatly accelerated, is shortened from dozens of hours to dozens of hours in the prior art, simultaneously improves the quality and the yield of the Cu-BTC, reduces the energy consumption in the reaction process, and finally reduces the cost of the Cu-BTC, thereby being particularly suitable for mass production of the Cu-BTC.

(2) According to the invention, by adding the ionic liquid, especially 1-butyl-3-methylimidazolium tetrafluoroborate, the ionic liquid can play a role of a solvent and a catalyst at the same time, the reaction rate of a copper ion solution and trimesic acid can be accelerated, the reaction time is greatly shortened, and the quality and the yield of Cu-BTC are improved. The trimesic acid salt solution is adopted to provide the organic ligand, so that the solubility of the organic ligand in water is increased, the reaction rate of the copper ion solution and the trimesic acid is further accelerated, and the yield of Cu-BTC is improved.

(3) In addition, important process parameters in the preparation process are designed in a targeted manner, such as the concentration and the ratio of each solution, the centrifugal treatment during reaction, the drying treatment time and temperature and other parameters, so that the reaction rate of the copper ion solution and the trimesic acid can be further improved, the reaction time of the Cu-BTC is controlled, and the yield of the Cu-BTC is improved.

(4) The preparation method disclosed by the invention is simple in process, short in time consumption of the preparation process, good in repeatability and capable of meeting the requirement of large-scale production.

Drawings

FIG. 1 is a process flow diagram of the rapid Cu-BTC preparation method of the present invention;

FIG. 2 shows N of Cu-BTC obtained in example of the present invention₂Adsorption-desorption curves;

FIG. 3 is a graph of pore size distribution of Cu-BTC obtained by an SF method according to an embodiment of the present invention;

FIG. 4 is an XRD pattern of Cu-BTC obtained by an example of the present invention and an XRD pattern of theoretical Cu-BTC;

FIG. 5 is an SEM image of Cu-BTC obtained in the example of the present invention;

FIG. 6 is a thermogravimetric plot of Cu-BTC obtained in accordance with an example of the present invention;

FIG. 7 shows the CO at room temperature of Cu-BTC obtained by comparative example of the present invention₂Adsorption profile.

FIG. 8 shows N of Cu-BTC obtained by comparative example of the present invention₂Adsorption-desorption curves;

FIG. 9 is a graph showing a pore size distribution of Cu-BTC obtained by a comparative example of the present invention, which was fitted by SF;

FIG. 10 is an XRD pattern of Cu-BTC obtained by the comparative example of the present invention and an XRD pattern of theoretical Cu-BTC;

FIG. 11 is an SEM photograph of Cu-BTC obtained by a comparative example of the present invention;

FIG. 12 is a thermogravimetric plot of Cu-BTC obtained for a comparative example of the present invention;

FIG. 13 shows CO at room temperature for Cu-BTC obtained by comparative example of the present invention₂Adsorption profile.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

To better explain the invention, specific examples and comparative examples are given below:

example 1

The embodiment provides a method for rapidly synthesizing Cu-BTC, which comprises the following steps:

(1) dissolving 0.271g of 98% pure 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid into 9mL of 0.2mol/L copper nitrate solution, and stirring to uniformly mix the solution;

(2) dropwise adding 12mL of sodium trimesate solution with the concentration of 0.1mol/L into the solution obtained in the step (1) while stirring, and fully stirring;

(3) centrifuging the product obtained in the step (2) at 25 ℃ for 2min at the rotating speed of 5000r/min, and pouring out the supernatant;

(4) adding absolute ethyl alcohol into the product obtained in the step (3), and fully stirring;

(5) standing the stirred product for 1h at 25 ℃;

(6) and (4) centrifuging the product obtained in the step (5) at the rotating speed of 5000r/min for 2min, and drying at the temperature of 80 ℃ for 12h to quickly synthesize the obtained Cu-BTC (material A).

