JP2636090B2 - Method for producing silica gel impregnated with silver nitrate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing silver nitrate impregnated silica gel.

[0002]

2. Description of the Related Art Silica gel impregnated with silver nitrate is used as a packing material for liquid chromatography for separating a paraffin component and an olefin component of a petroleum fraction. When this silver nitrate impregnated silica gel is used as a filler for liquid chromatography, the degree of separation of each component in the petroleum fraction varies depending on the amount of silver nitrate impregnated. Must be impregnated.

However, silica gel is added to a silver nitrate solution obtained by dissolving a required amount of silver nitrate in a solvent soluble in silver nitrate such as methanol and acetonitrile, mixed, and then the solvent is distilled off to obtain a silica gel impregnated with silver nitrate. The method has the following disadvantages.

(I) Since a large amount of solvent is used for the silica gel used, not only the entire amount of silver nitrate cannot be impregnated in the silica gel, but also the amount of silver nitrate impregnated in the silica gel tends to vary.

(Ii) It is necessary to use a large amount of a solvent and distill off the solvent, resulting in an increase in cost.

(Iii) After distilling off the solvent, it is necessary to recover the unimpregnated silver nitrate adhering to the vessel wall and the like. (iV) When chloroform is used to pack the obtained silver nitrate-impregnated silica gel into a column for liquid chromatography, since the chloroform contains ethanol as a stabilizer, silver nitrate elutes from the silver nitrate-impregnated silica gel with ethanol.

[0007]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide the above-mentioned prior art method for producing silica gel impregnated with silver nitrate which has the above-mentioned disadvantages.
A method for producing a silver nitrate-impregnated silica gel that eliminates (i), (ii), (iii) and (iV) and allows a target amount of silver nitrate such as silver nitrate to be accurately and uniformly impregnated into silica gel such as silica gel. Is to do.

[0008]

The method for producing a silver nitrate-impregnated silica gel according to the present invention, which achieves the above object, comprises a step of bringing silica gel into contact with a silver nitrate solution while applying ultrasonic vibration to impregnate the silver nitrate into the silica gel. The ratio of the amount of water adsorbed on the silica gel to the volume of the solvent is 0.95 to 1.
The solution is characterized by being a solution obtained by dissolving silver nitrate in a solvent having an amount in the range of 05.

Hereinafter, the present invention will be described in detail.

The shape of the silica gel used in the present invention may be any shape such as a spherical shape and a crushed shape. When the silica gel is spherical, the particle size is 3 to 200 μm.
m is preferred. When the silica gel is in a crushed form, the main dimension (longest dimension) is preferably from 3 to 200 μm. The preferred pore size of the silica gel is 3 to 300 angstroms.

As the silica gel impregnated with silver nitrate in the present invention, it is preferable to use a silica gel which has been dried in a vacuum at a high temperature and then cooled in a desiccator. This vacuum drying is preferably performed at 100 ° C. for 3 hours.

In the present invention, it is necessary to previously measure the amount of water adsorbed on the silica gel. This is performed, for example, by the following method.

(I) After the silica gel is vacuum-dried at a high temperature, it is allowed to cool in a desiccator. The conditions for the vacuum drying and the cooling are preferably the same as those for the silica gel impregnated with silver nitrate.

(Ii) Next, a predetermined amount of silica gel is placed in a container such as a beaker, and its weight (Wdry) is weighed.

(Iii) Next, water is added dropwise while vibrating the silica gel in the container with ultrasonic waves or the like until the entire silica gel is wet. This determination of wetness is made visually. (iV) Next, the weight of the whole wet silica gel (Wwe
t) is measured, and the amount of adsorbed water is determined from the difference between Wwet and Wdry.

According to the present invention, the ratio between the amount of water adsorbed on silica gel and the solvent capacity determined above is 0.95 to 1.0.
A solution in which silver nitrate is dissolved in an amount of solvent in the range of 5 is prepared in advance. As the solvent, a solvent capable of dissolving silver nitrate is used, and examples thereof include water, methanol, ethanol, acetonitrile, and a mixture thereof.

However, it is needless to say that the solvent capacity is preferably as close as possible to the amount of water adsorbed on the silica gel. The amount of silver nitrate dissolved in the solvent is appropriately determined according to the target amount of silver nitrate to be impregnated in the silica gel.

According to the present invention, the silver nitrate solution thus prepared is brought into contact with the above-mentioned silica gel to impregnate the silica gel with silver nitrate, for example, as follows.

(I) A predetermined amount of silica gel is collected in a container such as a beaker.

(Ii) Next, while applying ultrasonic vibration to the silica gel in the container, silver nitrate is dissolved in a solvent in an amount such that the ratio of the amount of water adsorbed on the silica gel to the solvent volume is in the range of 0.95 to 1.05. The resulting solution is added dropwise little by little. Frequency of the ultrasonic vibrations applied is 10～100KH _z preferably 30
100KH _z, high frequency output is preferably set to 30 to 1,000.

