Effect of the structural characteristics of naphthenic acids on the corrosion kinetics of an AISI SAE 1005
Abstract
Processing crudes with high naphthenic acid content causes corrosion problems on the crude oil distillation units. The total acid number (TAN) is commonly used to evaluate the corrosivity of crude oils; thus for decision-making related to corrosion mitigation and control in refineries. However, the TAN only represents the number of carboxylic groups present in the crude oil and does not consider the structural characteristics of the naphthenic acids, nor their reactivity, which are highly relevant to corrosion. On the other hand, the study of naphthenic acids as fractions with specific structural characteristics should enable the identification of differences in the corrosivity of crude oil with the same naphthenic acid concentration. In this research work, the fractioning of a commercial mixture of naphthenic acids was performed using the ionic strength of their respective salts. The structural characterization of the obtained fractions was conducted using Fourier-transform infrared and mass spectroscopy, gel permeation chromatography, and nuclear magnetic resonance. Furthermore, the corrosion rate of AISI SAE 1005 steel exposed to each fraction of naphthenic acids in the temperature range between 270 and 350 ºC was determined. Based on these results, a kinetic model of parallel reactions for predicting the concentration of dissolved iron in crude oil containing a mixture of naphthenic acids is proposed and validated.
References
Dettman, H.D., Li, N., Luo, J. (2009). Refinery corrosion organic acid structure, and Athabasca bitumen. Corrosion 2009, Nace International (ID 09336), Atlanta, USA
Dettman, Heather; LUO, Jingli. (2010). The influence of naphthenic acid and sulphur compound structure on global crude corrosivity under vacuum distillation. CORROSION.
Yepez, Omar (2007). On the chemical reaction between carboxylic acids and iron including the special case for naphthenic acid. FUEL, 86 (7-8), 1162-1168. https://doi.org/10.1016/j.fuel.2006.10.003
Alvisi, P.P; Lins, Vanesa F.C. (2011) An overview of naphhthenic acid corrosion in a vacuum distillation plant. Engineering Failure Analysis, 18(5), 1403-1406, https://doi.org/10.1016/j.engfailanal.2011.03.019 .
Qu, D.R, et al. (2006). High temperature naphthenic acid corrosion and sulphidic corrosion of Q235 and 5Cr1/2Mo steels in synthetic refining media. Corrosion Science, 48(8), 1960-1985. https://doi.org/10.1016/j.corsci.2005.08.016
Biryukova, OV, et al. (2007). Biodegradation of naphthenic acids by rhizosphere microorganisms. Chemosphere, 67(10), 2058-2064. https://doi.org/10.1016/j.chemosphere.2006.11.063
Saadine, T. (1996). Review of critical factors affecting crude corrosivity. CORROSION, (607).
Mejía, C. Quiroga, H. Laverde, D. Hernandez, M and Goméz, M.A. (2012). A kinetic study of esterification of naphthenic acids from a Colombian heavy crude oil, CT&F-Ciencia Tecnología y Futuro, 4(5), 21-31. https://doi.org/10.29047/01225383.219
Kapusta, D. (2004). Safe processing of acid crudes. CORROSION, 04637.
Dettman, H. Li, N. and Luo, J. (2009). Refinery Corrosion, organic acid structure and Athabasca bitumen. CORROSION, 09336.
Messer, B. Beaton, M. Tarlton, B. and Phillips. (2004). New theory for naphthenic acid corrosivity of Athabasca Oil sands crudes. CORROSION, 04634.
Freitas, S., Malacarne, M.M., Romão, W., Dalmaschio, G.P., Castro, E.V.R., Celante, V.G., Freitas, M.B.J.G. (2013). Analysis of the heavy oil distillation cuts corrosion by electrospray ionization FT-ICR mass spectrometry, electrochemical impedance spectroscopy, and scanning electron microscopy. FUEL, 104, 656-663. https://doi.org/10.1016/j.fuel.2012.05.003
ASTM International. (2012). ASTM G31-12a. Standard Guide for Laboratory Immersion Corrosion Testing of Metals, ASTM International, West Conshohocken, PA.
ASTM International. (2007). ASTM D664-07, Standard Test Method for Acid Number of Petroleum Products by Potentiometric Titration, ASTM International, West Conshohocken, PA.
Jego, G, etal. (2013). Calibration and performance evaluation of the STICS crop model for simulating timothy growth and nutritive value. Field Crops Res., 151, 65-77. https://doi.org/10.1016/j.fcr.2013.07.003
Jamieson, P.D, et al. (1991). A test of the computer simulation model ARCHWHEAI on wheat crops grown in New Zeland. Field Crops Res., 27, 337-350. https://doi.org/10.1016/0378-4290(91)90040-3
Muhammad, Khan, et al. (2016). A-non Catalytic supercritical methanol route for effective desacidification of naphthenic acids. Fuel, 182, 650-659. https://doi.org/10.1016/0378-4290(91)90040-3
Rongbao, Li; ZENGMIN, Shen; BAILING, Li. (1988). Structural analysis of polycyclic aromatic hydrocarbons derived from petroleum and coal by 13C and 1H-n.m.r spectroscopy. Fuel, 67(4), 565-569. https://doi.org/10.1016/0016-2361(88)90355-9
Williams, R.B. (1958). Characterization of hydrocarbons in petroleum by nuclear magnetic resonance spectrometry. Am. Test. Mater. Spec. Tech., 224, 168-194. https://doi.org/10.1520/STP46925S
Quian, S.A, et al. (1985). Structural characterization of pitch feedstocks for coke making: use of 13C coupled 1H n.m.r. spectroscopy. Fuel, 64(8), 1085-1091. https://doi.org/10.1016/0016-2361(85)90111-5
Poveda, Juan C, et al. (2012). Average molecular parameters of heavy crude oils and their fractions using NMR spectroscopy. Journal of Petroleum Science and Engineering, 84-85, 1-7. https://doi.org/10.1016/j.petrol.2012.01.005
Wang, Xiaoqi; YONGAN, Gu. (2011). Characterization of Precipitated Asphaltenes and Deasphalted Oils of the Medium Crude Oil-CO2 and Medium Crude Oil-n-Pentane Systems. Energy&Fuels, 25(11), 5232-5241. https://doi.org/10.1021/ef201131n
Jin, Peng; Robbins, W; Bota, G. (2018). Kinetic Reaction Modelling of Naphthenic Acid Corrosion and Sulfidation in Refineries – A Mechanistic Model. CORROSION, 74(12), 1351–1362. https://doi.org/10.5006/2880
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