Ti-incorporated MFI zeolite (Ti-MFI-MW) has been synthesized with microwave heating. Their physicochemical properties such as surface hydrophobicity, and adsorption and catalytic properties have been compared with those of Ti-incorporated MFI zeolite (Ti-MFI-CH) prepared by conventional hydrothermal method. Competitive adsorption measurements with toluene and water revealed that the hydrophobicity index of Ti-MFI-MW (8.0) is higher than that of Ti-MFI-CH (6.2). IR spectra showed that Ti-MFI-MW also has a lower content of surface hydroxyl groups and adsorbs a larger amount of 1-hexene than Ti-MFI-CH. These results pointed out that Ti-MFI-MW is more hydrophobic than Ti-MFI-CH. Epoxidation reactions of 1-hexene and styrene with hydrogen peroxide have been conducted to investigate catalytic properties of the Ti-MFI zeolites according to the synthesis method. The conversions and epoxide selectivities over Ti-MFI-MW are higher than those over Ti-MFI-CH due to the enhanced surface hydrophobicity.

Sensors have become an integral part of all the activity of modern human being. Amongst the sensors, humidity sensor is a vital requirement of human life and industrial applications and therefore needs exact monitoring. Although humidity sensors designed from ceramic materials, polymers and composites have been studied, ceramic sensors are preferred for their chemical and physical stability in an environment, which is suitable for its applications, processing ability and possibility of achieving predetermined properties. Although many oxides such as SnO2, 1 ZnO, TiO2, 3 ZrO2 4 SiO2 5 are being studied for the development of humidity sensors, the research for newer methods and the materials is unending because of specific requirements of various applications in terms of sensitivity, selectivity, response time, low cost of manufacture, compactness and microprocessor compatibility. Moreover, it is almost impossible to develop an ideal universal humidity sensor for all applications. TiO2 based humidity sensors are studied vigorously, as it is likely to show better sensitivity because of its hydrophilic property. It is studied more in thin film form. However, it is reported that thin film sensors show lower sensitivity than those shown by porous ceramic sintered counterparts. TiO2 is known to have a hysteresis in humidity sensitivity curve. It was thought that the use of additives would be useful to get over this drawback. The additives are reported to minimize the hysteresis in TiO2 humidity sensors. 10

Der Einbau von Metall und die mikrowellengestützte Synthese von MFI-Zeolithen führen zur Kristallstapelung in einer Richtung und somit zu einer Fasermorphologie (siehe Bilder des Ti-MFI-Zeoliths). Diese Struktur hat ungewöhnliche physikochemische Eigenschaften zur Folge, nämlich eine geringere Packungsdichte und höhere Hydrophobie als nichtfasrige Analoga, womit bessere Katalyseeigenschaften und bessere größenselektive Adsorption einhergehen.

Tungsten oxide-modified TiO2 thin films were formed on a glass substrate by sol-gel and dip coating processes using acetyl acetone as a chelating agent. The hydrophilic properties of the thin films were investigated with illumination of UV light. The dependence of water contact angle on material composition and morphology of the film is established with SEM image and AFM profile. The surface morphology was controlled with the change of precursor concentration. 0.01 M of tungsten oxide-modified TiO2 have shown the highest hydrophilicity after UV-irradiation. The effect of composition on photoinduced hydrophilicity of the WO3TiO2 films was also investigated. The films were characterized by XRD, SEM, AFM and XPS.

Syntheses of cobalt- and vanadium-incorporated aluminophosphate molecular sieves (CoAPO and VAPO) with AFI and CHA structures have been studied using an alkaline or neutral gel under microwave irradiation and conventional hydrothermal heating. Microwave synthesis gives rise to the selective crystallization of CoAPO-34 with a CHA structure and VAPO-5 with an AFI structure, while the conventional hydrothermal crystallization brings CoAPO-5 and VAPO-34 through the gradual transformation of CoAPO-34 and VAPO-5, respectively, as the crystallization time increases. These results reveal that the relative stabilities of metal-incorporated aluminophosphate (MeAPO) molecular sieves between AFI and CHA structures depend on the type of incorporated metal ions. This work also suggests that microwave syntheses of MeAPO molecular sieves preferentially induce a kinetically favorable MeAPO phase in a short period of crystallization time. The synthesis of VAPO-5 in an alkaline condition is for the first time reported in this work.

