CHEMICAL COMPOSITION OF FUEL OIL RAW MATERIAL AND SYNTHESIS OF CORROSION INHIBITOR FROM IT

ABSTRACT

This article presents the reaction mechanisms and experimental methods for obtaining a corrosion inhibitor against corrosion of technological devices from components contained in residual fuel oil obtained from atmospheric oil distillation units at oil refineries. The amount of the fuel oil raw material component, its chemical composition, the necessary equipment and devices for obtaining a corrosion inhibitor, and the processes for its synthesis are presented. Also, sulfuric acid was used for extraction with alkali and recovery to separate naphthenic acid from the fuel oil. In chemical modification, naphthenic acids reacted with amines to form amide salts, which are corrosion inhibitors. The novelty of the scientific research work was the time interval for the synthesis of the corrosion inhibitor was 6-8 hours, and the temperature was 180-200 ^oC.

АННОТАЦИЯ

В данной статье представлены механизмы реакций и экспериментальные методы получения ингибитора коррозии против коррозии технологических устройств из компонентов, содержащихся в остаточном мазуте, получаемом на установках атмосферной перегонки нефти на нефтеперерабатывающих заводах. Приведены количество сырьевого компонента мазута, его химический состав, необходимое оборудование и устройства для получения ингибитора коррозии, а также процессы его синтеза. Также для экстракции щелочью и рекуперации для отделения нафтеновых кислот от мазута использовалась серная кислота. При химической модификации нафтеновые кислоты реагировали с аминами с образованием амидных солей, являющихся ингибиторами коррозии. Новизна научно-исследовательской работы заключалась в том, что временной интервал синтеза ингибитора коррозии составлял 6-8 часов, а температура 180-200 ^oC.

Keywords: fuel oil, corrosion, inhibitor, device, synthesis, naphthene, amide, naphthenate, ethylenediamine, fatty acids, toluene.

Ключевые слова: мазут, коррозия, ингибитор, устройство, синтез, нафтены, амиды, нафтенат, этилендиамин, жирные кислоты, толуол.

Introduction. Nowadays, the processing of oil and gas residues and the extraction of valuable products from them are growing day by day. An example of this is the crude oil raw material, which is the residue of the column after distillation of oil in an AT device[1].

Crude oil is the residue remaining after atmospheric distillation in the oil refining process. It has a complex composition and mainly consists of the following components:

1. Hydrocarbons (up to 80-95% in total): The main part of fuel oil is hydrocarbons. They are divided into the following groups:

Paraffins up to 15-30% (Alkanes): Saturated hydrocarbons, can have a chain or ring structure[2].

Naphthenes up to 20-40% (Cycloalkanes): Saturated hydrocarbon rings.

Aromatic hydrocarbons up to 20-50%: Hydrocarbons containing benzene rings.

Aromatic-naphthenic hydrocarbons up to 10-25%: Hydrocarbons combining aromatic and naphthenic structures.

2. Heteroatomic compounds (up to 5-20% in total): In addition to hydrocarbons, fuel oil also contains compounds containing sulfur, nitrogen, oxygen and metal atoms.

Sulfur compounds up to 1-8%: Thiols (mercaptans), sulfides, disulfides, thiophenes and other sulfur heterocyclic compounds.

Nitrogen compounds up to 0.1-2%: Pyridines, quinolines, pyrroles, carbazoles and other nitrogen heterocyclic compounds.

Oxygen compounds up to 0.5-5%: Phenols, carboxylic acids, esters and other oxygen compounds.

3. Organometallic compounds up to 0.1-1%: Fuel oil may contain organocomplex compounds of vanadium, nickel, iron and other metals. These compounds can cause corrosion and pollution when used as fuel.

4. Asphaltenes and resins up to 5-20%: Asphaltenes and resins are a mixture of high molecular weight, polar compounds that give fuel oil its black color and increase its viscosity.

The processing of fuel oil and the production of useful products from it are one of the important tasks of the oil refining industry. To achieve these tasks, this article presents information on the production of corrosion inhibitors, which are currently the most important raw material for industrial technological devices[3-6].

