الكلمات المفتاحية الخاصة بالمكنز الزراعي (أجروفوك)

2022

Aliyev, M. | Bairamova, H. | Mammadova, G. | Ibragimova, L. | Tagiyev, J.

The quality of food products of animal origin in their markets is controlled by veterinary specialists of veterinary and sanitary examination laboratories. Veterinary and sanitary examination laboratories are organized on the market in ¬ with the established procedure. They are part of a city or district animal disease control station, a district (interdistrict) veterinary laboratory. The main task of the laboratory is veterinary and sanitary examination of food products of animal and plant origin sold on the market, as well as the implementation of measures to prevent human diseases and the spread of infectious animal diseases through products. The quality of the products is monitored in accordance with current standards, rules and procedures. Veterinary specialists of laboratories are responsible for the correctness of the examination, the sanitary well-being and quality of food products allowed for sale, the implementation of measures to comply with sanitary conditions on the market. The article presents the results of scientific and economic experience on the use of vitamin-mineral mixture in the diets of dairy cows. As a result of feeding 100 g of vitamin and mineral supplements to dairy cows, the quality of milk improved. Install. It was found that feeding a complex mineral supplement to dairy cows contributed to an increase in daily milk yield. Milk obtained from Holstein cows and buffaloes was carried out in sanitary and hygienic conditions, which affects the acidity of milk and is of great importance in obtaining a fermented milk product — yogurt. The acidity of milk is one of the important qualitative indicators.

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Publishing center Science and Practice - Russian Federation

2022

Brovko, R. | Lakina, N. | Doluda, V.

Zeolites of various nature are widely used in the chemical industry, the fuel and energy sector of the economy as sorbents, catalysts and materials for the creation of inorganic membranes for various purposes. At the same time, it is possible to change the acid properties of the surface of zeolites both by varying the ratio of silicon to aluminum or silicon to phosphorus, and by joint synthesis of zeolites of various types with different acidic properties. The presented article provides a method for the sequential production of a zeolite of a mixed structure type MFI and mordenite. Synthesis of the original MFI type zeolite was carried out using seed grains by the hydrothermal method for 72 hours, followed by washing and drying of the zeolite. To obtain a layer of mordenite on the surface of the MFI type zeolite, the initial zeolite was pretreated with alkali and then treated with n-butylamine. In this way, nine samples of zeolite with different acidic surface properties were obtained. Determination of the acidic properties of the surface was carried out by the method of ammonia chemisorption followed by its desorption from the surface of the zeolite. For this purpose, the test sample was loaded into a quartz cuvette, purged with argon at a temperature of 800°С, after which the temperature dropped to 150°С, and the surface of the zeolite was treated with ammonia. Subsequently, the test sample was heated up to 800°С with registration of desorption curves. The amount of adsorbed ammonia was carried out according to previously prepared calibration curves. The synthesized samples of zeolites had different acidity from 0.48 to 0.72 mmol(NH3)/g(sample). In this case, the total acidity of the samples correlated with the ratio of silicon to aluminum in the zeolite samples. Also, depending on the ratio of the MFI and mordenite structures in the zeolite sample, it is possible to vary not only the number, but also the strength of the formed acid sites. So, an increase in the content of mordenite contributes to an increase in the strength of acid centers. The developed method for the synthesis of mixed structure zeolites of the MFI type mordenite made it possible to control the surface acidity of the synthesized samples.

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Publishing center Science and Practice - Russian Federation

2022

Mikhailov, S. | Monzharenko, M. | Brovko, R. | Doluda, V.