The syntheses of two nanoporous nickel phosphates, VSB-1 and VSB-5, have been investigated to elucidate the effect of various synthesis parameters such as pH, type of base, reaction time, and heating method. The pH is found to be the most important factor to direct the structure in the synthesis. These molecular sieves are easily synthesized in a suitable pH range even without organic template molecules. VSB-1 is crystallized only in acidic conditions (pH = 3.5-4.8), while VSB-5 is prepared in weakly basic conditions (pH = 7.5-9.2). The reaction yield of VSB-1 increases with increasing pH, while VSB-5 shows the opposite trend. Compared with conventional hydrothermal synthesis, the microwave irradiation method increases the reaction rates of the two nickel phosphates by about 60 times, and the synthesis of VSB-1 and VSB-5 can be completed within 1 min at 190 and 180 degrees C, respectively. It is demonstrated that the molecular sieves can be synthesized continuously under microwave irradiation due to these fast crystallizations.

The effect of synthesis parameters such as H2O/Ti, Ba/Ti and OH−/Ti ratios and heating methods (microwave irradiation and hydrothermal heating) on the synthesis of BaTiO3 crystals has been investigated to prepare nanocrystalline BaTiO3 crystals. The nanocrystals (less than 30 nm) were synthesized with microwave irradiation of reaction mixture prepared from conventional chloride precursors. The crystal size decreased with an increase of hydroxide and barium concentrations, whereas the size decreased with a decrease of the water concentration. Synthesis of BaTiO3 with the microwave provided advantages of fast crystallization and decreased crystal size.

Zeolite SUZ-4 is found to be a very selective and stable catalyst for producing dimethyl ether in methanol dehydration because the formed dimethyl ether is hardly converted to hydrocarbons, different from ZSM-5 zeolite.

