Examinando por Autor "Coto, Baudilio"

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A Generalized Model to Predict the Liquid-Liquid Equilibrium in the Systems Furfural+Lubricating Oils
(ELSEVIER, 2006) Coto, Baudilio; van Grieken, Rafael; Peña, José L.; Espada, Juan J.
In the lubricating oil manufacturing process, the aromatic content of vacuum distillates is reduced by solvent extraction, frequently with furfural. These mixtures present very complex composition which makes difficult the description of the liquid-liquid equilibrium involved. In previous studies, the possibility to describe such equilibrium by using a reduced number of pseudo-components and the NRTL model has been stated. In this work, a generalized model to describe the liquid-liquid equilibrium in the systems furfural+lubricating oils is presented. The generalized model is based on a correlation of pseudo-component properties (specific gravity, density, refractive index and sulfur content) and NRTL parameters with the oil average boiling temperature which has been developed from the model description for SPD and HND mixtures. This method allows set up a suitable thermodynamic model for any lubricant oil cut by using as experimental information only the average boiling point and three physical properties (density, refractive index and sulfur content) of the distillate used as feed. The accuracy of the model was checked by simulating single-stage extractions carried out with different lube oil cuts within the range SPD-HND in different experimental conditions. Calculated and experimental yields, furfural content and physical properties of the raffinates and extracts were compared and a good agreement was obtained.
A model to predict physical properties for light lubricating oils and its application to the extraction process by furfural
(ELSEVIER, 2006) Coto, Baudilio; van Grieken, Rafael; Peña, José L.; Espada, Juan J.
In the lubricating oil manufacturing process, the aromatic content of vacuum distillates is reduced by solvent extraction, frequently with furfural. In this work, a method based on average pseudo-components properties is developed to calculate physical properties (density, refractive index and sulfur content) of hydrocarbon mixtures. Obtained values were compared to those calculated by other methods reported in the literature, obtaining similar results. In order to simulate the extraction operation, a model based on a reduced number of pseudo-components and the NRTL model is reported for the system furfural+SPD lubricating oil. Thereafter, the extraction operation was simulated by using such model and Aspen Plus® commercial software. Good agreement was found between predicted and experimental values of yield, furfural content, composition and physical properties for raffinates and extracts.
A new method for the determination of wax precipitation from non-diluted crude oils by fractional precipitation
(ELSEVIER, 2008) Coto, Baudilio; Martos, Carmen; Peña, José L.; Espada, Juan J.; Robustillo, María D.
Wax precipitation is one of the most important flow assurance problems. Unfortunately, experimental data are very scarce to confirm existing models for prediction of such precipitation problem. This work reports a new experimental method. Multistage fractional wax precipitation was carried out by decreasing the temperature of crude oil. No solvent dilution was used, so the effect of solvent on temperature wax precipitation was avoided. The reproducibility of the method was tested with comparable results. The precipitation curve and the wax appearance temperature were obtained for two crude oils with different chemical nature using the reported method.
Acidity reduction using ionic liquids: Extraction, kinetic, and theoretical study
(Elsevier, 2023-07-15) Arenas-Fernández, Plácido; Aguilar-Galindo, Fernando; Suárez, Inmaculada; Coto, Baudilio
Naphthenic acids (NAs) are toxic compounds naturally present in most petroleum sources with a highly variable concentration depending on their origin. Their occurrence in crude oil can produce severe corrosion problems and catalyst deactivation in oil refineries, consequently impacting their economic value and productivity. Thus, extracting and recovering the NA from crude oil is necessary. In this work, the extraction capacity of two ionic liquids (ILs) of different nature has been studied: 1-ethyl-3-methylimidazolium acetate, [EMIm][OAc], and trihexyltetradecylphosphonium dicyanamide, [P14,6,6,6][CCN2]. In addition, kinetic data were obtained for [P14,6,6,6][CCN2], and a theoretical kinetic model was developed to adjust the experimental data. Two extraction mechanisms have been analyzed using molecular dynamics computational simulations and quantum mechanical calculations. Molecular dynamic results show that a cluster of IL is first formed in each extraction process, and NA molecules are deposited on its surface. Different outcomes are obtained for diffusion coefficient values and radial distribution function. Furthermore, the quantum chemistry calculations show that a proton transfer is thermodynamically favorable in the case of [EMIm][OAc], thus extraction mechanism occurs through a neutralization reaction, whereas for [P14,6,6,6][CCN2], it is not, pointing to a physical extraction.
