Using a porous alumina support, seeding for the preparation of a zeolite separation membrane is conducted by placing the electrodes for electrophoretic deposition (EPD) on both sides of the support. In this case, two electrokinetic phenomena are observed: electrophoresis of the seed crystal particles and electroosmotic flow of the solvent within the porous alumina support. When water and acetone are used, the direction of electroosmotic flow is opposite to that of EPD, and the strength of electroosmotic flow with water is higher than that with acetone. In contrast, with methanol, the direction of the electroosmotic flow is the same as that for EPD, with a weak particle charge. The results show that both the support and the solvent contribute to the change in the strength and direction of the electroosmotic flow.

The synthesis of a novel layered silicate SSA-1 (SSA: silicate synthesized with a quaternary amine) was achieved in the SiO2-H2O-TEAOH (TEAOH: tetraethylammonium hydroxide - as an organic structural directing agent) system. The crystal structure of SSA-1 involved two silicate layers composed of bre [10T]-type CBU (Composite Building Unit) and TEAOH in interlayers. The topotactic transformation of SSA-1 by calcination was examined, resulting in a porous material (PML-1: porous material transformed from a layered silicate) with a 108 m(2) g(-1) BET surface area and 0.035 cm(3) g(-1) pore volume. PML-1 is a siliceous microporous material with silanols in the framework and possesses unique properties, such as hydrophilicity, in spite of all its silica composition. The most reasonable crystal structure of PML-1 was successfully determined on the basis of the crystal structure of SSA-1 by a combination of manual modelling, PXRD pattern simulation, DFT optimization and Rietveld analysis. Additionally, an interlayer expanded siliceous zeolite SSA-1 (IEZ-SSA-1) was also successfully prepared by silylation using trichloro(methyl) silane under acidic conditions. IEZ-SSA-1 showed hydrophilicity or hydrophobicity properties by changing the functional group of the pillar part in the interlayer. Additionally, IEZ-SSA-1 showed a large gas adsorption property (537 m(2) g(-1) and 0.21 cm(3) g(-1)).

A highly oriented UiO-66 film, with a monocrystalline layer, was successfully prepared by the solvothermal method. Acetic acid, which served as a modulator, was essential to achieve high film orientation. Water played an important role in promoting the intergrowth of UiO-66 crystals.

The hydrothermal conversion of FAU type zeolite with various structure-directing agents was investigated. The highly crystalline and pure RUT and MTN type zeolites were obtained in the presence of tetramethylammonium hydroxide and benzyltrimethylammonium hydroxide, respectively. As compared to amorphous silica/-Al(2)O(3) source, the crystallization rate for the formation of RUT type zeolite was clearly faster when FAU type zeolite was employed as Si and Al sources.

The hydrothermal conversion of FAU zeolite into aluminous MTN zeolite is described here. In the presence of both benzyltrimethylammonium hydroxide (BTMAOH) and sodium chloride (NaCl) the highly crystalline and pure MTN zeolites with Si/Al ratios of 21-23 could be obtained from the hydrothermal conversion of FAU zeolite. Based on powder XRD refinement and 13 C CP/MAS NMR spectra, BTMA + ions were not present in cages of the obtained zeolites, but TMA + ions existed instead. It means that BTMAOH underwent degradation during the conversion. Moreover, the effects of Si/Al ratio of starting FAU zeolite, synthesis parameters (BTMAOH/SiO 2 and H 2 O/SiO 2 ratios) and the addition of alkali metal chlorides on the hydrothermal conversion of FAU zeolite into MTN zeolite are discussed. As compared to amorphous SiO 2 /γ-Al 2 O 3 , which produced impurity, the hydrothermal conversion of FAU zeolite showed a fast crystallization rate and a high selectivity to MTN zeolite formation. These phenomena indicate that the assembly of locally ordered aluminosilicate species coming from the decomposition or dissolution of FAU zeolite should be taking part in the conversion process.