Angewandte ChemieVolume 116, Issue 21 p. 2879-2882 Zuschrift Nanoporous Metal-Containing Nickel Phosphates: A Class of Shape-Selective Catalyst† Jong-San Chang Dr., Jong-San Chang Dr. [email protected] Catalysis Center for Molecular Engineering, Korea Research Institute of Chemical Technology (KRICT), P.O. Box 107, Yusung, Taejon 305–600, Korea, Fax: (+82) 42-860-7676Search for more papers by this authorJin-Soo Hwang Dr., Jin-Soo Hwang Dr. Catalysis Center for Molecular Engineering, Korea Research Institute of Chemical Technology (KRICT), P.O. Box 107, Yusung, Taejon 305–600, Korea, Fax: (+82) 42-860-7676Search for more papers by this authorSung Hwa Jhung Dr., Sung Hwa Jhung Dr. Catalysis Center for Molecular Engineering, Korea Research Institute of Chemical Technology (KRICT), P.O. Box 107, Yusung, Taejon 305–600, Korea, Fax: (+82) 42-860-7676Search for more papers by this authorSang-Eon Park Prof., Sang-Eon Park Prof. [email protected] Department of Chemistry, Inha University, Incheon 402-751, Korea, Fax: (+82) 32-874-7674Search for more papers by this authorGérard Férey Prof., Gérard Férey Prof. Institut Lavoisier, UMR 8637, Université de Versailles Saint Quentin, 45 avenue des Etats-Unis, 78035 Versailles Cedex, FranceSearch for more papers by this authorAnthony K. Cheetham Prof., Anthony K. Cheetham Prof. [email protected] Materials Research Laboratory, University of California, Santa Barbara, CA 93106, USA, Fax: (+1) 805-893-8797Search for more papers by this author Jong-San Chang Dr., Jong-San Chang Dr. [email protected] Catalysis Center for Molecular Engineering, Korea Research Institute of Chemical Technology (KRICT), P.O. Box 107, Yusung, Taejon 305–600, Korea, Fax: (+82) 42-860-7676Search for more papers by this authorJin-Soo Hwang Dr., Jin-Soo Hwang Dr. Catalysis Center for Molecular Engineering, Korea Research Institute of Chemical Technology (KRICT), P.O. Box 107, Yusung, Taejon 305–600, Korea, Fax: (+82) 42-860-7676Search for more papers by this authorSung Hwa Jhung Dr., Sung Hwa Jhung Dr. Catalysis Center for Molecular Engineering, Korea Research Institute of Chemical Technology (KRICT), P.O. Box 107, Yusung, Taejon 305–600, Korea, Fax: (+82) 42-860-7676Search for more papers by this authorSang-Eon Park Prof., Sang-Eon Park Prof. [email protected] Department of Chemistry, Inha University, Incheon 402-751, Korea, Fax: (+82) 32-874-7674Search for more papers by this authorGérard Férey Prof., Gérard Férey Prof. Institut Lavoisier, UMR 8637, Université de Versailles Saint Quentin, 45 avenue des Etats-Unis, 78035 Versailles Cedex, FranceSearch for more papers by this authorAnthony K. Cheetham Prof., Anthony K. Cheetham Prof. [email protected] Materials Research Laboratory, University of California, Santa Barbara, CA 93106, USA, Fax: (+1) 805-893-8797Search for more papers by this author First published: 12 May 2004 https://doi.org/10.1002/ange.200353502Citations: 2 † This work was partially supported by the Korean Ministry of Science and Technology through the Research Center for Nanocatalysis (KN-0329), one of the National Science Programs for Key Nanotechnology and Institutional Research Program, and by the MRL Program of the National Science Foundation under Award No. DMR00-80034. The authors thank all of the CCME members (KRICT) related to this work for their beneficial contributions. Read the full textAboutPDF ToolsRequest permissionAdd to favorites ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinkedInRedditWechat Graphical Abstract Zeolith-Ersatz: Das nanoporöse Nickelphosphat VSB-1 zeigt Zeolith-artiges Verhalten bei sehr schwacher Acidität und Basizität (siehe Bild). Durch Austausch von Metallionen oder Beladen der VSB-1-Struktur mit Metallen erhält man Feststoffe mit viel versprechenden Eigenschaften, z. B. Formselektivität oder Aktivität bei Redox- und Photokatalyse. Supporting Information Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2001/2004/z53502_s.pdf or from the author. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article. References 1S. T. Wilson, B. M. Lok, C. A. Messina, T. R. Cannan, E. M. Flanigen, J. Am. Chem. Soc. 1982, 104, 1146. 