Цеолиты представляют собой особый класс структурированных алюмосиликатов, обладающих развитой внутренней поверхностью, большим количеством микропор, что позволяет использовать их как в качестве сорбентов, мембранных материалов и катализаторов. Цеолит ZSM-5 представляет собой алюмосиликат, образованный параллельными каналами с диаметром 5,3–5,6Å соединенными между собой синусоидальными каналами с диаметром 5,1–5,5Å. При этом наличие атомов алюминия в кристаллической решетке цеолита дает возможность осуществления реакций дегидрирования, этерификации, изомеризации и ароматизации, а присутствие микроканалов существенно увеличивает число столкновений реагирующих соединений, что приводит к существенному увеличению скорости химических превращений в таких системах. Синтез цеолита ZSM-5 с использованием структуронаправляющих агентов известен с конца 70-х годов прошлого века, при этом высокая стоимость используемых структуронаправляющих агентов и большая продолжительность гидротермального синтеза, и необходимость последующих постсинтетических процедур приводят к высокой стоимости получаемого цеолита. Одним из возможных путей удешевления синтеза цеолита ZSM-5 является непосредственное использование цеолита ZSM-5 в качестве структурообразующего агента, при этом условия проведения синтеза оказывают решающее значение на структуру образующегося цеолита. В статье приводятся результаты исследования синтеза цеолита ZSM-5 и исследование его кислотных свойств с использованием реагентов местного производства. Для получения цеолита использовался предварительно размолотый силикагель, гидроксид натрия и алюминат натрия. Предварительно взвешенный образец силикагеля заливался раствором гидроксида натрия и перемешивался при 70 °C для образования коллоидного раствора, после чего добавлялся предварительно приготовленный раствор алюмината натрия и проводился гидротермальный синтез при 180°C в течение 24 часов. В процессе синтеза варьировалось соотношение Si/Al в диапазоне от 7,5 до 2000, при этом полученная кислотность составляла от 0,002 до 0,265 ммоль(NH3)/г(ZSM-5). Установлено, что синтез ZSM-5 с использованием предварительно приготовленных растворов реагентов превосходит метод с использованием непосредственного растворения твердых реагентов в автоклаве. Увеличение отношения Si/Al с 7,5 до 100 приводит к соответствующему увеличению поверхностной кислотности с 0,066 ммоль(NH3)/г(ZSM-5) до 0,265 ммоль(NH3)/г(ZSM-5). Дальнейшее увеличение отношения Si/Al до 2000 приводит к снижению поверхностной кислотности до 0,002-0,005 ммоль(NH3)/г(ZSM-5). Разработан надежный и простой метод синтеза цеолита ZSM-5, обеспечивающий выход цеолита до 97%. | Zeolites are a special class of structured aluminosilicates with a developed inner surface and a large number of micropores, which allows them to be used as sorbents, membrane materials, and catalysts. Zeolite ZSM-5 is an aluminosilicate formed by parallel channels with a diameter of 5.3–5.6Å interconnected by sinusoidal channels with a diameter of 5.1–5.5Å. At the same time, the presence of aluminum atoms in the zeolite crystal lattice makes it possible to carry out dehydrogenation, esterification, isomerization, and aromatization reactions, and the presence of microchannels significantly increases the number of collisions of reacting compounds, which leads to a significant increase in the rate of chemical transformations in such systems. The synthesis of ZSM-5 zeolite using structure-directing agents has been known since the late 70s of the last centuries, while the high cost of structure-directing agents used and the long duration of hydrothermal synthesis and the need for subsequent post-synthetic procedures lead to a high cost of the resulting zeolite. One of the possible ways to reduce the cost of the synthesis of ZSM-5 zeolite is the direct use of ZSM-5 zeolite as a structure-forming agent, while the synthesis conditions play a decisive role in the structure of the resulting zeolite. The article presents the results of a study of the synthesis of ZSM-5 zeolite and a study of its acidic properties using locally produced reagents. Zeolite was prepared using pre-milled silica gel, sodium hydroxide, and sodium aluminate. The pre-weighed silica gel sample was filled with sodium hydroxide solution and stirred at 70 ℃ to form a colloidal solution, after which the pre-prepared sodium aluminate solution was added, and hydrothermal synthesis was carried out at 180 ℃ for 24 hours. During the synthesis, the Si/Al ratio was varied in the range from 7.5 to 2000, while the resulting acidity ranged from 0.002 to 0.265 mmol(NH3)/g(ZSM-5). It was found that the synthesis of ZSM-5 using pre-prepared reagent solutions is superior to the method using direct dissolution of solid reagents in an autoclave. An increase in the Si/Al ratio from 7.5 to 100 leads to a corresponding increase in surface acidity from 0.066 mmol(NH3)/g(ZSM-5) to 0.265 mmol(NH3)/g(ZSM-5). A further increase in the Si/Al ratio to 2000 leads to a decrease in surface acidity to 0.002–0.005 mmol(NH3)/g(ZSM-5). A reliable and simple method for the synthesis of ZSM-5 zeolite has been developed, providing a zeolite yield of up to 97%.

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Publishing center Science and Practice - Russian Federation

2022

Monzharenko, M. | Mikhailov, S. | Brovko, R. | Doluda, V.