(Iii) After the silver nitrate solution is dropped, the application of ultrasonic vibration is continued for a predetermined time (for example, 10 minutes).

(IV) Next, the silica gel wetted with the silver nitrate solution is vacuum-dried at a high temperature to evaporate the solvent, and then left to cool in a desiccator to obtain a silica gel impregnated with silver nitrate. For example, in the case of silica gel, vacuum drying is preferably performed at 100 ° C. for 3 hours.

According to the present invention, the amount of water adsorbed on the silica gel is determined in advance, and the ratio of the amount of water adsorbed to the solvent capacity is set to 0.1.
Since a solution in which silver nitrate is dissolved in an amount of a solvent in the range of 95 to 1.05 is brought into contact with silica gel, substantially all of silver nitrate is impregnated in silica gel. Therefore, it is possible to obtain a silver nitrate-impregnated silica gel impregnated with a target amount of silver nitrate accurately and uniformly. When the silver nitrate impregnated silica gel thus obtained is used as a packing material for liquid chromatography, it becomes possible to accurately separate substances, and when used as a catalyst for various chemical reactions, Can be performed successfully. Silica gel impregnated with silver nitrate is suitable as a packing material for liquid chromatography for separating paraffins and olefins of petroleum fractions.

As shown in the following Examples, packing of silica gel impregnated with silver nitrate into a column is performed by adding carbon tetrachloride to silica gel containing silver nitrate and applying ultrasonic vibration to form a slurry.
Preferably, the slurry is filled in a column. This filling method is safer than chloroform as a solvent, and therefore uses carbon tetrachloride that does not contain ethanol as a stabilizer. In that silver nitrate is prevented from being eluted from the silica gel impregnated with silver nitrate.

[0025]

The present invention will be further described with reference to the following examples.

Example 1 (1) Silica gel As silica gel, a commercially available product (trade name: YMC-GELS)
IL-120-S5, manufactured by YMC Corp.) was used. This silica gel was vacuum-dried at 100 ° C. for 3 hours before use, and then allowed to cool in a desiccator.

(2) Measurement of Adsorbed Water Amount of Silica Gel The silica gel (after vacuum drying and cooling) of the above (1) was placed in a beaker, and its weight (Wdry) was weighed. W
The dry was 1 g.

Next, water was dropped onto the silica gel in the beaker while applying ultrasonic vibration (frequency 42 KHz, high frequency output 70 W) until the entire silica gel was wet. The determination of wetness was made visually.

Next, the weight of the silica gel wetted with water (Ww
et) was weighed. Wwe is 1.95 g and Ww
The difference between et and Wdry revealed that the amount of adsorbed water per g of silica gel was 0.95 g. This amount of absorbed water of 0.95 g corresponds to a volume of 0.95 ml.

(3) Preparation of Silver Nitrate Solution Using silver nitrate, a predetermined amount of the silver nitrate was dissolved in a solvent (water / ethanol 2/1 (2/1 (water / ethanol)) having the same volume as the amount of adsorbed water per 2 g of silica gel (1.9 g = 1.9 ml). (V / V) mixed solution) to prepare the following five types of silver nitrate solutions.

Silver nitrate concentration Silver nitrate solution (i) 0.105% (W / V) 〃 (ii) 0.210% (W / V) 〃 (iii) 0.316% (W / V) 〃 (iv) 0 .421% (W / V) 〃 (v) 0.737% (W / V) (4) Impregnation of silver nitrate into silica gel Silica gel of above (1) (after vacuum drying and cooling) 2
g of the silver nitrate solution obtained in the above (3) while placing the beaker in an ultrasonic cleaner and applying ultrasonic vibration (frequency 42 KHz, high frequency output 70 W).
9 ml was dropped using a Komagome pipette, and application of ultrasonic vibration was continued for 10 minutes after the drop. Thereafter, the silica gel wetted with a silver nitrate solution was vacuum-dried at 100 ° C. for 3 hours to evaporate the solvent, and then allowed to cool in a desiccator to obtain a silver nitrate-impregnated silica gel. Table 1 shows the results of measuring the amount of silver nitrate impregnated on the obtained silver nitrate-impregnated silica gel. From Table 1, it was clear that the silver nitrate-impregnated silica gel obtained in this example was impregnated with silver nitrate in almost the same amount as the target amount of silver nitrate to be impregnated. In addition, the above impregnation operation was separately performed twice more, and in each case, good results were obtained, and there was no variation in the silver nitrate impregnation amount.

(5) Liquid Chromatography Carbon tetrachloride was added to the silver nitrate-impregnated silica gel obtained in the above (4) at a concentration of 1 g / 10 ml, and ultrasonic vibration was applied to obtain a slurry. This slurry was placed in a column packer and packed under the following conditions.