10.1021/ja00368a062 CASWeb of Science®Google Scholar 2 2aA. K. Cheetham, G. Férey, T. Loiseau, Angew. Chem. 1999, 111, 3466; 10.1002/(SICI)1521-3757(19991115)111:22<3466::AID-ANGE3466>3.0.CO;2-M Google ScholarAngew. Chem. Int. Ed. 1999, 38, 3268; 10.1002/(SICI)1521-3773(19991115)38:22<3268::AID-ANIE3268>3.0.CO;2-U CASPubMedWeb of Science®Google ScholarG. Férey, A. K. Cheetham, Science 1999, 283, 1125; 10.1126/science.283.5405.1125 CASWeb of Science®Google Scholar 2bC. N. R. Rao, S. Natarajan, S. Neeraj, J. Am. Chem. Soc. 2000, 122, 2810; 10.1021/ja993892f CASWeb of Science®Google Scholar 2cC. N. R. Rao, S. Natarajan, A. Choudhury, S. Neeraj, A. A. Ayi, Acc. Chem. Res. 2001, 34, 80. 10.1021/ar000135+ CASPubMedWeb of Science®Google Scholar 3 3aJ. M. Thomas, Angew. Chem. 1994, 106, 963; 10.1002/ange.19941060904 CASGoogle ScholarAngew. Chem. Int. Ed. Engl. 1994, 33, 913; 10.1002/anie.199409131 Web of Science®Google Scholar 3bM. E. Davis, Chem. Eur. J. 1997, 3, 1745; 10.1002/chem.19970031104 CASWeb of Science®Google Scholar 3cF. Schüth, W. Schmidt, Adv. Mater. 2002, 14, 629; 10.1002/1521-4095(20020503)14:9<629::AID-ADMA629>3.0.CO;2-B CASWeb of Science®Google Scholar 3dA. Corma, Chem. Rev. 1997, 97, 2373. 10.1021/cr960406n CASPubMedWeb of Science®Google Scholar 4M. E. Davis, Nature 2002, 417, 81. 10.1038/nature00785 CASWeb of Science®Google Scholar 5P. Feng, X. Bu, G. D. Stucky, Nature 1997, 388, 735. 10.1038/41937 CASWeb of Science®Google Scholar 6 6aN. Guillou, Q. Gao, M. Nogues, R. E. Morris, M. Herview, G. Férey, A. K. Cheetham, C. R. Acad. Sci. Ser. IIc 1999, 2, 387; 10.1016/S1387-1609(00)88550-3 CASWeb of Science®Google Scholar 6bJ.-S. Chang, S.-E. Park, Q. Gao, G. Férey, A. K. Cheetham, Chem. Commun. 2001, 859. 10.1039/b009160j CASWeb of Science®Google Scholar 7P. M. Forster, J. Eckert, J.-S. Chang, S.-E. Park, G. Férey, A. K. Cheetham, J. Am. Chem. Soc. 2003, 125, 1309. 10.1021/ja028341v CASPubMedWeb of Science®Google Scholar 8N. Guillou, Q. Gao, P. M. Forster, J.-S. Chang, M. Nogues, S.-E. Park, G. Férey, A. K. Cheetham, Angew. Chem. 2001, 113, 2913; 10.1002/1521-3757(20010803)113:15<2913::AID-ANGE2913>3.0.CO;2-P Google ScholarAngew. Chem. Int. Ed. 2001, 40, 2831. 10.1002/1521-3773(20010803)40:15<2831::AID-ANIE2831>3.0.CO;2-Z CASPubMedWeb of Science®Google Scholar 9J. M. Thomas, R. Raja, Chem. Commun. 2001, 675. 10.1039/b100369k CASWeb of Science®Google Scholar 10 10aJ. H. Lunsford, J. Catal. 2003, 216, 455; 10.1016/S0021-9517(02)00070-2 CASWeb of Science®Google Scholar 10bK. P. Reis, V. K. Joshi, M. E. Thompson, J. Catal. 1996, 161, 62. 10.1006/jcat.1996.0162 CASWeb of Science®Google Scholar 11S.-E. Park, L. Huang, C. W. Lee, J.-S. Chang, Catal. Today 2000, 61, 117. 10.1016/S0920-5861(00)00351-5 CASWeb of Science®Google Scholar 12R. Raja, T. Khimyak, J. M. Thomas, S. Hermans, B. F. G. Johnson, Angew. Chem. 2001, 113, 4774; 10.1002/1521-3757(20011217)113:24<4774::AID-ANGE4774>3.0.CO;2-H Google ScholarAngew. Chem. Int. Ed. 2001, 40, 4638. 10.1002/1521-3773(20011217)40:24<4638::AID-ANIE4638>3.0.CO;2-W CASPubMedWeb of Science®Google Scholar 13C. Perego, A. Carati, P. Ingallina, M. A. Mantegazza, G. Bellussi, Appl. Catal. A 2001, 221, 63. 10.1016/S0926-860X(01)00797-9 CASWeb of Science®Google Scholar 14 14aU. Romano, A. Esposito, F. Maspero, C. Neri, M. Clerici, Stud. Surf. Sci. Catal. 1990, 55, 33; 10.1016/S0167-2991(08)60131-7 CASWeb of Science®Google Scholar 14bJ. A. Martens, P. Buskens, P. A. Jacobs, Appl. Catal. A 1993, 99, 71. 10.1016/0926-860X(93)85040-V CASWeb of Science®Google Scholar 15T. Kocha, M. Yamaguchi, H. Ohtaki, T. Fukuda, T. Aoyagi, Biochim. Biophys. Acta 1997, 1337, 319. 10.1016/S0167-4838(96)00180-X CASPubMedWeb of Science®Google Scholar 16 16aM. Matsuoka, M. Anpo, J. Photochem. Photobiol. C 2003, 3, 225; 10.1016/S1389-5567(02)00040-0 CASGoogle Scholar 16bY. H. Yeom, N. Ulagappan, H. Frei, J. Phys. Chem. A 2002, 106, 3345. 10.1021/jp011056y CASWeb of Science®Google Scholar 17A. Ribera, I. W. C. E. Arends, S. de Vries, J. Perez-Ramirez, R. A. Sheldon, J. Catal. 2000, 195, 287. 10.1006/jcat.2000.2994 CASWeb of Science®Google Scholar 18C. Pulgari, P. Peringer, P. Albers, J. Kiwi, J. Mol. Catal. A 1995, 95, 61. 10.1016/1381-1169(94)00156-1 Web of Science®Google Scholar Citing Literature Volume116, Issue21May 17, 2004Pages 2879-2882 This is the German version of Angewandte Chemie. Note for articles published since 1962: Do not cite this version alone. Take me to the International Edition version with citable page numbers, DOI, and citation export. We apologize for the inconvenience. ReferencesRelatedInformation

