Acidic Crude Oil Research Articles

Application of thin layer activation technique for monitoring corrosion of carbon steel in hydrocarbon processing environment

Acidic crude oil transportation and processing in petroleum refining and petrochemical operations cause corrosion in the pipelines and associated components. Corrosion monitoring is invariably required to test and prove operational reliability. Thin Layer Activation (TLA) technique is a nuclear technique used for measurement of corrosion and erosion of materials. The technique involves irradiation of material with high energy ion beam from an accelerator and measurement of loss of radioactivity after the material is subjected to corrosive environment. In the present study, TLA technique has been used to monitor corrosion of carbon steel (CS) in crude oil environment at high temperature. Different CS coupons were irradiated with a 13 MeV proton beam to produce Cobalt-56 radioisotope on the surface of the coupons. The corrosion studies were carried out by subjecting the irradiated coupons to a corrosive environment, i.e, uninhibited straight run gas oil (SRGO) containing known amount of naphthenic acid (NA) at high temperature. The effects of different parameters, such as, concentration of NA, temperature and fluid velocity (rpm) on corrosion behaviour of CS were studied.

Characterization of Naphthenic Acids in Thermally Degraded Petroleum by ESI(−)-FT-ICR MS and 1H NMR after Solid-Phase Extraction and Liquid/Liquid Extraction

Naphthenic acids (NAs), present in a typical Brazilian acid crude oil and its thermal degradation products, were investigated using two separation methodologies: solid-phase extraction (SPE) and li...

Study of the Corrosive Behavior of the AISI 1020 Steel in Acid Crude Oil by Microscopic Techniques (LM, AFM and SEM/EDX) and Raman Spectroscopy

Microscopic techniques were combined to study the influence of corrosion rate on the morphologic behavior of AISI 1020 steel specimens submitted to thermal degradation of a typical acid crude oil (total acid number (TAN) = 2.1390 mg KOH g-1 and total sulfur (S) = 0.7778 wt.%). The techniques used were light microscopy (LM), scanning electron microscopy/energy dispersive spectroscopy (SEM/EDX), atomic force microscopy (AFM) as well as Raman spectroscopy. Assays were performed in six different degradation time (t = 6, 12, 24, 36, 48 and 72 h) at 320 oC. After the exposure of the specimens to petroleum, a reduction above 37% in the TAN after t = 72 h was observed, with a maximum corrosion rate during the first periods of degradation (t = 6 and 12 h). Correlating the TAN and corrosion rate data with the microscopic data, the images of LM, AFM, and SEM/EDX showed that after 6 h of exposure to petroleum, a passivation film was formed on the surface of the steel. This film consisted of two layers, an external one, formed of FeS, and an internal one, composed of iron oxides and oxyhydroxides. However, after 48 h of thermal degradation, this morphology was altered to a single layer of FeS coating the steel surface.

The application of overall equipment effectiveness to support the development of a steamless nut-separated palm oil mill

A steamless nut-separated palm oil mill has been developed based on small-scale community's requirements with the purpose to overcome constraints faced by a conventional palm oil mill. The current paper discusses challenges in the development and technology transfer of the steamless nut-separated palm oil mill, including communication about technology performance, uncategorised problems, and limited flow of financial information. To overcome these challenges, the proposed approach is to use OEE-based plant performance indices and its estimated corresponding financial performance indices to communicate about the technology performance. In this work, the calculation of OEE was derived based on data obtained from palm oil mills. In addition, the performance factor was sub-categorised into the reception and extraction factors to relate the plant performance to the mill capacity and oil extraction rate, which are common variables used in palm oil mills. Moreover, the quality factor was derived based on free fatty acid of crude palm oil. A simulated plant operating data was used for the purpose of demonstrating the proposed approach. The figures of world-class OEE and its components were also used to identify the area for initiating process improvement activities and estimate the potential performance of the technology.

Facile and Low-cost Synthesis of Mesoporous Ti-Mo Bi-metal Oxide Catalysts for Biodiesel Production from Esterification of Free Fatty Acids in Jatropha curcas Crude Oil.

