Vycor glass porous membrane

Kameyama, T., K. Fukuda and M. Dokiya. 1981. Possibility for effective production of hydrogen from hydrogen sulfide by means of a porous Vycor glass membrane. Ind. Eng. Chem. Fundam. 20 97-99. 

Decomposition of Hydrogen Sulfide Porous ir-AljOj/MoSj membranes Porous Y-AI2O3 membranes Porous Vycor glass membranes Abe (1987) Kameyama et al. (1981) Kameyama et al. (1979, 1981a, b)... 

Decomposition of Hydrogen Iodide Porous Vycor glass membranes Nonporous Pd/Ag membranes Itoh et al (1984) Yeheskel, Leger and Courvoisier (1979)... 

Dehydrogenation of Cyclohexane to Benzene Porous AljOj membranes Porous Vycor glass membranes Nonporous Pd/Ag membranes Fleming (1987) Shinji et al. (1982), Itoh (1987, Itoh et al. 1988) Sun and Khang (1988) Wood (1968), Itoh (1987), Gryaznov (1970)... 

T. Kameyama, M. Dokiya, M. Fujishige, H. Yokokawa and K. Fukuda, Possibility for Effective Production of Hydrogen from Hydrogen Sulfide by Means of a Porous Vycor Glass Membrane , Ind. Eng. Chem. Fu-nam., 20 97-99 (1981). 

Most porous membranes used in CMRs are made from oxide materials, although carbon membranes have also been used [1, 14, 22], However, although they possess very good separative properties, they have received less attention in CMR applications, probably due to their limited resistance to oxidative atmospheres. Vycor glass membranes also have certain drawbacks (brittleness, lack of high-temperature resistance) [9] for use in CMRs. Porous membranes in CMRs are, most often, made from ceramic materials or, more recently, from zeolites. 

Different ways have been proposed to prepare zeolite membranes. A layer of a zeolite structure can be synthesized on a porous alumina or Vycor glass support [27, 28]. Another way is to allow zeolite crystals to grow on a support and then to plug the intercrystalline pores with a dense matrix [29], However, these two ways often lead to defects which strongly decrease the performance of the resulting membrane. A different approach consists in the direct synthesis of a thin (but fragile) unsupported monolithic zeolite membrane [30]. Recent papers have reported on the preparation of zeolite composite membranes by hydrothermal synthesis of a zeolite structure in (or on) a porous substrate [31-34]. These membranes can act as molecular sieve separators (Fig. 2), suggesting that dcfcct-frcc materials can be prepared in this way. The control of the thickness of the separative layer seems to be the key for the future of zeolite membranes. 

A porous Vycor glass membrane and a porous gamma-alumina membrane, both having about the same pore diameter of 4 nm, were used to study the separation of hydrogen from other components in the gasification mixture [McMahon et al., 1990]. At a temperature up to a maximum hydrogen concentration of about 40% in the... 

Figure 9.2 Calculated total conversion profile of cyclohexane to benzene in a porous shell-and-tube Vycor glass membrane reactor with membrane thickness as a parameter [ltohetal.,1985]...

Exposures of some metal oxide membranes, both dense and porous, to extreme pH conditions (e.g., pH less than 2 or greater than 12) can cause structural degradations, particularly with extended contact time. The extent of degradation depends on the specific phase of the material, porosity, and temperature. Steam can also be deleterious to some metal oxide and Vycor glass membranes. For example, as mentioned earlier, porous glass membranes undergo slow structural changes upon exposure to water due to partial dissolution of silica. 

Shown in Table 9.7 are some examples of incorporating catalysts into porous ceramic membranes. Both metal and oxide catalysts have been introduced to a variety of ceramic membranes (e.g., alumina, silica, Vycor glass and titania) to make them catalytically active. The impregnation/heat U eatment procedures do not appear to show a consistent cause-and-effeci relationship with the resulting membrane permeability. For example, no noticeable change is observed when platinum is impregnated into porous Vycor glass... 

Table 10.2 lists most of the published models of packed-bed (inert) porous membrane shell-and-tube reactors. The membrane materials used to validate the models are primarily porous Vycor glass or alumina membranes. 

Figure 10.10 Effect of space time on conversion of partial oxidation of methanol in a porous Vycor glass membrane reactor (350 C, 60% air) [Song and Hwang, 1991]...

Shindo Y, Obata K., Hakuta T., Yoshitome H., Todo N. and Kato J., Permeation of hydrogen through a porous vycor glass membrane, Adv. Hydrogen Energy Progr, 2 325 (1981). 

Harold M.P., Cini P, Patenaude B. and Venkataraman K., The catalytically impregnated ceramic tube An alternative multiphase reactor, AIChE Symposium Series 85 (265) 26 (1989). Song J.Y. and Hwang S.-T, Formaldehyde production from methanol using a porous Vycor glass membrane. Proceedings of ICOM 90, Chicago, (30)540 (1990). 

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