Wetted‐wall column study on CO₂ absorption kinetics enhancement by additive of nanoparticles

Abstract

Nanoparticles suspended in solutions are considered to have the potential to enhance gas‐liquid mass transfer and have been studied for gas separation. In order to reveal the mechanisms of kinetics enhancement, the diffusion and reaction process should be carefully examined. In this paper, CO2 absorption kinetics of amine‐based solutions with additive of SiO2 and Al2O3 nanoparticles were investigated by wetted‐wall column experiments. Measurements at different conditions, including solid loading, pressure, and solvent flow rate, show a significant enhancement on CO2 absorption kinetics. The experiment and model analysis indicate that the micro convective motion induced by particle Brownian movement plays a primary role in mass transfer enhancement. Three solutions, MEA, MDEA, and PZ which have different kinetics were selected to study the impact of nanoparticles on absorption kinetics of solutions with different reaction rate. It is interesting to find that the increased ratio of absorption kinetics by nanoparticle follows the same order with increased solvent reaction rate with CO2, which is PZ > MEA > MDEA. The wetted‐wall kinetic model indicates that a diffusion controlled kinetics for PZ solution could result in much more significant kinetic enhancement with additives of nanoparticles. By operation conditions optimization, the liquid side mass transfer rate of MEA solution can be increased over 15%.© 2015 Society of Chemical Industry and John Wiley & Sons, Ltd

Enhanced CO2 Absorption and Desorption by Monoethanolamine (MEA)-Based Nanoparticle Suspensions

“…Model for CO 2 Diffusivity in the Liquid Phase. Because of our previous work, 14 the CO 2 absorption into MEA satisfies the pseudo-first-order reaction conditions. So, k L is the function of the kinetic rate constant (k 2 , expressed in terms of m 3 /(mol s)), the bulk concentration of solvent in the liquid phase (C sol bulk , given in units of mol/m 3 ), the CO 2 diffusion coefficient in the liquid phase (D CO 2 L , given in units of m 2 /s), and the Henry's law constant for CO 2 in the liquid phase (H CO 2 , expressed in terms of Pa m 3 /mol):…”

“…Wang et al established masstransfer models in nanofluids to estimate the increased CO 2 diffusivity into MEA in a wetted-wall column and found that the microconvective motion contributed ∼80% of the increased CO 2 diffusivity in liquid bulk, which supports the reliability of the shuttle effect and the boundary mixing effect. 14 Kim used high-speed camera images of CO 2 bubbles in methanol/Al 2 O 3 mixture, but did not observe bubbles breaking in nanofluids. 13 For better understanding of nanoparticles roles in mass-transfer enhancement, it is necessary to establish the methodology that can be used to quantify these mechanisms.…”

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“…It is also not suitable for industrial application since a higher viscous solvent leads to a longer residence time and larger equipment size [50]. Utilizing nanoparticles into solvents can significantly increase the viscosity of the solvent [51]. This limits gas diffusion and pumping, which impacts the total cost and energy of the process [52].…”

Effect of Modified Fe3O4 Magnetic NPs on the Absorption Capacity of CO2 in Water, Wettability Alteration of Carbonate Rock Surface, and Water–Oil Interfacial Tension for Oilfield Applications

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