Blend membranes comprising polyetherimide and polyvinyl acetate with improved methane enrichment performance

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• Biogas is a sustainable energy source, but its low methane content requires purification to increase caloric value.
• Membrane technology offers a promising, novel approach for methane enrichment compared to traditional methods.
• Polymeric membranes face limitations in methane enrichment, necessitating the exploration of new material combinations.

Purpose of the Study:

• To investigate the potential of blend membranes composed of polyetherimide (PEI) and polyvinyl acetate (PVAc) for biogas enrichment.
• To characterize the morphological, thermal, and structural properties of the prepared PEI/PVAc blend membranes.
• To evaluate the gas separation performance (CO2/CH4 and CO2/N2 selectivity and permeance) of these membranes.

Main Methods:

• Blend membranes of PEI and PVAc were fabricated using the wet-phase inversion technique.
• Membrane characterization included Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), and Differential Scanning Calorimetry (DSC).
• Gas permeation tests were conducted at varying feed pressures (2-6 bar) to assess membrane performance.

Main Results:

• FTIR confirmed interactions between PEI and PVAc, while SEM revealed an anisotropic porous structure with a dense skin layer.
• DSC indicated miscibility of PEI and PVAc in blends, evidenced by a single glass transition temperature.
• CO2 permeance increased by 40.47% with 4 wt% PVAc addition at 2 bar. Optimal CO2/CH4 selectivity improved by ~26% with 2 wt% PVAc at 2 bar, and CO2/N2 selectivity reached 22.50 at 4 bar.

Conclusions:

• PEI/PVAc blend membranes exhibit enhanced separation performance compared to pure PEI membranes.
• PVAc addition effectively improves both permeance and selectivity for biogas components.
• These findings highlight PVAc as a valuable component for developing advanced polymeric membranes for efficient biogas enrichment.