Preparation process and application of modified 3A molecular sieve

Abstract

The invention belongs to the field of molecular sieves, and particularly relates to a preparation process and application of a modified 3A molecular sieve. The preparation method of the modified 3A molecular sieve comprises the following steps: preparing molecular sieve particles; coating with clay, activating and roasting to obtain a roasted molecular sieve; carrying out alkalization treatment, and converting into an unbonded molecular sieve; carrying out potassium exchange, controlling the potassium exchange degree to be 30-60%, and drying to obtain a potassium exchange molecular sieve; subjecting the potassium exchange molecular sieve to primary roasting, dust removal through blowing and secondary roasting, wherein the primary roasting and the secondary roasting are carried out in a controlled atmosphere, and the controlled atmosphere is air with the dew point temperature of -20 DEG C to 10 DEG C. According to the preparation method of the modified 3A molecular sieve disclosed by the invention, the prepared molecular sieve has relatively high water absorption and extremely low CO2 interception; the strength and wear resistance are further improved, and the special requirements of a four-bed molecular sieve carbon dioxide removal system on the drying bed molecular sieve are met.

Description

technical field [0001] The invention belongs to the field of molecular sieves, and in particular relates to a preparation process and application of a modified 3A molecular sieve. Background technique [0002] Carbon dioxide is one of the products of human metabolism. When the concentration of carbon dioxide in the air of closed cabins such as submarines, space stations, and civil air defense projects accumulates to a certain level, it will cause dizziness, confusion, nausea, and vomiting. When the concentration reaches 5% , people's breathing can only last 30 minutes, when it reaches more than 10%, it will cause people to lose consciousness or even die. The concentration of carbon dioxide in the air is 400ppm, and spaceflight requires control of the concentration of carbon dioxide below 5000ppm, preferably 3000ppm, because the space in the spacecraft cabin is small, once out of control, the concentration of carbon dioxide will rise rapidly; especially for long-term, manned ...

AI Technical Summary

Problems solved by technology

[0005] The main defect of this design includes two aspects: the one is that the 13X molecular sieve in the drying bed absorbs the moisture in the air, while the CO in the air 2 The adsorption capacity also reaches 6% (CO 2 Concentration of 6000ppm, temperature at 23°C), 10-30% CO entering the four-bed molecular sieve system 2 Because the adsorption of 13X is trapped in the drying bed, during the desorption cycle, the carbon dioxide trapped in the drying bed returns to the cabin with the desorption and desorption of the drying bed, resulting in the CO of the whole system 2 The removal efficiency is only 70-80%, which is a structural defect in the existing four-bed molecular sieve system in the International Space Station

The second is that the drying bed is filled with silica gel. During the regeneration and desorption process of the drying bed, the contact between the silica gel and the water droplets in the high-humidity air is prone to fragmentation, which increases the bed resistance and affects the operation of the system. In order to avoid the contact between the silica gel and the water droplets in the air Fragmentation, the four-bed molecular sieve system of the space station adds a 13X protective layer, but the defect of this scheme is to increase the volume of the four-bed molecular sieve, and because of the existence of the 13X protective layer, one part increases the drying bed to CO 2 Adsorption capacity

[0006] In addition, industrial enterprises also use the combination of traditional silica gel and traditional 3A molecular sieve products to achieve gas dehydration and drying, but the water absorption of the 3A molecular sieve used is only 19-21% (GB / T10504-2017), while the water absorption of 13X molecular sieve can be reached 26%, compared with 13X molecular sieve, 3A molecular sieve although CO 2 Lower adsorption capacity, but also lower product water absorption

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