Corrosion inhibitors can be obtained from fuel oil by the following methods:

1. Fatty acid-based inhibitors:

When fuel oil is cracked, fractions containing fatty acids are formed. These fatty acids are then reacted with amines (for example, ethylenediamine) to form imidazolines and amides.

Imidazolines and amides are effective against corrosion in the oil and gas industry, especially against H₂S and CO₂ corrosion[7].

2. Naphthenic acid-based inhibitors:

Some fuel oils contain naphthenic acids. These acids are reacted with ammonia or amines to form naphthenates.

Naphthenates can be used as corrosion inhibitors.

3. Amines and polyamines:

Fuel-derived raw materials (e.g. olefins) can be reacted with ethylene oxide and ammonia to synthesize amines and polyamines[8].

Amines and polyamines form a protective layer on the metal surface and inhibit corrosion.

Experimental parts. The process of obtaining corrosion inhibitors from fuel oil is multi-stage and the reactions occurring at each stage can be different. Therefore, the most important reactions are discussed below.

1. An extraction method is used to isolate naphthenic acids.

In this step, naphthenic acids are extracted from fuel oil using an alkaline solution (NaOH or KOH).

RCOOH + NaOH → RCOONa + H₂O

RCOOH + KOH →RCOOK + H₂O

where RCOOH is naphthenic acid; RCOONa is sodium naphthenate; RCOOK is potassium naphthenate. (R-represents the naphthene ring, which can be a cycloalkane or a cycloalkene).

In the next step, an acid (sulfuric acid or hydrochloric acid) is added to recover the naphthenic acids from the aqueous phase:

2RCOONa + H₂SO₄ → 2 RCOOH + Na₂SO₄

RCOONa + HCl → RCOOH + NaCl

2. Chemical Modification (Amine Reaction):

In this step, naphthenic acids react with amines to form amide or amine salts, which are corrosion inhibitors.

Formation of amine salt:

RCOOH + R’NH₂ → [R’NH₃] + [RCOO]-

Amide formation at high temperatures:

RCOOH + R’NH₂ → RCONHR’ + H₂O

where R’ is the organic radical of the amine (alkyl, aryl); RCONHR’ is the amide.

If ethylenediamine (EDA) is used, the reaction proceeds as follows:

Amide formation:

RCOOH + H₂NCH₂CH₂NH₂ → RCONHCH₂CH₂NH₂ + H₂O

At high temperatures, the formation of imidazoline proceeds according to the following reactions:

RCONHCH₂CH₂NH₂ → (C=N-CH₂-CH₂-NH)R + NH₃

The reactions are usually carried out in a solvent (toluene, xylene, isopropyl alcohol).

Temperature affects the rate of the reaction (usually 50-200 °C).

Catalysts (acids) can accelerate the reactions.

The above reactions are simplified, in fact, complex mixtures are involved and many by-products can be formed. Therefore, the purification step is very important.

These reactions are acid-base reactions in which naphthenic acid (RCOOH) reacts with sodium hydroxide (NaOH) or potassium hydroxide (KOH) to form sodium naphthenate (RCOONa) or potassium naphthenate (RCOOK) and water (H₂O).

Reaction sequence:

1. In aqueous solution, sodium hydroxide (NaOH) or potassium hydroxide (KOH) dissociates into ions:

NaOH (s) → Na⁺ + OH⁻

KOH (s) → K⁺ + OH⁻

2. The hydroxide ion (OH⁻) accepts a proton (H⁺) from the naphthenic acid, resulting in the formation of water (H₂O) and the naphthenic acid being converted into the negatively charged naphthenate ion (RCOO⁻).

RCOOH + OH⁻ → RCOO⁻ + H₂O

3. The resulting naphthenate ion (RCOO⁻) combines with a sodium ion (Na⁺) or a potassium ion (K⁺) to form the corresponding sodium naphthenate (RCOONa) or potassium naphthenate (RCOOK) salt.

Na⁺ + RCOO⁻ → RCOONa

K⁺ + RCOO⁻ → RCOOK

As a result, sodium naphthenate (RCOONa) or potassium naphthenate (RCOOK) salts are formed in aqueous solution, which are highly soluble in water and can be separated from fuel oil during alkaline extraction.