[0033] Table 1 also shows the results of measuring the amount of silver nitrate impregnated on the silver nitrate-impregnated silica gel packed in the column. From Table 1, it can be seen that the silver nitrate impregnation amount after the column packing was almost the same as that before the column packing, and that the silver nitrate was not eluted from the silica gel by the solvent (carbon tetrachloride containing ethanol as a stabilizer) during the column packing. It became clear.

Next, a silica gel column impregnated with silver nitrate having a silver nitrate concentration of 0.19% (obtained using the silver nitrate solution (ii)) and a commercially available NH ₂ column (trade name: Lichr)
Osorb NH ₂ (manufactured by Kanto Chemical Co., Ltd.) was connected in series by liquid chromatography to LCO (light cycle oil: olefin content 5) which was a petroleum fraction by liquid chromatography.
%, A paraffin content of 30% and an aroma content of 65%). The result is shown in FIG. For reference, FIG. 2 shows the result of the same LCO component separation using a silica gel column not impregnated with silver nitrate and a column in which the commercially available NH ₂ column is connected in series.

As is apparent from a comparison between FIG. 1 and FIG. 2, when the silver nitrate impregnated silica gel obtained in this example is used, a peak of an olefin component and a peak of a paraffin component appear clearly, and both can be separated. On the other hand, when silica gel not impregnated with silver nitrate was used, the olefin peak and the paraffin peak overlapped, and the two could not be separated.

[0036]

[Table 1]

Comparative Example 1 Into a beaker, 2 g of the same silica gel as used in Example 1 (after vacuum drying and cooling) was added, and 10 ml of acetonitrile was added to form a slurry.

Separately, for the weight of silica gel (2 g),
Silver nitrate in an amount corresponding to 0, 6, 0.8, 1.0, 1.5, 2.0, 3.0 and 5.0 wt% in methanol 10
The resultant was dissolved in methanol to prepare a total of seven types of methanol solutions of silver nitrate.

Next, the above slurry and a methanol solution of silver nitrate were mixed, subjected to ultrasonic vibration (frequency: 42 kHz, high-frequency output: 70 W) for 10 minutes, and then vacuum-dried at 30 ° C. for 3 hours. The example silver nitrate impregnated silica gel was obtained. Table 2 shows the results of measuring the amount of silver nitrate impregnated for the two types of the obtained silver nitrate-impregnated silica gels. As shown in Table 2, the silica gel impregnated with silver nitrate obtained in the present comparative example was impregnated with silver nitrate in a much smaller amount than the target amount of silver nitrate to be impregnated.

Next, seven types of silica gel impregnated with silver nitrate obtained in this comparative example were packed in a column, and the amount of silver nitrate impregnated after filling was measured. The details are as follows. That is, chloroform was added to the silver nitrate impregnated silica gel of this comparative example at a rate of 1 g / 1.
The slurry was added so as to be 0 ml, and ultrasonic vibration was applied to obtain a slurry. This slurry was placed in a column packer and packed under the following conditions.

[0041] Table 2 shows the results of determining the amount of silver nitrate impregnated for the silver nitrate-impregnated silica gel packed in the column. As shown in Table 2, the amount of silver nitrate impregnated after filling the column was significantly lower than the target amount of silver nitrate impregnation for all of the seven types of silica gel impregnated with silver nitrate. Also, comparing the silver nitrate impregnation amount before and after the column packing for the two types of silver nitrate impregnated silica gel, the silver nitrate impregnation amount after the column packing is significantly lower than that before the column packing, and the silver nitrate impregnated with the solvent (including ethanol as a stabilizer). Chloroform) to elute from the silica gel.

[0042]

[Table 2]

[0043]

As described above, according to the present invention, there has been provided a method for producing a silver nitrate-impregnated silica gel capable of accurately and uniformly impregnating silica gel with a target amount of silver nitrate.

[Brief description of the drawings]

FIG. 1 is a liquid chromatogram of LCO (light cycle oil) using the silica gel impregnated with silver nitrate obtained in Example 1 as a filler.

FIG. 2 is a liquid chromatogram of LCO using silica gel not impregnated with silver nitrate as a filler.

Claims (2)

(57) [Claims] 1. A step of impregnating silica gel with silver nitrate by bringing silica gel into contact with a silver nitrate solution while applying ultrasonic vibration, wherein the silver nitrate solution has a ratio of the amount of water adsorbed on the silica gel to the solvent capacity of 0. A method for producing silver nitrate-impregnated silica gel, which is a solution obtained by dissolving silver nitrate in a solvent in an amount ranging from 95 to 1.05. 2. A silver nitrate impregnation characterized by adding carbon tetrachloride to silver nitrate impregnated silica gel obtained by the method according to claim 1 and applying ultrasonic vibration to form a slurry, and filling the slurry into a column. Silica column packing method.