EXTRACTION OF CORROSION INHIBITORS SOLUBLE IN PETROLEUM PRODUCTS AND THEIR ANALYSIS

ABSTRACT

The article presents information on corrosion inhibitors soluble in nitrogen-containing petroleum products. The functional groups of the obtained inhibitors were determined by IR and NMR spectra, as well as by the results of studying the metal surface morphology using atomic force microscopy. The protection levels of the synthesized corrosion inhibitor in the petroleum product environment were determined. Gasoline, gas condensate and diesel fuel were used as petroleum products. The tests were carried out under atmospheric conditions according to GOST 9.506.87. The inhibitory efficiency of the corrosion inhibitor was determined gravimetrically. The areas of application of the obtained inhibitor were studied.

АННОТАЦИЯ

В статье приведены сведения об ингибиторах коррозии, растворимых в азотсодержащих нефтепродуктах. Функциональные группы полученных ингибиторов определяли по ИК- и ЯМР-спектрам, а также по результатам изучения морфологии поверхности металла методом атомно-силовой микроскопии. Определены уровни защиты синтезированного ингибитора коррозии в среде нефтепродуктов. В качестве нефтепродуктов использовались бензин, газовый конденсат и дизельное топливо. Испытания проводились в атмосферных условиях по ГОСТ 9.506.87. Ингибирующую эффективность ингибитора коррозии определяли гравиметрическим методом. Изучены области применения полученного ингибитора.

Keywords: Corrosion inhibitors, nitrogen, organic compounds,  fatty acids, gas-condensate well.

Ключевые слова: Ингибитор коррозии, азот, органические соединения, жирные кислоты, газ-конденсатная скважина.

Introduction. Currently, metal constructions are the main devices of production enterprises in the world. The molecule consists of two main parts - a hydrocarbon radical, a fairly high-molecular and branched structure, providing the composition of molecules and components containing nitrogen and phosphorus, and a functional group responsible for the protective properties of this compound [1].

In the global production of corrosion inhibitors composed of organic compounds, hydrocarbon-soluble inhibitors make up about 30% of the volume, the largest part of which (~70%) is used in oil refining. In most cases, corrosion inhibitors are composed of various organic compounds containing heteroatoms: nitrogen, sulfur, oxygen, and phosphorus. The effectiveness of the inhibitory action of the substances is in the following sequence in the series of heteroatoms: O < N < S < P. However, since the toxicity of the products also increases in this series, nitrogen-containing compounds are usually chosen for industrial use. Although it is less effective than compounds containing sulfur or phosphorus, they are a less toxic compound [2].

The purpose of the article. Obtain a corrosion inhibitor containing phosphorus and nitrogen, which is used in small quantities for waterproofing and corrosion protection of metal structures and pipes made of ferrous metals, and determine its properties. To achieve this goal, it is necessary to define the following tasks:

1) Obtain and study the parameters of a corrosion inhibitor containing phosphorus and nitrogen, and study the physicochemical properties of this inhibitor.

2) Develop corrosion inhibitor compositions based on fatty acids soluble in petroleum products and study the physicomechanical properties of inhibitors based on them.

Methods of obtaining and research. The inhibiting properties of corrosion inhibitors were determined using the gravimetric method. The method involves determining the mass loss of metal samples during their stay in inhibited and non-inhibited test environments, followed by an assessment of the inhibitor's protective ability based on changes in corrosion rate.

Each of our studies was conducted in accordance with GOST 9.506.87. The test samples were selected in accordance with GOST 9.905-82.

In accordance with it, the product of dichloroethane interaction with ammonia was placed in a three-necked flask equipped with a reflux condenser, thermometer, and stirrer, vegetable oil was added, and the mixture was stirred until a homogeneous mass was formed. Stirring was continued for several hours at a certain temperature. The resulting corrosion inhibitor was dissolved in amounts of 1%, 3%, and 5% in gasoline, condensate, and motor oil environments. Numerous studies of the resulting solutions were then conducted.

Experimental part. A corrosion inhibitor containing nitrogen was obtained with a mixture consisting of 2,2-dichloropropane, the main product of which the organochlorine waste was isolated at temperatures of 55-65 ⁰C and 65-71 ⁰C. Below is the IR spectrum of the amine compound obtained as a result of the reaction of ammonia and organochlorine compounds.

Figure 1. An amine compound obtained based on the reaction of chlorinated organic compounds and ammonia

The composition and structure of isolated organochlorine compounds and ammonia synthesis were studied using IR-spectrometer technology (IK-Fure, SHIMADZU, Japan) in the field up to 4000 cm-1. As a result of the obtained synthesis, in IR spectroscopy, we can see the absorption line in the IR range of 2924-2854 cm-1, asymmetric valence vibrations of the -CH2- group. We can see deformational vibrations of the –NH- group in the 1745 cm-1 region, and valence vibrations in the 3008 cm-1 region.

In order to study the composition and structure of the PF-1 corrosion inhibitor used in the test, the NMR spectrum was analyzed and the results of the analysis were obtained.

Figure 2. NMR spectrum of corrosion inhibitor PF-1

The absorption line of NMR spectroscopy of PF-1 inhibitor containing nitrogen soluble in liquid hydrocarbons for corrosion protection is shown. The hydrogen molecule bonded to the carbon in this N2 molecule is 5.339 m.d. , the hydrogen molecule connected to the 1`-carbon is 3.520 m.d., the hydrogen molecule connected to the 2`-carbon is 3.574 m.d. Also, the hydrogen associated with carbon 2 was 2.183 m.d., the hydrogen belonging to carbon 3 was 1.283 m.d., the hydrogen belonging to carbon 7 was 1.326 m.d., the hydrogen belonging to carbon 11 was 2.770 m.d. we can see.

Results and their discussion. Mechanisms of action of PF-1 brand corrosion inhibitor containing nitrogen soluble in hydrocarbons on metal constructions were determined. Including tests on petroleum fuels and motor oils in order to protect the metal surface from corrosion using GOST-9.506.87 "Methods for determining the protective ability of metal corrosion inhibitors in water-oil environment" research work was carried out.

Table 1.

Values of inhibition coefficient (g), full surface coverage (th), protection level (Z) of PF-1 brand corrosion inhibitor as a result of concentration and temperature

Corrosion rates and protection levels of the synthesized corrosion inhibitor PF-1 in various aggressive environments were studied and the best protection level was found to be 98.6%.

The surface morphology of the St3 steel sample used in the test was studied using an atomic force microscope with and without an inhibitor.

Figure 3. Micrograph of the surface morphology of the St3 steel sample in the condensate environment, obtained using an atomic force microscope

Conclusion. Mechanisms of action of PF-1 brand corrosion inhibitor, which contains nitrogen soluble in hydrocarbons, on metal structures. Tests were conducted on petroleum fuel and motor oils to protect the metal surface from corrosion according to the GOST-9.506.87 standard. As a result of the tests, it was found that the level of protection reached 98.6%. Also, when the surface morphology of the metal surface was studied using an atomic force microscope, it was found that the synthesized corrosion inhibitor protected the metal surface when the inhibitor was introduced into the medium.

References:

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