SU997795A1 - Method of producing water vapour adsorbent - Google Patents

Description

The invention relates to chemical technology, in particular, to the production of modified sorbents that can be used as gas dryers in static and dynamic conditions. . Phosphoric anhydride is known to be one of the most effective absorbers of moisture vapor, providing a high degree of drying of gases. Cl. The disadvantages that prevent its widespread use as a sorbent of moisture are the volatility of harmful vapors; high hygroscopicity of the fine powder, which significantly reduces its effective use, since a film of phosphoric acid is formed on the surface of phosphorus pentoxide particles, resulting in a decrease in the activity of the chemisorbent with respect to water vapor; difficulty of regeneration. The closest in technical support and the achieved result is a method of obtaining an adsorbent of water vapor, including the processing of silica gel with phosphoric acid G23. A disadvantage of the known method of modification is the uncertainty of the chemical composition of the surface and, therefore, poor reproducibility of the sorption properties. For example, a sample of silica gel impregnated with fsfsfnoy acid containing 4 phosphors, when saturated with water vapor, becomes sticky. After washing the impregnated sample of water into the head sample, the phosphorus content in it decreases and ranges from 1.06 to 1.4 mg-at / g. The aim of the invention is to increase the adsorption capacity. This goal is achieved by the described method of obtaining an adsorbent of water vapor, including drying silica gel at 200-36 ° C, treating phosphorus oxychloride vapors at 20300 ° C to a phosphorus content of the target product of 1-1.6 mg-at / g and removing gaseous products. Treatment with phosphorus oxychloride and water vapor can be repeated multiple times (2-3 times) until the phosphorus content in the final product is 1-1.6 mg-at / g. The silica gel is treated with water vapor until the release of HCt is stopped. % As a result, the specified sorbent is covered with a uniform phosphorus oxide layer and acquires a higher water absorption capacity than the original product. For example, if the initial silica gel with a relative humidity of up to 70% has a moisture capacity of 6-8 wt.%, Then phosphorus-containing silica gel has, depending on the phosphorus content, a moisture capacity of 20-40% at the same relative humidity. At the same time, with the proposed adsorbent, the ability to regenerate remains at the same level and the regeneration trocess is carried out under the same conditions as with the initial silica gel. The optimum amount of phosphorus (in terms of phosphorus pentoxide) included in the sorbent is 1-1.6 mg-at / g, and the lower limit is due to the fact that COOT corresponds to the 1st monolayer of phosphorus-oxygen groups covering the entire surface of the sorbent and the upper limit is limited by the fact that with a higher phosphorus content the surface layer acquires the disadvantages of phosphoric anhydride, i.e. becomes sticky due to the formation of phosphoric acid in contact with humid air. The lower limit of the drying process is due to the fact that physically sorbed moisture is not completely desorbed at temperatures below 200 ° C and the amount of drying during silica gel drying ROCES H20 decreases 300 Phosphorus sorbed per 1 treatment cycle. The lower limit of the treatment process (20 ° C) is due to the convenience of carrying out the process without additional heating. Example 1. The initial silica gel of the grade SSC with a specific surface of 250 (GOST 3956-36 is dried to remove physically sorbed moisture, placed in an environment with a relative humidity of 70% and a temperature of 20 ° C and maintained to constant weight. Then the sorbent is regenerated at 200 ° C for 2 hours. The adsorption capacity of the sorbent is 6 wt.% At a relative humidity of 70% and is maintained after regeneration. Example 2. A portion of the starting silica gel, dried as in example 1, is treated with phosphorus oxychloride vapor in a flow-through reactor type at 20 ° C. Dry air removes unreacted phosphorus oxychlohydride and HC. The phosphorus content (in terms of P relative humidity 70% in the sample is 1 mg-at / g or 31 mg / g. Adsorption capacity is determined as in Example 1 and is 20% by weight. After regeneration, it is maintained. Example 3. A sample of silica gel L in Example 1 is treated with POCEj vapors at and then (after removing volatile products) with a current of moist air, the surface is hydrated, the formed HC E and repeating the oxychloride treatment operation Example 2. The content of phosphorus and adsorption capacity at a relative humidity of 70% before and after regeneration are 1.3 mg at / g and 25% by weight, respectively. Example 4. A weighed silica j-j of example 1 is treated analogously to example 3 with, with the treatment cycle repeated three times. The phosphorus content and the adsorption capacity at a relative humidity of 70% before and after regeneration are 1.6 mg-at / g and 35% by weight, respectively. Example 5 Silica gel is treated analogously to Example 4 to a phosphorus content on the surface of the sorbent of more than 1.6 mg-at / g. The adsorption capacity of the sorbent is 35%, however, the sample is covered with a sticky film of phosphoric acid. The data for the examples are tabulated. Thus, the proposed phosphorus-containing silica gel has a higher moisture capacity compared to the initial and known silica gels, while maintaining the ability to regenerate njHi in the same conditions as the original silica gel, and as a result, lower energy consumption than during regeneration of sorbents. The economic effect of using this modified sorbent for drying the internal volumes of sealed devices is determined by improving the quality and operational reliability of the devices, i.e. by increasing their lifespan. The calculation takes into account the expected coefficient of change of the parameter by increasing the service life of 1.12-1.3. The annual economic efficiency in this case is 300 thousand rubles.

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Claims (2)

1. A method for producing an adsorbent of water vapor, including treatment of the collar with the compound of the compound, to the fact that, in order to increase the adsorption capacity, the silica gel before treatment is dried, vacuum, and the treatment is carried out with vapors of phosphorus oxychloride with subsequent treatment with water vapor and removal of gaseous reaction products. 2, the method according to claim 1, about tl and h and y and with the fact that drying The sample becomes sticky due to the formation of phosphoric acid. 20 25 20 25 35 35 The sample is covered with a sticky film silica gel is carried out at 200-300 ° C, and treatment of silica gel with phosphorus oxychloride vapor is carried out at 20-300 ° C until the phosphorus content in the target product is 1-1.6 mg-at / g. Sources of information 35 accepted in 5 attention during examination; 1. Van Weser. Phosphorus and its compounds. M., Publishing House) Foreign Literature, 1962, p. 642. 2. Keltsev N.V. Fundamentals of adsyubts40noy technique M., 1976, p. 97t98.