Publicación: Siloxanes capture by ionic liquids: Solvent selection and process evaluation
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2020-12-01
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info:eu-repo/semantics/openAccess
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Elsevier
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Nowadays, 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.
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Categorías UNESCO
Palabras clave
Siloxanes, Ionic liquids, Biogas, Absorption
Citación
Centro
E.T.S. de Ingenieros Industriales
Departamento
Ingeniería Eléctrica, Electrónica, Control, Telemática y Química Aplicada a la Ingeniería