The systematic study on the synthetic route of the siliceous zeolite RWR with a small 8-MR straight channel by topotactic conversion of crystalline layered silicate RUB-18 was carried out by using several topotactic precursors obtained from Na-RUB-18. Intermediate layered structures of topotactic precursors were designed by intercalation of amine molecules and acid treatment. Crystal structures of two kinds of TMAOH intercalated RUB-18s (TMA-RUB-18-poly1 and TMA-RUB-18-poly2) and their acidified TMA-RUB-18 were determined by ab initio structure analysis using X-ray powder diffraction data. The layered structure of TMA-RUB-18-poly1 and TMA-RUB-18-poly2 had tetragonal symmetry of space group P42/nmc, and the lattice parameters were estimated to be a=7.4121Å, c=22.615Å for TMA-RUB-18-poly1 and a=7.3718Å, c=29.342Å for TMA-RUB-18-poly2. Two silicate layers were involved in a unit-cell and TMA+ cations were intercalated in the interlayer. The layer stacking sequence was completely different from that of Na-RUB-18. Structure of acidified TMA-RUB-18 had also tetragonal symmetry of space group I41/amd and lattice parameters a=7.4722Å, c=37.242Å with four silica layers. Stacking sequence in acidified TMA-RUB-18 was similar to that of Na-RUB-18 although a large shrinking of interlayer distance (ca. 2.0Å) was observed. In the acidified TMA-RUB-18, one-dimensional pseudo pore was constructed by semi-circular geometry derived from the framework structure and stabilized by formation of hydrogen bonding between the terminal silanol groups, which faced each other with atomic distance d(O–O) of ca. 2.5Å. By the dehydration–condensation of silanol groups during careful calcination, zeolite RWR could be successfully prepared from the acidified TMA-RUB-18.

Hydrothermal synthesis of beta (BEA) zeolite with NH4F as a fluoride source was investigated in detail. The highly crystalline BEA zeolites with a wide range of Si/Al ratios from 10 to infinity could be easily obtained. From an evaluation of the thermal stability of BEA zeolites synthesized with and without NH4F, it was found that the thermal stability of BEA zeolite synthesized with NH4F is relatively higher than that of BEA zeolite synthesized without NH4F, although the thermal stability decreases with an increase in the Al content. The addition of NaOH hardly affected the thermal stability of BEA zeolite synthesized with NH4F. The enhanced thermal stability was attributed to much less framework defects.

Influences of various additives oil the direct synthesis of high-silica mordenite (MOR) zeolite with tetraethylammonium hydroxide (TEAOH) were studied in detail. The addition of NaF as a fluoride source enhanced the nucleation and crystal growth of MOR zeolite. The addition of NH4NO3 as a mineralizer was also effective for the synthesis of high-silica MOR zeolite. The MOR zeolites synthesized with NaF and NH4NO3 were found to have much less framework deflects as compared to those synthesized without additives. Under well-optimized conditions, the highly crystalline and pure MOR zeolite with a Si/Al ratio of approximate to 34 was synthesized by adding seed crystals as well as NaF and NH4NO3.

