Extração e caracterização de ácidos naftênicos por espectrometria de massas de altíssima resolução e exatidão (ESI-FT-ICR MS)
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Data
2012-03-09
Autores
Colati, Keroly Alaíde Pascoal
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Universidade Federal do Espírito Santo
Resumo
Naphthenic acids are present in crude oil as a complex mixture of compounds with a wide structure variation. These compounds are mainly responsible for corrosion problems, formation of stable emulsions and unwanted deposits. The total acid number (TAN) is the classical way of monitoring the acidity in oils. TAN increase is usually associated with the oil corrosion rate. Naphthenic acids can be obtained from crude oils by procedures extraction such as liquid/liquid extraction with alkaline solutions, solid/liquid extraction and others. Instrumental methods of analysis such as Infrared Spectroscopy (FTIR) and Mass Spectrometry of high resolution accuracy coupled to electrospray source (ESI (-) FT-ICR MS) have been used for characterization of acidic components in petroleum. Thus, the main objective of this study was to characterize naphthenic acid extracted from two samples (AM1 and AM2) of oil with high NAT value using the technique ESI (-) FT-ICR MS. Naphthenic acids were extracted by alkaline alcoholic solutions of pH 7, 10 and 14. TAN analyses were performed in the original oil and residual. ESI (-) FT-ICR MS and FTIR analysis were made in the original oils, waste and acidic fractions. The extraction process was very satisfactory. The TAN reduction was of 92% for AM1 and AM285% for both extracted at pH 14. It was verified by FTIR analysis the concentration of carboxylic acids in acidic fractions by increase absorption in the region of 1706 cm-1. Is was also observed the presence of nitrogen compounds by absorption in 3380 cm-1. MS analysis showed that for both oil samples acidic species are concentrated in a range of m/z 200 to 650 centered in 360 Da. The O2 class carbon distribution is C14-C46 and DBE = 2-14. O2species contained in the oil samples showed mostly DBE in the range 3 to 4 with no change during extraction process. In waste oil sample AM1 was detection of species with DBE < 3 which were not detected in the original oil. N, NO2 and O2 class were the most abundant for all samples analyzed. N class remain in residual oil showing migration in low proportion for the acid fractions 14. Therefore, the extraction method was very efficient for reducing the total acidity of the oil samples, as well as the assignment of the molecular weight was obtained with excellent accuracy thus enabling very satisfactory characterization of naphthenic acids presents by ESI (-) FT-ICR MS.
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Naphthenic acid , Extraction , Ácidos naftênicos , Espectroscopia no infravermelho
Citação
COLATI, Keroly Alaíde Pascoal. Extração e caracterização de ácidos naftênicos por espectrometria de massas de altíssima resolução e exatidão (ESI-FT-ICR MS). 2012. 65 f. Dissertação (Mestrado em Química) – Universidade Federal do Espírito Santo, Centro de Ciências Exatas, Vitória, 2012.