Example 2

(1) dissolving 0.226g of 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid with the purity of 99 percent into 10mL of copper acetate solution with the concentration of 0.1mol/L, and stirring to uniformly mix the solution;

(2) dropwise adding 40mL of potassium trimesate solution with the concentration of 0.05mol/L into the solution obtained in the step (1) while stirring, and fully stirring;

(3) centrifuging the product obtained in the step (2) at 25 ℃ at the rotating speed of 7000r/min for 5min, and pouring out the supernatant;

(5) standing the stirred product for 3h at the temperature of 20 ℃;

(6) and (4) centrifuging the product obtained in the step (5) at the rotating speed of 7000r/min for 5min, and drying at the temperature of 60 ℃ for 18h to quickly synthesize the obtained Cu-BTC.

Example 3

(1) dissolving 0.339g of 97% pure 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid into 10mL of 0.3mol/L copper nitrate solution, and stirring to uniformly mix the solution;

(2) dropwise adding 37.5mL of 0.2mol/L potassium trimesate solution into the solution obtained in the step (1) while stirring, and fully stirring;

(3) centrifuging the product obtained in the step (2) at the temperature of 30 ℃ for 10min at the rotating speed of 4000r/min, and pouring out the supernatant;

(5) standing the stirred product at 30 ℃ for 2 h;

(6) and (4) centrifuging the product obtained in the step (5) at the rotating speed of 4000r/min for 10min, and drying at 70 ℃ for 24h to quickly synthesize the obtained Cu-BTC.

Example 4

(1) dissolving 0.419g of 1-butyl-3-methylimidazolium bistrifluoromethanesulfonylimide ionic liquid with the purity of 99% into 10mL of copper acetate solution with the concentration of 0.1mol/L, and stirring to uniformly mix the copper acetate solution and the copper acetate solution;

(2) dropwise adding 100mL of 0.05mol/L potassium trimesate solution into the solution obtained in the step (1) while stirring, and fully stirring;

(3) centrifuging the product obtained in the step (2) at 25 ℃ for 5min at the rotating speed of 5000r/min, and pouring out the supernatant;

(5) standing the stirred product for 3h at the temperature of 20 ℃;

(6) and (4) centrifuging the product obtained in the step (5) at the rotating speed of 5000r/min for 5min, and drying at the temperature of 80 ℃ for 12h to quickly synthesize the obtained Cu-BTC.

Example 5

(1) dissolving 0.419g of 1-butyl-3-methylimidazolium bistrifluoromethanesulfonylimide ionic liquid with the purity of 99% into 20mL of copper acetate solution with the concentration of 0.1mol/L, and stirring to uniformly mix the copper acetate solution and the copper acetate solution;

(2) dropwise adding 20mL of 0.05mol/L potassium trimesate solution into the solution obtained in the step (1) while stirring, and fully stirring;

(5) standing the stirred product for 3h at the temperature of 20 ℃;

Comparative example

The comparative example is a method for rapidly synthesizing Cu-BTC, and comprises the following steps:

(1) measuring 9mL of 0.2mol/L copper nitrate solution, dropwise adding 12mL of 0.1mol/L sodium trimesate solution into the copper nitrate solution while stirring, and fully stirring;

(2) centrifuging the mixture obtained in the step (1) at 25 ℃ for 2min at the rotating speed of 5000r/min, and pouring out the supernatant;

(3) adding absolute ethyl alcohol into the precipitate obtained in the step (2), and fully stirring;

(4) standing the stirred product for 1h at 25 ℃;

(5) and (4) centrifuging the product obtained in the step (4) at the rotating speed of 5000r/min for 2min, and drying at the temperature of 80 ℃ for 12h to obtain the Cu-BTC (material B).

Analysis and comparison of results were performed on Cu-BTC prepared by two methods:

analysis was carried out on the material a obtained in example 1:

(1) pore structure and adsorption properties

The sample of the material A prepared by the invention was analyzed by an Autosorb-iQ full-automatic gas adsorption analyzer manufactured by Kangta instruments, and the pore structure and specific surface area are shown in Table 1.

