(537d) Synthesis and Characterization of Nanoporous Polyethersulfone Membranes As Support for Composite Membrane in CO2 Separation: From Lab to Pilot Scale

Authors: 
Wu, D., The Ohio State University
Zhao, L., The Ohio State University
Vakharia, V., The Ohio State University
Salim, W., The Ohio State University
Han, Y., The Ohio State University
Ho, W. S. W., The Ohio State University
Nanoporous polyethersulfone (PES) membranes were prepared from PES/N-methyl-2-pyrrolidone (NMP)/2-methoxyethanol (2-ME) casting solutions with water as coagulant by both vapor- and non-solvent-induced phase inversion steps successively under various preparation parameters. 2-ME was incorporated into the casting solution as a pore-forming additive because of its high affinity with water, leading to more open membrane morphology. A detailed study of the effects of different parameters, including polymer concentration, 2-ME/NMP ratio, relative humidity, water vapor exposure time, and water coagulation bath temperature, was conducted in lab-scale experiments to determine the operation guidelines for pilot-scale fabrication. 14-inch wide PES membranes were fabricated successfully by using a continuous casting machine. A parametric study in the pilot-scale fabrication was also carried out. The surface morphologies of the PES membranes were characterized by scanning electron microscopy (SEM). The morphological differences between both scales by the same preparation conditions were compared. Based on the guidelines established from the lab-scale experiments, the casting solution composition and coagulation bath temperature were optimized in the pilot-scale continuous casting machine to fabricate the 14-inch wide PES membrane with a desirable morphology suitable for use as the substrate of composite membrane in CO2 separation. The developed fabrication process also showed the potential for the commercial production of the PES membrane in a larger scale by the vapor- and non-solvent-induced phase inversion technique. In addition, a pilot-scale PES membrane with a pore size of ~ 69 nm and surface porosity of ~ 17% was employed in the continuous Zeolite-Y (ZY) nanoparticle deposition. A thin ZY layer with a controlled thickness and a uniform coverage was prepared. PES membranes deposited with ZY particles were also utilized as the substrate of composite membrane for CO2 capture from flue gas in coal-fired power plants. From the gas transport measurement by using a simulated flue gas, the prepared composite membrane with an amine-containing selective cover layer showed a CO2 permeance of > 800 GPU (1 GPU = 10-6 cm3 (STP)·cm-2·s-1·cmHg-1) and a CO2/N2 selectivity > 140, indicating the great potential for CO2 capture from flue gas.