CO2 capture in a hollow fiber membrane contactor coupled with ionic liquid: Influence of membrane wetting and process parameters

Abstract

The present work demonstrates the potential of coupling ionic liquid 1-ethyl-3-methylimidazolium ethylsulfate ([emim][EtSO 4 ]) and hollow fiber membrane contactors for post-combustion CO 2 capture. CO 2 absorption experiments in counter-current configuration were carried out, followed by a comprehensive two-dimensional dynamic modeling based on steady state and pseudo-steady state operating modes. The model considers the level of wetting of porous hollow fibers. An overall mass transfer coefficient of 3.99 10 -5 m.s -1 and CO 2 flux 6.1 10 -5 mol.m -2 .s -1 were obtained for 100 ml.min -1 of gas flowing inside the fibers. The model predicted the effects of membrane wetting, porosity, tortuosity, module length, fiber inner diameter, gas and absorbent flow rates. Membrane wetting has a noteworthy effect on CO 2 capture efficiency. A smaller amount of wetting can cause a huge resistance in CO 2 transport through the membrane. The separation efficiency was enhanced by using membranes with high porosity and low tortuosity and decreased by enhancing the gas flow rate and absorbent flow rate reduction. CO 2 capture is enhanced by increasing module length and reduction of inner diameter of fibers.

CO2 Desorption Performance from Imidazolium Ionic Liquids by Membrane Vacuum Regeneration Technology

“…The diffusivity (D) was given by the diffusivity-viscosity correlation developed by Morgan et al [ 56 ], and its dependence on temperature was assumed to be of the Arrhenius type. The term of the first order gas-liquid chemical reaction ( ) was estimated from the value of the overall mass transfer coefficient based on Qazi et al [ 46 ].…”

“…The discretization method was based on the finite difference (FD) approach using the 4th order central finite difference (CFD4). Selecting an appropriate number of nodes (particularly in the radial direction) for the finite element analysis was very critical [46]. Under these considerations, 50 nodes were proposed in the axial and the radial directions to be in accordance with the 2-directional (r, z) mass transport.…”

“…where T G is the gas-phase temperature; M CO 2 is the molecular weight of CO 2 (in g/mol) and P is the pressure in the gas phase (kPa). A porous membrane is used in this work for which the effective diffusivity is found by the following equation [46]:…”

“…Gas and Membrane Diffusivities The CO 2 diffusion coefficient in the gas phase can be calculated by the Maxwell–Gilliland equation [ 58 ]: where is the gas-phase temperature; is the molecular weight of CO 2 (in g/mol) and P is the pressure in the gas phase (kPa). A porous membrane is used in this work for which the effective diffusivity is found by the following equation [ 46 ]: where ε and τ are porosity and tortuosity of the porous membrane.…”

“…A porous membrane is used in this work for which the effective diffusivity is found by the following equation [ 46 ]: where ε and τ are porosity and tortuosity of the porous membrane.…”