Application of a generalized model to the estimation of physical properties and description of the aromatic extraction from a highly paraffinic lubricating oil
(ELSEVIER, 2008) Coto, Baudilio; van Grieken, Rafael; Peña, José L.; Espada, Juan J.
In the lubricating oil manufacturing process, the aromatic content of vacuum distillates is reduced by solvent extraction, frequently with furfural. In this work, a generalized model (based on a reduced number of pseudo-components and the NRTL model) for estimation of activity coefficients is applied to the simulation of the extraction process of aromatics by furfural from a highly paraffinic Argentinian lubricating oil. Such model proposes a linear dependence between the pseudo-component properties and the NRTL parameters with the average boiling point of the distillate used as feed. Physical properties of the mixtures are calculated using the calculated pseudo-component properties. Obtained values are compared to those calculated by other methods reported in the literature, obtaining no remarkable deviations, but showing the influence of the paraffinic content on the accuracy of the predictions. The extraction process is simulated using the calculated pseudo-component properties and the NRTL parameters by means of Aspen Plus® commercial software. Good agreement was found between predicted and experimental values of yield, furfural content and composition.
Combination of molecular dynamics simulation and COSMO to understand asphaltenes aggregation
(Taylor and Francis Ltd., 2023-05-28) Arenas-Fernández, Plácido; Suárez, Inmaculada; Coto, Baudilio
Asphaltenes interaction produces problems in oil transport and recovery, and understanding the association process is vital to improving economic and industrial production. Here, we propose the COSMO model in combination with molecular dynamics (MD) simulations to complement the results obtained by Newtonian mechanics with quantum results to get reliable association data. Four asphaltene molecules were studied with toluene and heptane solvents. COSMO showed molecular interaction tendencies, which were later verified with MD. The average aggregation number was calculated through MD and turned out to be entirely dependent on the aromaticity due to π-π stacking. The aromatic rings are responsible for aggregation, while the sulfur heteroatom plays a less fundamental role. Viscosity is also related to the aggregation process; a higher tendency in aggregation increases the dynamic viscosity. Diffusion coefficients were correlated with the aromaticity, dipole moment, and molecular weight. Finally, a mathematical comparison between COSMO and MD results is accomplished.
Combination of molecular dynamics simulation, COSMO-RS, and experimental study to understand extraction of naphthenic acid
(Elsevier, 2021-09-27) Arenas, Plácido; Suárez, Inmaculada; Coto, Baudilio
The forecast of an increase in the consumption of petroleum products, together with the growing scarcity of new deposits, makes it necessary to take full advantage of existing ones. The main problem faced by the petrochemical industry is high acid crude oils, which produce corrosion in equipment and high monetary losses. Crude oil acidity is usually calculated by making use of the total acid number (TAN). Current operations for the elimination of naphthenic acid (NA) have several drawbacks so at present this has led to new lines of research, among which the application of ionic liquids (ILs) in the extraction of this compound stands out. In this work, the extractive behavior of 6 different ILs has been analyzed with simulations of molecular dynamics (MD), a technique based on classical mechanics that allows visualizing the movement of molecules while they interact. This allows us to study the extraction mechanism of NA by ILs, as well as transport properties such as diffusion coefficients. In addition, it will be experimented in the laboratory with the same cases to contrast the results obtained, making use of a synthetic crude oil (SC, 150 g/mol, TAN equal to 3.8), which was treated with every IL at four different temperatures (30, 70, 90 and 120 °C). The IL/NA ratio implemented was 1:1 mol/mol, which corresponded more or less with the IL/crude ratio of 0.015 g/g. To support (MD) results and experimental results, the COSMO-RS model was used to characterize ILs analyzing the results obtained by the σ-profile. COSMO-Therm was put into practice to study the theoretical predictions of the TAN in the liquid/liquid phase equilibria where results were in agreement with the experimental ones except for acetate, whose extraction mechanism is supposed to be different (neutralization). Computer simulation suggests that a longer alkyl chain of [BMIm] respect [EMIm] behaves better in extraction, and it seems that the anion plays a major role in the extraction process of the NA than the cation of the ILs. This tendency has been correlated with the experimental results.
