Persona: Santiago Lorenzo, Rubén
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Publicación Assessment of Ionic Liquids as H2S Physical Absorbents by Thermodynamic and Kinetic Analysis based on Process Simulation(Elsevier, 2019-09-07) Lemus, Jesús; Xiao Outomuro, Ana; Bedia, Jorge; Palomar Herrero, José Francisco; Santiago Lorenzo, RubénA comprehensive evaluation of ionic liquids (ILs) as potential H2S absorbents was performed using both molecular and process simulation. First, the Conductor-like-Screening MOdel for Real Solvents (COSMO-RS method) was applied to select promising ILs absorbents and to understand the H2S gas solubility from a molecular point of view. The ILs screening more than 700 ionic combinations determines that H2S physical absorption is mainly controlled by the hydrogen-bond acceptor capacity of the anion, due to the easily hydrogen bond formation when mixed with the acidic solute. Based on molecular simulation analysis, 6 ILs of different nature were evaluated in a typical industrial packed absorption column using COSMO-based/Aspen Plus methodology. Equilibrium based simulations demonstrated higher H2S separation efficiency (i.e. lower solvent expenses and smaller equipment sizes) when increasing H2S absorption capacity of the IL solvent. In contrast, rigorous process simulation analysis (including kinetic equations) reveals a strong mass transfer kinetic control in the H2S absorption in commercial packed column, which severely limits the maximum H2S absorption given by thermodynamics. As a result, ILs that present the best performance in the thermodynamic aspect, become worse for the operation. In fact, it was found that H2S recovery at given operating conditions increases when decreasing the viscosity of IL, being 1-ethyl-3-methylimidazolium dicyanamide, the one that presents the best absorbent performance, requiring the lowest operating temperatures and liquid volume flows. Lastly, the absorption operation was designed to achieve fixed H2S recovery using different liquid/gas feed ratios, resulting in column heights and diameters inside the typical range marked by heuristic rules for usual industrial packed columns. In sum, current prospective study based on COSMO-RS and Aspen Plus have been proved as a useful tool to analyze the potential industrial application of ILs in the H2S capture and to select the most adequate ILs, before starting with experimental tests, highly demanding in cost and time.Publicación Methanol-Promoted Oxidation of Nitrogen Oxide (NOx) by Encapsulated Ionic Liquids(ACS, 2019-09-13) Mossin, Susanne; Bedia, Jorge; Fehrmann, Rasmus; Palomar Herrero, José Francisco; Santiago Lorenzo, RubénThe removal of nitrogen oxides (NOx) has been extensively studied due to their harmful effects to health and environment. In this work, encapsulated ionic liquids (ENILs) are used as catalysts for the NO oxidation at humid conditions and low temperatures. Hollow carbon capsules (CCap) were first synthesized to contain different amounts of 1-butyl-3-methylimidazolium nitrate IL ([bmim][NO3]), responsible for the catalytic oxidation. Then, the materials were characterized using different techniques, by analyzing microstructure, porosity, elemental composition, and thermal stability. The catalytic performance of ENIL materials was tested for NO conversion at different conditions. Thus, NO concentration was fixed at 2000 ppm at dry and humid conditions. Then, the methanol promotion of the reaction was demonstrated, increasing the NO conversion values in all cases, and the alcohol/water ratio was optimized. The temperature effect was studied as well, using the optimal conditions based on the previous measurements. The results reflect that humid conditions do not have a negative effect in terms of NO conversion when using ENILs, opposite behavior as observed for CCap and traditional catalysts studied before. The low amount of IL inside the material (40% in mass) was found to be the optimum for the task, reaching conversions of almost 45%.Publicación Acetylene absorption by ionic liquids: A multiscale analysis based on molecular and process simulation(Elsevier, 2018-10-02) Bedia, Jorge; Moreno, D.; Moya, C.; Riva Silva, Juan de; Larriba, M.; Palomar Herrero, José Francisco; Santiago Lorenzo, RubénA COSMO-based/Aspen Plus multiscale simulation methodology was used to evaluate a wide variety of ionic liquids (ILs), more than 300, as potential acetylene absorbents. First, by means of Conductor-like-Screening Model for Real Solvents (COSMO-RS) method, molecular simulations were conducted to select ILs with adequate thermodynamic (Henry’s law constants) and kinetic (diffusion coefficients) properties as acetylene absorbents, using N,N-dimethylformamide (DMF) as benchmark industrial solvent for such solute absorption. Then, the operating units of acetylene absorption of an acetylene and argon mixture, and exhausted solvent regeneration were modeled in Aspen Plus. Simulations of absorption column using equilibrium based design model demonstrated that at least two ILs (1-butyl-3-methylimidazolium cation and acetate and sulfonate anions) present competitive solvent performance in acetylene absorption respect to DMF. In contrast, process analyses with a more realistic rate-based column model revealed that the mass transfer rate clearly controls the acetylene absorption with ILs compared to DMF, due to their viscosity differences. Finally, modeling solvent regeneration stage showed clear advantages of using ILs as acetylene absorbents since efficient acetylene recovery is achieved by flash distillation (vacuum pressure and temperature increase), operation hindered in the case of DMF due to is high volatility, requiring the solvent regeneration by a distillation equipment with higher operating and investment costs. Current COSMO-based/Aspen Plus approach has been demonstrated useful to perform preliminary analyses of the potential application of ILs in new separation processes, before starting with experimental essays, highly demanding in cost and time.Publicación Encapsulated Ionic Liquids to Enable the Practical Application of Amino Acid-Based Ionic Liquids in CO2 Capture(Academic Publishing International Limited, 2018-09-21) Lemus, Jesús; Moya, Cristian; Moreno, Daniel; Alonso Morales, Noelia; Palomar Herrero, José Francisco; Santiago Lorenzo, RubénThe performance of three amino-acid-based ionic liquids (aa-ILs) has been evaluated in CO2 capture by means of gravimetric measurements. The tested aa-ILs were 1-butyl-3- methylimidazolium prolinate, [Bmim][PRO]; 1-butyl-3-methylimidazolium methioninate, [Bmim][MET]; and 1-butyl-3-methylimidazolium glycinate, [Bmim][GLY]. First, the CO2 chemical absorption process was analyzed by in situ Fourier transform infrared spectroscopy−attenuated total reflection (FTIR-ATR), following the characteristic vibrational signals of the reactants and products, and comparing them with theoretical measurements obtained by quantum chemical calculations. This study let us confirm a mechanism of CO2 chemical absorption on amino-acid-based ILs. Then, gravimetric experiments were carried out to characterize the CO2 capture by aa-ILs. It was found that CO2 absorption quantification of these ILs was rather slow, because of their high viscosities, so alternative methodologies had to be employed to use them as absorbents in CO2 capture. In this sense, aa-ILs were encapsulated in porous carbon capsules (aa-ENIL), since it has been previously reported as material that defeats the kinetic limitations and preserves the favorable CO2 capture capacity of the neat ILs, promoting efficient chemical absorption. These aa-ENIL materials permit evaluation of CO2 capture at equilibrium and experimentally characterize the thermodynamics absorption phenomena, in terms of reaction enthalpy and the contribution of physical (H) and chemical (Keq) CO2 absorption for each IL. ENIL materials allow a fast CO2 capture with high sorption capacity and easy regeneration due to the favorable thermodynamics and kinetics of the process.