Paraffin dehydrocyclization. Part 9. Conversion of n-octane with PtSn catalysts at atmospheric pressure
1994; Science Press; Volume: 88; Issue: 3 Linguagem: Inglês
10.1016/0304-5102(93)e0280-t
ISSN1873-3131
AutoresRam Srinivasan, Burtron H. Davis,
Tópico(s)Catalysis for Biomass Conversion
ResumoTin alters the activity and stability of a series of Pt-alumina catalysts. Depending upon the support, dehydrocyclization may occur by a monofunctional metal catalysed pathway or in combination with a bifunctional pathway involving both metal and support. The initial tin added by coimpregnation with Pt is found to decrease the activity of a catalyst based on acidic alumina but to promote the activity of one based on a nonacidic support. When the catalyst based on an acidic alumina contains sufficient tin to eliminate the acidity of the support, and thereby the bifunctional pathway, the activity pattern vs. Sn/Pt ratio for the nonacidic and acidic based catalysts have a similar form. For similar Sn/Pt bulk compositions, a catalyst based upon coprecipitated tin-aluminum oxide differs significantly from the one based on an acidic or non-acidic alumina support. The results show that tin may serve (1) to enhance metal dispersion at lower loading, (2) to form a Pt:Sn = 1:1 alloy with a higher dehydrocyclization activity than Pt alone, (3) to modify the aromatics selectivity from the dehydrocyclization of n-octane and (4) to poison acid sites and thereby eliminate the more rapid pathway to produce aromatics.
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