Deasphalting of crude oils: A molecule-based model to explore an optimization approach and alternative solvents
(Elsevier, 2024-08) Heras, Igor De Las; Dufour, Javier; Coto, Baudilio
Actual motivation to reduce environmental impact leads to an increase in the study of green technologies, even those used in processes with fossil fuels. However, far from the proposed reduction of such energies, heavier crude oils are being processed to fulfill the energy demand. Heavy crude oils require an upgrading process to mitigate the effect of noxious components or contaminants such as asphaltenes and heavy metals. In this work, a deasphalting process was studied by simulation as a pretreatment to eliminate the heavy compounds of crude oil. The simulation of such a deasphalting process was carried out by Aspen Plus® software by combining a model for crude oil, formed by 33 molecules and able to describe its complex composition, mainly in the asphaltene fraction, and a model for the phase equilibria that use liquid-liquid equilibrium equations and the modified UNIFAC (Dortmund) model. A new objective function, including extraction yield, asphaltene reduction, and the ratio solvent/crude oil, was proposed and used to optimize extraction conditions and compare the performance of several solvents. Up to 12 pure solvents of different nature (tert-butanol, n-butanol, iso-propanol, methanol, ethylene glycol, acetone, methyl-isobutyl ketone, per-fluoro heptane, anisole, 1-metil-2-pyrrolidone, sulfolane, and n-heptane) were checked as well as some binary mixtures of them to explore more sustainable alternatives against conventional paraffin as precipitating agents. Satisfactory results were obtained when alcohols or ketones were used. A deeper study was developed to understand the effects of the alcohols' molecular structure (branching, chain length, and molecular weight) as solvents. Higher branching reduces the solvent/oil ratio, while higher molecular weight leads to higher extraction yield but poorer asphaltene reduction
Effects in the solubility of CaCO3: experimental study and model description.
(Elsevier, 2012-03-23) Coto, Baudilio; Martos, M. Carmen; Peña, José L.; Rodríguez, Rosalía; Pastor, Gabriel
Crude oil is usually co-produced with reservoir water, with increasing content in the production fluid along field life. Changes in temperature, pressure, and/or chemical composition may cause significant precipitation of inorganic salts (¿scales¿) during production. Therefore, the knowledge of the influence that different variables may have on salt solubility is critical to anticipate or identify potential flow assurance problems related to scales. The present work is specifically focused in the study of calcium carbonate precipitate formation as a main component of ¿scales¿. Due to the number of variables involved in calcium carbonate precipitation (temperature, pressure, CO2 partial pressure, other salt content) and the heterogeneity of reservoir conditions, there are serious limitations to perform a full experimental study covering all the possible precipitation scenarios. Solubility data presented in this work, both previously reported and experimentally determined, cover a wide range of experimental conditions. A simulation model that allows quantitative predictions in different scenarios is an interesting tool. A versatile simulation algorithm was developed using ASPEN PLUS® 7.1 from Aspen Technology, Inc., that allows different experimental conditions and the quantification of the influence of temperature, pressure and pH in CaCO3 solubility. This simulation scheme was applied to describe both literature and new experimental solubility data. Predicted results were in reasonable agreement with experimental information. The solubility of calcium carbonate decreases with temperature, increases with pressure and shows a maximum in presence of NaCl. The CO2 partial pressure has strong effect because it is direct relation with solution pH that modify the amount of ionic species present in the aqueous solution, and hence increasing the solubility of calcium carbonate. Special attention was devoted to such pH effect but, in order to have a fully predictive model, no parameters fit was carried out. The main conclusion of this work is the suitable simulation scheme to describe and predict the solubility of calcium carbonate at different conditions.
Engineered PP impact copolymers in a single reactor as efficient method for determining their structure and properties
(Elsevier, 2021) Pastor-García, María Teresa; Suárez, Inmaculada; Expósito, María Teresa; Coto, Baudilio; García-Muñoz, Rafael A.
