ABSTRACT
This chapter provides some critical analyses of the existing methods aimed at controlling membrane gas separation processes. Several approaches are possible: selection of materials with heterogeneous spatial structure; employment of unsteady-state gas separation processes; use of mobile membranes; application of flowing liquid membranes, etc. In contrast to the steady-state separation factor, the nonsteady-state separation factor depends on the time of diffusion. Under steady-state conditions the Henry I (mobile)-Henry II (immobile) model predicts the equality of gas fluxes through defects and homogeneous media. The main class of "microheterogeneous" structures is made up of dispersion media, i.e., solids containing a dispersion of inclusions of a specific shape and size. Application of moving membranes allows one to accomplish spatial separation of gas-mixture components. The membrane permabsorber consists of two cells (absorption cell and desorption cell) and the liquid specifically selected as an agent for extraction that circulates between them.
