Development of poly(amidoamine) dendrimer/poly(vinyl alcohol) hybrid membranes for CO₂ separation

Abstract

A novel hybrid membrane of poly(amidoamine) (PAMAM) dendrimer/cross-linked poly(vinyl alcohol) (PVA) was developed for the selective separation of CO₂ from a mixture of CO₂ and H₂. PAMAM dendrimers were incorporated into a cross-linked PVA matrix to improve CO₂ separation performance at elevated pressures. An organic metal compound di-isopropoxy-bis(triethanol aminato) titanium (Ti cross-linker) was selected as the PVA cross-linker. The characterization of PAMAM/cross-linked PVA hybrid membranes was conducted using Fourier transform infrared spectrometry/attenuated total reflectance (FTIR/ATR), wide-angle X-ray diffraction (WAXD), and small-angle X-ray scattering (SAXS) spectra. Cross-linking of PVA with Ti cross-linker was confirmed by FTIR/ATR spectra. WAXD spectra showed that the relative crystallinity of PAMAM/PVA hybrid membrane decreased greatly when compared with PVA film. SAXS results indicated that PAMAM and PVA are compatible in the PAMAM/PVA hybrid membrane. To improve the CO₂ separation performance, the addition of amino acids such as glycine, proline, and 2,3-diaminopropionic acid was investigated. Separation performance was improved by addition of amino acids, such as proline. The resulting PAMAM/cross-linked PVA membrane with 5 wt.% proline addition demonstrated an high CO₂/H₂ selectivity of 38 with CO₂ permeance of 1.9 × 10⁻¹² (m³(STP)/(m² s Pa)) at CO₂ partial pressure of 560 kPa at 60 °C. The PAMAM dendrimer/cross-linked PVA membrane shows great potential for CO₂ separation from H₂ at elevated pressures that are typically found in IGCC processes.

Keywords:

• Poly(amidoamine) dendrimer
• Cross-linked poly(vinyl alcohol)
• Hybrid membrane
• CO₂ separation

Acknowledgments

This work was supported by the Ministry of Economy, Trade and Industry (METI). The authors acknowledge the assistance of Ms. Rie Sugimoto for the gas separation tests.

Notes

7th Aseanian Membrane Society Conference (AMS7), 4–7 July 2012, Busan, Korea