Zeolite industrial solvents, dehydration

In spite of all these hurdles, there are already industrial-scale applications of zeolite membranes for solvent dehydration [106] by pervaporation plants using tubular zeolite A membranes with 0.0275 m of permeation area each (see Section 10.2.3). Li et al. [280] have prepared large area (0.0260 m ) ZSM-5 membranes on tubular a-alumina supports. This work is also interesting from the industrial point of view because the authors used inexpensive n-butylamine as template. Indeed, the cost required for industrial modules, on a general basis, is still far from clear. However, it must be noted that most of the costs can be ascribed to the module, and only 10%-20% to the membrane itself [3]. This underlines again the importance of preparation of zeolite membranes on cheaper, alternative supports that can also pack more area per unit volume. 

Urtiaga A, Gorri ED, Casado C, and Ortiz I. Pervaporative dehydration of industrial solvents using a zeolite NaA commercial membrane. Sep Purif Technol 2003 32(l-3) 207-213. 

Zeolite membranes show high thermal stability and chemical resistance compared with those of polymeric membranes. They are able to separate mixtures continuously on the basis of differences in the molecular size and shape [18], and/or on the basis of different adsorption properties [19], since their separation ability depends on the interplay of the mixture adsorption equilibrium and the mixture. Different types of zeolites have been studied (e.g. MFI, LTA, MOR, FAU) for the membrane separation. They are used still at laboratory level, also as catalytic membranes in membrane reactors (e.g. CO clean-up, water gas shift, methane reforming, etc.) [20,21]. The first commercial application is that of LTA zeolite membranes for solvent dehydration by pervaporation [22], Some other pervaporation plants have been installed since 2001, but no industrial applications use zeolite membranes in the GS field [23]. The reason for this limited application in industry might be due to economical feasibility (development of higher flux membranes should reduce both costs of membranes and modules) and poor reproducibility. 

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