Total Acid Number Value Research Articles

Experimental study of the effect of oil polarity on smart waterflooding in carbonate reservoirs

This study investigates the influence of oil polarity on interfacial tension (IFT), contact angle, oil recovery, and effluent pH in smart water and Low-salinity water injection. The results indicate that the interaction between the hydration shell of ions and the polar components (PCs) of oil is crucial. Increasing oil polarity enhances the potential for interaction with the hydration shell of ions, leading to reduced IFT, altered wettability, and improved oil recovery; which could be boosted by the contribution of a higher number of anions in the smart water bulk through the enhancement of their interaction with the PCs (especially acidic components) of oil. The study demonstrates that increasing the SO42− concentration in seawater increased oil recovery for oils with higher acid component content, as indicated by total acid number values of 0.87, 0.99, and 1.32 mgKOH/g, the tertiary oil recovery factors for these oils were 61.10%, 69.82%, and 87.09%, respectively. The effluent pH results align with the findings of contact angle and oil recovery, confirming the dominant influence of anions on oil recovery. The interaction between the PCs of oil and the hydration shell of ions is thus highlighted as a critical factor in the observed outcomes.

Strategi Perbaikan Kualitas Biosolar Berdasarkan Kandungan Air dan TAN yang Meningkat Akibat Penyimpanan di Ruang Terbuka

This study conducted a trial of B-30 products stored in miniature storage tanks outdoors to produce B-30 offspec products. Tests were also carried out on offspec B-30 products blended with new biosolar products. The research focused on the analysis of water content and Total Acid Number (TAN) using tools and materials that have been determined. The test results showed that biosolar products stored for two weeks in open space had an increase in moisture content and TAN value. An increase in water content is due to condensation during prolonged storage, while an increase in the TAN value indicates damage to the product. The addition of new biosolar in biosolar offspec aims to improve the quality of BioSolar damaged by storage. This study is relevant to understand the impact of storage on biosolar quality and improvement strategies that can be done.

Pengaruh Variasi Waktu Operasi Mesin Terhadap Perubahan Nilai Viskositas Dan Total Acid Number Untuk Pelumas Gearbox

Lubricating is one of the methods to prevent temperature rise and wear due to friction among gearbox components. The lubricant quality is an essential factor in ensuring lubricant functions optimally. Long-term use of the machine changes lubricant quality, which can be measured by viscosity parameters and Total Acid Number (TAN). This research aims to determine the effect of machine operating time on viscosity and TAN lubricant changes of milling machine gearbox heads (Headstock) used for educational purposes. The study used a quantitative research method in which data was collected using statistical data analysis tools and selecting a random sampling. Forty samples of Shell Tellus 46 lubricant were taken every 5 hours for 200 operation hours with an operating temperature of 27.5-44.4°C and 300 rpm speed. Viscosity testing uses Visgage and Fluidscan to check TAN. Data analysis using a simple linear regression analysis method with the statistical software Minitab 21.3. The results showed that operating time had a significant effect on: 1) a 95% change in viscosity value with 3.67 cSt (7.39%) decline or 0.018776 cSt per operation hour; 2) 99.34% change in TAN value with 0.27 mg KOH/g (16.56%) increase or 0.001297 mg KOH/g per operation hour.

Study on the Alternative Solvent of Methylbenzene in the Total Acid Number Titration of Current Jet Fuels.