The development of new methods for the synthesis of zeolites and the improvement of existing methods for the synthesis of zeolites in order to reduce their cost and improve the quality of the final product is an important task of modern chemistry and chemical technology. Existing methods for the synthesis of zeolites, including hydrothermal synthesis methods, are extremely time-consuming and expensive due to the widespread use of structure-forming agents. At the same time, traditional methods for solving the above problems by increasing the rate of hydrothermal synthesis by increasing the temperature are not optimal, due to the possibility of the formation of additional inorganic phases at high temperatures. Zeolite BETA is one of the most commonly used aluminosilicates both as a catalyst and as a material for creating inorganic membranes for various purposes, while the synthesis of the above zeolite is extremely long and takes from 5 to 10 days. The presented article presents the results of the development of a method for obtaining BETA zeolite by a hydrothermal method under the influence of ultrasound. A study of the influence of temperature and the ratio of silicon to aluminum in the reaction medium on the yield of zeolite is also given. It has been established that an increase in the temperature of hydrothermal synthesis from 80 ℃ to 120 ℃ contributes to an increase in the yield of zeolite up to 97%. An increase in the molar ratio of silicon to aluminum, on the contrary, leads to a decrease in the zeolite yield to 15%. It is shown that the synthesis under conditions of ultrasonic treatment with a power of 6 mW/cm2contributes to an increase in the yield of the target product by 2–4 times, and an increase in the rate of formation of BETA zeolite by 2–8 times. | Разработка новых методов синтеза цеолитов и совершенствование существующих методов синтеза цеолитов с целью их удешевления и повышения качества конечного продукта является важной задачей современной химии и химической технологии. Существующие методы синтеза цеолитов, включая гидротермальные методы синтеза, являются крайне длительными и дорогостоящими, в связи с широким использованием структуроформирующих агентов. При этом традиционные методы решения вышеуказанных проблем путем увеличения скорости гидротермального синтеза за счет увеличения температуры не являются оптимальными, в связи с возможность образования дополнительных неорганических фаз при высокой температуре. Цеолит BETA является одним из наиболее часто используемых алюмосиликатов как в качестве катализатора, так и в качестве материала для создания неорганических мембран различного назначения, при этом синтез вышеуказанного цеолита является крайне длительным и занимает от 5 до 10 суток. В представленной статье приведены результаты разработки метода получения BETA цеолита гидротермальным методом под воздействием ультразвука. Также приведено исследование влияния температуры и соотношения кремния к алюминию в реакционной среде на выход цеолита. Установлено, что увеличение температуры гидротермального синтеза с 80°C до 120 °C способствует увеличению выхода цеолита до 97%. Увеличение же мольного соотношения кремния к алюминию наоборот приводит к уменьшению выхода цеолита до 15%. Показано, что проведение синтеза в условиях ультразвуковой обработки с мощностью 6 мВт/см2 способствует увеличению выхода целевого продукта в 2–4 раза, и увеличению скорости образования BETA цеолита в 2–8 раз.

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Publishing center Science and Practice - Russian Federation

2022

Brovko, R. | Lakina, N. | Doluda, V.

The decrease in stocks of traditional fossil fuels contributes to the widespread growth of interest in renewable sources of raw materials and energy. Bioethanol can become a serious alternative to traditional types of fossil raw materials and fuels due to the possibility of its widespread production from agricultural waste and wood processing. Bioethanol can be used directly as a fuel, or after transformation into hydrocarbons. The transformation of bioethanol into hydrocarbons is carried out using zeolites and zeotypes of various types, while the main problem encountered for these systems is deactivation during the catalytic transformation. In this case, one of the possible solutions to this problem is the regulation of the acidic and diffusion properties of the catalytic surface of zeolites. Changing the acidic properties can contribute to a significant increase in the stability and activity of zeolites. In this case, the variation of acidic properties is possible by combining different types of zeolites. The article presents the results of a study of a mixed zeolite of the MFI type and mordenite in the reaction of the transformation of ethanol into hydrocarbons. Zeolite synthesis was carried out by a sequential method using zeolite seed grains for the synthesis of MFI structures and n-butylamine for the synthesis of a mordenite layer. The synthesized sample was tested on a flow-type setup with a tubular reactor. The effect of temperature, specific ethanol feed rate, and total pressure in the system was investigated. An increase in the reaction temperature from 350℃ to 370℃ contributed to an increase in the rate of accumulation of liquid hydrocarbons from 0.52 to 0.64 g(HC)/(g(Cat)*h), while a further increase in temperature to 430℃ contributed to a decrease in the rate of formation of liquid hydrocarbons to 0.32 g(HC)/(g(Cat)*h). An increase in the specific feed rate of ethanol from 0.5 to 2 g(EtOH)/(g(Cat)*h) contributes to a decrease in the yield of liquid hydrocarbons. An increase in the total pressure in the system from 1 atm to 15 atm promotes an increase in the rate of accumulation of liquid hydrocarbons from 0.34 to 0.83 g(HC)/(g(Cat)*h).

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Publishing center Science and Practice - Russian Federation