ChBE Seminar Series: Lloyd M. Robeson
Tuesday, November 30, 2010
11:00 a.m.-12:15 p.m.
Room 2110, Chemical and Nuclear Engineering Bldg.
Professor Ray Adomaitis
Membrane Gas Separation: The Upper Bound and Other Correlations
Dr. Lloyd M Robeson
Member, National Academy of Engineering
Member, Clark School Innovation Hall of Fame
Adjunct Professor, Lehigh University
Separation of common gas mixtures by polymeric membranes has been commercial for over 30 years and continues to grow as a low cost, energy efficient unit operation. An empirical correlation was noted 20 years ago which observed that common gas pairs (from the list of O2, N2, CO2, H2, He, CH4) exhibited an upper bound relationship with polymeric membranes. This upper bound was expressed as a line on a log-log plot of separation factor versus permeability of the more permeable gas above which virtually no data exists. The upper bound relationship was later derived from fundamental principles (by B. Freeman) offering theoretical justification. The structure-property characteristics of polymers offering upper bound performance will be discussed as well as commercial applications involving membrane separation of gases. The upper bound relationship is a function of temperature and a recent coauthored paper has predicted the temperature dependence based on fundamental relationships.
An additional correlation employing a large database of permeability values for the common gases yields a correlation: Pj = kPin where Pi and Pj are the permeabilities of gases i and j chosen such that n>1.0. Linear behavior of the plots (log Pj versus log Pi) of all the possible gas pairs are observed over nine orders of magnitude implying that solution-diffusion behavior exists for all known polymeric membranes. The value of n correlates with the gas kinetic diameters; in agreement with theory. Additionally, the values of n can be employed to determine the kinetic diameters of these gases offering a more accurate set of data for gas diffusion in polymers than existing to date.
About the Speaker
Lloyd M Robeson received his BS degree in Chemical Engineering from Purdue University in 1964 and his PhD in Chemical Engineering from the University of Maryland in 1967. He was employed at Union Carbide Corporation from 1967 to 1986 and at Air Products and Chemicals, Inc. from 1986 to 2007 at which time he retired. His career in industry was primarily involved with polymer science and engineering. During his industrial career he worked in areas of polymer blends, polymer composites, permeability, engineering polymers, extrusion polymerization, flame retardant polymers, thermoplastic polyurethanes, polyolefins and ethylene copolymers, environmental stress failure, biomedical applications, carbon fiber reinforced thermoplastics, water soluble polymers, polymer processing, reactive extrusion compatibilization, dynamic mechanical properties, block and graft copolymers, emulsion polymers, adhesives, water soluble polymers, polymers for electronic applications, conducting polymers and membrane separation processes. He is a member of the National Academy of Engineering and is in the College of Engineering Innovation Hall of Fame at the University of Maryland along with Distinguished Alumnus Honors from both Purdue University and the University of Maryland. His publications number ~100 including two books on the subject of polymer blends. He is the (co)author of 100 US patents which has translated into a number of commercial products. Presently, he is an Adjunct Professor at Lehigh University.