Evaluation of the acidic characteristics of a jet fuel, especially for the total acid number (TAN), is of great significance to ensure flight safety. Methylbenzene is commonly used as the titration solvent; however, it is poisonous and harmful to the environment. It is highly desirable to develop an alternative solvent for methylbenzene to extract the acidic compounds from the jet fuel during the determination of the TAN. Here, we develop a desirable alternative solvent of a mixed ethanol–water solution with the volume ratio of ethanol to water of 99:1, which exhibits a value of TAN similar to that of the solvent of methylbenzene in potentiometric titration and acid–base titration methods. The TAN value derived from the different titration solvents was in the order of 2.96 μg KOH g–1 (Vcyclohexane/Visopropanol/Vwater = 100:99:1) > 2.68 μg KOH g–1 (Vmethylbenzene/Visopropanol/Vwater = 100:99:1) ≈ 2.6 μg KOH g–1 (Vabsolute ethanol/Vwater = 99:1) > 2.34 μg KOH g–1 (Visopropanol/Vwater = 99:1). The current report presents a nontoxic and eco-friendly alternative solvent for methylbenzene, which may open up an avenue for evaluating the TAN of jet fuels.

Extraction Of Naphthenic Acid From Indonesian Crude Oils By Methanol-Ammonium Solution

Indonesia’s crude oil which has a total acid number (TAN) with a concentration more than 0.5 mg KOH/g are often found. The presence of naphtenic acid tends to increase the value of TAN. The existence of naphthenic acid needs to be reduced to avoid problems in the petroleum refining process because it will cause problems of corrosion, foaming, etc. On the other hand, naphthenic acid may have a value-added as an emulsifier, antiseptics timber, preservatives, and so on. This study extracted naphthenic acid from some Indonesian crude oils which have relatively high TAN value oil with the code A, B and C. Extraction of naphthenic acid from crude B shows quite high results of that is equal to 65.47% with a purity level of 96.6%

SYNERGISTIC EFFECT OF WATER AND CO-SOLVENTS ON THE HYDROTHERMAL LIQUEFACTION OF AGRICULTURAL BIOMASS TO PRODUCE HEAVY OIL

Hydrothermal liquefaction was performed on Alberta, Canada's agricultural biomass, corn stover and wheat straw, at an operating temperature of 300°C, initial reactor pressure of 600 psi and zero min retention time. Effects of adding co-solvents (methanol, ethanol, and 2-propanol) on yield and quality of heavy oil has been studied. 2-propanol exhibited to be a promising co-solvent that has improved the quality of heavy oil. Hydrothermal liquefaction of corn stover using a water−2-propanol mixture produced heavy oil having oxygen content of 18.8 wt.%, higher heating value of 32.17 MJ/kg, and total acid number value of 81.74 mg KOH/g oil. Hydrothermal liquefaction of wheat straw using water−2-propanol mixture produced heavy oil showing an oxygen content of 17.99 wt.% and higher heating value of 32.94 MJ/kg.

Efficient naphthenic acid extraction from high acidic oil using novel 1,5-diazabicyclo[4.3.0]non-5-ene based ionic liquids

In this work, the high acidic crude oil deacidification study was performed with novel 1-alkyl-1,5-diazabicyclo[4.3.0]non-5-ene (DBN) based ionic liquids (ILs). Firstly, we took advantage of the systematic COSMO-RS (Conductor-like Screening Model for Real Solvents) calculations to screen the possible ILs with good acid extraction performance from the combinations of 94 cations and 56 anions. Four 1-alkyl-1,5-diazabicyclo[4.3.0]non-5-enium imidazolide ([DBN-R][IM]) ILs with varying alkyl chains were eventually identified and synthesized successfully. Their deacidification performances were tested experimentally and different factors, including the alkyl chain length, ILs/oil mass ratio, temperature, and the initial total acid number (TAN) value of the simulated acidic oil, were also studied in detail. The experimental results showed that [DBN-R][IM] exhibited excellent performances on naphthenic acids (NAs) removal and [DBN-Et][IM] could achieve 93% of NAs removal employing the ILs/oil mass ratio of 0.06 at room temperature for the acidic oil with the TAN value of 3.28 mg KOH/g. COSMO-RS analyses were also used to elucidate the unusual effects of the alkyl chain length and temperature on the NAs extraction performances. Additionally, a two-step deacidification strategy was proposed aiming at realizing more efficient NAs extraction. Finally, density functional theory (DFT) calculations were carried out and the independent gradient model (IGM) analyses were applied to the IL-NAs system to get insight into the deacidification mechanism of the ILs.