Impact polypropylene (PP) copolymers (IPCs) are important materials for many commercial applications. These materials are usually synthetized through different methods involving two consecutive reactions in the same phase or in different phases. Here, a laboratory-scale synthesis method based on a sequential liquid- and gas-phase two-step process in a single reactor is developed. Propylene homopolymers and IPCs were synthesized with varying amounts of comonomers and hydrogen. The IPC materials obtained were fully characterized via analytical temperature rising elution fractionation (TREF), differential scanning calorimetry (DSC), 13C nuclear magnetic resonance (13C NMR), gel permeation chromatography with an infrared detector (GPC-IR5), Charpy impact, scanning electron microscopy (SEM), and cross-fractionation chromatography (CFC). The addition of only ethylene to the second step in the absence of hydrogen led to the creation of an ethylene-propylene (EP) copolymer with similar impact strength to that of a propylene homopolymer. The addition of hydrogen to the first step dramatically shortened the length of the PP chains and inhibited catalytic active centers that led to EP copolymer synthesis. This material exhibited very low molecular weight, low ethylene incorporation, and rubbery phases irregularly distributed along the isotactic polypropylene (iPP) matrix, resulting in the formation of an EP copolymer material with poor impact properties. IPCs synthesized without hydrogen and with a 50/50 (v/v) mixture of propylene/ethylene monomers in the second step enhance ethylene incorporation, facilitating adequate homogeneous and heterogeneous ethylene distribution and resulting in a high increment of amorphous ethylene-propylene-rubber (EPR) domains, which remarkably improves impact properties. Additionally, a criterion based on the ratio between EEE and EPE + PEP triads ranging between 1 and 2 was also established to predict the impact resistance of any heterophasic PP. Fractionation of the optimal sample provided a detailed understanding about the microstructure of this copolymer through the study of the molecular weight and composition of the fractions via GPC-IR, analytical TREF, and DSC measurements. Finally, the liquid–gas-phase two-step IPC material was compared, by means of SEM and CFC measurements, with synthesized IPC using liquid–liquid-phase two-step polymerization, and the results showed that the range of EP composition as well as ethylene distribution in the molar mass molecules of the IPCs was correlated to their mechanical behavior. This proves that crystalline families composed of high-molecular-weight EP copolymers in the liquid–gas-phase process can act as a compatibilizing agent between the iPP matrix and the elastomeric rubbery phase, allowing one to improve the impact resistance of the IPC, more so than that of IPCs obtained in the gas–gas and liquid–liquid phases. The results indicate that the synthesis of IPC resins in a single reactor is an efficient experimental method for fundamental research on IPCs.
Experimental data and modeling of viscosities and densities of pyrene + toluene + heptane mixtures at T = (293.15 to 343.15) K
(Elsevier, 2023) Tenorio, Maria José; Suárez, Inmaculada; Díaz Magdaleno, Julia; González, Miguel A.; Coto, Baudilio
Oil mixtures are a complex system that remains unclear. Its study is particularly challenging due to the many variables involved in their properties. These include, for instance, the compositions of the mixture and the nature of their compounds. To simplify the study of these systems, it is proposed to model them with simpler mixtures, as in the case of using hydrocarbon mixtures to describe the behavior of crude oil. Two mixtures have been prepared; the one hand, a binary mixture of pyrene in toluene, and on the other hand, a ternary mixture of pyrene in toluene/heptane has been prepared. Their densities and dynamic and kinematic viscosities have been measured from (293.15 to 343.15) K at atmospheric pressure. The compositions of binary and ternary systems are 1.0, 2.5, 5.0, 7.5, 10.0, 12.5, and 15.0 % weight fraction of pyrene. In the case of ternary systems, several toluene/heptane mass ratios have been studied, from 0.1 to 10. This article presents new experimental results of density and viscosity for the mixtures studied. Therefore, a theoretical study has been carried out to describe experimental data. Viscosity models, such as Ideal, Refutas, Ratcliff, UNIFAC-Visco, and Krieger, have been checked and, in some cases, have been modified to analyze the dependence of viscosity on temperature, composition, and possible association of pyrene. Standard deviations for each model and system have been calculated. Modified Ratcliff and Krieger models presented an excellent agreement with experiments.