Metalloaluminophosphate molecular sieves with AFI topology, in which a part of aluminum is substituted isomorphously to alkaline earth metals: Mg, Ca, Sr, and Ba (MAPO-5; M = Mg, Ca, Sr and Ba), were synthesized by hydrothermal synthesis (HTS) method and two types of dry-gel conversion (DGC) methods: vapor-phase transport (VPT) and steam-assisted conversion (SAC) methods, using triethylamine (Et3N) as a structure-directing agent (SDA). Systematic studies were carried out by varying the synthesis parameters such as gel composition including content of alkaline earth metals and SDA, amount of external bulk water, and heating time. It has been observed that MO/Al2O3 ratio of starting gel plays an important role in the crystallization of the molecular sieves. The ratios from 0.025 to 0.10 gave pure MAPO-5 with AFI topology; however, MAPO-34 with CHA topology was observed as an impurity with further increase of the Mg content. The amount of Et3N also played important role for the crystallization: Et3N/Al2O3 ratios from 0.38 to 0.76 gave pure MgAPO-5 and CaAPO-5, whereas SrAPO-5 and BaAPO-5 were obtained as pure phase from 0.76 to 1.52. MAPO-5 molecular sieves were crystallized even in the absence of external bulk water. Period for crystallization was studied from 3 to 48 h; the highest intensities were observed between 12 and 18 h for all cases. The occluded SDA was removed by calcination at 550 degrees C. The molecular sieves were characterized by XRD, ICP, TG-DTA, SEM, FT-IR, N-2 and pyridine adsorption, and NH3-TPD. Alkaline earth metals, at least a part of them, are isomorphously substituted in the framework of AFI topology judging from NH3-TPD, unit cell parameters, and their FT-IR spectra of adsorbed pyridine. The substitution of alkaline earth metal with aluminum produced acidic sites in the molecular sieves: substitution of Al3+ to Mg2+ enhanced the appearance of strong acidity; however, only weak acidities appeared for CaAPO-5, SrAPO-5, and BaAPO-5 in small amount.The isopropylation of benzene and biphenyl was examined over MAPO-5 by VPT method to characterize their acidic properties. Their catalytic activity decreases in the order: MgAPO-5 >> CaAPO-5 >= SrAPO-5 >= BaAPO-5; >> APO-5; moderate to good selectivity for 4,4'-DIPB was observed in the level of 50-70% for all MAPO-5. These catalytic properties support strongly the incorporation of alkaline earth metals in the AFI framework. (c) 2005 Elsevier Inc. All rights reserved.

We have succeeded in the synthesis of a thermostable zeolite with a novel framework structure (CDS-1: Cylindrically Double Saw-edged zeolite; CDO topology) from a novel layered silicate (PLS-1: Pentagonal-cylinder Layered Structure) by topotactic dehydration-condensation between pure silicate layers consisting of face sharing of pentagon cylinders. The purely siliceous zeolite CDS-1 has a chemically inert silicate framework and consequently no acid sites. In order to expand the catalytic potential of CDS-1, incorporation of various metals into the zeolite framework is necessary. In this study, we tried to prepare the Al containing CDS-1 zeolite (Al-CDS-1) by (1) alumination of CDS-1 zeolite and (2) transformation of Al-PLS-1. The catalytic performance was also evaluated by a few test reactions such as I-hexene and cumene cracking and dehydration of 2-propanol.

Effect of ammonium salts on the direct hydrothermal synthesis of high-silica mordenite (MOR) zeolite with tetraethylammonium hydroxide was investigated. The addition of NH4NO3 to the system restrained the formation of MFI zeolite and quartz, and accelerated the crystallization rate of high-silica MOR zeolite. The MOR zeolite synthesized with NH4NO3 was very poorer in framework defects as compared with sample obtained without NH4NO3 as indicated by IR and 29Si MAS NMR techniques. It was also indicated by nitrogen adsorption study that the micropore and external surface areas of the MOR zeolites synthesized with ammonium salts are considerably larger than that of sample without ammonium salts. Under well-optimized conditions, the highly crystalline and pure MOR zeolite with a Si/Al ratio of ≈34 was successfully prepared by adding seed crystals and NaF as well as NH4NO3.

Without Abstract

ZSM-5 type zeolites containing alkaline earth metals (M-HZSM-5) were prepared Under various synthesis conditions and their hydrothemial stability was investigated. It was found that the average crystal size of M-HZSM-5 can be easily controlled by addition of H3BO3 with no reduction of the amount of alkaline earth metal Occluded. It was also found that the hydrothemial stability of M-HZSM-5 evaluated by steaming at 600 degrees C depends upon not the crystal size but the amount of the alkaline earth metal occluded. Ca-, Sr- and Ba-HZSM-5 showed the higher hydrothermal stability, and Ca- and Sr-HZSM-5 exhibited the high selectivity to light olefins in methanol conversion even after steaming at 600 degrees C for 7 days.

