CN101357321A - Preparation method of silica gel composite adsorbent - Google Patents

Abstract

A method for preparing a silica gel composite adsorbent in the technical field of material preparation. The steps are as follows: 1. Put the silica gel in a vacuum container to heat and evacuate it; 2. Use water as a solvent to prepare a metal salt solution; 3. Put the metal salt solution Add it into the vacuum container being heated, so that all the silica gel is soaked in the salt solution; 4. Stop heating the vacuum container, and soak the silica gel in the metal salt solution at room temperature and vacuum for 12 hours to 24 hours; The silica gel after the salt solution is filtered out with a filter and dried; 6. Place the dried silica gel in a constant temperature and humidity box, and the constant temperature and humidity box is set under low temperature and high humidity conditions, so that the silica gel and the metal salts remaining on the surface can be adsorbed Water vapor, the metal salt on the surface absorbs water and becomes a solution and breaks away from the silica gel surface; 7. When the silica gel no longer has a solution to flow out, take out the silica gel and dry it to obtain the silica gel composite adsorbent of the present invention. The method of the invention improves the adsorption capacity of silica gel.

Description

Preparation method of silica gel composite adsorbent

technical field

The invention relates to a preparation method in the technical field of thermal engineering, in particular to a preparation method of a silica gel composite adsorbent.

Background technique

As a good desiccant, silica gel has been widely used in the fields of drying, dehumidification and adsorption refrigeration. However, the adsorption capacity of silica gel is relatively small. When used in dehumidification or adsorption refrigeration systems, a large amount of silica gel must be filled in order to meet a certain dehumidification capacity or cooling capacity, resulting in a relatively large system.

Through literature retrieval to prior art, it is found that "A family of new working materials for solid sorption air conditioning systems" published by Aristov et al. A series of new working fluids in solid adsorption air conditioners), this paper proposes to increase water absorption by mixing silica gel and calcium chloride (lithium bromide) metal salt to form a composite adsorbent, specifically by soaking silica gel in a certain concentration of salt solution , and then dried at 200 °C until the quality remained unchanged to prepare the composite adsorbent. Studies have shown that the metal salt content in the composite adsorbent is 21.7% to 57.0%; and the water absorption of the composite adsorbent is 7.5 times that of the pure silica gel adsorbent. The disadvantage is that only a small part of the metal salt enters the pores of the silica gel, and most of the metal salt is directly attached to the surface of the silica gel particles after drying. Therefore, the metal salt attached to the surface is prone to deliquescence loss during the water absorption process, causing the composite adsorbent to absorb water. amount of attenuation. In addition, when the composite adsorbent is filled in the metal heat exchanger, the deliquescent metal salts will cause corrosion to the heat exchanger. Therefore, the composite adsorbent cannot be applied in practical systems.

Contents of the invention

The present invention aims at the deficiencies of the above-mentioned prior art, and proposes a preparation method of silica gel composite adsorbent. Most of the metal salts enter the pores of silica gel through vacuum immersion, and the metal salts on the surface of silica gel are removed by hydrolysis process, and finally silica gel is obtained. The composite adsorbent improves the adsorption performance of silica gel and avoids the attenuation of the adsorption performance of the composite adsorbent and the corrosion problems caused by the metal heat exchanger.

The present invention is achieved through the following technical solutions, specifically comprising the following steps:

Step 1, heat the silica gel particles in a vacuum container and vacuumize, and stop vacuuming after removing the air in the pores of the silica gel;

The silica gel is coarse-porous silica gel with an average pore diameter of 8nm-60nm.

The temperature of the heating is 80°C to 100°C.

Step 2, using water as a solvent to prepare a metal salt solution;

The metal salt solution has a mass concentration of 20%-50%.

The metal salt is one of CaCl ₂ , SrCl ₂ , LiCl, LiBr.

Step 3, adding the metal salt solution into the vacuum container that is being heated, so that the silica gel particles are all soaked in the salt solution. During this process, the vacuum container must be kept in a vacuum state;

Step 4, stop heating the vacuum container, so that the silica gel is soaked in the metal salt solution at room temperature and under vacuum conditions;

The time of soaking is 12 hours to 24 hours.

Step 5, filter out the silica gel soaked in the saline solution with a strainer and dry;

The drying temperature is 110°C to 120°C.

Step 6, place the dried silica gel in a constant temperature and humidity box, so that the silica gel and the metal salt remaining on its surface absorb water vapor, and the metal salt on the surface absorbs water to form a solution and then separates from the silica gel surface;

The constant temperature and humidity box has a temperature of 25°C to 35°C and a humidity of 85% to 95%.

In step seven, when no solution flows out from the silica gel, the silica gel is taken out and dried to obtain a silica gel composite adsorbent.

The drying temperature is 110°C to 120°C.

In the silica gel composite adsorbent, the mass content of the metal salt is 15% to 25%.

