Examinando por Materia "Grand canonical Monte Carlo simulation"

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    Analysis of CO2 adsorption in amine-functionalized porous silicas by molecular simulations
    (American Chemical Society, 2015-06-01) Builes S.; López-Aranguren, P.; Fraile, J.; Vega, L.F.; Domingo, C.; Universidad EAFIT. Departamento de Ingeniería de Procesos; Desarrollo y Diseño de Procesos
    We present the results of a combined experimental-molecular simulations approach concerning the capacity for CO2 adsorption of aminosilica hybrid products synthesized using supercritical fluids. Two porous supports were examined for amine functionalization, an ordered mesoporous silica (MCM-41) and a disordered silica gel (SG40). The textural properties of the studied materials were analyzed by low-temperature N2 adsorption-desorption isotherms and compared to those of molecular simulations using the grand canonical Monte Carlo simulation method. The CO2 adsorption capacity of these materials was evaluated by recording CO2 adsorption isotherms up to 100 kPa. Molecular simulations of the CO2 adsorption behavior of selected samples were performed to gain a fundamental understanding of the effect of functionalization. This study shows that in the functionalized materials, the distance between nitrogen atoms of the grafted amines is a critical factor for the occurrence of CO2 chemisorption, providing some insight into key parameters for designing adsorbent materials for CO2 capture and separation. The relationship between the adsorption results with N2 and CO2 allow us to compare the potential applications of the materials in CO2 adsorption and separation processes. A correlation of the N2 adsorption at a given pressure with the CO2 adsorption at a different pressure allowed the prediction of which materials will perform well for these processes. The hybrid products with high amine density have desirable features required for industrial sorbents, such as an enhanced CO2 adsorption capacity and selectivity. © 2015 American Chemical Society.
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    A Comparative Assessment of Emerging Solvents and Adsorbents for Mitigating CO2 Emissions From the Industrial Sector by Using Molecular Modeling Tools
    (Frontiers Media S.A., 2020-01-01) Bahamon D.; Alkhatib I.I.I.; Alkhatib N.; Builes S.; Sinnokrot M.; Vega L.F.; Universidad EAFIT. Departamento de Ingeniería de Procesos; Desarrollo y Diseño de Procesos
    The possibilities offered by molecular modeling tools to obtain relevant data at process conditions, while also gaining molecular insights on the techniques used for CO2 capture and separation, are presented here using selected case studies. Two different technologies, absorption with amine-based systems and adsorption on porous materials, were explored, using the molecular-based equation of state, soft-Statistical Associating Fluid Theory (SAFT), and Grand Canonical Monte Carlo simulations, respectively. The aqueous monoethanolamine (MEA) system was set as the benchmark for absorption and compared to the performance of 8 alternative amine-based systems, while 16 adsorbents belonging to different families (zeolites, metal–organic frameworks, amorphous silicas, and activated carbons), bare or functionalized with alkylamines, were investigated for the separation of CO2 by adsorption. In addition to obtaining molecular information on the CO2 capture process, the models were further used to examine the CO2 capture performance in terms of cyclic working capacity and energy index as key performance indicators, allowing the identification of promising systems that can improve the current ones to be further evaluated for separation in non-power industries. Results show that for the same total amine mass concentration, non-aqueous amine solvents have a 5–10% reduction in cyclic working capacity, and a 10–30% decrease in the energy index compared to their aqueous counterparts due to their lower heat of vaporization and specific heat capacity. In addition, M-MOF-74, NaX, and NaY structures present the best results for adsorption in temperature swing adsorption (TSA) processes. Similar values of energy requirements to those of amine-based systems (2–2.5 MJ kg CO2–1) were obtained for some of the adsorbent; however, the disadvantage of the TSA process versus absorption should be considered. These results confirm the reliability of molecular modeling as an attractive and valuable screening tool for CO2 capture and separation processes. © Copyright © 2020 Bahamon, Alkhatib, Alkhatib, Builes, Sinnokrot and Vega.