Investigation of the drying process of ehfef in the technology of obtaining a nanocatalyst from the retention substance bentonite

. In this study, the study of the drying process using the energy of a convective electromagnetic field (electromagnetic field of extremely high frequency) was considered when obtaining a nanocatalyst from bentonite of a trapping substance based on the "Zol-gel" technology. Also, the bentonite layer "Navbahor" is a textural description of samples, the effect of bentonite heating on the size of microporosity, heating from surface to surface, distribution and chemical composition of the porosity diameter in accordance with the size of unmodified bentonite.


Introduction
A promising direction for the production of materials with nanoparticles includes systematized matrix media, including zeolite, molecular sieve (Sita), microemulsion micelles, gels, polymers, glass, and liquid crystals.In recent years, Zol-gel technology has been conducting large-scale scientific and practical research on the synthesis of a mass of inorganic and organoinorganic materials at low temperatures. It differs from other technologies in a number of characteristics, such as simplicity of the equipment used in the technology, energy efficiency, environmental safety, economic efficiency, flexibility of coinage, etc. [1][2][3][4][5][6][7][8]. The reason is that nanocatalysts exhibit high catalytic activity, selectivity, stability, etc. The high efficiency of nanocatalysts is associated with the processes of roughing and transfer (transportation) of charge, energy, mass, and information in them, and these processes occur in nanotubes as well as in chemical reactions in nanotubes. The practical application of such catalysts leads to an unprecedented improvement in the environmental characteristics of many processes and technologies in industry, a reduction of harmful emissions emitted into the atmosphere, the creation of environmentally friendly types of alternative energy resources, and new products and materials.One of the most important textural characteristics of porous materials, in particular catalysts and adsorbents, is their comparative surface and porosity size. Many researchers have tried to divide the pores in sorbents into different categories [9]. When creating a consistent classification of cereals, an attempt at classification, usually based on their origin and size, was made by Kaneko [10]. One of the most important textural characteristics of porous materials, in particular catalysts and adsorbents, is their comparative surface and porosity size. Many researchers have tried to divide the pores in sorbents into different categories [9]. An attempt at creating a consistent classification of cereals, usually based on their origin and size, was made by Kaneko [10]. Typically, in solids with high dispersion, primary particles interact with secondary particles under the action of surface forces.
These ensembles are called aggregates if the effect between the particles bound by the mischief is weak. As a result of the weak interaction between the aggregated particles, pores appear between them. This kind is called the inner porous of the porous. Internal cavities are formed either in solution, as a result of reactions occurring on the surface, or as a result of high pressures and temperatures. The pores of the external type are formed as a result of the absorption of foreign substances into the primary shell of the body and their subsequent removal in various ways.
According to the IUPAC classification, pores are also classified according to their geometric shape. According to the geometric shape of porosity, cylindrical, conical, cubic, rhombic, and ellipticoid shapes are distinguished [11]. The geometric shape and porosity dimensions determine the slope of the adsorption process as well as the shape of the sorption isotherms. As a rule, cylindrical porridges are found in aluminum and magnesium oxides, prismatic porridges are found in fibrous cellulose, ellipticoid porridges are found in soil and fagangan coal, and porridges between successive spherical granules are found in triraidi silica [12]. In most cases, the sol-gel method is used to obtain nanoparticles. This method is of great importance due to the simplicity, cost-effectiveness, environmental safety of equipment, and economic efficiency of the resulting product [13]. It is also distinguished by the fact that the initial precursors carry out the goulite polycondensation reaction under mild conditions and by the possibility of introducing monomer oxides of functional groups, polymers, and metals of variable valence into the reaction system, using a single solvent for all reagents and the ability to control both the structure and the size of the final product [14].Usually, in the Zol-gel process, gelolysis reactions involving water are carried out with the participation of an acid or alkaline catalyst [15].Based on the analysis of the literature [17][18][19][20][21][22], it was found that the prospect of using a nanoparticle-based catalyst in catalysis is associated with the following two scientific aspects: Firstly, as the particle size decreases, a large percentage of atoms settle on the surface, so a catalyst consisting of nanoparticles will have a large surface area. The surface will be very active in reactions. Secondly, many properties of nanosystems depend on their size (size effect). Therefore, When it comes to changing the size of nanoparticles, it is possible to control not only the activity, but also the selectivity of the scales. When the size of the catalytic membrane decreases, the reaction rate increases dramatically. Currently, high energy costs and raw materials for existing technologies with heterogeneous catalysts force the introduction of registered processes and the search for new methods. One of the ways to solve this problem is to carry out the process on nanocatalysts. Therefore, in the synthesis of inorganic oxide materials, the Sol-gel process has an advantage over other methods, and the ultradispersity of bunda makes it possible to obtain new crystalline and amorphous phases, reducing the microhomogeneity of the resulting compounds and creating unique structures with high porosity, thus ensuring their high purity and uniformity of component distribution.According to the technological scheme for obtaining a multicomponent catalyst in the entrapping substance bentonite, with the formation of a lyosal solvent, colloidal particles are distributed into particles of 3-4 nm. The main parameters of the bond are the rn value of the environment, water and the ratio of the retaining substance, as well as the presence and nature of catalysts. there is as much dressing gel as there are colloidal granules if the rn value is high and the amount of water is greater. By distinguishing spatial views with the separation of individual particles, the system takes a certain form. During the technological process, gel aging occurs, and the spatial appearance is enhanced. In the process of drying the technology, 30-80% of the porosity of the material is formed, and in the latest technological process, the gel is thermally condensed during burns and the porosity of the medium-sized porous decreases.In general, based on the Zol-gel technology in obtaining a nanocatalyst: Zol maturation and gel formation, drying under supercritical conditions or washing the gel with solvents, the gel is formed into an aerogel, and during subsequent drying, a cerogel is formed, that is, the nanoparticles are sunk and a thin layer (a retaining substance) is obtained from the powder. being formed.
As can be seen from the above, one of the main processes in the Sol-gel technology is the heat treatment of this material: the drying and firing process. Currently, these processes are carried out with conventional heat and mass transfer. In a material formed in this way, the porosity quality will not be high, and porosity is one of the main indicators of catalytic sorbents. Therefore, the study of the drying process in the technology of obtaining a nanocatalyst from the retaining substance bentonite and its implementation in the EMC is extremely relevant.