TABLE 1 parameters of specific surface area and pore structure of the material A obtained according to the invention

Sample (I)	Specific surface area of micropores (m)²/g)	Total pore volume (cm)³/g)	Pore volume (cm) of micropores³/g)
				A	1267	0.624	0.448

FIG. 1 shows N of Material A₂The adsorption-desorption isotherm is analyzed to obtain that the specific surface area of the material A is larger (1267 m)²In terms of/g). From the pore size distribution of the material A in FIG. 2, it can be seen that the pore size of the material A is mostly concentrated around 0.45nm, and a small amount of micropores exist around 0.50 nm.

(2) Nature of crystal structure

The crystal structure of the material A in the embodiment of the invention is characterized by adopting an X-ray diffractometer of X' Pert3Powder model, which is produced by the company Pasacaceae in the Netherlands, and the operation conditions are as follows: 60KV, 60mA, step size 0.02 deg. The XRD pattern obtained is shown in figure 3. As can be seen from FIG. 3, the characteristic peak and the theoretical peak of the material A prepared by the method are well corresponded, which indicates that the material A prepared rapidly has uniform phase and good crystal structure.

(3) SEM atlas characterization

The morphology of material a of the example of the present invention was characterized using an environmental scanning electron microscope model MAIA3, manufactured by czech teskin, as shown in fig. 4. As can be seen from FIG. 4, the rapidly prepared material A has uniform morphology and complete structure.

(5) Thermogravimetric profiling

The thermal stability of material a of the example of the invention was characterized using a model Q600SDT instrument, manufactured by TA corporation, usa, as shown in fig. 5. As can be seen from fig. 5, the mass loss before 200 ℃ was about 30%, which is the mass of water and residual ethanol contained in the material a. Material a had a significant mass loss around 320 c, indicating that the material structure was destroyed, so the pyrolysis temperature of material a was around 320 c.

(6)CO₂Adsorption analysis

The CO of the material A prepared by the invention is carried out at room temperature (25 ℃) by adopting an Autosorb-iQ full-automatic gas adsorption analyzer produced by Kangta instruments₂The adsorption experiment, the resulting adsorption curve is shown in FIG. 6. As can be seen from FIG. 6, the CO of material A increases with the relative pressure₂The adsorption capacity is increased continuously, and the maximum adsorption capacity is close to 120cm³/g。

Analysis of comparative material B:

(1) pore structure and adsorption properties

The sample B of the material prepared in the comparative example of the present invention was analyzed by an Autosorb-iQ fully automatic gas adsorption analyzer manufactured by Kangta instruments of America, and the pore structure and specific surface area were as shown in Table 2.

TABLE 2 parameters of specific surface area and pore structure of the material B obtained in the comparative example

Sample (I)	Specific surface area of micropores (m)²/g)	Total pore volume (cm)³/g)	Pore volume (cm) of micropores³/g)
				B	466	0.250	0.163

From N of material B of FIG. 7₂The analysis of the adsorption-desorption isotherm can show that the Cu-BTC prepared quickly without adding the ionic liquid has smaller specific surface area (466 m)²/g) of 37% of the specific surface area of Cu-BTC prepared in the comparative example by adding an ionic liquid. From the pore size distribution diagram of material B in FIG. 8, it can be seen that the pore size of material B is mostly concentrated around 0.45nm, and a small amount of micropores are distributed around 0.50 nm.

(2) Nature of crystal structure

The crystal structure of comparative example material B of the present invention was characterized using an X' Pert3Powder model X-ray diffractometer, manufactured by Pasacaceae, Netherlands, under the operating conditions: 60KV, 60mA, step size 0.02 deg. The XRD pattern obtained is shown in figure 9. As can be seen from FIG. 9, the characteristic peaks of theoretical Cu-BTC correspond to the characteristic peaks of the material B prepared in the comparative example, indicating that the material B is Cu-BTC, but other characteristic peaks appear, indicating that impurities exist in the material B prepared in the comparative example. The prepared material B is not a pure-phase substance, which indicates that the reaction is not thorough, and the quality of the material B is poorer than that of the material A prepared by adding the ionic liquid.

