Zeolite-based membranes characteristics

As can be seen in Table 19.2, and with some more details in Table 19.3 (this last table shows a short list of some relevant membranes used in the ethyl acetate production research together with separation factors and fluxes obtained), zeolite-based membranes (mordenite and zeolite A) were also tested by De La Iglesia et al. (2007) in an ISU-type continuous membrane reactor packed with Amberlyst 15. Both membranes were capable of shifting the equilibrium (in <1 day) and, in particular, mordenite membranes allowed conversions of approximately 90% and high separation factors of H20/ethanol and H20/acetic acid (>170). Moreover, because of the lower content in aluminum, under acid conditions, mordenite membranes were more stable than zeolite A. Hence, mordenite was also used by De La Iglesia et al. (2006), in another work, to prepare two-layered mordenite-ZSM-5 composite membranes, as shown in Figure 19.15. A tubular alumina tube was used as support. As a result, the feasibility of coupling the separation characteristics of the mordenite layer with the catalytic behavior of the H-ZSM-5 layer was demonstrated. 

Ceramic membranes are proposed as advantageous with respect to resistance toward fouling as compared to organic polymer-based membranes. In this category, zeolite membranes have received considerable attention because of their superior characteristics of thermal, mechanical, chemical, and radiation stability. 

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