Methods
The search for bentonite drying of EHFEF convective was carried out on a device. The experimental device for drying in the resonator chamber "electronics" of a microwave oven, assembled on the basis of a microwave oven, is a single unit, which includes a control panel, a drying chamber, an air duct, and drying, a system for measuring the mass of the required material, and a microwave energy generator. The operating frequency of the microwave oven was 2450 MHz, and the magnetron generator of microwave energy had a capacity of 2.0 kW. The device is a rectangular resonator with the dimensions of the drying chamber of 400 x 350 x 250 mm.
Inside the drying chamber there is a rotating divider device, which ensures an even distribution of the microwave area in the chamber. To control the incoming power to the working chamber, the anode wire of the microwave generator is connected via a laboratory autotransformer (LATR), and the magnetron power is 0.5 -0.2 kW. the interval may change.Inside the drying chamber, there is a rotating divider device, which ensures an even distribution of the microwave area in the chamber. To control the incoming power to the working chamber, the anode wire of the microwave generator is connected via a laboratory autotransformer (LATR), and the magnetron power is 0.5-0.2 kW. The interval may change.
To measure the mass of the drying material directly during the drying process, this is carried out with a measurement accuracy of 500 using vlk-0.01 type scales installed at the bottom of the drying chamber. On the scale palette and camera, the sole is made with an ebonite-dielectric axis. Drying of the material is carried out on a mesh base made of textolite. The air in the drying chamber is supplied directly to the material from the side. The air is heated by an electric heater. The air velocity is carried out by an autotransformer using a damper in the range of 0.2-0.6 m/s and a temperature of 20-3800 C. The air inlet and outlet are carried out by a metal mesh in the drying chamber. The air temperature is measured by a pyrometer-thermocouple (chrome-Copel with a diameter of 0.2 mm) of the KSP-4M recorder, and the Duar tank is filled with water [22]. When drying in a microwave oven, the temperature of bentonite and the chamber itself, invented by J.M. Kurbanov and made in the form of ampoules and capillaries from an alumobromosilicate bottle, is measured by a special thermometer that is filled with 90% of the mixture. because the dielectric conductivity of the dioxide is lowTo reduce the distortion of the electromagnetic field at the measured point, there is an air column in the capillary.
For drying after the initial treatment of bentonite from the Navajor deposit, 200 gr. mass is placed on the bottom of the cell. Then a temperature heater is installed and the oven is turned on, where a constant air parameter is maintained: v = 0.1-0.3 M / s; t_ = 85-3000 ° C and is heated in microwave energy. A certain supply of microwave energy is carried out in vibration mode every 2-1 minutes until the set temperature inside the material is reached within 2-4 seconds. Thus, the material is dried until the humidity reaches 2.8%. The experiment was carried out at various microwave energy capacities: 0.14; 0.25; 0.5 kW.The chemical composition of bentonite from the Navbahor deposit was determined by methods in accordance with the standards of the International Union of Theoretical and Applied Chemistry.
The acidic properties of the universal sorption gas analyzer USGA-101 were analyzed using the method of thermodestrated desorption of ammonia.The qualitative and quantitative composition of the reaction products was analyzed in Crystal 5000 chromatography with capillary colon and flame ionization detectors. The amount of hydrogen and carbon oxides was carried out in the gas chromatography "Crystal-5000", which was equipped with a detector and a column for retaining the PropakQ phase by thermal conductivity.The determination of the porous structure and the comparable surface surface of the catalysts was carried out in an automatic gas adsorption analyzer using the Brunauer, Emmet, and Wyres (bet) method. The comparative surface surface was calculated at 77 K using a nitrogen adsorption isotherm. The size and pore size of the catalysts were determined from data on desorption and adsorption isotherms, respectively, at a relative pressure R/R0=0.99 in accordance with the BJH (Barette-Joyner-Halend) model.    Analysis of the drying of Navahar bentonite (in powder form) obtained by various methods of energy supply shows that drying using microwave energy is effective.

