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H-ZSM-5 membrane

Scanning electron photograph of an H-ZSM-5 membrane obtained using in situ crystallization. Left top view. Right ... [Pg.274]

Bernal MP, Coronas J, Menendez M, and Santamarfa J. Coupling of reaction and separation at the microscopic level Esterification processes in a H-ZSM-5 membrane reactor. Chem Eng Sci 2002 57 1557-1562. [Pg.319]

With regard to C-PVMRs using bifunctional membranes, an interesting contribution was also made by Bernal et al. (2002). In particular, the H-ZSM-5 membrane used in this work had sufficient catalytic activity to perform the esterification reaction, and at the same time it was selective for water permeation. The conversion obtained at... [Pg.587]

Haag S, Hanebuth M, Mabande G T P, Avhale A, Schiwieger W and Dittmeyer R (2006), On the use of a catalytic H-ZSM-5 membrane for xylene isomerisation , Micropor Mesopor Mater, 96,168-176. [Pg.266]

As described in the previous section, the silica-alumina catalyst covered with the silicalite membrane showed exceUent p-xylene selectivity in disproportionation of toluene [37] at the expense of activity, because the thickness of the sihcahte-1 membrane was large (40 pm), limiting the diffusion of the products. In addition, the catalytic activity of silica-alumina was not so high. To solve these problems, Miyamoto et al. [41 -43] have developed a novel composite zeohte catalyst consisting of a zeolite crystal with an inactive thin layer. In Miyamoto s study [41], a sihcahte-1 layer was grown on proton-exchanged ZSM-5 crystals (silicalite/H-ZSM-5) [42]. The silicalite/H-ZSM-5 catalysts showed excellent para-selectivity of >99.9%, compared to the 63.1% for the uncoated sample, and independent of the toluene conversion. [Pg.220]

Figure 4. Comparison of Propane Aromatization Performances of a Palladium Membrane Reactor (PMR) and a Conventional Reactor (CR) using a Ga-H-ZSM-5 Catalyst... Figure 4. Comparison of Propane Aromatization Performances of a Palladium Membrane Reactor (PMR) and a Conventional Reactor (CR) using a Ga-H-ZSM-5 Catalyst...
The pervaporation of water/acetic acid mixmres was also evaluated with ZSM-5 membranes by the Matsukata group [129] the initial values of the separation factors in a 50 wt% acetic acid aqueous solution were around 10 to 20 due to the preferential adsorption of acetic acid which decreased the amount of water adsorbed. To increase the amount of water adsorbed, a surface modification that consisted of an alkali treatment with NaOH was carried out. After the treatment, the water flux and separation factor increased markedly, reaching values up to 381 and 0.783 kg/m h, respectively. [Pg.294]

Yildirim MH, Cures AR, Motuzas J, Julbe A, Stamatialis DF, Wessling M (2009) Nafion/H-ZSM-5 composite membranes with superior performance for direct methanol fuel cells. J Membr Sci 338 75-83... [Pg.208]

A few studies have been made on PV with acidic feeds using zeolite membranes. Hydrophilic zeolites, in general, are not suitable in low pH environments because acid leaches Al from the framework. Zeolite manbranes used for low pH PV, therefore, need to have relatively high Si/Al ratios so that the framework is not destroyed when Al is removed. Stainlesssteel supports are usually used for these applications because AI2O3 supports are susceptible to degradation by acids. A Ge-ZSM-5 membrane removed acetic acid from a 5 wt % acetic acid-water mixture at 363 K with a = 14 and a 16.8 mol/m h flux (Tan et al. 2006). [Pg.302]

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. [Pg.587]

Millot, B. M6thivier, A. Jobic, H. Moueddeb, H. Dalmon, J.A., Permeation of linear and branched alkanes in ZSM-5 supported membranes. Micropor. Mesoporo. Mater. 38 (2000) 85-95. [Pg.275]

Tetrahydrofuran, THF, is an important industrial solvent and forms an azeotropic mixture at 5.3 wt% with water (see Table 10.3). To separate water/THF, Li et al. [148] tested the pervaporation performance of different hydrophihc zeolite membranes, zeolite A, zeohte Y, MOR, and ZSM-5. The preliminary test showed that the separation factor increased as the Si/Al ratio of the zeohte decreased, except for the case of zeolite A. This fact is probably due to the lower quality of this membrane with respect to the others since in the permeation of triisopropylbenzene (TIPB), showed the highest flux, 3.1 g/m h, indicating the presence of nonselective defects. Therefore, the best results were obtained with zeolite Y, rendering a separation factor of 300 with a water flux of 2.24 kg/m h at 60°C. The water flux increased with water concentration in the feed, up to a value of 15 wt%, indicating that the zeolite was saturated, as was the same for the case of water/ethanol mixtures in zeolite A, previously described. At the same time, the separation factor decreases as water concentration decreased. The stabihty of the membrane was also studied, showing a stable performance after 35 h of operation. [Pg.294]

Kalipcilar H, Gade SK, Ealconer JL, and Noble RD. Synthesis and separation properties of B-ZSM-5 zeohte membranes on monohth supports. J Membr Sci 2002 210(1) 113-127. [Pg.315]

ZSM-5 zeolite. Transport D values were Consequently, the diffusion coefficient calculated from FR results assuming that particles are spheres of lO-pm diameter (0) Data determined by the MEMBRANE (A), TAP( ), and QENS (H) methods were taken from refs. 13 and 14 and are given for comparison. [Pg.591]

T.C. Bowen, H. Kalipcilar, J.L. Falconer, and R.D. Noble, Pervaporation of Organic/Water Mixtures through B-ZSM-5 Zeolite Membranes on Monolith Supports. J. Membr. Sci., 2003, 215, 235-247. [Pg.266]


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