CN115449086A - A kind of amino-modified MIL-101 (Cr) and its preparation method and application - Google Patents

Abstract

The invention belongs to the technical field of preparation of compounds, and particularly relates to amino modified MIL-101 (Cr) and a preparation method and application thereof. The preparation method comprises the following steps: carrying out vacuum degassing on MIL-101 (Cr) to obtain a degassed MIL-101 material; mixing degassed MIL-101 (Cr) and ethanol, mixing the obtained ethanol solution of MIL-101 (Cr) and an amino modifier, and carrying out grafting reaction to obtain amino modified MIL-101 (Cr); the amino modifier is ethylenediamine, diethylenetriamine or triethylenetetramine. In the amino modified MIL-101 (Cr) of the invention, the amino is directly connected with an organic ligand and does not occupy unsaturated metal sites, so that the CO is positioned at the metal sites ₂ AdsorbedOn the basis of the addition of amino-CO ₂ Thereby promoting the adsorption of CO ₂ Adsorption of (2).

Description

A kind of amino-modified MIL-101 (Cr) and its preparation method and application

technical field

The invention belongs to the technical field of compound preparation, and in particular relates to an amino-modified MIL-101 (Cr) and its preparation method and application.

Background technique

At present, metal organic framework materials have good adsorption properties for harmful gases due to their large surface area and pore structure. Although MIL-101(Cr) also has a large specific surface area and pore structure, when it is used as a carbon dioxide adsorption material, it completes the adsorption through the van der Waals interaction between carbon dioxide gas molecules and MIL-101(Cr). This binding force is relatively weak, and the adsorbed substances are prone to desorption, resulting in relatively small carbon dioxide adsorption capacity and poor adsorption performance.

Contents of the invention

In view of this, the object of the present invention is to provide a kind of amino-modified MIL-101 (Cr) and its preparation method and application, and the amino-modified MIL-101 (Cr) prepared by the preparation method provided by the present invention is to carbon dioxide Has good adsorption properties.

In order to solve the above problems, the invention provides a kind of preparation method of amino-modified MIL-101 (Cr), comprising the following steps:

Carry out vacuum degassing to MIL-101(Cr) to obtain degassed MIL-101(Cr);

Mix the degassed MIL-101(Cr) with ethanol, mix the ethanol solution of the obtained MIL-101(Cr) with an amino modifier, and perform a grafting reaction to obtain amino-modified MIL-101(Cr);

The amino modifier is ethylenediamine, diethylenetriamine or triethylenetetramine;

The mass ratio of the MIL-101 (Cr) to the amino modifier is 1:0.009-0.07.

Preferably, the temperature of the grafting reaction is 100-130° C., and the time is 10-13 hours.

Preferably, the vacuum degassing temperature is 110-130° C., the holding time is 10-15 hours, and the vacuum degree is -0.01-0.09 MPa.

Preferably, after the grafting reaction, cooling, solid-liquid separation, washing and drying of the product obtained in the grafting reaction are further included.

Preferably, the drying temperature is 80°C.

Preferably, the preparation method of the MIL-101 (Cr) comprises the following steps:

Chromium nitrate, terephthalic acid and water are mixed for hydrothermal reaction to obtain the MIL-101 material.

Preferably, the temperature of the hydrothermal reaction is 220° C., and the holding time is 8 hours.

The present invention also provides the amino-modified MIL-101(Cr) prepared by the above-mentioned preparation method, the specific surface area of the amino-modified MIL-101(Cr) is 2800-3000m ² /g, and the pore volume is 0.7 ~1.4cm ³ /g, and the average pore diameter is 1.2~2.2nm.

The present invention also provides the application of the amino-modified MIL-101(Cr) obtained by the above-mentioned preparation method or the above-mentioned amino-modified MIL-101(Cr) in the adsorption of carbon dioxide.

Preferably, the CO ₂ adsorption capacity of the amino-modified MIL-101(Cr) is 850-1050 mg/g.