Continuous desalting concept on ionic liquid-mediated de-acidification process of crude oil: A pilot study

Desalting process concept was tested using methyltrimethylammonium methylcarbonate [N4441][MeCO3] treated Pyrenees crude oil (initial Total Acid Number (TAN) of 1.6 mg KOH/g oil) with the aim to gain empirical evidences on the effectiveness of in-line water washing and electrostatic aided phase separation as mean to recover the naphthenic acid derivatives for recycling. The treated crude oil (final TAN value of less than 0.3 mg KOH/g oil) was subjected to typical operating scheme such as single stage desalting and effects of water wash volumes. The novelty of the work comes from the utilisation of ionic liquids to neutralise acid components of the crude oil. Furthermore, the work is also able to test the hypothesis of whether naphthenate salts behave as is its inorganic counterpart and quantify the solubility behaviour in water as extraction medium. The effectiveness of such scheme will be measured against naphthenic acids derivative percent recovery in the wash water. The results indicate the electrostatic conditions can facilitate the recovery of the naphthenate salts post neutralization with high recovery rate of average of 70.6 % with 30 % water wash volume in a single-stage contact, observed over 12 hours steady-state operation. The water wash weight was observed to increase post separation which indicate hydrocarbon carry-over in the heavy phase due to formation of tight water – oil emulsion. The technique is viable should the amount of water required is available and the process water can be recycled safely into the desalter again without causing tripping to the desalter. Ionic liquid can be used in conjunction with desalter and the presence of electrostatic field did hasten the separation of the phases, however the amount of water used may hinder the viability of the solution.

Oxidative stability performance of new azophenol derivatives as antioxidants in working fluids for high-temperature solar applications

In solar applications, the oxidation stability of heat transfer fluidsreducesthe thermal energy storage cost. In this work, the effect of new two azophenols, namely -2-sec-butyl-4-((3-chlorophenyl) diazenyl) phenol and 2-sec-butyl-4-((3-nitrophenyl) diazenyl)phenol, was studied to produce an oil that has good characteristics and is compatible with metals such asstainless steel, carbon steel, aluminum, and copper, which are generally used to manufacture pipes, heat exchangers, receivers, and storage tanks. The prepared compounds were characterized using spectroscopy analysis. The prepared compounds were added to a heat transfer fluid under operating conditions in the presence of iron and copper as catalysts. At different time intervals, the samples were tested by measuring the total acid number value. The results of this measurement show that compound II performed better than compound I. Additionally, the quantum chemical parameters were calculated. The theoretical calculations were compatible with the experimental results.

The Application of K/Al2O3 with Ethanolic 2-Metylimidazole for the Extraction of Naphthenic Acid from Crude Oil

The world's economy is largely dependent on fossil fuels such as petroleum crude oil. Crude oil processing in the oil refinery can cause serious corrosion problems associated with the presence of naphthenic acids (NAs) which reduce the quality of the oil. The presence of these acidic compounds leads to an increase in the Total Acid Number (TAN) value and a decrease in the oil price which can affect the oil industry. The aim of this study was to overcome corrosion problems by reducing the TAN to less than 1.0 mg KOH/g using ethanolic 2-methylimidazole with the aid of a K/Al2O3 catalyst. Petronas Penapisan Melaka crude oil with an original TAN value of 4.38 mg KOH/g was used as feedstock in this study. The parameters investigated were reaction time, reaction temperature, catalyst loading and catalyst calcination temperature. The alumina supported catalyst was synthesized through Incipient Wetness Impregnation (IWI) methods and characterized using X-ray Diffraction Spectroscopy (XRD) and Scanning Electron Microscopy (SEM). The TAN of crude oil was successfully lowered to 0.74 mg KOH/g using a K/Al2O3 catalyst at a calcination temperature of 1000oC. Increasing the calcination temperature from 700 to 1000oC further reduced the TAN value of crude oil.