Compared with the prior art, the beneficial effects of the present invention are specifically as follows: metal salts can enter the pores of silica gel particles through vacuum immersion, increasing the adsorption capacity of the adsorbent. And the residual metal salt on the surface of the silica gel composite adsorbent is removed by the hydrolysis method, which solves the corrosion problem of the metal heat exchanger after the metal salt is absorbed and hydrated. The adsorption capacity of the silica gel composite adsorbent prepared by the invention is 2 to 4 times that of pure silica gel.

Description of drawings

Fig. 1 is a flowchart of the present invention.

Detailed ways

The embodiments of the present invention are described in detail below in conjunction with the accompanying drawings: this embodiment is implemented on the premise of the technical solution of the present invention, and detailed implementation methods and specific operating procedures are provided, but the protection scope of the present invention is not limited to the following the described embodiment.

Embodiment one

As shown in Figure 1, put silica gel particles with an average pore diameter of 8.0-10.0 nm in a vacuum container and heat and vacuumize at a temperature of 85°C; stop vacuuming after removing the air in the silica gel pores;

Using water as a solvent, configure a LiCl solution with a mass concentration of 30.0%;

Add the LiCl solution into the vacuum container that is being heated, so that the silica gel particles are completely immersed in the salt solution; during this process, the vacuum container must be kept in a vacuum state;

Then stop heating the vacuum container, so that the silica gel is soaked in the metal salt solution for 12 hours at room temperature and under vacuum conditions;

Filter out the silica gel soaked in the LiCl solution with a filter and dry it at 120°C;

Place the dried silica gel in a constant temperature and humidity chamber with a temperature of 30°C and a humidity of 90%, so that the silica gel and the metal salts remaining on its surface absorb water vapor, and the LiCl on the surface absorbs water to form a solution and then detaches from the silica gel surface;

When there is no more solution flowing out of the silica gel, the silica gel is taken out and dried at 120°C to prepare a silica gel-LiCl composite adsorbent.

The new silica gel-LiCl composite adsorbent prepared in this example, and the residual LiCl on the surface of the silica gel composite adsorbent was removed by hydrolysis method solved the corrosion problem caused to the metal heat exchanger after LiCl absorbs water and hydrated; the silica gel-LiCl composite adsorbent The mass content of LiCl is 20.0%, and its adsorption capacity is twice that of pure silica gel.

Embodiment two

As shown in Figure 1, put silica gel particles with an average pore size of 10.0-20.0nm in a vacuum container and heat and vacuumize at 90°C; stop vacuuming after removing the air in the pores of the silica gel;

Using water as a solvent, the configuration mass concentration is 30.0% CaCl ₂ solution;

Add the CaCl ₂ solution into the vacuum container that is being heated, so that the silica gel particles are completely immersed in the salt solution; during this process, the vacuum container must be kept in a vacuum state;

Then stop heating the vacuum container, so that the silica gel is soaked in the metal salt solution for 18 hours at room temperature and under vacuum conditions;

Filter out the silica gel soaked in the CaCl ₂ solution with a filter and dry it at 120°C;

Place the dried silica gel in a constant temperature and humidity chamber with a temperature of 30°C and a humidity of 95%, so that the silica gel and the metal salt remaining on its surface absorb water vapor, and the _CaCl2 on the surface absorbs water to form a solution and then detaches from the silica gel surface;

When there is no more solution flowing out from the silica gel, the silica gel is taken out and dried at 120° C. to prepare the silica gel-CaCl ₂ composite adsorbent.

The novel silica gel-CaCl composite adsorbent prepared in this example, and remove the residual _CaCl on the surface _of the silica gel composite adsorbent by hydrolysis method solves the corrosion problem caused to the metal heat exchanger after _CaCl absorbs water and liquefies; silica gel-CaCl ₂ The mass content of _CaCl2 in the composite adsorbent is 15.0%, and its adsorption capacity is 2.5 times that of pure silica gel.

Embodiment three

As shown in Figure 1, put silica gel particles with an average pore diameter of 20.0-60.0nm in a vacuum container and heat and vacuumize at a temperature of 90°C; stop vacuuming after removing the air in the silica gel pores;

Adopting water as a solvent, configuring a SrCl _solution with a mass concentration of 50.0%;

Add the SrCl ₂ solution into the vacuum container that is being heated, so that the silica gel particles are completely immersed in the salt solution; during this process, the vacuum container must be kept in a vacuum state;

Then stop heating the vacuum container, so that the silica gel is soaked in the metal salt solution for 24 hours at room temperature and under vacuum conditions;

Filter out the silica gel soaked in the _SrCl2 solution with a filter and dry it at 110°C;

Place the dried silica gel in a constant temperature and humidity chamber with a temperature of 30°C and a humidity of 95%, so that the silica gel and the metal salt remaining on its surface absorb water vapor, and the SrCl ₂ on the surface absorbs water to form a solution and then detaches from the silica gel surface;

When there is no more solution flowing out of the silica gel, the silica gel is taken out and dried at 110° C. to prepare the silica gel-SrCl ₂ composite adsorbent.