Extraction of aromatic and polyaromatic compounds with NMP: experimental and model description
(Elsevier, 2021) Coto, Baudilio; Suárez, Inmaculada; Tenorio, Maria José; Huerga, Isabel
Optimization of the extraction process for reducing aromatic and/or polyaromatic compounds is of primary interest in crude oil refining. Several solvents are described for carrying out such operations (furfural, N-methyl-pyrrolidone -NMP-, dimethyl-sulfoxide -DMSO-, …) and experimental data and model description are required for the correct design of the separation operations and the optimization of the conditions. In this work, liquid-liquid equilibria (LLE) data were determined for oil multicomponent mixtures formed by n-dodecane + mono-aromatic + poly-aromatic with NMP at ambient temperature (298.15 K) and pressure and covering a wide range of the solvent/oil ratios. A new analytical method based on NMR was developed, calibrated, and tested to fully determine the composition of equilibrium phases despite the high number of compounds. Obtained values for distribution constants and selectivities are higher than one and ranging 1-15, respectively, for aromatic compounds and even higher for polyaromatic components. Thus NMP appears as a suitable solvent for carrying both separations. The experimental data were predicted by several versions of the UNIFAC model, including the UNIFAC, modified UNIFAC (Dortmund), modified UNIFAC (NIST), and UNIFAC, including fitting parameters. Overall, modified UNIFAC (Dortmund) yields the best results, even when deviations obtained for some of the compositions are around 40% of the value, and simulations carried out with such models should be considered cautiously
Fast and simplified determination of PCA and aromatic carbon content of treated distilled aromatic extract (TDAE) by NMR
(Springer, 2022-02-24) Coto, Baudilio; Huerga, Isabel; Suárez, Inmaculada; Contreras, Verónica; Pérez, Ponciano
Aromatic oils obtained during lubricants production (DAE) have high value as rubber extenders in tire manufacturing, but they have high carcinogenic potential due to the content of polycyclic aromatic compounds (PCA). Legislation on PCA content requires additional treatment to reach treated oils (TDAE) with PCA content lower than 3% according to the IP-346 method. IP-346 is a highly time-consuming and high uncertainty method, and several proposals have tried to replace it, but nowadays, there is no standard alternative. In this work, an extensive collection of samples covering a broad PCA content were obtained and characterized by physical properties, NMR, and aromatic and PCA content. Several correlations were tested to establish an optimum procedure to estimate the aromatic and the PCA content according to the requirement of high accuracy and low time and effort. The combination of several properties does not improve the accuracy of the correlation, and simpler equations were preferred. Integrated spectra appear as an acceptable characterization method as NMR percent of the total aromatic proton and polycyclic aromatic proton correlates satisfactory with the number of aromatic carbons and PCA content, respectively. The Refractive index yields the best results for the correlation to PCA content. Obtained deviations compare favorably with methods previously described in the literature and with the uncertainty involved in the experimental method. They can be considered adequate methods to analyze such magnitudes routinely.
Liquid-Liquid Equilibrium in the Systems Furfural+Light Lubricating Oils using UNIFAC
(ELSEVIER, 2007) Espada, Juan J.; Coto, Baudilio; Peña, José L.
In the lubricating oil manufacturing process, the aromatic content of vacuum distillates is reduced by solvent extraction, frequently with furfural. The complex composition of such mixtures makes the description of the liquid-liquid equilibrium involved difficult. In previous studies, the possibility to describe such equilibrium by using a reduced number of pseudo-components and the NRTL model has been stated. In this work, a different approach model was checked by using four model-molecules and a group contribution method. The molecular structure of model-molecules was determined regarding their different chemical nature and their physical properties. Dortmund modified UNIFAC model was used and the interaction parameters were calculated by correlating equilibrium data using AspenPlus©. The developed model was applied to describe the extraction operation of a light lubricating oil with furfural. Two sets of extraction experiments were considered. One of them was used to fit the needed parameters and the second one to check the predictive capability of the model. In both cases good agreement was obtained between experimental and calculated values for yields, furfural content composition and sulfur content of the involved mixtures. Most calculated values are as accurate as those obtained with the previously model, but a better description of the sulfur content was obtained.