Oxidation Studies on Mineral Insulating Oil Using an Accelerated Method with Continuous Online Monitoring

In this study, an alternative method was applied to evaluate the accelerated oxidation of mineral insulating oils using continuous real time monitoring, with smaller samples and lower experimental times than the standard ASTM D2440 method. Using this method, the influence of temperature and presence of a metal catalyst on the oxidation behavior was evaluated. The activities of commercial metal passivators and antioxidants were also studied at different conditions. The addition of the metal passivators (BTA: 1,2,3-benzotriazole, and Irgamet-39: n-(1,2,3-benzotriazol-1-methyl)-n-alkylamine) at low concentrations (8 mg/kg) increased the induction period (IP) of doped samples. Furthermore synergetic effects on retarding the oxidation reactions when using both metal passivators and two commercial antioxidants (DBPC, 2,6-di-tert-butyl-p-cresol, and Irganox L115, 2,2'-thiodiethylen-bis(3,5-di-tert-butyl-4 hydroxyphenyl-proprionate) were observed, increasing the IP values by up to 25 times when compared to a fresh oil sample. Experimental IP values from this newly proposed technique (up to 10 h) may be used to estimate the Total Acid Number values obtained when using the ASTM D2440 method (164 h).

Total Acid Number Reduction of Acidic Petroleum Crude Oil by Using 2-Methylimidazole in Polyethylene Glycol and Ca/Al<sub>2</sub>O<sub>3</sub> Catalyst

The Naphthenic Acid (NA) found in the acidic crude oil is one of the main challenges that can lead to corrosion problem in oil refinery equipment and reduces the quality of the oil. In this study, catalytic neutralization reaction was investigated in order to lowering Total Acid Number (TAN) in crude oil to less than one mg KOH/g utilizing 2-Methylimidazole in Polyethylene Glycol (PEG) with aid of Ca/Al2O3 catalyst. The catalyst were supported on the alumina beads through Incipient Wetness Impregnation (IWI) methods and heated in an oven for 24 hours at 80-90°C then calcined at calcination temperatures of 800, 900 and 1000°C. The result showed that Ca/Al2O3 catalyst successfully reduced to 0.52 mg KOH/g from original TAN value 4.22 mg KOH/g by using a catalyst at calcination temperature 1000°C, 0.39 wt % (7 beads) of catalyst loading and 1000 ppm of 2-Methylimidazole in PEG. It can be concluded that catalytic deacidification method was effective method in reducing NAs from the crude oil and can lowered the TAN value to less than 1 mg KOH/g.

The Effectiveness of Ni/Ce/Al<sub>2</sub>O<sub>3</sub> Catalyst in the Extraction of Naphthenic Acids from Acidic Crude Oil

Processing of petroleum crude oil with high total acid number (TAN) lead to corrosion problems in oil refinery equipment, storage, facilities and even reduces the performances of the oil. The purpose of this study is to overcome the corrosion problem in oil refinery by reducing the TAN in the oil to less than 1 mgKOH/g. A 2-methylimidazole in ethanol with the aid of Ni/Ce (10:90)/Al2O3 catalyst through the catalytic deacidification technique. The catalyst was prepared by using Incipient Wetness Impregnation (IWI) methods on alumina beads as catalyst support and calcined at 800°C, 900°C and 1000°C. Ni/Ce (10:90)/Al2O3 catalyst was characterized by using Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction Spectroscopy (XRD) and Brunauer-Emmett-Teller (BET) to study physicochemical properties of the catalyst. The results shows that Ni/Ce (10:90)/Al2O3 catalyst successfully reduced TAN in crude oil to 0.50 from 4.22 mg KOH/g at 1000°C calcination temperature and catalyst loading of 0.39% (7 beads). XRD analysis proposed Al2O3 and CeO2 fcc was the active site for Ni/Ce (10:90)/Al2O3 catalyst. C-H alkanes stretching, -CH2- alkanes stretching and pure metal oxides stretching modes were detected on the catalyst at wavelength of 2952.49 to 2852.82, 1599.38, and 862.81 to 537.27 cm-1 respectively by FTIR analysis after catalytic deacidification process which indicates that there were impurities that have adsorbed on the catalyst surface. As a conclusion, the catalysts successfully reduced the TAN value of acidic crude oil to less than 1.00 mg KOH/g.

