Effect of Water and Organic Pollutant in CO2/CH4 Separation Using Hydrophilic and Hydrophobic Composite Membranes.

Clara Casado-Coterillo,Ángel Irabien,Aurora Garea

doi:10.3390/membranes10120405

Clara Casado-Coterillo, Ángel Irabien + Show 1 more

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https://doi.org/10.3390/membranes10120405

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Journal: Membranes	Publication Date: Dec 8, 2020
Citations: 12	License type: CC BY 4.0

Affiliation: Universidad de Cantabria

Abstract

Membrane technology is a simple and energy-conservative separation option that is considered to be a green alternative for CO2 capture processes. However, commercially available membranes still face challenges regarding water and chemical resistance. In this study, the effect of water and organic contaminants in the feed stream on the CO2/CH4 separation performance is evaluated as a function of the hydrophilic and permselective features of the top layer of the membrane. The membranes were a commercial hydrophobic membrane with a polydimethylsiloxane (PDMS) top layer (Sulzer Chemtech) and a hydrophilic flat composite membrane with a hydrophilic [emim][ac] ionic liquid–chitosan (IL–CS) thin layer on a commercial polyethersulfone (PES) support developed in our laboratory. Both membranes were immersed in NaOH 1M solutions and washed thoroughly before characterization. The CO2 permeance was similar for both NaOH-treated membranes in the whole range of feed concentration (up to 250 GPU). The presence of water vapor and organic impurities of the feed gas largely affects the gas permeance through the hydrophobic PDMS membrane, while the behavior of the hydrophilic IL–CS/PES membranes is scarcely affected. The effects of the interaction of the contaminants in the membrane selective layer are being further evaluated.

Highlights

Membrane gas separation of CO2 from synthesis gas, natural gas or biogas is a potential energy-efficient alternative to other separation techniques with potential for biogas upgrading as an alternative energy source from anaerobic digestion and landfills [1,2]
CO2 /CH4 separation is challenging due to the variability of the biogas composition, which depends on the source and seasonal conditions [7]
The results shown in Figure for the separation in the presence of humidity affect the hydrophilic membrane (Figure 3b) is mostly affected by CO2 concentration in the feed rather than the hydrophilic membrane differently thanincreasing the PDMSCO

Summary

Introduction

Membrane gas separation of CO2 from synthesis gas, natural gas or biogas is a potential energy-efficient alternative to other separation techniques with potential for biogas upgrading as an alternative energy source from anaerobic digestion and landfills [1,2]. Separation of CO2 from methane is important to use biogas as a natural gas substitute [3]. CO2 /CH4 separation is challenging due to the variability of the biogas composition, which depends on the source and seasonal conditions [7]. Both feed flow rate and feed concentrations change during the CO2 /CH4 separation when the feed concentration of the valuable component is at least 65 mol % at a pressure in the range between 3.1 and 4.1 bar [8]

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