Mesoporous Ti-Mo bi-metal oxides with various titanium-molybdenum ratios were successfully fabricated via a facile approach by using stearic acid as a low-cost template agent. thermal gravity (TG) /differential scanning calorimetry (DSC) analysis, X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, nitrogen adsorption-desorption isotherm, NH3 temperature-programmed desorption (NH3-TPD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) measurements indicated these materials possessing mesoporous structure, sufficient pore size and high acid intensity. The catalytic performance of prepared catalysts was evaluated by esterification of free fatty acids in Jatropha curcas crude oil (JCCO) with methanol. The effects of various parameters on FFA conversion were investigated. The esterification conversion of 87.8% was achieved under the condition of 180°C, 2 h, methanol to JCCO molar ratio of 20:1 and 3.0 wt.% catalyst (relative to the weight of JCCO). The mesoporous catalysts were found to exhibit high activities toward the simultaneous esterification and transesterification of JCCO. Furthermore, the catalyst could be recovered with a good reusability.

Reduction of naphthenic acids in high TAN crude oil using a fluid catalytic cracking catalyst

ABSTRACTA commercial Fluid Catalytic Cracking (FCC) catalyst is used to reduce naphthenic acids (NAs) in a high Total Acid Number (TAN) crude oil sample. The influence of temperature, oil/catalyst ratio is investigated using non-treated and thermally treated FCC catalyst. It is shown that the FCC catalyst is capable of reducing NAs with a reduction in TAN of 15.9% and 13.22% at an oil/catalyst ratio of 3:1 and 4:1 respectively. Thermal pre-treatment of the FCC catalyst, in combination with an increase in the temperature of the Crude Oil to 190°C, resulted in an overall TAN reduction of 22.34%.

Surfactant-less alkali-cosolvent-polymer floods for an acidic crude oil

Alkali-surfactant-polymer floods can increase the oil recovery in many reservoirs by lowering interfacial tension (IFT). Surfactants are the most expensive chemicals in these processes. However, surfactant requirement is low in case of crude oils which contain naphthenic acids. These acids with the addition of an alkali generate in-situ soap which results in lowering the oil-water IFT. The goal of this work is to investigate if surfactants can be eliminated from the formulation in case of sufficiently acidic crude oils to reduce the cost. Low IFT formulations were obtained by varying the alkali concentration in the absence of synthetic surfactants. A cosolvent was added to lower the viscosity of microemulsions and to obtain the low IFT region in the desired salinity range. Various cosolvents were systematically tested to obtain the desired phase behavior. For comparison, alkali-surfactant-polymer (ASP) and alkali-cosolvent-polymer (ACP) formulations were developed for the same crude oil using synthetic surfactants. One-dimensional ASP and ACP corefloods were performed in sandstone cores to test these formulations. The ASP coreflood showed 84.5% oil recovery and 0.1 mg/g-rock surfactant retention in a Berea core. ACP corefloods showed 80–90% oil recovery in Berea cores and minimal cosolvent retention, and 97% recovery in a Boise core. The study shows that comparable oil recoveries could be obtained from ASP and ACP corefloods for a sufficiently acidic crude oil, provided the cosolvent selection is performed carefully.

Comparison in Catalytic Activities of Sulfated Cobalt-Tin and Sulfated Aluminium-Tin Mixed Oxides for Esterification of Free Fatty Acids to Produce Methyl Esters

In this study, sulfated tin oxide was modified with cobalt oxide and aluminium oxide resulting in sulfated cobalt-tin (SO42-/Co2O3-SnO2) and sulfated aluminium-tin (SO42-/Al2O3-SnO2) mixed oxide catalysts, respectively. Their catalytic activities for esterification of free fatty acids (FFA) in crude palm oil were investigated. Cobalt-tin and aluminium-tin mixed oxides were prepared by co-precipitation method. The mixed oxides were further impregnated with sulfate ions by immersing in sulfuric acid solution, dried and calcined at 450-500 °C. The properties of SO42-/Co2O3-SnO2 and SO42-/Al2O3-SnO2 samples were determined by nitrogen adsorption, X-ray diffraction and potentiometric titration. The activities of SO42-/Co2O3-SnO2 and SO42-/Al2O3-SnO2 catalysts were tested in a stirred-tank reactor equipped with a reflux condenser. Esterification between crude palm oil containing 10-10.2 wt% of FFA and methanol was carried out at various reaction times. The comparison in the catalytic activities of SO42-/Co2O3-SnO2 and SO42-/Al2O3-SnO2 was made. The results showed that the SO42-/Al2O3-SnO2 had higher catalytic activity than SO42-/Co2O3-SnO2 in esterification of FFA to produce methyl esters.