Computational and Experimental Studies of Biolubricant Stability Derived from Oleic Acid

In the present work, the stability of six biolubricant compounds, i.e. Acetal, Ketal, D[4.4], D[4.5], Cyclic-6, and Cyclic-7, was evaluated both theoretically and experimentally. These compounds were prepared from oleic acid through hydroxylation and esterification reactions. The computational study of the compounds was conducted by using the Density Functional Theory (DFT) method at B3LYP level of theory and 6-31 G (d,p) basis set. The theoretical stability was reflected from the internal energy value of the hydrolysis reaction of the biolubricant compounds to form the 9,10-dihydroxystearic acid. The order of stability is given as follows: Cyclic-6 (-3.458 kJ/mol) > Acetal (-3.446 kJ/mol) > Cyclic-7 (-3.364 kJ/mol) > D[4.5] (-3.343 kJ/mol) > D[4.4] (-3.261 kJ/mol) > Ketal (-3.058 kJ/mol). On the other hand, the experimental stability of the biolubricant compounds was measured using the American Society for Testing and Material (ASTM) standard method for total acid number (TAN) and total base number (TBN). It was found that the Cyclic-6 derivative yielded the lowest TAN (1.37 mg KOH/g) and TBN (3.53 mg KOH/g) values compared to the other biolubricant compounds. Meanwhile, the Cyclic-6 also showed the lowest internal energy value (-3.458 kJ/mol) from the computational study due to the high stability of six-membered ring. These results reveal that the experimental TAN and TBN values could be predicted from the theoretical internal energy value, i.e. TAN (mg KOH/g) = 35.183 (DE) – 123.02 (R2 = 0.9226) and TBN (mg KOH/g) = 105.71 (DE) – 369.72 (R2 = 0.8946), which is remarkable.

Applying chemometric procedures for correlation the FTIR spectroscopy with the new thermometric evaluation of Total Acid Number and Total Basic Number in engine oils

Currently, the main trend is to employ spectroscopic techniques for the condition assessment of used engine oils. That is a consequence of the requirement for increasing the Oil Condition Monitoring (OCM) efficiency. Usually, FTIR (Fourier Transform Infra-red) Spectroscopy is employed to achieve the ability of measuring used engine oil and uses the FTIR spectrum to generate a relation between attribute-spectrum. To allow this connection, it is necessary to develop chemometric studies. However, this procedure needs a previous validation to correlate the spectrum with the value of the attribute measured by standardised techniques. One of the potential attribute for study is the acidification of the engine oil by the Total Acid Number (TAN), specially employing the ASTM D8045 standard that measures the TAN level by thermometric titration. The new standard offers a better chemical path to quantify accurately the TAN value of used engine oil. And other basic parameter is the Total Basic Number (TBN) that also is possible to quantify by thermometric determinations. Both of these parameters are correlated, therefore this study is focused on the generation of a mathematical model that describes the condition of the engine oil employing the shape of its FTIR spectrum. Specifically, in this work has been shown the applicability of chemometric procedures in conjunction with thermometric titration for determining TAN and TBN values of an used engine oil.

