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Download fileCO2 Capture by Supported Ionic Liquid Phase: Highlighting the Role of the Particle Size
journal contribution
posted on 2019-06-27, 00:00 authored by Ruben Santiago, Jesus Lemus, Daniel Hospital-Benito, Cristian Moya, Jorge Bedia, Noelia Alonso-Morales, Juan J. Rodriguez, Jose PalomarCO2 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.