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  • 1
    Electronic Resource
    Electronic Resource
    Novel Preparation of Nano-Sized TiO〈sub〉2〈/sub〉 and ZrO〈sub〉2〈/sub〉 Particles by Nanocasting with Nanoporous SiO〈sub〉2〈/sub〉 and Selective Dissolution (2007)
    s.l. ; Stafa-Zurich, Switzerland
    Solid state phenomena Vol. 124-126 (June 2007), p. 643-646 
    Details
    ISSN: 1662-9779
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Physics
    Notes: High surface area and uniform nano-sized TiO2 and ZrO2 were prepared readily by theinfiltration of metal alkoxides into the nanoporous SiO2, SBA-15 and the following selectivedissolution of SiO2. The obtained particles of TiO2 and ZrO2, 8.1 nm were nanocrystalline of whichthe structure were anatase and tetragonal, respectively. The surface area and pore volume of thenanocrystalline metal oxides can be increased to above 200 m2g-1 and 0.30 cm3g-1, respectively
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/02/23/transtech_doi~10.4028%252Fwww.scientific.net%252FSSP.124-126.643.pdf
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  • 2
    Electronic Resource
    Electronic Resource
    Beta Zeolites Modified with Lanthanum and Cerium Oxides for the Isomerization of Hexane (2007)
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 539-543 (Mar. 2007), p. 2323-2328 
    Details
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/02/15/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.539-543.2323.pdf
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  • 3
    Electronic Resource
    Electronic Resource
    Skeletal isomerization of 1-butene over mesoporous materials (1999)
    Springer
    Catalysis letters 57 (1999), S. 209-215 
    Details
    ISSN: 1572-879X
    Keywords: 1-butene ; skeletal isomerization ; mesoporous material ; acid site concentration ; monomolecular reaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract On the skeletal isomerization of 1-butene, mesoporous materials with mesopores too large to expect any shape selectivity have been used in order to investigate the effects of the concentration of acid sites on the conversion of 1-butene and the selectivity for isobutene. The concentrations of acid sites can be varied through the control of the Si/Al ratio. The conversion of 1-butene increases with increasing the aluminium content of mesoporous materials, while the selectivity for isobutene decreases. The results of ammonia TPD, IR measurement of 1-butene adsorption, and TG analysis of used catalysts indicate that distant location of activated 1-butene molecules induces the monomolecular reaction over the mesoporous materials with low aluminium content, resulting in high selectivity for skeletal isomerization. On the mesoporous material with high aluminium content, however, the high concentration of activated 1-butene molecules accelerates the multimolecular oligomerization and, thus, reduces the selectivity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1019028522765
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  • 4
    Electronic Resource
    Electronic Resource
    Skeletal isomerization of 1-butene over ferrierite and ZSM-5 zeolites: influence of zeolite acidity (1996)
    Springer
    Catalysis letters 36 (1996), S. 249-253 
    Details
    ISSN: 1572-879X
    Keywords: skeletal isomerization of 1-butene ; ferrierite ; ZSM-5 zeolite ; SiO2/Al2O3 ratio ; acidity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Three ferrierite (FER) and five ZSM-5 (MFI) zeolites with SiO2Al2O3 ratio ranging from 27 to 2000 are tested as catalysts for the skeletal isomerization of 1-butene at 350–450°C and atmospheric total pressure in order to study the influence of acidity and pore structure of zeolite on conversion and selectivity. The catalytic and NH3 temperature-programmed desorption results from FER and MFI catalysts with the same SiO2/Al2O3 ratio reveal that the pore structure of FER zeolite rather than its acidity may play an important role in achieving high selectivity for the skeletal isomerization of 1-butene to isobutene.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00807628
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  • 5
    Electronic Resource
    Electronic Resource
    The role of carbonaceous deposits in the skeletal isomerization of 1-butene over ferrierite zeolites (1996)
    Springer
    Catalysis letters 41 (1996), S. 189-194 
    Details
    ISSN: 1572-879X
    Keywords: 1-butene skeletal isomerization ; ferrierite ; catalyst modification ; carbonaceous deposits
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The inner pores of ferrierite (FER) with a Si/Al ratio of 21 have been modified by plasma-polymerized propylene loading and subsequent thermal treatment under a flow of He at 550°C in order to identify the exact role of carbonaceous deposits (coke) in the skeletal isomerization of 1-butene. It was found that even a small weight loading (0.8 wt%) of carbonaceous deposits within the inner pores of FER zeolite was sufficient to modify the pore structure of the zeolite, leading to a noticeable enhancement of the selectivity to isobutene. This may be attributed to the increased spatial constraints inside the pores which restrict undesired side reactions, such as 1-butene dimerization followed by cracking to light hydrocarbons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00811489
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  • 6
    Electronic Resource
    Electronic Resource
    Skeletal isomerization of 1‐butene on synthetic clinoptilolite zeolite (1998)
    Springer
    Catalysis letters 55 (1998), S. 105-112 
    Details
    ISSN: 1572-879X
    Keywords: 1‐butene skeletal isomerization ; synthetic clinoptilolite ; carbonaceous deposits ; spatial constraints