The invention provides a preparation method of amino-modified MIL-101(Cr), comprising the following steps: vacuum degassing MIL-101(Cr) to obtain degassed MIL-101(Cr); degassing The final MIL-101 (Cr) is mixed with ethanol, and the ethanol solution of the gained MIL-101 (Cr) is mixed with an amino modifier to carry out a grafting reaction to obtain an amino modified MIL-101 (Cr); the amino modifier It is ethylenediamine, diethylenetriamine or triethylenetetramine; the mass ratio of the MIL-101(Cr) to the amino modifier is 1:0.009-0.07. The present invention uses the organic ligand of the terminal amino group as the amino modifier, and the amino modifier is added dropwise to the ethanol solution of MIL-101 (Cr) to carry out the grafting reaction, so that the amino modifier enters or attaches to the MIL- The pores or surfaces of 101(Cr) do not occupy unsaturated metal sites. Therefore, the adsorption of amino groups to CO ₂ is added on the basis of the adsorption of CO ₂ on metal sites. Amino groups belong to basic groups, while CO ₂ belongs to For acidic oxides, the adsorption process belongs to chemical adsorption, so after the modified MIL-101(Cr) adsorbs _CO2 , it is not easy to desorb, thus increasing the amount of _CO2 adsorbed.

Description of drawings

Fig. 1 adopts the N that the DETA modified MIL-101 (Cr) that embodiment 1 prepares adopts BET method to test and obtain The adsorption _- desorption isotherm figure;

Fig. 2 is the DETA modified MIL-101 (Cr) that embodiment 1 prepares to _CO The adsorption test figure;

Fig. 3 is the adsorption test graph of 0.03-DETA-MIL-101, 0.03-EDA-MIL-101 and 0.03-EDA-MIL-101 for CO ₂ in Examples 1-3.

detailed description

The invention provides a kind of preparation method of amino-modified MIL-101 (Cr), comprising the following steps:

Carry out vacuum degassing to MIL-101(Cr) to obtain degassed MIL-101(Cr);

The degassed MIL-101(Cr) is mixed with ethanol, the ethanol solution of the obtained MIL-101(Cr) is mixed with an amino modifier, and a grafting reaction is carried out to obtain the amino-modified MIL-101(Cr).

In the present invention, the MIL-101 (Cr) is subjected to vacuum degassing to obtain the degassed MIL-101 (Cr).

In the present invention, the preparation method of the MIL-101(Cr) preferably comprises the following steps:

Chromium nitrate, terephthalic acid and water are mixed for hydrothermal reaction to obtain the MIL-101 material.

In the present invention, the water is preferably deionized water; the mass ratio of the chromium nitrate and terephthalic acid is preferably 1:0.415; the mass ratio of the chromium nitrate and water is preferably 1:12～15, more preferably Preferably it is 1:13-14.

In the present invention, the temperature of the hydrothermal reaction is preferably 220° C.; the holding time of the hydrothermal reaction is preferably 8 hours.

In the present invention, after the hydrothermal reaction, it is preferred to further include suction filtration, washing and drying of the product obtained from the hydrothermal reaction in sequence.

In the present invention, the suction filtration is not specifically limited, and the hydrothermal reaction product can be obtained by the suction filtration operation well known to those skilled in the art. In the present invention, the washing is preferably performed sequentially with N,N-dimethylformamide washing and absolute ethanol washing. In the present invention, the drying temperature is preferably 80° C. and the drying time is 12 hours.

In the present invention, the temperature of the vacuum degassing is preferably 110-130°C, more preferably 120°C, the holding time is preferably 10-15h, more preferably 11-12h; the degree of vacuum is preferably -0.10-0.09MPa, More preferably, it is 0 MPa.

After the degassed MIL-101 (Cr) is obtained, the present invention mixes the degassed MIL-101 (Cr) with ethanol, mixes the ethanol solution of the obtained MIL-101 (Cr) with an amino modifier, and performs grafting reaction , to obtain amino-modified MIL-101 (Cr).

In the present invention, the amino modifier is ethylenediamine, diethylenetriamine or triethylenetetramine. In the present invention, the mass fraction of MIL-101(Cr) in the ethanol solution of MIL-101(Cr) is preferably 1.5-2.5%, more preferably 1.9-2.3%. In the present invention, the mass ratio of the MIL-101 (Cr) to the amino modifier is preferably 1:0.009-0.07, more preferably 1:0.04-0.06.

In the present invention, the mixing is preferably adding the amino modifier dropwise into the ethanol solution of MIL-101(Cr).

In the present invention, the temperature of the grafting reaction is preferably 100-130° C., more preferably 120° C., and the time is preferably 10-13 hours, more preferably 12 hours. In the present invention, after the grafting reaction, cooling, solid-liquid separation, washing and drying of the product obtained in the grafting reaction are also included.

