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Volumn 103, Issue 28, 1999, Pages 5787-5796

Structure and density of Mo and acid sites in Mo-exchanged H-ZSM5 catalysts for nonoxidative methane conversion

Author keywords

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Indexed keywords


EID: 20544433008     PISSN: 15206106     EISSN: None     Source Type: Journal    
DOI: 10.1021/jp990866v     Document Type: Article
Times cited : (311)

References (47)
  • 17
    • 20544433174 scopus 로고    scopus 로고
    • note
    • H-ZSM5 samples (0% Mo) were heated to higher temperatures (973 K) in order to ensure complete isotopic exchange.
  • 18
    • 20544450776 scopus 로고    scopus 로고
    • note
    • 27Al NMR signal, indicating that 1.0 s was sufficient to allow full relaxation of all Al spin states. In this case, the NMR signal peak area, integrated using Peakfit (Jandel Scientific), is proportional to the number of Al centers represented in that peak.
  • 21
    • 20544452251 scopus 로고    scopus 로고
    • note
    • Experiments using unheated lines overestimated the amount of carbon deposited on the catalyst because of condensation of naphthalene and heavier products in the gas transfer lines.
  • 22
    • 20544436420 scopus 로고    scopus 로고
    • note
    • HP 6890 gas chromatograph (Hewlett-Packard) equipped with a Carboxen 1000 packed column (3.2 mm x 2 m, Supelco) connected to a thermal conductivity detector and with a HP-1 capillary column (methyl silicone, 0.32 mm x 50 m x 1.05 mm, Hewlett-Packard) connected to a flame ionization detector.
  • 23
    • 20544442457 scopus 로고    scopus 로고
    • note
    • All gases were >99.99% purity (from Praxair and Matheson) and were passed through molecular sieve (13X and 5A) traps before use. Flow rates were metered using electronic mass flow controllers (Porter Instruments).
  • 25
    • 20544467896 scopus 로고    scopus 로고
    • note
    • The initial concentration of Mo for this sample was 4.0 wt %, but after temperature-programmed treatment in air up to 973 K the sample contained 3.6 wt % Mo (Table 3).
  • 27
    • 20544453008 scopus 로고    scopus 로고
    • note
    • The initial Mo concentration for this sample was 8 wt %, but after temperature-programmed treatment in air the sample contained 6.3 wt % Mo (Table 3).
  • 29
    • 20544457536 scopus 로고    scopus 로고
    • note
    • 2O.
  • 30
    • 20544466642 scopus 로고    scopus 로고
    • note
    • 2(g)/O(s)-D exchange were used for Mo-containing samples in the calculations shown in Table 4, because this led to a more accurate hydrogen atom balance.
  • 36
    • 20544448443 scopus 로고    scopus 로고
    • note
    • 3 vapor exchange preparation (Figure 6) results in only 4.3 wt % Mo, which is much less than expected if the external ZSM5 surface area was covered and framework OH groups were exchanged with Mo.
  • 38
    • 85088082529 scopus 로고    scopus 로고
    • note
    • 3 may eventually spread into a monolayer, but below 773 K the weak bonds between bilayers are more likely to break than the strong Mo-O-Mo bonds within bilayers.
  • 39
    • 85088080388 scopus 로고    scopus 로고
    • note
    • 2/g for a monolayer.
  • 40
    • 4344607102 scopus 로고
    • Heteropoly and hopoly Oxometalates
    • Jorgensen, C. K., Ed.; Springer-Verlag: Berlin
    • Pope, M. T. Heteropoly and hopoly Oxometalates; Inorganic Chemistry Concepts; Jorgensen, C. K., Ed.; Springer-Verlag: Berlin, 1983.
    • (1983) Inorganic Chemistry Concepts
    • Pope, M.T.1
  • 42
    • 85088082631 scopus 로고    scopus 로고
    • note
    • 2 is 940 K, so mobility of ions in the O-Si-O lattice of ZSM5 should occur between 673 and 973 K.


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.