Membrane-based gas separation

Transport in non-porous polymeric membranes is based on the so-called ‘solution–diffusion’ concept [1,2]. This model, formulated in the 19th century, is grounded in the works of J. K. Mitchell [3], T. Graham [4] and S. von Wroblewski [5], who demonstrated that the presence of microscopic open pores or capillaries was not a prerequisite for mass transfer through polymeric films (or septa as they were referred to), such as natural rubber. First, Graham in 1829 [4], and then Mitchell in 1831 [3], noted that gases were capable of permeating through non-porous rubber films and that this process was related to gas dissolution and diffusion in the polymeric materials. The currently accepted interpretation of such experiments was given several decades later by Graham [4] (this and other articles from the early history of membrane science have been reproduced, in part, in a special issue of the Journal of Membrane Science) [6]. Because he did not find a monotonic correlation between the rates of transport and the known gas phase diffusion coefficients of the penetrant molecules, Graham concluded that the process of permeation comprised two stages: sorption of gas by the rubber ‘that must depend upon a kind of chemical affinity’ and diffusion of the sorbed gas molecules [4]. The sorbed gas, as he wrote, ‘comes to evaporate . . . . and reappears as gas on the other side of the membrane. Such evaporation is the same into vacuum and into another gas, being equally gas-diffusion in both circumstances’ [4]. Empirical observations of the pressure and thickness dependence of the steady-state gas permeation rate or flux, N, led von Wroblewski [5] to propose the following relation:

Transport of Gases and Vapors in Glassy and Rubbery Polymers

Mixed matrix membranes using carbon molecular sieves: II. Modeling permeation behavior

https://www.pure.ed.ac.uk/ws/files/25007192/EmergingCO2capture_20April2015_final.pdf

Emerging CO2 capture systems

E.S. Sanders

Papers

“Second component” effects in sorption and permeation of gases in glassy polymers

Pure and mixed gas sorption of carbon dioxide and ethylene in poly(methyl methacrylate)

Mixed gas sorption in glassy polymers: Equipment design considerations and preliminary results

Implications of the Dual-Mode Sorption and Transport Models for Mixed Gas Permeation