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  • 1
    Electronic Resource
    Electronic Resource
    Stability of Fe/ZSM‐5 de‐NOx catalyst: effects of iron loading and remaining Brønsted acid sites (1999)
    Springer
    Catalysis letters 61 (1999), S. 71-76 
    Details
    ISSN: 1572-879X
    Keywords: Fe/ZSM‐5 ; steam treatment ; deactivation ; hydrothermal stability ; SCR ; de‐NOx
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The stability of Fe/ZSM‐5 de‐NOx catalyst has been investigated. The samples are prepared by sublimation of iron chloride. Substantial amount of protons are found to remain in the fresh catalyst after washing and calcination. After 10 h exposure to wet exhaust gas at 600°C, the catalyst is severely deactivated. The presence of steam induces dealumination of the ZSM‐5 matrix, because the protons provide the point of attack by water. In addition, highly reactive distorted tetrahedral iron species and tetrahedral species change to less reactive octahedral iron ions or iron agglomerates upon aging treatment. With the second sublimation of iron chloride, the iron loading is increased and thus the concentration of remaining protons is reduced. Also, the catalyst turns out to preserve more reactive iron ions after aging treatment. In conclusion, the second sublimation is believed to bring about a remarkable improvement in the stability of the Fe/ZSM‐5 catalyst although its de‐NOx activity is slightly decreased.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1019044032219
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  • 2
    Electronic Resource
    Electronic Resource
    Improvement in hydrophobicity of Ti-MCM-41 using a new silylation agent MSTFA (2000)
    Springer
    Catalysis letters 65 (2000), S. 141-145 
    Details
    ISSN: 1572-879X
    Keywords: silylation ; MSTFA ; hydrophobicity ; Ti-MCM-41 ; epoxidation ; cyclohexene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A new silylation agent, N-methyl-N-(trimethylsilyl) trifluoroacetamide (MSTFA), has been employed for the trimethylsilylation of Ti-MCM-41. The FT-IR spectra revealed that the hydrophobic trimethylsilyl group, –Si(CH3)3, in MSTFA can replace the hydrogen in the silanol at room temperature. By virtue of their high volatility, MSTFA and its derivative, N-methyl trifluoroacetamide, can be readily removed after silylation. The MSTFA silylated Ti-MCM-41 is found to be more hydrophobic than that silylated by BSTFA and to bring about a significant enhancement in the yield of epoxide from cyclohexene epoxidation with aqueous H2O2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1019096617082
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  • 3
    Electronic Resource
    Electronic Resource
    Silylation of Ti‐MCM‐41 by trimethylsilyl‐imidazole and its effect on the olefin epoxidation with aqueous H2O2 (2000)
    Springer
    Catalysis letters 66 (2000), S. 245-249 
    Details
    ISSN: 1572-879X
    Keywords: silylation ; trimethylsilyl‐imidazole ; hydrophobicity ; Ti‐MCM‐41 ; cyclohexene epoxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Ti‐MCM‐41 catalyst was silylated with a new silylating agent, N‐trimethylsilyl‐imidazole (TMSI). TMSI was found to be more effective to improve the hydrophobicity and the catalytic performance of Ti‐MCM‐41 than other silylating agents. Different levels of silylation were obtained by varying the silylation time. A linear relationship was observed between the degree of silylation and each of the intensity ratios I1260/I1083,I845/I1083 and I760/I1083 of SiMe3 spectra bands detected by FT‐IR or the intensity ratio SiMe3/SiO2 of the 29Si‐MAS‐NMR signals. High level of silylation degree significantly enhances both the catalytic activity and the selectivity to epoxide.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1019072228411
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  • 4
    Electronic Resource
    Electronic Resource
    Isomerization ofn-hexane overplatinum loaded zeolites (1996)
    Springer
    Reaction kinetics and catalysis letters 57 (1996), S. 323-337 
    Details
    ISSN: 1588-2837
    Keywords: n-Hexane ; isomerization ; Pt/H-β ; Pt/H-MOR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The effect of the calcination temperature of bifunctional Pt/zeolites on the isomerization ofn-hexane has been investigated. The catalyst calcined at 350°C showed the highest metal dispersity and the best activity. The higher selectivity of dimethylbutanes over Pt/H-β than over Pt/H-MOR might be attributed to the combined effect of acidity, channel structure and pore size of zeolites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02064746
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