SO2 interference on separation performance of amine-containing facilitated transport membranes for CO2 capture from flue gas

Abstract

Post-combustion carbon capture using membranes is a key approach to control CO2 emissions from power plants using fossil fuels. The minor contaminants, such as SO2 and O2, may influence the long-term membrane performance. With the presence of SO2 in the feed gas, SO2 could preferably react with amine carriers and hinder the permeation of CO2 in the amine-containing facilitated transport membranes. Possible amine degradation and competitive reactions would reduce membrane performance with real flue gas. With SO2 concentrations of 0.7–5ppm, two amine-containing facilitated transport membranes were tested at 57 and 102°C, respectively. Unstable membrane performance was observed at 102°C for the membrane containing Lupamin® as fixed-site carrier and potassium glycinate (K-Gly) as mobile carrier in the presence of SO2. On the contrary, two membranes containing polyvinylamine (PVAm) as fixed-site carrier and amino acid salts as mobile carriers showed stable separation performance in the presence of 1–3ppm SO2 at 57°C. Therefore, the operating temperature plays a significant role in the membrane stabilities in the presence of SO2. In addition, the infrared (IR) spectra of the membrane components exposed to SO2 with respect to exposure time were collected. It was found that the amines reacted with SO2 to form sulfite products irreversibly at 102°C. The spectral results were consistent with the observed membrane separation performance. The stable membrane performances of the facilitated transport membranes at 57°C with SO2 at ppm levels indicate the applicability of the developed amine-containing membranes for use in CO2 capture from real flue gas.