SYNTHESIS AND PROPERTIES OF THIOUREA BASED INHIBITORS

ABSTRACT

Today, the demand for oil and its products is increasing in the world. This leads to the expansion of the oil industry. The development of the industry leads to the increase of existing problems in them. One of them is corrosion of metals. At the same time, metal corrosion is causing huge economic damage. Inhibitors can be used as a solution to this problem. This article describes the production and properties of corrosion inhibitors using local raw materials.

АННОТАЦИЯ

Сегодня в мире увеличивается спрос на нефть и продукты ее переработки. Это приводит к расширению нефтяной промышленности. Развитие отрасли приводит к увеличению имеющихся в них проблем. Одним из них является коррозия металлов. В то же время коррозия металлов наносит огромный экономический ущерб. Ингибиторы могут быть использованы как решение этой проблемы. В данной статье описаны производство и свойства ингибиторов коррозии с использованием местного сырья.

Keywords: oil and gas extraction, thiourea, inhibitor,  сhloride acid, fluoride acid, acetic acid, formic acid, pipe material

Ключевые слова: нефтегазодобыча, тиомочевина, ингибитор, хлоридная кислота, фтористая кислота, уксусная кислота, муравьиная кислота, материал труб

Humanity's need for fossil fuels is still increasing, although an alternative form of such energy is currently being sought. 60% of the world's energy needs come from oil and gas. Therefore, the traditional way of extracting fossil fuels will not disappear for the next few decades. Extraction of geothermal waters for use as a source of energy is also of primary importance and its use is increasing day by day. Corrosion is worth studying in the oil production industry, as corrosion problems account for a large proportion of the total annual costs of oil and gas production companies worldwide. Manifested as leakage of oil or gas from reservoirs, pipelines and other devices. Corrosion problems are usually associated with operational and maintenance problems, leading to partial or complete shutdown of the process, which in turn causes significant economic losses[1-3].

In oil and gas extraction, high concentration acids of 5-28 percent are usually used, which create an aggressive environment for mild, carbon and low-alloy steels. Chloride, fluoride, acetic or formic acids are introduced into wells during the acid stimulation process and cause serious corrosion problems. In the absence of corrosion inhibitors, overall corrosion rates are very high (>100 mm/year) and can increase with increasing temperature and acid concentration. During acid treatment, metallic materials can also be exposed to acidic solutions, and sometimes to H₂S and CO₂ at high temperatures. Due to the problems listed above, the acid treatment process requires a high level of protection against corrosion of pipe materials and other used devices. This makes it necessary to use inhibitors together with the acid solution in such processes[4-7].

The properties of thiourea-formaldehyde resins and, in particular, their stability, can be improved by including some modifiers. It is considered a necessary condition to develop a method of synthesizing oligomers based on thiourea-formaldehyde-acrylic acid and to study their physico-chemical properties using them as inhibitors. The decisive factors for the condensation reaction between thiourea and formaldehyde in aqueous solution are:

• initial ratio of reactants;
• concentration of hydrogen ions;
• reaction time and temperature.

Considering the above, thiourea-formaldehyde oligomers modified with acrylic acid were synthesized. The initial proportions of reagents for this are as follows: thiomochevina (99,8%) 100 g, formalin (39,4%) 40-50 g, acrylic acid (98,2%) (In addition to providing an acidic environment of the solution, it acts as a modifier)- 7 g and water - 300 g were obtained. The synthesis was carried out in the following order: first, thiourea and formalin were dissolved in water at a temperature of 20-60 °C. Acrylic acid was poured into the solution in small portions, while controlling the temperature, the temperature of the mixture was not allowed to rise above 50 °C. Table 1 lists the initial components and variants of the components for the preparation of oligomers. The duration of the synthesis process was 0,5-3,0 hours, the resulting polycondensation products were light to dark brown liquids with a density of 1,22-1,35 g/cm³ and pH = 7,5-8,5.

In variants I-II of the experiment, viscous oligomers were formed, and in variants III-IV, a viscous-fluid oligomer was formed. This indicates that condensation between the oligomer and acrylic acid results in a product with a different physical state. Modified oligomers are soluble in water and ethanol. For the purpose of comparison, thiourea-formaldehyde oligomers were synthesized under the same conditions and their properties were studied.

Table 1.

Components and variants of initial components in the synthesis of oligomers

Undoubtedly, acid molecules separate the active functional groups of the reacting components and therefore prevent the formation of oligomers with a large molecular mass. Table 2 shows the physical and chemical parameters of aminoaldehyde oligomers obtained with different empirical options.

Table 2.

Physicochemical parameters of aminoaldehyde oligomers according to different experimental options

The high reactivity of the methylol groups contained in the condensation product of the oligomer can be considered as a result of the reaction with acrylic acid. This is the reason for the reduction of free methylol groups in the oligomer and the reduction of the amount of condensation that occurs during oligomer storage. As a result of the research, the optimal proportions of the components of the reaction mixture and the modifying additive were found, as a result of which it is possible to obtain a new inhibitor based on aminoaldehyde oligomers. In the studies, it was found that the changes in the surface of the steel taken as a sample and the efficiency of the passivations are related to the transition of the corrosion rate to the state of passivation.

References:

1. В. Ахмедов, Б. Олимов, Г. Гафурова. Винилацетилен иштирокида винил эфирлар олиш. НамДУ илмий ахборотномаси - Научный вестник НамГУ 2021 йил 9-сон. 37-43 б.
2. B.B. Olimov, V.N. Akhmedov, G.A. Gafurova. Application of derivatives of diatomic phenols as corrosion inhibitors. Euro Asian Conference on Analytical Research (Germany) ISBN: 978-1-913482-99-2. 2021. 15 October. p. 136-138.
3. Олимов Б.Б., Гафурова Г.А., Кудратов О.Х. Production and properties of corrosion inhibitors in the oil and gas industry // Universum: химия и биология: электрон. научн. журн. 2022. 2(92). URL: https://7universum.com/ru/nature/archive/item/13009
4. Olimov B., Akhmedov V., Gafurova G. Production and use of corrosion inhibitors on the basis of two-atomic phenols and local raw materials // Universum: химия и биология : электрон. научн. журн. 2021. 11(89). URL: https://7universum.com/ru/nature/archive/item/12473
5. Olimov B.B., Sadiqova M.I., Beshimov I.A. Technology of obtaining effective corrosion inhibitors in the oil and gas industry // Universum: технические науки: электрон. научн. журн. 2022. 1(94). URL: https://7universum.com/ru/tech/archive/item/12950
6. Олимов Б.Б. [и др.]. Synthesis and properties of nitrogen-retaining corrosion inhibitors//Universum: химия и биология : электрон. научн. журн. 2022. 4(94). URL: https://7universum.com/ru/nature/archive/item/1330
7. Olimov B. B., Yoldosheva N. J. Gravimetric study of the mechanism of action of corrosion inhibitors used in the oil and gas industry //Международный научно-образовательный электронный журнал «Образование и наука в xxi веке». Выпуск. – №. 19.