Mordenite membranes

Lin X, Kikuchi E, and Matsukata M. Preparation of mordenite membranes on alpha-alumina tubular supports for pervaporation of water-isopropyl alcohol mixtures. Chem Commun 2000 11 957-958. 

Zhang YF, Xu ZQ, and Chen QL. Synthesis of small crystal polycrystaUine mordenite membrane. J Membr Sci 2002 210 361-368. Casado L, Mallada R, Tellez C, Coronas J, Menendez M, and Santamarla J. Preparation, characterization and pervaporation performance of mordenite membranes. J Membr Sci 2003 216(1-2) 135-147. 

Li G, Kikuchi E, and Matsukata M. Separation of water-acetic acid mixtures by pervaporation using a thin mordenite membrane. Sep Purif Technol 2003 32 199-206. 

Rao N, Andersen TP, and Ge P. Tin mordenite membranes for direct methanol fuel-ceUs. Solid State Ionics 1994 72 334—337. Poltarzewski Z, Wieczorek W, Przyluski J, and Antonucci V. Novel proton conducting composite electrol3des for apphcation in methanol fuel cells. Solid State Ionics 1999 119 301-304. 

It is now possible to prepare defect-free zeolite membranes for use in separations.221 (More details on separations can be found in Chap. 7.) A mordenite membrane on a porous alumina support had a separation factor for benzene over p xylene of more than 160.222 A ZSM-5 membrane on porous alumina separated /7-butane over isobutane by a factor of 31 at 185°C.223 The next step is to use them in membrane reactors to separate products as they form. 

Growth of oriented mordenite membranes on porous a-A Os supports... 

A highly oriented mordenite membrane with c-axis of crystals perpendicular to the support surface was successfully prepared on a porous a-alumina support. Seeding was essential to form a compact layer of mordenite. Based on the XRD and SEM results, it was concluded that "evolutionary selection" mechanism significantly contributes to the formation of a sharply oriented mordenite layer. Pervaporation results for separation of a water/iso-propanol (10 90, w/w) mixture showed highly preferential permeation (a=3615) of water through the oriented mordenite membrane. 

The use of postsynthetic alkaline hydrothermal treatments improves the properties of mordenite membranes, dissolving amorphous/nonzeolitic materials deposited during hydro-thermal synthesis while promoting further crystallization on the membrane [50]. 

The economic feasibility of mordenite membranes for pervaporation of acetic acid/water mixtures has been also studied by the researchers of Mitsubishi [209]. The membrane performance in pervaporation was measured in a feed mixture of water (50 wt.%)/AAc (50 wt.%) to be 10.9 kg m /h for permeate flux and to be 0.77 x 10" mol mV(s Pa) for water permeance with separation factor of 500 at 130°C. 

Zhang YF, Xu ZQ, Chen QL. Synthesis of small crystal polycrystalline mordenite membrane. J Membr Sci 2002 210 361-368. 

Navajas A, MaUada R, TeUez C, Coronas J, Menendez M, Santamaria J. Preparation of mordenite membranes for pervaporation of water-ethanol mixtures. Desalination 2002 148 25-29. 

Sato K, Sugimoto K, Kyotani T, Shimotsuma N, Kurata T. Synthesis, reproducibUity, characterization, pervaporation and technical feasibUity of preferentially b-oriented mordenite membranes for dehydration of acetic acid solution. J Membr Sci 2011 385-386 20-29. 

Rao N, Andersen TP, Ge P. Tin mordenite membranes for direct methanol fuel-cells. Solid State Ionics 1994 72 334—337. 

Mordenite membranes were prepared by seeded hydrothermal synthesis onto commercial ceramic tubular supports by Casado et al. (2003) and nsed for the PV of alcohol-water mixtures. It was reported by them that selective adsorption of water on zeolite pores and small intercrystalline defects controlled the separation mechanism in the mordenite. 

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. 

A polycrystalline mordenite membrane with a small ciystallite size was prepared using tetraethylammonium bromide as a template and by aging. The smallest crystals obtained were around 4. 5 pm [02Z1]. Mordenite with crystal diameter smaller than 100 nm has been obtained by [04H1]. 

Yamazaki, S., and Tsutsumi, K., Adsorption characteristics of synthesized mordenite membranes. Adsorption. 

---