Alumina supports produced by dry-pressing and sintering at different temperatures for developing carbon molecular sieve membranes. Issue 22 (15th November 2021) - Neves, Thaís Martins
Abstract: Supports for carbon molecular sieve membranes (CMSM) were fabricated by dry-pressing alumina powder and sintering at different temperatures. The CMSM were obtained by pyrolysis of precursor membranes prepared from the deposition of two, three, or four layers of a polyetherimide (PEI) solution onto alumina disks. The physical properties of the supports varied according to sintering temperature, where supports sintered at 1200 °C exhibited large pore size and volume, and the CMSM formed over these structures had low gas permeance due to resistance generated by the carbon intruded into the ceramic substrates. Carbon selective layers with large d-spacing were formed over the rough surface of supports sintered at 1400 °C. The multiple layers of PEI deposited onto these dense structure substrates remained on their top surface, and carbon layers with a more tortuous path for gas molecule diffusion were formed, reducing CMSM permeance. CMSM prepared from supports sintered at 1300 °C and coated by three layers of PEI yielded the carbon membrane with the best performance in terms of O2 /N2, CO2 /N2, and CO2 /CH4 gas pair separation. The results suggest the methodology employed in this study is promising for the preparation of alumina supports and that sintering temperature influences their structural characteristics and, consequently, CMSM separation properties.