In the present invention, the cooling is preferably to room temperature, and the cooling method is not specifically limited. In the present invention, the solid-liquid separation method is centrifugation, and the rotational speed of the centrifugation is preferably 4000-7000 rpm, more preferably 5000 rpm. The centrifugation time is preferably 3 minutes. In the present invention, the washing reagent is preferably ethanol, and the washing times are preferably 3 times. In the present invention, the drying temperature is preferably 100-110° C., more preferably 105° C., and the drying time is preferably 12 hours.

The present invention also provides the amino-modified MIL-101(Cr) prepared by the above-mentioned preparation method, the specific surface area of the amino-modified MIL-101(Cr) is preferably 2800-3000m ² /g, more preferably 2900m2/g ² /g; the pore volume of the amino-modified MIL-101(Cr) is preferably 0.7-1.4 cm ³ /g, more preferably 1.0-1.3 cm ³ /g, and the pore diameter is preferably 1.2-2.2 nm, more preferably 1.5-2.0nm.

The present invention also provides the application of the amino-modified MIL-101(Cr) prepared by the above-mentioned preparation method in absorbing carbon dioxide.

In the present invention, the CO ₂ adsorption capacity of the amino-modified MIL-101(Cr) is preferably 850-1050 mg/g, more preferably 900-1040 mg/g.

In order to further illustrate the present invention, the technical solutions provided by the present invention are described in detail below in conjunction with the examples, but they cannot be interpreted as limiting the protection scope of the present invention.

Example 1

Preparation of MIL-101(Cr):

Mix 4g of chromium nitrate, 1.66g of terephthalic acid, and 48g of deionized water, ultrasonicate at room temperature for 20 minutes, stir for 1 hour and mix well, then pour it into the Teflon lining, and then put the lining on an explosion-proof Teflon high pressure Put it in an oven, and conduct a hydrothermal reaction at a temperature of 220°C for 8 hours. After the reaction, wait for the autoclave to cool down to room temperature naturally, and then centrifuge the product obtained from the hydrothermal reaction to obtain a precipitate. The MIL-101(Cr) was obtained after being washed with formamide and absolute ethanol several times and then dried (the drying temperature was 80° C. and the drying time was 12 h).

Preparation of amino-modified MIL-101(Cr):

0.5g MIL-101(Cr) was vacuum degassed in a vacuum oven at 120°C for 12h to obtain the degassed MIL-101(Cr), and the degassed MIL-101(Cr) was mixed with 30mL of absolute ethanol, Then use a pipette gun to add 0.01, 0.03, 0.05, and 0.07 mL of DETA dropwise, stir for 10 min, and then transfer the mixture into a 100 mL reaction kettle with polytetrafluoroethylene as the inner wall. Afterwards, the reaction kettle was sealed, and put into a constant temperature blast oven at 100°C for grafting reaction for 12 hours. After the grafting reaction, the product obtained from the grafting reaction is cooled (cooled to room temperature) and centrifuged (rotating speed is 4000rpm, time is 3min), and the product obtained by centrifugation is washed with ethanol for 3 times and then put into a vacuum oven for 12 hours at 100°C to dry, which is DETA Modified MIL-101 (Cr), denoted as 0.01-DETA-MIL-101, 0.03-DETA-MIL-101, 0.05-DETA-MIL-101 and 0.07-DETA-MIL-101.

Example 2

The difference from the "preparation of amino-modified MIL-101 (Cr)" in Example 1 is only that DETA is replaced by EDA to obtain 0.01-EDA-MIL-101, 0.03-EDA-MIL-101, 0.05-EDA-MIL -101 and 0.07-EDA-MIL-101.

Example 3

The difference from the "preparation of amino-modified MIL-101 (Cr)" in Example 1 is only that DETA is replaced by TETA to obtain 0.01-TETA-MIL-101, 0.03-TETA-MIL-101, 0.05-TETA-MIL -101 and 0.07-TETA-MIL-101.

The present invention uses the BET method to test the DETA-modified MIL-101 (Cr) prepared in Example 1, and obtains the _N2 adsorption-desorption isotherm diagram, see FIG. 1 . According to Figure 1, the specific surface area, pore volume and average pore diameter of DETA-modified MIL-101 (Cr) can be calculated, and the results are shown in Table 1.