English

Crude palm oil from the mesocarp of Elaeis guineensis Jacq fruits is one of the most consumed vegetable oil in the world. The quality of palm oil assessed mainly by its free fatty acids (FFA) content and impurities, varies between the artisanal and industrial extraction and supply systems. The objective of this paper is to highlight the main parameters that influence the acidity or FFA content of crude palm oil produced by the smallholder artisanal sector. Three parameters examined are: crude palm oil production and extraction methods, microbial activity and oil palm genotype. These three parameters strongly increase lipase activity and hence palm oil acidity. In addition to endogenous lipase in fruit mesocarp, microorganisms found in palm oil are also involved in lipase activity e.g. Aspergillus sp, Mucor sp, Penicillium and Candida for fungi; and bacteria such as Bacillus, Pseudomonas, Micrococcus, Staphylococcus and Enterobacter. To improve the quality of palm oil, smallholders must first seek oil palm progenies with low acidity oil and respect the standard cultural practices for palm oil production. Key words: Elaeis guineensis Jacq, palm oil acidity, microorganisms, production systems, genotype.

Synthesis and characterization of 12-tungstophosphoric acid intercalated layered double hydroxides and their application as esterification catalysts for deacidification of crude oil

12-tungstophosphoric acid (H3PW12O40, HPW) intercalated layered double hydroxides (LDH) (M2+/Al3+=2, M2+=Mg2+, Zn2+, Ni2+) were prepared by an ion-exchange method. The as-prepared LDH show a strong reflection around 8.4° corresponding to a basal spacing of 1.05nm, which is considered as heteropolyacid salts or polytungstate intercalated LDH in almost all literature. Further systemic experiments and characterizations demonstrated that such reflection can be attributed to the intercalation of HPW, in which HPW may graft with the vacancies in the layer and orient in the interlayer with the C2 axis perpendicular to the layers. HPW intercalated LDH show higher catalytic activity than nitrate LDH for the esterification between ethylene glycol and naphthenic acids in crude oil. It is found that the total amount of acidic sites dominates the esterification activity. Due to the immobilized HPW active sites and the enlarged interlayer space, HPW intercalated LDH may act as an interlayer catalytic reactor to improve the esterification activity.

Influence of different irrigation and nitrogen levels on crude oil and fatty acid composition of maize (<em>Zea mays</em> L.)

The effect of irrigation and nitrogen fertilizer levels on the crude oil and fatty acid composition of maize cultivars was studied. Three levels of irrigation (50, 75 and 100% of field capacity) and nitrogen (100, 200 and 300 kg·ha-1) were used for treatment groups. After harvest, the crude oils were extracted and fatty acid profiles were determined by Gas Chromatography system. The study was repeated for two years and the interaction effects of fertilizer and irrigation were determined. Our results show that the crude oil content was affected positively by the fertilizer and the irrigation applications. As expected, the most abundant fatty acid was linoleic and the harvest year did not alter it. The highest linoleic acid content value was obtained with a 50% field capacity and 300 kg·ha-1 fertilizer treatment combination. In addition, fatty acid contents varied with the changing of interaction effects except for myristic and palmitic acid. Oleic acid was the second abundant fatty acid in the oil samples and the lowest oleic acid value was obtained with a 50% field capacity and 300 kg·ha-1 fertilizer treatment combination. Oleic acid content tended to increase with 75% field capacity but 100% field capacity treatment decreased in it.

Coupling of subcritical methanol with acidic ionic liquids for the acidity reduction of naphthenic acids

Abstract The presence of naphthenic acids (NAs) in crude oil is the major cause of corrosion in the refineries and its processing equipment. The goal of this study is to reduce the total acid number (TAN) of NAs by treating them with subcritical methanol in the presence of acidic ionic liquid (AIL) catalysts. Experiments were carried out in an autoclave batch reactor and the effect of different reaction parameters was investigated. It was observed that TAN reduction was positively dependent on the temperature and concentration of the AIL whereas excess of methanol has a negative effect. Approximately 90% TAN reduction was achieved under the optimized reaction conditions using [BMIM]HSO4 as catalyst. It was also perceived from the experimental results that the AILs with longer alkyl chain exhibited higher catalytic activity. The activity and stability of AIL showed that they can be promising catalyst to esterify NAs under subcritical methanol.

