Yoshimichi Kiyozumi

Preparation and characterization of ZSM-5 zeolite film

The ZSM-5 zeolite film was prepared from a clear aqueous solution of a synthesis mixture with high H2O/SiO2. The large differences in morphology and SiO2/Al2O3 ratio between outer and inner sides of the films were observed.

Potentials of silicalite membranes for the separation of alcohol/water mixtures

Polycrystalline silicalite membranes were prepared on porous sintered stainless steel and alumina supports. The liquid separation potential of the membrane was investigated using various alcohol/water mixtures by pervaporation. The silicalite membrane showed a high alcohol permselectivity. Adsorption experiments of water and alcohols suggest that the high alcohol permselectivity is attributable to the selective sorption of alcohol into the silicalite membrane.

Selective Adsorption of Biopolymers on Zeolites

Zeolites adsorb biopolymers on their surface and may be suitable as a new type of chromatographic carrier material for proteins, nucleic acids, and their conjugates. We report here various parameters that influence the adsorption of biopolymers on synthesized zeolites with regard to the Si/Al2 ratio and three-dimensional structure. There are three physicochemical principles that may underly the adsorption: 1) below the isoelectric point (pI), mainly Coulombic attraction similar to ion-exchange chromatography; 2) at pI, hydrophobic interactions (a kind of van der Waals attraction) plus the three-dimensional mesopore structure; and 3) above pI, the sum of the Coulombic repulsion and attraction forces, such as the hydrophobic interaction, and also substitution reaction of water on the Al molecule with a protein amino-base. At high Si/Al2 ratio in the presence of a small amount of Al and with mesopores between the zeolite particles, maximal adsorption was seen at pI and was suggested to be dependent on the number of hydrophobic interaction points on the mesopores, and their morphology. The application of zeolites to biochemistry and biotechnology is also discussed.

Layered double hydroxides and their pillared derivatives – materials for solid base catalysis; synthesis and characterization

Abstract Mg–Al and Zn–Al L(ayered) D(ouble) H(ydroxide)s have been prepared and characterized. Thermal and dehydration/rehydration behaviour was studied by thermoanalytical methods (TG, DTG, DTA) and 27 Al M(agic) A(ngle) S(pinning) NMR spectroscopy, X-ray diffractometry (XRD) and S(canning) E(lectron) M(icroscopy). Acid–base properties of the calcined samples were investigated by T(emperature) P(rogrammed) D(esorption) of preadsorbed CO 2 and the double-bond isomerization reaction of 1-butene. Heat treatment destroyed the layered structure, which could be only partially reconstituted by rehydration. On calcination mixed oxide with the predominance of basic sites were formed. Pillaring of the LDHs with organic (terephtalate, dodecyl sulphate) as well as inorganic (oxometallate, ferrocyanide) anions were also performed. The materials were characterized by infrared (IR) spectroscopy, XRD and BET measurements. Heat stabilities of the pillared substances were investigated too. Pillaring by various methods proved to be successful, however, decreased heat resistance was found in the intercalated materials relative to the host LDHs.

Synthesis and characterization of a ferrierite made by recrystallization of an aluminium-containing hydrated magadiite

Abstract A new method for the synthesis of high-silica ferrierite (Si/Al=15–18) by recrystallization of aluminium-containing magadiite varieties in air-dry state and aqueous suspension with piperidine as template is reported. Details on removal and thermal stability of the template occluded during the synthesis (four molecules per unit cell) are given. Properties (e.g. thermal and hydrothermal stability, acidity) of ferrierites prepared by the dry synthesis technique are presented and compositional and morphological characteristics of the products are compared with those of ferrierite conventionally prepared from alkaline SiO 2 /Al 2 O 3 gel in aqueous medium.

Structure of aluminium methylphosphonate, AIMepO-β, with unidimensional channels formed from ladder-like organic–inorganic polymer chains

The crystal structure of a microporous aluminium methylphosphonate AIMepO-β is described; the skeleton built up of fused four-ring chain forms unidimensional channels of approximately 5.8 A cross-section fringed with methyl groups running parallel to the c-axis.

Recrystallization of magadiite varieties isomorphically substituted with aluminum to MFI and MEL zeolites

Abstract Magadiite varieties isomorphically substituted with aluminum and their aluminosilicic acid derivatives retaining the framework topology of magadiite are recrystallized, after incorporation by ion exchange of four TPA and TBA ions, to MFI- and MEL-type zeolites, respectively. The recrystallization degree and the size and shape of the zeolite crystallites formed can be controlled by the amount of template applied. Partial recrystallization results in products which promise to be advantageously applicable as catalysts because of the small crystallite size of the zeolitic component.

Structure and properties of TiO2SiO2 prepared by sol-gel method in the presence of tartaric acid

Structure and textural properties of TiO{sub 2}-SiO{sub 2} (Ti/Si = 0.2) composites prepared by sol-gel process in the presence of tartaric acid have been investigated. The specific surface areas of the TiO{sub 2}-SiO{sub 2} gels calcined at 400 C varied from ca. 250 m{sup 2}/g to ca. 750 m{sup 2}/g depending on the amount of tartaric acid used. After calcination at 800 C, TiO{sub 2} in the composite started to crystallize to anatase phase. However, the intensity of the X-ray diffraction peak of anatase crystallite was different between the composites. Infrared and Raman spectra suggest that the Ti-O-Si bond is present in the TiO{sub 2}-SiO{sub 2} in a wide calcination temperature range. Total acid amount in the calcined TiO{sub 2}-SiO{sub 2} samples was proportional to the BET surface area.

Effect of malic acid on structure of silicon alkoxide derived silica

Abstract The effect of malic acid on specific surface area, pore size distribution and gel structure of sol-gel derived silica gels was investigated. Tetraethoxysilane (TEOS) used as starting material was modified with malic acid prior to hydrolysis. The specific surface area of calcined gels increased and the pore size distribution shifted to smaller values and became sharper with an increase in malic acid. Malic acid affected particle size and the extent of condensation due to its acidity and condensation hindrance. Under high malic acid concentrations particulate gels were formed. Malic acid chemically bonded or adsorbed to silica polymers prevented particle growth and condensation among particles. Gels obtained at above malic acid/TEOS = 1.17 (mol/mol) and calcined at 450°C for 3 h showed high specific surface areas about 1000 m 2 g −1 . The gel had uniform mesopores with around 2 nm radius.

Steaming of ZSM-5 zeolite film

Abstract The change in morphology of the ZSM-5 zeolite films during steaming at 443 K was studied. The crystal growth of zeolite, 5–10 μm in size, from the layer of microcyrstalline ZSM-5 zeolites was first visualized by scanning electron microscopy.