Catalytic study of Ni/Ce/Al2O3 and Ni/Ca/Al2O3 on the removal of naphthenic acid from petroleum crude oil utilizing sodium thiocyanate in ethanol

The naphthenic acids (NAs) present in the crude oil can lead to the corrosion problems in oil refinery equipment apart from reduces the performances of the oil. In this study, the method to remove NA were done by means of extraction using sodium thiocyanate in ethanol with the aid of Ni/Ca/Al2O3 and Ni/Ce/Al2O3 catalysts at 27 °C reaction temperature. The catalyst was prepared by incipient wetness impregnation method (IWI) and calcined at three different temperature, 800, 900 and 1000 °C respectively. The efficiency of the extraction was affected by the catalyst calcination temperature. Both catalysts calcined at 800 and 900 °C gave total acid number (TAN) value more than 1 mg KOH/g while by using Ni/Ca(10:90)/Al2O3 and Ni/Ce(10:90)/Al2O3 calcined at 1000 °C the TAN value were reduced to 0.28 and 0.65 mg KOH/g respectively. Brunauer-Emmett Teller (BET) result shows both catalysts have large surface area that provide more reaction cites when calcined at 1000 °C. X-ray Diffraction Spectroscopy (XRD) analysis of Ni/Ca/Al2O3 catalyst revealed that the active site was dominated by the Al2O3 species while CeO2 was the active site for Ni/Ce/Al2O3 catalyst. In conclusion, both catalysts reduced the TAN value of acidic crude oil efficiently.

Prediction of the total acid number (TAN) of colombian crude oils via ATR–FTIR spectroscopy and chemometric methods

Reactions as the attack by naphthenic and hydrogen sulfide have caused corrosion problems in the petroleum industry due to they affect the crude oil heating furnaces and distillation towers at temperatures between 220 and 400 °C. The total acid number (TAN) measurement has been used as a test to quantify the acid compounds in crude oils and has shown to be a reliable indicator of their corrosion degree. However, the standard method for the TAN measurement, ASTM D-644, involves long times, environment unfriendly wastes and high costs for each analysis. A more appropriate method for the TAN determination is implemented in this paper, by correlating Fourier transform infrared spectroscopy (FTIR) spectral data of the samples with the standard method measurements using multivariate regression models. In particular, the intensities and frequencies of their mid-infrared attenuated total reflectance (MIR-ATR) spectra (4000 - 400 cm−1) are used as independent variables of several principal component regression (PCR) and partial least squares regression (PLSR) models. The latter are employed to correlate the spectra with their respective TAN values so as to obtain a suitable prediction model. Twenty-six (26) samples of Colombian crude oils are used for the study with a TAN ranging from 0.1 to 6.8 mg KOH/g crude oil (ASTM D-664). The models are evaluated according to the coefficient of determination (R2), the root mean square error of calibration (RMSEC) and of prediction (RMSEP). The best model is obtained via PLSR using as few as four components (i.e. factors), which attains a calibration R2 of 0.981 and an RMSEC of 0.317 mg KOH/g crude oil, while for prediction it attains an R2 of 0.996 and an RMSEP of 0.160 mg KOH/g crude oil. It is observed that the functional groups COOH, CH3 and CH2 contribute the most to the prediction models. The designed methodology is faster and environmentally friendly since it does not require sample pretreatment and the use of toxic reagents, and of low-cost compared with the standard procedure since FTIR measurements can be easily taken anywhere using a hand-held or portable spectrometer and a laptop.

Oil acidity reduction by extraction with [EMIM][EtSO4]: Experimental and model description

