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  • 1
    ISSN: 1572-879X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The effects of SiO2/Al2O3 ratio of H-mordenite on the selectivity of encapsulated products in the pores and of bulk products were investigated in the isopropylation of biphenyl. The selectivity of 4,40 -diisopropylbiphenyl (4,40 -DIPB) of bulk products was varied with SiO2/Al2O3 ratio. Highly dealuminated H-mordenite gave a selectivity higher than 80%, whereas the selectivity was low for H-mordenite with SiO2/Al2O3 ratio of 10-20. On the other hand, the selectivity of 4,40 -DIPB in encapsulated DIPB isomers was higher than 85% for all H-mordenites regardless of SiO2/Al2O3 ratio. These results show that all H-mordenites catalyze the isopropylation of biphenyl with high shape-selectivity inside the pore. The low selectivity of 4,40 -DIPB in bulk products for H-mordenites with low SiO2/Al2O3 ratio was not due to a lack of shape-selectivity of the H-mordenites, but to non-regioselective isopropylation at the external acid sites. Non-regioselective catalysis over H-mordenite with low SiO2/Al2O3 ratio could be induced by choking pores by coke deposition.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Catalysis letters 57 (1999), S. 217-220 
    ISSN: 1572-879X
    Schlagwort(e): H-mordenite ; isopropylation ; biphenyl ; 4,4'-DIPB ; isomerization ; encapsulated products
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The effects of reaction temperature on the selectivity for bulk products and for encapsulated products in the pores were investigated in the isopropylation of biphenyl over a highly dealuminated H-mordenite under 0.8 MPa of propylene. The selectivity for 4,4'-diisopropylbiphenyl (4,4'-DIPB) in bulk products was changed with the increase of reaction temperature: it decreased with increasing that for thermodynamically stable 3,3'- and 3,4'-DIPB. However, the selectivity for 4,4'-DIPB in encapsulated products was as high as 85–90% between 200 and 350ºC. These results show that H-mordenite catalyzes the isopropylation of biphenyl inside the pore with high shape selectivity at these temperatures, and that the decrease of the selectivity for 4,4'-DIPB in the bulk products is due to its isomerization to 3,3'- and 3,4'-DIPB on external acid sites.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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