Ti-ZSM-5 prepared by secondary synthesis, from the reaction of H-ZSM-5 with vapor phase TiCl4, was characterized with several physicochemical techniques including FT-IR and UV/VIS-DRS. It was found that zeolite structure, surface area and pore volume did not change, and the framework aluminum could not be replaced by titanium atom during the secondary synthesis of Ti-ZSM-5. The incorporation of titanium into the framework might be due to reaction of TiCl4 with the silanol groups associated with defects or surface sites. The formation of extra-framework titanium could not be avoided, unless the samples were further treated by water vapor at 550 degreesC or higher temperature. High temperature steam treatment of Ti-ZSM-5 prepared by chemical vapor deposition with TiCl4 was efficient to prevent the formation of non-framework titanium species. Ti-ZSM-5 zeolites prepared in this work contained only framework titanium species and exhibited improved catalytic property close to TS-1 prepared by hydrothermal synthesis.

ion-exchanged H-ZSM-5 (NaH-ZSM-5) shows higher DME selectivity than H-ZSM-5 dueto the selective removal of strong acid sites.Key Words : Dehydration, DME, Methanol, ZSM-5 zeoliteIntroductionDimethyl ether (DME) is a useful chemical intermediatefor the preparation of many important chemicals, such asdimethyl sulfate and high-value oxygenated compounds.

The paper shortly reviews the basic direct approaches applied in searching for viable solutions to solar fuel production. These are generally distinguished in molecular and semiconductor (non-molecular) systems, however, hybrid strategies, proposed recently, have also been included. The most promising efforts are considered, highlighting key aspects and emerging critical issues. Special attention is paid to aspects such as electrode architecture, device design, and main differences in the scientific vision and challenges to directly produce solar fuels. This overview could be useful to orientate the readers in the wide panorama of research activities concerning water splitting, natural and artificial photosynthesis, and solar fuel production through the identification of common aspects, specialties and potentialities of the many initiatives and approaches that are developing worldwide in this field with the final aim to meet world energy demand.

SAPO-5 and SAPO-34 molecular sieves can be selectively formed with microwave irradiation and hydrothermal heating, respectively, of the same gel irrespective of the acidity or the type of the templates such as triethylamine and N,N,N′,N′-tetraethylethylenediamine. The SAPO-5 structure may transform into the SAPO-34 structure with increase of crystallization time probably due to the relative stability of the two phases at the reaction conditions. Crystallization with microwave irradiation can be used as a phase selective synthesis method for unstable material because of fast crystallization.