Microwave-Assisted Synthesis of Ethylene Glycol-Intercalated NiAl LDHs and Their Application for Intracrystalline Catalytic Esterification with Naphthenic Acids in Crude Oil

Ethylene glycol (EG)-intercalated layered double hydroxides (LDHs) with various Ni/Al molar ratios were prepared by a microwave-assisted ion exchange method. In comparison with the conventional ion exchange method, this method can achieve a more ordered layered structure and reduce the ion exchange time from 12 h to 30 min. The as-prepared EG-intercalated LDHs were used as esterification catalysts to remove naphthenic acids in crude oil. It is found that EG-intercalated LDHs may act as nanosized intracrystalline catalytic microreactors, attributed to the preintercalated EG which reduces the diffusion resistance, the enlarged interlayer space which facilitates the access of naphthenic acids, and metal catalytic sites in the layer. The confined interlayer space enhances the collision between reactants and accelerates the reaction. Therefore, EG-intercalated LDHs exhibit several times higher acid removal ratio and EG conversion than nitrate LDHs. The increasing Ni/Al ratio increases the amount of catalytic s...

Physicochemical characteristics of high free fatty acid crude palm oil

The physicochemical properties of different grades of Malaysian crude palm oil (high free fatty acid crude palm oil (HFFA-CPO) and low free fatty acid crude palm oil (LFFA-CPO)) were analyzed in this study to determine their applicability as edible oils. The percentages of free fatty acids (FFAs%), iodine value, hydroxyl value, unsaponifiable value, moisture content for HFFA-CPO and LFFA-CPO were 8.7 ± 0.3 and 3.8 ± 0.1%; 53.1 ± 0.4 and 56 ± 0.3 g I2 /100 g; 32.5 ± 0.6 and 18.5 ± 0.9 mg KOH/g oil; 0.31 ± 0.01 and 0.46 ± 0.02%; 0.31 ± 0.01 and 0.33 ± 0.01%, respectively. The fatty acid compositions were determined using a gas chromatography-flame ionization detector (GC-FID). The results showed that the dominant fatty acids are palmitic acid (43.2%–44.4%) and oleic acid (39.8%–41.4%). The major triacylglycerols (TAGs) of HFFA-CPO and LFFA-CPO estimated using high-performance liquid chromatography (HPLC), were POP (30.8%–33.6%) and POO (24.9%–29.7%). In general, the physicochemical properties of HFFA-CPO and LFFA-CPO are consistent with the standard Malaysian crude palm oil, with the exception of FFAs%, hydroxyl value, moisture contents.

The catalytic deacidification of acidic crude oil using Cu-doped alkaline earth metal oxide catalysts

ABSTRACTNaphthenic acids (NAs) tend to cause operational problems that can lead to the deactivation of catalysts. To overcome the problem, catalytic deacidification was introduced utilizing an ammonia solution in ethylene glycol with the aids of alkaline earth metal catalyst with alumina as a support. The initial total acid number observed for NAs in n-dodecane was 4.21 mg KOH/g. In total, 1,000 mg/L of 0.4% NH3-EG were used as the acid removal agent. Calcium, barium, and magnesium catalysts were tested in this study. The results showed Cu/Ca/Al2O3 was found to be the best catalyst that could be used to enhance the reaction.

Equilibrium partitioning of naphthenic acids and bases and their consequences on interfacial properties

This article aims to create a model to accurately predict the equilibrium partitioning of naphthenic acids and basic crude oil components between the oil and water phase. The model was tested on 2 acids and 2 bases. After a review of the properties of crude oil acids and bases, the equilibrium partitioning of acids and bases with different molecular weight was analyzed over a pH interval using heptane as the oil phase and 3.5wt.% NaCl as the water phase. Phenylacetic acid would represent the low molecular weight acid while 4-heptylbenzoic acid was chosen to represent the high molecular weight one. Likewise, 4-ethylaniline and 4-decylaniline were chosen as corresponding bases. The partitioning of the two acids and the low molecular weight base was successfully modelled by considering the acid dissociation constant pKa in aqueous phase and the partition ratio Pwo of the non-ionized species between oil and aqueous phase. The high molecular weight base did not significantly partition into the aqueous phase at the pH range studied. The results show that acid species are more water soluble than basic species of similar molecular weight. In presence of calcium the partitioning of acids is successfully modelled by accounting for the precipitation of naphthenate soap with a solubility constant Ks. The kinetic interfacial tension between heptane and 3.5% NaCl aqueous buffer was also analyzed with oils that contained single compounds, two bases, two acids and all four components over a pH interval to identify any interfacial acid-base interactions. No significant interfacial interaction could be identified, mostly due to similar pKa values.

