Persona: Santiago Lorenzo, Rubén
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Santiago Lorenzo
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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 Fatty alcohol/water reaction-separation platform to produce propylene carbonate from captured CO2 using a hydrophobic ionic liquid(Elsevier, 2021-11-15) Hernández, Elisa; Moya, Cristian; Vela, Sonia; Navarro, Pablo; Palomar Herrero, José Francisco; Santiago Lorenzo, RubénThe combined use of a hydrophobic ionic liquid catalyst and a fatty alcohol is presented to synergistically improve cycloaddition reaction of CO2 to epoxides producing cyclic carbonates and envision catalyst recovery by cyclic carbonate removal using water as extracting solvent. This approach is described for the production of propylene carbonate using trihexyl(tetradecyl)phosphonium 2-cyanopyrrolide catalyst -which chemically captures CO2 reactant- and 1-decanol/water mixture as extracting solvent. The novel use of fatty alcohols on CO2 cycloaddition reaction not only permits the effective separation of the catalyst and the product purification, but also improves the CO2 conversion in the reactor, and opens the challenge of process intensification by integrated CO2 capture and conversion.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 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 Siloxanes capture by ionic liquids: Solvent selection and process evaluation(Elsevier, 2020-12-01) Moya, Cristian; Palomar Herrero, José Francisco; Santiago Lorenzo, RubénNowadays, new technologies are being developed to substitute conventional energy resources. Biogas has emerged to avoid the intensification of global warming and promote waste valorization. However, undesirable chemicals must be removed prior to its utilization. Siloxanes stand out as biogas contaminants since they can damage process equipment’s. Therefore, in this work, COSMO-based/Aspen Plus computational methodology was applied to evaluate, as first-time, ionic liquids (ILs) as siloxanes absorbents on biogas upgrading context. Thus, molecular simulation using COSMO-RS method was used to analyze the interactions between siloxanes/ILs based on excess properties. Moreover, it was used to select the most promising ILs among a wide sample (9 0 0) of solvents for latter process simulation stage based on thermodynamics (Henry’s law constants) and kinetics (low viscosity). The results revealed that ILs with fluorinated anions are the best for the task. Then, the performance of selected ILs on siloxane capture at industrial scale was evaluated by means of Aspen Plus process simulations. Thus, the absorption efficiency in a packed column was analyzed by comparing the silicon concentration in outlet gas stream for each IL, using a rigorous RADFRAC column in Rate-base mode. Operating pressure inside the column was also studied as key operating variable. Last, simulations of the complete siloxane capture processes were carried out to treat a realistic biogas stream, including the analysis of both absorption and regeneration columns. Process simulation results revealed that thermodynamics is the key property for the selection of ILs for siloxanes capture. Moreover, most of the selected ILs can satisfy silicon outlet concentration legislation (< 5 mgSi/Nm3 ) in almost all the studied operating conditions. Last, solvent regeneration using air stripping column demonstrated the reversibility of the process in mild conditions of temperature (100 °C) and vacuum pressure (0.1 bar). In sum, ILs are proposed as promising siloxanes absorbents of siloxanes-containing streams, mainly focused on biogas upgrading.Publicación CO2 Capture by Supported Ionic Liquid Phase: Highlighting the Role of the Particle Size(2019-06-27) Lemus, Jesús; Hospital Benito, Daniel; Moya, Cristian; Bedia, Jorge; Alonso Morales, Noelia; Rodríguez Jiménez, Juan J.; Palomar Herrero, José Francisco; Santiago Lorenzo, RubénCO2 capture by fixed-bed sorption has been evaluated using Supported Ionic Liquid Phase (SILP) based on the ionic liquid 1-butyl-3-methylimidazolium acetate ([bmim][acetate]). The SILP sorbent was prepared with three remarkably different mean particle sizes and characterized by porous texture, morphology, thermal stability, and elemental composition. The thermodynamics and kinetics of the CO2 capture process has been studied, testing the effects of SILP particle size, sorption temperature, gas flow rate, and CO2 partial pressure. The CO2 sorption isotherms at different temperatures were obtained by gravimetric measurements, revealing that the equilibrium sorption capacity is only due to the IL incorporated on the silica support of SILP. The experimental isotherms were successfully fitted to the Langmuir−Freundlich model. Fixed-bed experiments of CO2 capture were carried out to evaluate the performance of the SILP sorbents at different operating conditions. All the breakthrough curves were well described by a linear driving force model. The obtained kinetic coefficients revealed that the CO2 sorption rate in fixed-bed linearly increases when decreasing the SILP particle size and increasing the operating temperature. Higher CO2 partial pressure in the inlet gas stream led to a faster mass transfer rate, affecting both the mass transfer driving force and kinetic coefficient. Aspen Adsorption simulator was successfully applied to model the fixed-bed operation, highlighting the role of the particle size on separation efficiency. Simulations results indicate that at very low CO2 partial pressure chemical absorption is the controlling step, while increasing that partial pressure shifts the regime toward diffusion into the SILP. This methodology will allow designing CO2 sorption systems based on SILPs that fulfill the separation requirements at given conditions (CO2 partial pressure and temperature), minimizing the SILP needs by optimizing the particle size and type of IL.