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The MIL-53 metal-organic framework (MOF) is known to change reversibly from an open-pore framework (MIL-53-ht) to a closed-pore framework (MIL-53-lt) depending on the temperature, pressure, or guest molecules absorbed. Three frameworks of the additive, MIL-53-as synthesized (MIL-53-as), MIL-53-ht, and MIL-53-lt, were prepared, characterized, and combined with Matrimid® to form mixed-matrix membranes (MMMs) for gas separations. The MIL-53-ht/Matrimid® MMMs exhibited higher values of permeability compared to Matrimid® as well as an increased CO 2 /CH 4 selectivity suggesting that the open-pore MIL-53 framework was maintained in the polymer matrix. In addition to higher permeability values, MIL-53-as/Matrimid® MMMs showed higher selectivity for gas pairs with kinetic diameters differing by ⩾0.5 Å, including H 2 /O 2 , CO 2 /CH 4 , H 2 /CH 4 , and H 2 /N 2 , suggesting the presence of excess benzene dicarboxylic acid molecules within the pores that reduced its diameter enabling the material to discriminate between smaller and larger gases. MIL-53-lt did not retain its closed-pore form in the MMM. Rather, it irreversibly converted to the open-pore form (MIL-53-ht) due to the exchange of water present in the MIL-53 pores with chloroform solvent molecules during membrane casting and to pore penetration and confinement by Matrimid® polymer chains. This finding, that a polymer matrix stabilizes a MOF pore architecture within an MMM, is significant in that the desired selectivity of a MOF-MMM system may be achievable. [ABSTRACT FROM AUTHOR]

Three methods for the synthesis of silicalite-1 by recrystallization of layered silicates were investigated. The layered silicates included magadiite, kenyaite and octosilicate, which were made using poly(ethylene glycol) (PEG 200) as a template. Both as-synthesized and calcined forms of the layered silicates were used as the silica source. In the system of NaOH–TPABr–SiO2–H2O (Method 1), silicalite-1 as a single phase was synthesized using as-synthesized kenyaite, octosilicate, or calcined magadiite at 150 °C. Silicalite-1 with impurity was obtained from as-synthesized magadiite or calcined kenyaite. In the system of TPAOH–SiO2–H2O (Method 2), silicalite-1 could be obtained at temperatures of 135, 150 and 175 °C, using either the as-synthesized or calcined forms of the layered silicates. Compared to fumed silica, the layered silicates had a higher reactivity in the synthesis of silicalite-1. In the system of NaOH–TPAOH–SiO2–H2O (Method 3), pure silicalite-1 could be synthesized using as-synthesized magadiite, kenyaite and octosilicate as well as calcined kenyaite as the silica source at 150 °C. For each of the three methods, the degree of crystallinity and morphology of silicalite-1 were dependent upon the synthesis parameters, including the gel composition and the type of layered silicate as well as the reaction temperature and time. [Copyright &y& Elsevier]

Thin films of zeolite NaX have been prepared on the silica fibers via pulsed laser deposition (PLD) for the first time. Laser ablation of as-synthesized NaX onto silica fibers followed by a post hydrothermal treatment results in partially oriented NaX membranes on the silica fibers. A ∼5 μm thick film was obtained when hydrothermally treated the PLD thin film for 9 h. [Copyright &y& Elsevier]

Thin films of the zeolite MCM-22 have been prepared via pulsed laser deposition for the first time. Laser ablation of as-synthesized layered precursor MCM-22(P) onto TiN coated silicon wafers, polished graphite and porous stainless steel frits followed by a post-hydrothermal treatment results in partially oriented crystalline MCM-22(P) membranes where the a direction is largely normal to the substrate surface. Further heating leads to fully condensed MCM-22 zeolite membranes. These thin films were characterized by XRD, SEM and FT-IR spectroscopy. The oriented MCM-22 membrane grown on porous stainless steel was evaluated for the room temperature separation of the alcohol/water mixture and selective permeation of the water was observed. [Copyright &y& Elsevier]

