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Metal organic framework (MOF) membranes have received much attention for gas separation applications, with however limited information about their liquid separation properties. This paper reports a study of permeation and separation of liquid organics by a MOF-5 membrane in pervaporation mode. Multiple high quality MOF-5 membranes were reproducibly prepared by the secondary growth method for various experimental runs. The pervaporation of pure toluene, o-xylene, and 1,3,5-triisopropylbenzene (TIPB) and the separation of their binary mixtures were studied. The permeation flux and separation factors decrease with pervaporation on-stream time and steady state permeation flux could not be reached even after 10 h of pervaporation. The fouling effects do not change the crystalline structure of the MOF-5 membrane. The pervaporation flux with the mixture feed is lower than the pure component flux, and the reduction in the flux decreases with decreasing affinity of the permeating species with MOF-5. The mixture maximum separation factors for toluene/TIPB and o-xylene/TIPB are respectively about 26.7 and 14.6, significantly higher than the pure component ideal separation factor. The fluxes and separation factors cannot be restored to their original values upon membrane activation at 100 °C in vacuum.

Highly b-oriented, closely packed, MFI zeolitefilms are prepared on seeded stainless-steel plates using organic template-free,s econdary growth solutions,c ontaining aluminum sulfate as ac rystallization agent. The number of aoriented twin crystals is significantly reduced, and even eliminated, simply by restricting the pH value of the secondary growth solution to the narrowrange of 11.1-11.3. Values of pH can be adjusted through the controlled addition of (NH 4 ) 2 SO 4 or H 2 SO 4 to secondary growth solutions of the composition (1 SiO 2 :0.57 NaOH:137.5 H 2 O:0.0050 (Al 2 (SO 4 ) 3 ·18 H 2 O)) or by simply decreasing the molar composition of NaOH with no extra additives.MFI zeolite films are attractive for aw ide range of applications,i ncluding molecular sieve membranes,c atalytic membrane reactors,l ow-dielectric-constant materials,a nd corrosion-resistant coatings. [1] Both experimental data and simulation results [2] have suggested that the straight channel along the b-axis is the fastest diffusion pathway in MFI crystals and b-oriented zeolite films exhibit superior performance compared to randomly oriented ones. [3] At present, one of the most important applications of b-oriented MFI films is as membranes for separation of p-xylene from xylene isomers. [4] Therefore,s ynthesizing high-quality,b -oriented MFI zeolite films is of great interest from the viewpoint of both fundamental studies and practical applications.B-oriented MFI films have been grown on stainless-steel substrates through the accurate manipulation of synthesis solution composition [5] and kinetic parameters [6] for crystal nucleation and growth during in situ synthesis.Continuous boriented zeolite films and membranes were also successfully prepared on different supports with the secondary (seeded)growth method, taking advantage of ab-oriented zeolite seed layer deposited on the substrate prior to hydrothermal treatment. [7] Decoupling the nucleation and growth steps can significantly reduce the difficulty in manipulating the orientation of zeolite films,w hich in turn enhances the reproducibility and scalability of the zeolite layer synthesis.In the methods mentioned above for the synthesis of boriented MFI zeolite films,o rganic template (or structuredirecting agent, SDA) was necessary for the formation of zeolite crystals.T emplating agents are incorporated in zeolite pores during hydrothermal synthesis and acalcination step is necessary to follow the film/membrane synthesis process to remove the template and open the zeolite channels.D uring the calcination process,a na brupt shrinkage of the zeolite lattice,a nd differences in the thermal expansion characteristics of zeolite films and their supports yield substantial stresses that often result in microcracks in zeolite films. [8] These microcracks make zeolite films less effective in practical applications.Moreover,t he growth of a-oriented twin crystals is unavoidable when tetrapropylammonium hydroxide (TPAOH), the most common template,i su sed in the secondary growth method. [7...

Brodie's GO sheets are prepared, characterized and compared to Hummers’ GO sheets. GO-B membranes are synthesized on polyester substrates using filtration. Permeability reduction of large gas molecules (CH4, N2 and CO2) is more significant compared to permeability reduction of small gas molecules (H2 and He). Pressure filtration enhances the packing density of GO-B sheets.