Peculiar aspects of removal of chlororganic compounds from crude oil

UDK: 622.276.8 + 546.13

DOI: 10.24887/0028-2448-2020-8-103-105

Key words: crude oil, naphtha, removal, chlororganic compounds, sodium hydroxide

Authors: О.S. Tatyanina (TatNIPIneft, RF, Bugulma), F.R. Gubaidulin (TatNIPIneft, RF, Bugulma), S.N. Sudykin (TatNIPIneft, RF, Bugulma), L.М. Abdrakhmanova (TatNIPIneft, RF, Bugulma)

Treatment of naphtha contaminated with highly volatile chlororganic compounds using aqueous solutions of sodium hydroxide at high temperatures enables considerable reduction of organic chlorine content. Chromatography-mass spectrometry studies have demonstrated that alkyl halides degrade firstly. Efficiency of the removal of organic chlorine depends directly on naphtha treatment temperature: efficiency of reaction between chlororganic compounds and alkali improves with temperature increase. Degree of reduction in highly volatile chlororganic compounds depends on initial concentration and the composition of such compounds. The fullest extent of removal of highly volatile chlororganic compounds is achieved when chlorine is present in alkanes and alkenes: chloroform, dichloroethane, trichloroethylene, tetrachlorethylene. Based on the results of the studies, a technology for extraction of highly volatile chlororganic compounds from crude oil was proposed to enable efficient removal of chlorinated alkenes and alkanes. Considering future practical implementation of the technology, the optimal treatment temperature should be at least 180°С. To prevent boiling of reaction mixture the process should be conducted at excess pressure of at least 2 MPa. Treatment time at constant stirring – at least 6 hours. Loading and concentration of alkaline aqueous solution should be at least 25% and 10%, respectively. After the treatment, the main volume of aqueous phase is removed and crude oil can be directed to further processing.
Reaction of sodium hydroxide with chlorine-containing aromatic compounds requires harder conditions: temperatures in the range of 300 to 350°С and high pressures. Therefore, looking for new methods for removal of chlorinated aromatic compounds from crude oil is of current concern. Solution to this challenge is of great practical importance for all oil production companies because despite current prohibition to use chemicals containing chlororganic compounds, highly volatile chlororganic compounds can form as a result of reactions between chlorides-containing chemicals and interactions with petroleum hydrocarbons.
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