Table 1 Specific surface area, pore volume and average pore diameter of DETA modified MIL-101(Cr)

Adsorbent BET specific surface area m²/g Pore volume cm³/g Average pore size nm 0.01-DETA-MIL-101 2991.3696 1.310066 1.97595 0.03-DETA-MIL-101 2861.4154 1.260855 1.82461 0.05-DETA-MIL-101 2217.2824 0.996001 1.79680 0.07-DETA-MIL-101 1524.4502 0.773344 1.52917

The present invention tests the DETA-modified MIL-101 (Cr) prepared in Example 1 to the adsorption of CO ₂ , and the test results are shown in Fig. 2. As can be seen from Fig. 2, the CO ₂ The adsorption capacity is 850mg/g, and when the amount of DETA added is 0.03mL, the CO ₂ adsorption capacity increases to a maximum of 980 mg/g, and the adsorption capacity increases by 15.3%.

The present invention tests the adsorption of _CO by 0.03-DETA-MIL-101, 0.03-EDA-MIL-101 and 0.03-EDA-MIL-101 in Examples 1 to 3, and the test results are shown in Fig. 3, from Fig. 3 It can be seen that when the amount of EDA added is 0.03mL, the CO ₂ adsorption capacity increases up to 1045 mg/g, which is 23% higher than that of the unmodified MIL-101(Cr). According to Figure 3, the specific surface area, pore volume and average pore diameter of 0.03-DETA-MIL-101, 0.03-EDA-MIL-101 and 0.03-EDA-MIL-101 can be calculated, and the results are shown in Table 2.

Table 2 Specific surface area, pore volume and average pore diameter of 0.03-DETA-MIL-101, 0.03-EDA-MIL-101 and 0.03-EDA-MIL-101

Adsorbent BET specific surface area m²/g Pore volume cm³/g Average pore size nm MIL-101 3136.2256 1.331161 2.01980 0.03-EDA-MIL-101 2951.1578 1.291845 1.85432 0.03-DETA-MIL-101 2861.4154 1.260855 1.82461 0.03-TETA-MIL-101 2895.3569 1.262844 1.82967

The above is only a preferred embodiment of the present invention, and it should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, some improvements and embellishments can also be made. These improvements and embellishments It should also be regarded as the protection scope of the present invention.

Claims (10)

1. A preparation method of amino modified MIL-101 (Cr) is characterized by comprising the following steps:

carrying out vacuum degassing on MIL-101 (Cr) to obtain degassed MIL-101 (Cr);

mixing degassed MIL-101 (Cr) and ethanol, mixing the obtained ethanol solution of MIL-101 (Cr) and an amino modifier, and carrying out grafting reaction to obtain amino modified MIL-101 (Cr);

the amino modifier is ethylenediamine, diethylenetriamine or triethylenetetramine;

the mass ratio of the MIL-101 (Cr) to the amino modifier is 1: 0.009-0.07.

2. The preparation method according to claim 1, wherein the temperature of the grafting reaction is 100 to 130 ℃ and the time is 10 to 13 hours.

3. The preparation method according to claim 1, wherein the vacuum degassing temperature is 110-130 ℃, the holding time is 10-15 h, and the vacuum degree is-0.01-0.09 MPa.

4. The preparation method according to claim 1 or 2, further comprising, after the grafting reaction, sequentially cooling, performing solid-liquid separation, washing and drying on a product obtained by the grafting reaction.

5. The method according to claim 4, wherein the drying temperature is 80 ℃.

6. The method of claim 1, wherein the MIL-101 (Cr) is prepared by the method comprising the steps of:

mixing chromium nitrate, terephthalic acid and water, and carrying out hydrothermal reaction to obtain the MIL-101.

7. The method according to claim 6, wherein the hydrothermal reaction is carried out at 220 ℃ for 8 hours.

8. Amino-modified MIL-101 (Cr) prepared by the method of claim 1, wherein the amino-modified MIL-101 (Cr) is an amino-modified MIL-101The specific surface area of (Cr) is 2800 to 3000m ² Per gram, pore volume of 0.7-1.4 cm ³ (ii)/g, the average pore diameter is 1.2-2.2 nm.

9. Use of the amino-modified MIL-101 (Cr) of claim 8 for adsorbing carbon dioxide.

10. Use according to claim 9, characterized in that the amino-modified MIL-101 (Cr) is CO-reactive ₂ The adsorption capacity of the adsorbent is 850-1050 mg/g.

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