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A pure, highly crystalline clinoptilolite (CLI) zeolite with a Si/Al ratio of 5.8 has been synthesized using a small amount (1%) of seed crystals and tested as a catalyst for the skeletal isomerization of 1‐butene at 623–723 K at atmospheric pressure. The catalytic results are compared to those obtained from a ferrierite (FER) zeolite with a Si/Al ratio of 7.6. It is found that selectivity for isobutene is very high on CLI zeolite, but conversion was lower than for FER zeolite. The simulated distribution and calculated potential profile of 1‐butene molecules in CLI zeolite pore 10‐ring channels show that the spatial constraints imposed by the pores are very severe. The exceptional selectivity and the low conversion of CLI zeolite results from the strict restriction of adsorption to very specific sites, inhibiting dimerization, as well as from the high potential barrier which reduces mass transfer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1019070526033
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  • 7
    Electronic Resource
    Electronic Resource
    Liquid-phase degradation of polyethylene wax over mordenite catalysts with different Si/Al molar ratios (1999)
    Springer
    Catalysis letters 59 (1999), S. 221-227 
    Details
    ISSN: 1572-879X
    Keywords: polyethylene wax ; mordenite ; liquid-phase degradation ; dealumination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The catalytic liquid-phase degradation of polyethylene wax into fuel oil was studied using mordenite catalysts with various Si/Al molar ratios prepared by dealumination. The total yield of gas and liquid products showed a volcano plot along the Si/Al molar ratio of mordenite. No significant change was observed in the composition of the liquid product for all catalysts used in this study. Fast deactivation was anticipated on the mordenite catalysts with low Si/Al molar ratios such as 5 and 10, due to pore blocking by the carbon deposited on the external surface of the zeolite. A high activity and a long catalyst life were obtained on the mordenite catalyst with a Si/Al molar ratio of 12.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1019089025433
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  • 8
    Electronic Resource
    Electronic Resource
    Influence of the fluorine loading level on the skeletal isomerization of 1-butene over fluorine-modified alumina (1998)
    Springer
    Catalysis letters 51 (1998), S. 101-107 
    Details
    ISSN: 1572-879X
    Keywords: 1-butene ; skeletal isomerization ; fluorine-modified alumina ; acid site concentration ; monomolecular reaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract γ-alumina catalysts modified with different weight loadings of fluorine have been used for skeletal isomerization of 1-butene in order to investigate the effects of the fluorine loading level on the conversion of 1-butene and the selectivity to isobutene formation. Increasing the actual loading of fluorine up to 0.012 wt% led to an increase in conversion of 1-butene over fluorine-modified γ-alumina catalysts, while the high selectivity to isobutene remains almost unchanged. On the other hand, a clear trend of increasing 1-butene conversion with a decreasing selectivity to isobutene is observed for the γ-alumina catalysts with higher loadings of fluorine. An analysis of the results from the thermal analysis, NH3 temperature-programmed desorption, infrared and the 1-butene sorption measurments clearly indicates that the number of strong acid sites in the modified γ-alumina catalysts is greatly enhanced at fluorine loadings higher than 0.012 wt%, leading to the acceleration of 1-butene oligomerization followed by cracking to light hydrocarbons. Therefore, the 1-butene isomerization selectivity from fluorine-modified γ-alumina catalysts can be understood in terms of a competition between the monomolecular and bimolecular reaction pathways, which highly depend on the concentration of strong acid sites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1019037017971
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  • 9
    Electronic Resource
    Electronic Resource
    IR study on the reaction path of skeletal isomerization of 1‐butene (2000)
    Springer
    Catalysis letters 67 (2000), S. 207-213 
    Details
    ISSN: 1572-879X
    Keywords: molecularity ; skeletal isomerization ; butene ; zeolite
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The reaction molecularity of the skeletal isomerization on zeolite was deduced from IR spectra of adsorbed butene recorded with heating. Formation of polymeric species from adsorbed butene was observed on ZSM‐5 and beta zeolites, non‐selective catalysts for isobutene production. On the other hand, most of butene molecules adsorbed on ferrierite and clinoptilolite behaved monomolecularly, resulting in complete desorption even at ambient temperature. The exceptional selectivity for isobutene of ferrierite and clinoptilolite was ascribed to the sparse distribution of adsorbed butene molecules, suppressing bimolecular oligomerization and enhancing monomolecular skeletal isomerization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1019081925202
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  • 10
    Electronic Resource
    Electronic Resource
    Partial Oxidation of Ethylene Over Silver Catalyst Supported on Mesoporous Materials (2000)
    Springer
    Reaction kinetics and catalysis letters 69 (2000), S. 55-61 
    Details
    ISSN: 1588-2837
    Keywords: Ethylene oxide ; mesoporous material ; silver catalyst ; silane treatment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The partial oxidation of ethylene was investigated over silver catalysts supported on mesoporous materials. KIT-1 mesoporous materials with 30–50 wt.% silver exhibited a high conversion of ethylene and a relatively high selectivity for ethylene oxide. The selectivity of Ag/KIT-1 is enhanced by the modification of the silane.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005688624932
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