A joint study was organized to establish a standard set of conditions for the ion exchange of zeolite from sodium into proton-form. The sodium-form mordenite with Si/Al2=ca. 15 was ion exchanged into an NH4-form, followed by calcination according to various recipes. Then various advanced techniques for characterization (ICP, TG, XPS, SEM, XRD, N2 adsorption, 29Si and 27Al NMR, benzene diffusion, IR of OH and adsorbed pyridine and CO, ammonia TPD) were applied, and some test reactions (cracking of cumene, isopropylation of biphenyl, oligomerization of propene and chichibabin condensation of acetaldehyde and ammonia into picoline) were conducted. The ion exchange (removal of sodium) proceeded as expected, but remarkable differences were observed in physicochemical and catalytic properties of the thus-prepared proton-form samples. Exceptionally high temperature (383K) for the ion exchange resulted in the structural degradation, while most samples exchanged at 333–353K maintained the crystallinity and pore volume. The use of NH4Cl slightly changed the crystal morphology. Extra-framework aluminum species was formed on most samples after calcination above 773K. In contrast, calcination at 673K maintained the framework aluminum. Therefore, the dealumination is considered to proceed after complete removal of ammonia from the ammonium-form zeolite. However, the proton-form zeolite was stable under dry conditions, so it is speculated that the dealumination was induced by the contact of the proton-form zeolite to atmosphere with humidity. The total and Brønsted acidity decreased with the dealumination, while Lewis acidity increased. On the other hand, rapid heating of the ammonium type zeolite caused narrowing of the micropores. These structural changes seriously affected the catalytic activities for various reactions.

Ti-containing mesoporous silicas (Ti-MCM-41, Ti-MCM-48 and Ti-SBA-15) were prepared by the post-synthesis with Ti(OC4H9)(4) and their propylene polymerization behavior was investigated. It Was found that these Ti-containing mesoporous silicas combined with Al(i-C4H9)(3) provide the isotactic polypropylene. Polypropylenes outside and inside the mesopores of Ti-containing mesoporous silicas had different characteristics despite being polymerized concurrently. The crystallization of polypropylenes confined in the mesopores was considerably depressed due to the limited space.

New high-silica zeolite CDS-1 ( C ylindrically D ouble S aw-Edged zeolite; F ramework T ype C ode (FTC): CDO) was prepared by dehydration-condensation from novel layered silicate PLS-1 ( P entagonal-cylinder L ayered S ilicate) intercalating tetramethylammonium hydroxide between silicate layers. Synthesis conditions of PLS-1 was optimized by using SiO2-TMAOH-1,4-dioxane-H2O system without any alkali metal ions.

Novel acidic or basic aryl-alkyl disulfides having phenol, benzoic acid, benzenesulfonic acid, aniline, and benzylamine groups were synthesized as protective agents for gold (Au) nanoparticles. Monodisperse An nanoparticles passivated by these ligands were prepared using a chemical reduction technique, and self-assembled into well-ordered hexagonal close-packed (hcp) 2D superlattices on the substrate. We also present, for the first time, the formation of an aggregated multilayer of Au nanoparticles at a water-organic solvent interface by mixing separately synthesized acidic and basic Au nanoparticles. This film was definitely different from those obtained by the LB method and the conventional self-assembly method through solvent evaporation.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Direct hydrothermal synthesis of highly crystalline MOR with a Si/Al ratio of ca. 30 was achieved by a combination of tetraethylammonium hydroxide and NaF when Al(NO3)(3) was employed as an aluminum source. It was also found that the crystallinity and the Si/Al ratio of MOR zeolite hardly depend on the addition time of NaF. However, the content of fluorine in the as-synthesized MOR zeolite decreased markedly when NaF was added in the Course of crystallization process. The decrease in the fluorine content improved considerably the thermal stability of the as-synthesized MOR zeolite.

Pt nanoparticles-containing mesoporous silica MCM-41 (Pt/MCM-41) was directly synthesized using surfactant stabilized Pt nanoparticles after gel filtration. The obtained Pt/MCM-41 composite materials were characterized with XRD, UV-Vis, TEM and N-2 adsorption. It was found that the Pt nanoparticles are located inside the pores of MCM-41 even after calcination at 500 degrees C, Suggesting the high thermal stability of P nanoparticles within the mesopores.