Zeolite X films have been prepared utilizing pulsed-laser deposition onto TiN-coated silicon wafers and porous stainless steel disks. Laser ablation of zeolite X onto TiN-coated silicon wafers followed by a hydrothermal treatment resulted in partially oriented, crystalline NaX membranes. Hydrothermal treatment of laser-deposited films on stainless steel mesh produced a coated wire mesh with a ∼3-μm-thick zeolite X film. Hydrothermal treatment of the laser-deposited films on 0.5 μm diameter pore stainless steel frits resulted in a densely packed non-continuous film. [Copyright &y& Elsevier]

Perfluoro channel in a 2D MOF. [Display omitted] This study illustrates the expansion of the interlayer distance for hydrogen-bonded 2D frameworks resulting in increased pore volume and faster gas adsorption as a result of aryl ring rotation and electron-withdrawing effects. The 1D polymer chain, Cu(L1)BDC(Cl) 2 constructed from copper(II) and 2,2′-(1 H -imidazole-4,5-diyl)di-1,4,5,6-tetrahydropyrimidine (H-L1), reacts with terephthalic acid (H 2 BDC) to form a hydrogen-bonded 2D layered framework. Three hydrogen-bonded isoreticular 2D copper-based coordination polymers were constructed using different BDC analogues. Control of the pore size and interlayer distance was achieved by using different electron-withdrawing groups on the BDC linker. The reaction of Cu(L1)(Cl) 2 with the perfluorinated terephthalic acid analogue, resulted in C u(L1)BDC-F 4. This showed a six-time shorter gas adsorption time with only a slight increase in the channel size between the layers. The pore volume of Cu(L1)BDC-F 4 increased three times after modification of rotated tetrafluoro substituted aryl rings. The Cu(L1)BDC-Br and Cu(L1)BDC-NO 2 analogues increased the interlayer distance of the hydrogen-bonded 2D coordination polymers. The Cu(L1)BDC family was characterized by PXRD, SCXRD, TGA, FT-IR, etc. [ABSTRACT FROM AUTHOR]

There is growing interest in new ways to configure titanium dioxide (TiO2) as new applications emerge such as in photovoltaics and catalysis. A method has been developed for the preparation of mesoporous TiO2 fibers using electrostatic deposition. The mesoporous metal oxide fibers were prepared using Pluronic 123 as the template. The fibers contain anatase crystallized in the pore walls which transforms to rutile upon calcination above 800 °C. The electrospun fibers were evaluated for the photodecomposition of phenol and formic acid. [Copyright &y& Elsevier]

The mesoporous silica DAM-1 (Dallas Amorphous Material) has been synthesized in the presence of single walled carbon nanotubes (SWNT) using vitamin E TPGS as the template. It is proposed that this water soluble version of vitamin E wraps and partially debundles the SWNTs en route to partial encapsulation within the DAM-1 particles. XRD, adsorption, SEM and TEM provide evidence for occlusion of the nanotubes. [Copyright &y& Elsevier]

The process of electrospinning has been applied for the first time in the production of mesoporous molecular sieve fibers. Different organic templates and silica sources were used to reproducibly obtain a high density of SBA-15 and DAM-1 fibers with diameters in the range of a micron to a few hundred nanometers. [Copyright &y& Elsevier]

A novel strategy for imprinting mesoporous SBA-15 using chiral ruthenium complexes is reported. This imprinting strategy combines the triblock copolymer (PEO)20(PPO)70(PEO)20 template and the chiral dichlorotris(1,10-phenanthroline)ruthenium(II) complex. A chiral PEO helix is formed by interaction of the chiral ruthenium complex with the block copolymer during the templated synthesis of the mesoporous SBA-15 molecular sieves. Upon removal of the chiral ruthenium complex, a stereospecific cavity is created. Preliminary results indicate that stereoselective absorption of either Δ or Λ-Ru(phen)32+ isomers from a racemic mixture can be achieved depending on the chirality of the PEO chain. [Copyright &y& Elsevier]

A number of preparations for the synthesis of novel hexagonal mesoporous materials referred to as Dallas amorphous material-1 (DAM-1) have been developed using Vitamin E tocopheryl polyethylene glycol 1000 succinate (TPGS), a water-soluble form of the lipid soluble natural Vitamin E, as the structure directing agent. Depending upon the temperature and gel composition, highly ordered and hydrothermally stable 2-D hexagonal mesoporous DAM-1 with various morphologies could be achieved, including spheres, gyroids, discoids, hexagonal plates, and rods. [Copyright &y& Elsevier]