Mesoporous membrane

Gavriilidis, a., Yeung, K. L., Design and fabrication of zeolite-based microreactors and membrane microseparators, Micropor. Mesopor. Mater. 42 (2001)... 

Pan JH, Zhang X, Du Alan J, Sun DD, Leckie JO (2009) Self-etching reconstruction of hierarchically mesoporous F-Ti02 hollow microspherical photocatalyst for concurrent membrane water purifications. J Am Chem Soc 130 11256-11257... 

When these ID nanocrystals are deposited on a surface, typically a random direction exists for the elongating axis of each ID nanocrystal. However, if the preparation method leads to an alignment of the elongating axis in one single direction, e.g. when an ordered array is present, quasi-2E) nanostructures are present. This class of nanostructured Titania thin film may be extended to include also ordered mesoporous Titania membranes, e.g. when the pores are aligned in one single direction. 

The titanosilicate version of UTD-1 has been shown to be an effective catalyst for the oxidation of alkanes, alkenes, and alcohols (77-79) by using peroxides as the oxidant. The large pores of Ti-UTD-1 readily accommodate large molecules such as 2,6-di-ferf-butylphenol (2,6-DTBP). The bulky 2,6-DTBP substrate can be converted to the corresponding quinone with activity and selectivity comparable to the mesoporous catalysts Ti-MCM-41 and Ti-HMS (80), where HMS = hexagonal mesoporous silica. Both Ti-UTD-1 and UTD-1 have also been prepared as oriented thin films via a laser ablation technique (81-85). Continuous UTD-1 membranes with the channels oriented normal to the substrate surface have been employed in a catalytic oxidation-separation process (82). At room temperature, a cyclohexene-ferf-butylhydroperoxide was passed through the membrane and epoxidation products were trapped on the down stream side. The UTD-1 membranes supported on metal frits have also been evaluated for the separation of linear paraffins and aromatics (83). In a model separation of n-hexane and toluene, enhanced permeation of the linear alkane was observed. Oriented UTD-1 films have also been evenly coated on small 3D objects such as glass and metal beads (84, 85). 

Inorganic membranes employed in reaction/transport studies were either in tubular form (a single membrane tube incorporating an inner tube side and an outer shell side in double pipe configuration or as multichannel monolith) or plate-shaped disks as shown in Figure 7.1 (Shinji et al. 1982, Zaspalis et al. 1990, Cussler 1988). For increased mechanical resistance the thin porous (usually mesoporous) membrane layers are usually supported on top of macroporous supports (pores 1-lS /im), very often via an intermediate porous layer, with pore size 100-1500 nm, (Keizer and Burggraaf 1988). 

Bronid, J., Subotid, B., and Skreblin, M. (1999) Investigation of the influence of seeding on the crystallization of zeolite A in the membrane-type reactor micropor. Mesopor. Mater., 28, 73-82. 

Xomeritakis, G., Nair, S., and Tsapatsis, M. (2000) Transport properties of alumina-supported MFI membranes made by secondary (seeded) growth. Micropor. Mesopor. Mater., 38, 61-73. 

MFI-type zeolite membranes. Micropor. Mesopor. Mater., 43, 319-327. 

McLeary, E.E., Jansen, J.C., and Kapteijn, E. (2006) Zeolite based films, membranes and membrane reactors progress and prospects. Micropor. Mesopor. Mater., 90,198-220. 

Up to now, a variety of non-zeolite/polymer mixed-matrix membranes have been developed comprising either nonporous or porous non-zeolitic materials as the dispersed phase in the continuous polymer phase. For example, non-porous and porous silica nanoparticles, alumina, activated carbon, poly(ethylene glycol) impregnated activated carbon, carbon molecular sieves, Ti02 nanoparticles, layered materials, metal-organic frameworks and mesoporous molecular sieves have been studied as the dispersed non-zeolitic materials in the mixed-matrix membranes in the literature [23-35]. This chapter does not focus on these non-zeoUte/polymer mixed-matrix membranes. Instead we describe recent progress in molecular sieve/ polymer mixed-matrix membranes, as much of the research conducted to date on mixed-matrix membranes has focused on the combination of a dispersed zeolite phase with an easily processed continuous polymer matrix. The molecular sieve/ polymer mixed-matrix membranes covered in this chapter include zeolite/polymer and non-zeolitic molecular sieve/polymer mixed-matrix membranes, such as alu-minophosphate molecular sieve (AlPO)/polymer and silicoaluminophosphate molecular sieve (SAPO)/polymer mixed-matrix membranes. 

Weh, K., Noack, M., Sieber, L, and Caro, J. (2002) Permeation of single gases and gas mixtures through faujasite-type molecular sieve membranes. Micropor. Mesopor. Mater., 54, 27-36. 

Tomita, T., Nakayama, K., and Sakai, H. (2004) Gas separation characteristics of DDR type zeolite membrane. Micropor. Mesopor. Mater., 68, 71-75. 

Ciobanu, G., Carja, G., and Ciobanu, O. (2008) Structure of mixed matrix membranes made with SAPO-5 zeolite in polyurethane matrix. Micropor. Mesopor. Mater., 115 (1-2), 61-66. 

Grafting a modified cinchona alkaloid to hexagonal mesoporous molecular sieve SBA-15 afforded catalyst (27) with excellent activity. 1-Phenyl-1-propene was converted to the corresponding diol in 98% yield (98% ee), while trans-stilbene yielded the desired product in 97% yield (99% ee) [92]. Other examples in this field are the utilization of microencapsulated osmium tetroxide by Kobayashi [93] and the application of continuous dihydroxylation mns in chemzyme membrane reactors described by Woltinger [94]. 

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