Study of degradation of acid crude oil by high resolution analytical techniques

The extraction and refining process of unconventional oils, including heavy and extra heavy oils, has been a challenge to be overcome in the petrochemical industry. These oils typically comprise polar compounds responsible for some undesirable properties, such as naphthenic acids (NAs), which can be associated with the high corrosion rates in refineries. In this context, corrosion caused by NAs is among the most aggressive ones, and it can be accentuated when in presence of other compounds usually found in oil. Herein, a heavy oil sample was subjected to thermal degradation process at 350°C aiming the understanding of its behavior at the molecular level and to evaluate its physicochemical properties as a function of degradation time. Additionally, the oil was characterized by classic and high resolution analytical techniques. The obtained results showed that the oil exposed to longer degradation times (t≥24h) presented characteristics of “lighter” oil due to mainly disaggregation of resins and asphaltenes. Total Acid number (TAN) analysis displayed a decrease of 68.3% (from 2.0 to 0.75mg KOH g−1) of its initial value after 36h of degradation at 350°C. Other important changes observed included an increase in API gravity (of two decimal places from 17 to 19), and decreases in the pour point from −12 to −36°C, in the kinematic viscosity in 86.5% and of total sulfur content in 5.2% (from 0.58 to 0.55wt%). The HTGC and NMR results showed that the saturated fraction is not affected during the thermal stress process, whereas a subtle increase in the number of aromatic compounds was observed as a function of degradation time. This behavior can be attributed to the disaggregation of resins and asphaltenes as well as to the decarboxylation process. The last process was confirmed by ESI(-)-FT-ICR MS, where a reduction of average mass molar distribution from 466 to 450Da was observed.

Mesoporous Al–Mo Oxides as an Effective and Stable Catalyst for the Synthesis of Biodiesel from the Esterification of Free-Fatty Acids in Non-edible Oils

A kind of mesoporous Al–Mo mixed oxides as solid acid catalysts was designed and prepared through a facile and low-cost approach using stearic acid as a soft modifier, and investigated by X-ray diffraction, thermogravimetric, fourier transform infrared spectra, N2 adsorption–desorption, ammonia temperature programmed desorption and scanning electron microscopy. By using this catalyst, an environmentally benign process for esterification of free-fatty acids in non-edible Euphorbia lathyris crude oil with methanol was developed. It was shown that the activity of the catalysts for the esterification reaction is closely related to their mesoporous structures, surface area and acid properties. The Al–Mo solid acid catalyst exhibited an optimal esterification performance with 80.9% esterification efficiency under the optimum synthesis conditions. Moreover, the conversion remained over 73.2% after the catalyst being used for three times. These results showed that the catalysts have promising viability in esterification for biodiesel production in industry. Mesoporous Al–Mo oxides catalysts were prepared via a facile and low-cost modified approach and exhibited excellent catalytic activity and reusability in esterification reaction of high value acid non-edible oil and methanol. This material has great potential in the future production of biofuels used as the solid acid catalyst.

A micro-solid phase extraction in glass pipette packed with amino-functionalized silica for rapid analysis of petroleum acids in crude oils

A convenient micro-SPE was designed for rapid analysis of petroleum acids in crude oils.

Effect of Selected Polyhydric Alcohols on Refining Oil Loss in the Neutralization Step

AbstractAlkaline neutralization is a classical method for removal of free fatty acids (FFA) in crude oil. It is generally accompanied by neutral oil loss. Thus, reduction of refining losses associated with alkaline neutralization is very desirable. Refined, bleached and deodorized (RBD) palm oils with different FFA contents were used as oil models in this study. FFA in the oil models were neutralized with sodium hydroxide in polyhydric alcohols as neutralization media. Glycerol, propylene glycol and ethylene glycol in water were effective neutralization media. FFA in the oil models were totally removed in one step of neutralization, while percentages of refining losses were different. The losses were increased in the order of water > propylene glycol > ethylene glycol > glycerol used as neutralization media. Also, a higher concentration of polyhydric alcohol in the neutralizing media significantly reduced the percentage of refining loss (p < 0.05). Glycerol (90% in water) was the most effective neutralization media (p < 0.05). When neutralization was carried out on crude palm oil (containing 7.53% FFA), refining loss was reduced from 36.1% (in water) to 20.0% (in 90% glycerol in water).