Results and discussion
During the experiment, the criteria for the quality of the material were a visual assessment of the color of the dried bentonite, the condition of the surface, the final tension of the product, shrinkage, etc. The experimental results showed that changes in the air velocity and microwave power supplied to the surface plane had a strong effect on the drying process. The maximum value of the microwave power in the product is determined by the internal overpressure, especially at the beginning of the drying process, resulting in an uneven surface. In order to find the area of the rational drying regime, the experiment was planned on the basis of a full-fledged experimental matrix PFE-23. Selected variable factors: the power of the microwave generator with a limit of variability R = 0.4-0.6 kW, air velocity v = 0.1-2 M/s, air temperature T = 80-110 ℃.According to the results of a full-fledged experiment, the drying mode of bentonite weighing 0.2 kg will be reasonable at a microwave power of 0.52 kW, air velocity v = 0.2 M / s and air temperature 92 ℃, the total drying time in this mode is 18-22 min. is ni. The total power supply time of the microwave oven is 12-14 minutes, the frequency of gorenje microwave oven in the first drying period is activated every 2 minutes, in the second -after 1 minute, the maximum temperature of bentonite is 90℃.
As can be seen, when drying alternately modified bentonite clay by the methods of primary traditional drying (temperature 120-1500C) and convective drying method at low temperature (90-920C), the volume of their specific surface area and porosity decreases compared to the traditional method of samples, that is, at high temperature. Heat treatment of bentonite clay at temperatures above 100 °C leads to the fact that the layers irreversibly approach each other, with the release of intercellular water and deterioration of texture parameters.
Their initial "frame" at a relatively low temperature occurs mainly due to the formation of microporous thermal effects.
The number of porous is reduced, their surface area increases, and the average increase is 4-6 nm, and the texture improves by about 20-25%. This is because a lot of energy initially does not come from the surface, as in the case of heating the entire volume of the balcony, as in the case of a traditionalist. According to the standards of the International Union of Theoretical and Applied Chemistry, when studying sorbents, the study of specific surface area and porosity is mandatory, since it allows you to determine the type of sample with the most optimal adsorption properties. Adsorption is determined by the presence of holes in the test sample. Porous submicro-porridges with a diameter of less than 0.4 nm, sizes of 0.4-2 nm, micro-porridges, 2-50 nm, meso-porridges, and those with a diameter of more than 50 nm are called macroporridges. Macropores function as a channel for the penetration of substances into the sorbent. The meso-porridges are much smaller than macro-porridges. Their curvature ranges from 2 to 50 nm, which is much larger than the volume of adsorbed molecules. Filling the volume of these holes can be done by capillary condensation. The influence of the bentonite heating temperature on the micropore volume and surface tension is shown in Figure 4 a,b.
а -EHFE energy b-tradision method heating. Even so, the distribution of bentonite pore diameters by EHFE energy will have a character similar to the traditional method. While the average mesoporous diameter of all samples in the traditional way, regardless of the composition and modification conditions of natural bentonites, is constant and fluctuates within 4.0-4.1 nm, convective-EHFE is heated in Emm (Fig. 6, a, b) due to the fact that convective-EHFE is heated throughout the volume at relatively low temperatures, their average pore size increases slightly and is 5-6 nm. It should be noted that as a result of taking tablets, the size of the mesoglea may be slightly reduced.
When bentonite from the Navbahor deposit determines the chemical composition of the lot, we see that it is almost indistinguishable from its traditional method. However, we see that it is almost indistinguishable from his traditional method. The chemical composition of bentonite samples is given in Table 1.  Thus, bentonite is a light gray powder, odorless, practically insoluble in water and organic solvents, the value of the relative humidity of the suspension (100 to 5) is 7.1-8.7. The weak alkalinity of the suspension is explained by the presence of hydroxide soil and hydroxide metals in the layer.
According to its adsorption properties, it is a combined meso-microporous adsorbent with an average porosity of 4-6 nm, the adsorption activity for methylene blue is 62.0 bentonite/g. According to its technological properties, it is a fine powder of medium weight with an average yield index. According to the properties of the adsorbent, it is a combined adsorbent with a meso-macromicrobium, in which mesopores predominate.

Conclusion
When the drying process is carried out at a low temperature using the convective energy of EHFE EMC when nanocatalysts are obtained from the retention substance of bentonite "Navbahor" based on Zol-gel technology, the process is accelerated and an increase in the porosity of the catalysts is achieved.
The bentonite drying mode using convective radiation energy is reasonable at a microwave power of 0.52 kW, an air velocity of v = 0.2 M/s and an air temperature of 90-92℃. The total drying time in this mode is 18-22 minutes. The total power supply time of the microwave oven is 12-14 minutes, the frequency of gorenje microwave oven in the first drying period is activated every 2 minutes, in the second -1 minute, the maximum temperature of bentonite. 90℃. convective is due to heating throughout the volume at a relatively low temperature, due to their initial formation of a "frame", the number of pores becomes smaller, and their surface surface increases, and the average increase is 5-6 nm, the texture description improves by about 20-25%.