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Tubular EVA copolymer/SiO2/PEG composite membrane for CO2 removal from household biogas
Author(s)
Date Issued
March 1, 2025
Type
Article
Abstract
The fuel efficiency of household biogas is generally regulated by its CO2 content (25%–50%). To improve its heating value, atmospheric CO2 removal of household biogas using a polymeric membrane was attempted to avoid a complicated separation process. A tubular membrane of poly(ethylene-co-vinyl acetate), composed of 28% and 18% vinyl acetate (E28 and E18) modified with SiO2 and polyethylene glycol (PEG), was fabricated by blown film extrusion. Model biogas containing CO2/CH4 (40/60 v/v) was separated in an in-house continuous gas separation module, in which CO2 was mainly permeated out of the tubular membrane at atmospheric pressure. Blending the E28 matrix with E18 (10 wt%) improves the membrane processability and inhibits the CH4 permeation, leading to enhanced CO2/CH4 selectivity (from ~2.3 to 2.9). Well-dispersed SiO2 particles (0.5 wt%) increase the membrane modulus and suppress CH4 loss. However, adding more SiO2 (0.75–1.0 wt%) leads to higher total gas permeation flux with lower CO2/CH4 selectivity due to particle agglomeration. Incorporation of PEG (0.5–1.5 wt%) increased the membrane polarity and CO2 permeability. The CO2/CH4 selectivity was also improved (~5.3), only up to 1.0 wt% PEG content. Highlights: Composite EVA/SiO2/PEG membrane separates CO2/CH4 at atmospheric pressure. The concentration gradient across the membrane drives CO2/CH4 permeation. Adding SiO2 hinders CH4 permeability and enhances CO2/CH4 selectivity. Increasing PEG content enhances membrane polarity and interaction with CO2.
Citation
Polymer Engineering and Science, 65(3), 1123-1135, 2025