Liquid-Liquid Extraction of polyaromatic compounds with ionic liquid. A theoretical and experimental approach
(Elsevier, 2022) Arenas-Fernández, Plácido; Suárez, Inmaculada; Coto, Baudilio
Recent legislation worldwide aims to reduce the levels of polyaromatics compounds in lubricant bases due to their harmful effect on health. Ionic liquids have obtained broad interest as green recyclable extractants. Here, we presented new experimental data of liquid-liquid extraction implementing ionic liquids for the removal of aromatics compounds of synthetic crude oil in a 1:1 mass/mass ratio for temperatures ranging from 303.15 to 293.15 K. Selectivity and distribution constant data are obtained to know the extractive potential of each ionic liquid. To support the experimental results, several computational calculations have been performed. First, two predictive thermodynamic models COSMO-SAC and UNIFAC, have been applied, and the reliability of both models has been compared with experimental results. The results show that using UNIFAC is more accurate than using COSMO to predict extraction behavior. Second, the extractive process has been studied using molecular dynamics. This tool allows us to understand better how the extraction process occurs and the molecules’ situation when they reach equilibrium. It is shown that the cation of the ionic liquid is the primary driver of liquid–liquid extraction. In addition, molecular dynamics will enable a qualitative comparison between the performance of ionic liquids and the experimental results. It is a helpful tool to save time and material resources before laboratory experimentation.
Oil acidity reduction by extraction with imidazolium ionic liquids: Experimental, COSMO description and reutilization study
(Elsevier, 2021) Coto, Baudilio; Suarez, Inmaculada; Tenorio, Maria Jose; Nieto, Sandra; Alvarez, Nieves; Peña, Jose Luis
is a main problem because causes high corrosion rates and fouling during refining process. Reduction of crude oil TAN by means of ionic liquids (ILs) can be due to neutralization (basic ILs) or to extraction (ILs acting as solvent). In this work, a synthetic crude oil (SC, 150 g/mol, TAN equal to 3.8) was treated with [EMIm][EtSO4], [EMIm][SCN], and [EMIm][Cl] in the temperature range 30–120 °C and IL/crude ratio in the range 0.03–1 g/g. TAN reductions were up to 50% at high temperature and IL/SC ratio. Water washing and reuse of [EMIm][SCN] were studied. No structural changes were detected but IL TAN increased and reduced the extraction efficiency, probably due to the strong interaction between IL and acid that makes washing with water not completely efficient. However, the reduction in extraction efficiency was much faster for IL without any treatment and such reuse is not possible. The COSMO-RS model was used for the ILs characterization through the σ-profile and was successfully included in the simultaneous correlation of all the experimental data. COSMO-Therm was used to study the liquidliquid equilibria and the predictions of the TAN of the organic phase were in fair agreement with the experimental results. However, COSMO-RS was unable to predict the effect of temperature and described a decrease in TAN reduction as temperature increases. Reuse of IL was also modelled with COSMO-RS and the decrease in extraction efficiency was correctly described related to the IL acid content.
Simulation of pilot-plant extraction experiments to reduce the aromatic content from lubricating oils
(ELSEVIER, 2008) Espada, Juan J.; Coto, Baudilio; van Grieken, Rafael; Moreno, Juan M.
In the lubricating oil manufacturing process, the aromatic content from vacuum distillates is reduced by solvent extraction, frequently with furfural. These mixtures present very complex composition which makes difficult the description of the liquid¿liquid equilibrium involved. In previous studies the possibility to describe such equilibrium by using a reduced number of pseudo-components and the NRTL model has been shown. In this generalized model few physical properties of the lubricating oil used as feed are needed as experimental information. In this work, such model was applied to pilot-plant experiments carried out with different lube oils within the range (SPD¿HND). The accuracy of the model was checked by simulating multi-stage extractions using AspenPlus©. Calculated and experimental yields, and refractive index of the involved mixtures were compared and a good agreement was obtained for the experiments carried out with the heavier lubricating oil cuts.