The novel silica gel- _SrCl2 composite adsorbent prepared in this embodiment, and remove the residual _SrCl2 on the surface of the silica gel composite adsorbent by hydrolysis, and solve the corrosion problem caused to the metal heat exchanger after _SrCl2 absorbs water and liquefies; silica gel-SrCl ₂ The mass content of _SrCl2 in the composite adsorbent is 20.0%, and its adsorption capacity is 3 times that of pure silica gel.

Embodiment four

As shown in Figure 1, put silica gel particles with an average pore size of 10.0-20.0nm in a vacuum container and heat and vacuumize at 90°C; stop vacuuming after removing the air in the pores of the silica gel;

Using water as a solvent, configure a LiBr solution with a mass concentration of 40.0%;

Add the LiBr solution into the vacuum container that is being heated, so that the silica gel particles are completely immersed in the salt solution; during this process, the vacuum container must be kept in a vacuum state;

Then stop heating the vacuum container, so that the silica gel is soaked in the metal salt solution for 14 hours at room temperature and under vacuum conditions;

Filter out the silica gel soaked in the LiBr solution with a filter and dry it at 120°C;

Place the dried silica gel in a constant temperature and humidity chamber with a temperature of 25°C and a humidity of 90%, so that the silica gel and the metal salt remaining on its surface absorb water vapor, and LiBr on the surface absorbs water to form a solution and then detaches from the silica gel surface;

When the solution no longer flows out of the silica gel, the silica gel is taken out and dried at 120° C. to prepare the silica gel-LiBr composite adsorbent.

The new silica gel-LiBr composite adsorbent prepared in this example, and the residual LiBr on the surface of the silica gel composite adsorbent was removed by hydrolysis method solved the corrosion problem caused to the metal heat exchanger after the LiBr absorbed water and hydrated; the silica gel-LiBr composite adsorbent The mass content of LiBr in LiBr is 25.0%, and its adsorption capacity is 4 times that of pure silica gel.

Claims (10)

1, a kind of preparation method of silica gel composite absorbent is characterized in that, comprises the steps:

Step 1 is placed in the vacuum tank heating with silica gel particle and vacuumizes, and stops to vacuumize behind the air in removing the silica gel hole;

Step 2 adopts water as solvent, the configuration metal salt solution;

Step 3 adds metal salt solution in the vacuum tank that is heating, and makes silica gel particle all be immersed in the salting liquid, in this process, must keep being in vacuum state in the vacuum tank;

Step 4 stops to the vacuum tank heating silica gel being immersed in the metal salt solution under room temperature and vacuum condition;

Step 5 leaches the silica gel behind the immersion salting liquid and dry with filter screen;

Step 6 is placed on the silica gel of oven dry in the climatic chamber, breaks away from the silica gel surface after making the slaine adsorbed water steam of silica gel and remained on surface thereof, the slaine adsorbed water on surface become solution;

Step 7 when no longer including the solution outflow in the silica gel, is taken out silica gel and oven dry, has just made silica gel composite absorbent;

In the described silica gel composite absorbent, the mass content of slaine is 15%～25%.

2, the preparation method of silica gel composite absorbent according to claim 1 is characterized in that, described silica gel is silochrom, and average pore size is 8nm～60nm.

3, the preparation method of silica gel composite absorbent according to claim 1 is characterized in that, in the step 1, and described heating, its temperature is 80 ℃～100 ℃.

4, the preparation method of silica gel composite absorbent according to claim 1 is characterized in that, in the step 2, and described metal salt solution, its mass concentration is 20%～50%.

According to the preparation method of claim 1 or 4 described silica gel composite absorbents, it is characterized in that 5, in the step 2, described slaine is CaCl ₂, SrCl ₂, one of LiCl, LiBr.

6, the preparation method of silica gel composite absorbent according to claim 1 is characterized in that, in the step 4, and described immersion, its time is 12 hours～24 hours.

7, the preparation method of silica gel composite absorbent according to claim 1 is characterized in that, in the step 5, and described oven dry, its temperature is 110 ℃～120 ℃.

8, the preparation method of silica gel composite absorbent according to claim 1 is characterized in that, in the step 6, and described climatic chamber, its temperature is 25 ℃～35 ℃.

9, according to the preparation method of claim 1 or 8 described silica gel composite absorbents, it is characterized in that, in the step 6, described climatic chamber, its humidity is 85%～95%.

10, the preparation method of silica gel composite absorbent according to claim 1 is characterized in that, in the step 7, and described oven dry, its temperature is 110 ℃～120 ℃.

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