Nanofabrication of nanoporous materials under microwave irradiation was successfully implemented by the adhesion of crystallites through the condensation of hydroxyl groups on surface via selective adsorption of microwave energy on Ti species as a nanoglue. This microwave technique gave births of both the uniform size of hockey puck shaped crystals and the stacking of these crystals into fiber or rod types in the synthesis of nanoporous materials such as MFI and AIPO-5 zeolites. The formation of these nanostacked MFI-type zeolite crystals having nanorod shape was ascribed to the presence of metal species, which selectively absorbed microwave irradiation. These fibrous MFI zeolites provide exciting and unique physicochemical properties, for example, low packing density, high stability of the fibrous morphology and the enhanced hydrophobicity. The fabricated Ti-MFI and AIPO-5 show preferential adsorption of p-xylene over o-xylene, which may suggest that a longish molecule can be adsorbed preferentially on the longish nanoporous materials.

As a potential way of biomass utilization, hydrocarbon synthesis from bio-syngas (syngas obtained from biomass gasification) has been investigated. The Fischer-Tropsch reaction has been carried out using CO/CO2/H-2/Ar (11/32/52/5) mixture as a model for biomass-derived syngas on co-precipitated Fe/Cu/Al(or Si)/K catalysts in a fixed bed reactor. In the comparison of alumina and silica supports, alumina resulted in much higher activity for hydrocarbon production than silica. The reaction test with the catalysts containing various amounts of K revealed that K addition promoted the catalytic activity and the selectivities toward olefins and long-chain hydrocarbons, even though too high K promotion caused the gradual deactivation of the catalysts. The reaction with the model bio-syngas showed that almost only CO was converted to hydrocarbons. However, in the reaction with a balanced (i.e. H-2-enriched) feed gas, CO2 was converted to hydrocarbons as well as CO. A kinetic model has been developed for the reaction of bio-syngas and verified by the experimental data.

FeCl2 and 3-aminopropyltrimethoxysilane (ATMS) were grafted on Si-MCM-41. FeCl2, FeCl3, FePc(II) and FePc(III)Cl were also grafted with ATMS coupled Si-MCM-41, whose catalytic activities were evaluated by performing hydroxylation of phenol with H2O2. These chemically modified Fe-containing samples were characterized by FT-IR. When the FeCl2/Si-MCM-41 is used, the phenol conversion reveals about 16.5%. ATMS coupled Fe-containing Si-MCM-41 catalysts improve phenol conversion by 1.5–2 times and decrease the formation of benzoquinone remarkably, while catechol/hydroquinone is in the range of 2–3.5. The redox behavior between Fe(II) and Fe(III) is discussed based on ESR spectroscopy.

The deactivation of a coprecipitated Fe-Cu-K-Al catalyst has been studied in CO2 hydrogenation to hydrocarbons. After the catalyst had been employed in the reaction for 1500h at 300°C, 10atm and space velocity of 1800ml/gcath, it started to show significant decreases in the catalytic activity and selectivity. A long-term (2000h) reaction test led to 13% reduction in the hydrocarbon synthesis activity. The characterizations have been carried out by means of elemental analysis, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Mössbauer spectroscopy for the fresh catalyst, the activated catalyst and the deactivated catalyst. From the results, it can be deduced that the catalyst deactivation was caused by the increase in crystallinity of iron species, thus leading to the phase separation of Fe, Cu, Al and K.

The deactivation of impregnated Fe-K/alumina catalyst during CO2 hydrogenation to hydrocarbons has been studied. After the catalyst had been employed for 850h, a long-term (850h) reaction test led to 37% reduction in the hydrocarbon synthesis activity. With the deactivated catalyst, solvent extraction, reduction and oxidation–reduction treatments have been examined for the catalyst regeneration. The characterizations have been carried out by means of chemisorption, BET measurement, elemental analysis and X-ray diffraction with the fresh catalyst, the deactivated catalyst and post-treated catalysts. From the results, it can be deduced that the catalyst deactivation is mainly caused by the carbonaceous deposits. The deactivated catalyst has been successfully regenerated by the oxidation–reduction treatment.