Carboxylic compounds in crude oils are responsible of the acidity of the crudes and lead to high corrosion rates. The total acid number (TAN) quantifies acidity of crude oil and values higher than 0.5 define the crude oil as acid. Among the methods used to reduce the TAN of crude oils, those involving ionic liquids (ILs) are recently increasing. Most of involved ionic liquids are basic compounds that neutralize the naphthenic acid.In this work the ionic liquid [EMIM][EtSO4] acting as extraction solvent was investigated to reduce the TAN value of a synthetic mixture. Obtained reductions were up to 25% within the covered experimental conditions. Extraction temperature improves TAN reduction but only within a short temperature range, with the best results obtained around 50 °C. Investigation covers ionic liquid to crude oil ratios ranging 0.1–1 g/g and the highest ratios lead to the highest TAN reductions.UNIFAC, COSMO-RS and COSMO-SAC models allows describing liquid-liquid equilibria for such multicomponent systems. UNIFAC model required the fitting of interaction parameters for the pair IL-COOH and lead to accurate descriptions for the phase fractions and TAN values of both phases. COSMO models described an overestimation of the TAN reduction for the organic phase and a higher acid content in the IL phase. However, COSMO models shown being quite dependent on the way to obtain the σ-profile, and accuracy of the calculated values clearly improved when cation and anion were computed together allowing the shielding of the basic areas in the anion. Consequently, predictions carried out with such models for these complex mixtures should be considered with precaution.

EXTRACTION OF NAPHTHENIC ACIDS FROM ACIDIC PETROLEUM CRUDE OIL UTILIZING 2-METHYLIMIDAZOLE WITH THE AID OF Ca/Al2O3 AND Ce/Al2O3 CATALYSTS

Naphthenic acids (NAs) is one of the major sources of corrosion in oil pipelines and distillation units in crude oil refineries. Removing NA compounds from crude oils is regarded as one of the most crucial processes in heavy oil upgrading. Catalytic deacidification method had been developed in order to reduce the total acid number values in crude oil. Crude oil from Petronas Penapisan Melaka had been chosen to be studied with original total acid number (TAN) of 2.43 mg KOH/g. The parameters used were different catalyst calcination temperatures, catalyst loading, reagent concentration, reaction times and reaction temperature. Acid removal agent of 2-methylimidazole in ethanol and monometallic calcium and cerium doped with alumina were used as a catalyst. The results showed that with the aid of catalyst, the TAN can be reduced to lower than 1 mg KOH/g. Catalyst of Ca/Al2O3 calcined at 900oC gave a better reduction than Ce/Al2O3 with 83.54% of TAN reduction (2.43 to 0.4) for Ca/Al2O3 catalyst and 71.19% (2.43 to 0.7) for Ce/Al2O3 catalyst. The best catalyst underwent several characterization methods such as X-Ray Diffraction Spectroscopy (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Thermogravimetry Analysis (TGA-DTA) for its physicochemical properties. It can be concluded that catalytic deacidification method was effective in extracting NAs from the crude oil thus lowered the TAN value to less than 1 mg KOH/g.
 Keywords: Naphthenic acids; Crude oil; Catalysts

Corrosive character of Moringa oleifera Lam biodiesel exposed to carbon steel under simulated storage conditions

The corrosive character of Moringa oleifera Lam biodiesel was evaluated through static immersion tests with different carbon steels (CS1015 and CS4140) in absence and presence of the antioxidant tert-butylhydroquinone (TBHQ), at room temperature in the absence of light for 84 days. Biodiesel parameters, including oxidation stability (induction period, IP), total acid number (TAN) and iron concentration released from carbon steel, were monitored. The produced biodiesel presented an IP value of 4.9 h, which was increased to 6.2 h after the addition of 500 mg kg−1 TBHQ. After 84 days of immersion, IP values decreased in the first 21 days due to the contact with the metallic coupon, while TBHQ retarded this process. TAN value increased in 20% but the values were below the recommended limits (<0.5 mg g−1 KOH according to EN14214). Iron was detected in the biodiesels exposed to CS1015 (8 μg g−1), while in the presence of TBHQ this value decreased to 5 μg g−1, indicating corrosion inhibition by TBHQ. Iron was not detected in the biodiesels exposed to CS4140, which indicated that this material was more compatible with biodiesel. Notably, the oxidation stability of Moringa biodiesel was not affected (IP > 3 h) by the high Fe content.