RCOOH + H₂NCH₂CH₂NH₂ → RCONHCH₂CH₂NH₂ + H₂O

The following laboratory reagents, equipment and devices are required for the synthesis of the inhibitor: Naphthenic acids (RCOOH) - purified composition, ethylenediamine (H₂NCH₂CH₂NH₂) - at least 99% purity, Solvent (toluene, xylene, isopropyl alcohol) - dehydrated, catalyst (strong acid, e.g. sulfuric acid) - equipment: Three-necked flask, magnetic stirrer, reflux condenser, thermometer, heater, separatory funnel, rotary evaporator.

A certain amount of naphthenic acids (0.1 mol) is placed in a purified three-necked flask, 100 ml of toluene solvent is added to the flask, then the decanter is turned on and the naphthenic acids are dissolved. Gradually, ethylenediamine is added dropwise through a dropping funnel in a ratio of 0.1 mol or 1:1 molar. The mixture in the flask is thoroughly mixed and placed in an oil bath adapted for heating to ensure good reaction. In the oil bath device, the temperature is gradually increased to 150-180 °C. A water cooler is used to prevent the components released from the reaction from evaporating.

The reaction mixture is stirred for 6-8 hours. Water is released during the reaction.

Figure 1. Laboratory apparatus for obtaining a corrosion inhibitor

1-oil bath; 2-funnel; 3-reverse water cooler; 4-clamp; 5-thermometer; 6-mixer; 7-stand.

A laboratory device of the type Dyna-Stark is used to separate the water formed.

After the reaction is complete, the mixture is cooled to room temperature. The mixture is washed with water and the organic and aqueous phases are separated.

The organic phase is dried over sodium sulfate (Na₂SO₄) and the solvent is removed on a rotary evaporator. If the product needs to be further purified, it can be done by recrystallization or distillation.

The purity and composition of the product are determined using an IR spectroscopy device.

Conclusion. The article can be concluded that currently, obtaining corrosion inhibitors based on fuel oil raw materials requires deep chemical and technological work. In our work, the extraction of naphthenic acids from fuel oil, chemical modification, purification and separation were carried out. In this case, the synthesis of naphthenic acids, ethylenediamine and various solvents was carried out with a reaction time of up to 6 hours at a temperature of 150-180 ° C.

References:

1. M.A. Quraishi, N. Sardar, H. Ali, A study of some new acidizing inhibitors on corrosion of N-80 alloy in 15% boiling hydrochloric acid, Corrosion 58 (2002) 317–321.
2. Panoev Erali, Murodov Malikjon, Bozorov Gayrat, & Usmonov Safar (2022). A method for reducing corrosion during gas purification from sulfur components. Universum: технические науки, (10-7 (103)), 9-13.
3. Э.Р. Паноев, Х.Б. Дўстов, В.Н. Ахмедов, А.Х. Темиров Получение ингибитора коррозии на основе тиосемикарбазида, формалинной смолы и ортофосфатной кислоты // Formation of psychology and pedagogy as interdisciplinary sciences. International scientific conference № 4.Italia 2021. – P.  277–280.
4. Базорова Л.Ш, Курбанов М. Ж, Мурадов М. Н. Технология получения ингибитора коррозии на основе бициклических сераорганических соединений нефти // Universum: технические науки, №6 (111), 2023 – С. 18-21.
5. Olimov, B., Sodiqova, M., & Beshimov, I. Neft va gaz sanoatida samarali koroziyon gigibitorlarini olish texnologiyasi. Universum , 85-87.
6. Yamshchikova, S. va Tyusenkov, A. (2022 yil, iyun). Karbonat angidrid korroziyasi sharoitida inhibitorlarning himoya xususiyatlarini aniqlash. AIP konferentsiyasi materiallarida ( 2467-jild, №1, 020036-bet). AIP Publishing MChJ..
7. Jahongir, Y. va Vohid, A. (2024). Neft va gaz quvduqlari uchun koroziyon toghirishib kompleks ishlab chiqarish texnologiyasi. Universum: texnika fanlari , 8 (10 (127)), 50-53.
8. Olimov B.B. [i dr.]. 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.