(3) SEM atlas characterization

The structure of comparative example material B of the present invention was characterized using an environmental scanning electron microscope model MAIA3, manufactured by czech teskin, as shown in fig. 10. As can be seen from fig. 10: the material B in the comparative example exhibits a rod-like structure, which is very different from the polyhedral structure of theoretical Cu-BTC, indicating that the quality of the material B is poor.

(5) Thermogravimetric profiling

The thermal stability of comparative example material B of the present invention was characterized using a model Q600SDT instrument, manufactured by TA corporation, usa, as shown in fig. 11. As can be seen from fig. 11: the mass loss before 200 ℃ was about 30%, which is the mass of water and residual ethanol contained in material B. Material B had a significant mass loss around 320 c, indicating that the material structure was destroyed, so the pyrolysis temperature of material B was around 320 c.

(6)CO₂Adsorption analysis

CO of comparative example material B of the present invention was carried out at room temperature (25 ℃ C.) using an Autosorb-iQ fully automatic gas adsorption Analyzer manufactured by Kangta instruments Inc₂The adsorption experiment, the resulting adsorption curve is shown in fig. 12. As can be seen from fig. 12: CO of material B with increasing relative pressure₂The adsorption capacity is increased continuously, and the maximum adsorption capacity is close to 40cm³(ii) in terms of/g. CO of Material B at the same relative pressure compared with Material A obtained in the example₂CO much smaller than that of material A₂The amount of adsorbed CO of Material A₂The adsorptivity was much higher than that of material B.

It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims

1. A method for rapidly preparing Cu-BTC is characterized by comprising the following steps:

s1, adding an ionic liquid into a copper ion solution, stirring to mix uniformly, and then dropwise adding a trimesic acid salt solution while stirring until the mixture is uniformly mixed, wherein the ionic liquid is used as a solvent on one hand and a catalyst on the other hand to accelerate the reaction rate of copper ions and trimesic acid, and the ionic liquid is 1-butyl-3-methylimidazole tetrafluoroborate, 1-butyl-3-methylimidazole hexafluorophosphate, 1-butyl-3-methylimidazole trifluoromethanesulfonate or 1-butyl-3-methylimidazole bistrifluoromethanesulfonylimide, and the purity of the ionic liquid is 97-99%; the mass ratio of the ionic liquid, the copper ions and the trimesic acid salt is 1 (1-2) to 1-5;

s3 adding an organic solution to the precipitate obtained in step S2, stirring thoroughly, and standing;

2. The method for rapidly preparing Cu-BTC according to claim 1, wherein in step S1, the copper ion solution is copper nitrate, copper chloride or copper acetate, and the concentration of the copper ion solution is 0.1mol/L-0.3 mol/L.

3. The method for rapidly preparing Cu-BTC according to claim 2, wherein the concentration of the trimesate solution is 0.05mol/L to 0.2mol/L in step S1.

4. The method for rapidly preparing Cu-BTC according to claim 1, wherein in step S2, the time of the centrifugal treatment is 2min-10min, and the rotation speed is 4000r/min-7000 r/min.

5. The method for rapidly preparing Cu-BTC according to claim 4, wherein in step S3, the organic solution is absolute ethanol, acetone or chloroform; the standing temperature is 20-30 ℃, and the standing time is 1-3 h.

6. The method for rapidly preparing Cu-BTC according to claim 5, wherein in step S4, the time of the centrifugal treatment is 2min-10min, and the rotation speed is 4000r/min-7000 r/min; the drying temperature is 60-80 ℃, and the drying time is 12-24 h.