Simulation of the deasphalting process of crude oils: Models development and extraction conditions analysis
(Elsevier, 2021) Las Heras, Igor De; Dufour, Javier; Coto, Baudilio
Heavy crude oils are under constant investigation due to light oil exhaustion. So, its use is compulsory to meet the world energy demand. Heavy crude oils present several drawbacks as high content of metals, heteroatoms, and asphaltenes, and, therefore, upgrading processes are becoming essential. A deasphalting process, conventionally used for vacuum residue upgrading, can be an interesting pretreatment to eliminate the heavier phases and ease the crude processing in conventional refining facilities. Most of the models developed for deasphalting simulation show problems to be implemented in simulation software packages. In this work, a versatile deasphalting simulation method is developed, composed by the definition of a synthetic crude oil model, formed by discrete pseudo components, and a deasphalting model approaching the process to a liquid-liquid extraction based on the thermodynamic model modified UNIFAC (Dortmund). Both models were satisfactorily validated. The deasphalting method was used to explore the solvent/crude ratio, extraction temperatures, and alternative solvents in substitution of conventional light paraffins. Higher extraction temperatures did not enhance remarkably the deasphalting process and the optimum solvent to crude ratio depends on the solvent type. Alcohols were found as promising compounds as their use is recommended by some studies and they showed great deasphalting results.
Virtualization of Laboratory Practices Using Visual Basic Excel
(American Chemical Society, 2022-11-16) Coto, Baudilio; Suárez, Inmaculada; Tenorio, Maria José; Gonzalez, Miguel Ángel
The COVID-19 pandemic and its related restrictions forced the reorganization of learning methodology and gave a central role to remote learning. Laboratory experiments are the most affected activity, and several alternatives were described. This work proposes to create calculation tools by simply programming in Visual Basic of Excel to emulate the data acquisition of specific laboratory experiments. The approach appears useful in experiments with a simple setup followed by data analysis. The experiment of gas volumetric properties allows fixing pressure and temperature conditions and measuring the occupied volume. The developed program emulates such operations and reports a computed volume. Further data reduction is the same in both procedures. Such a virtual experience was successfully used with groups of over 100 students. The results obtained were satisfactory compared with those obtained in the laboratory. Detailed analysis of the grades shows that acquired skills are comparable in both methodologies. Consequently, the virtual approach is a flexible option for remote laboratory teaching to complement traditional experimentation.
Viscosities and Densities of Binary and Ternary Mixtures of Aliphatic and Polyaromatic Hydrocarbons: Pyrene +1-Methylnaphthalene + Dodecane at T = (293.15 to 343.15) K. Experiment and Modeling
(American Chemical Society, 2024-03-18) Tenorio, María José; González, Miguel A.; Magdaleno, Julia D.; Suárez, Inmaculada; Coto, Baudilio
This work presents new experimental viscosity and density data for aromatic and polyaromatic compounds in binary and ternary pyrene, 1-methylnaphthalene, and dodecane mixtures. The lack of experimental viscosity data for these mixtures requires the development of a new database, which is vital for understanding the behavior of mixtures in more complex systems, such as asphaltenes and fuels. The mixtures proposed in this work have been measured over a temperature range of (293.15 to 343.15) K at atmospheric pressure. Several mixture compositions have been studied at these conditions: 1.0, 2.5, 5.0, 7.5, 10.0, 12.5, and 15.0% pyrene mass fraction. The concentration of pyrene correlates with an increase in the viscosity and density values. At the lowest temperature in binary mixtures, the corresponding values reach 4.4217 mPa·s for viscosity and 1.0447 × 103 kg·m–3 for density, respectively. In ternary mixtures, the introduction of dodecane leads to the lowest maximum values of 3.5555 mPa·s for viscosity and 1.0112 × 103 kg·m–3 for density at the same temperature. The experimental data have been employed for the specific modification of viscosity models. These modifications could facilitate the prediction of the viscosity of mixtures that are more complex than those presented in this work. Various viscosity models have been employed, such as Linear, Ratcliff and Khan, modified UNIFAC-Visco, and Krieger–Dougherty. The settings in the models used reliably reproduce the experiment reliably. However, the Ratcliff model agrees excellently with the experiment, having a low standard deviation (2.0%) compared to other models. Furthermore, a model based on the equation of state of Guo is proposed to predict the viscosity values by modifying the specific parameters and adjusting them to the mixtures proposed in this work. The results from this study are compared to previous work, where pyrene, toluene, and heptane mixtures were analyzed. In this case, we find that the decrease of aggregation grade in the present systems is predicted by the model fixed in this work.