Solid super acids: Preparation and their catalytic activities for reaction of alkanes
1981; Elsevier BV; Volume: 68; Issue: 1 Linguagem: Inglês
10.1016/0021-9517(81)90046-4
ISSN1090-2694
AutoresHideshi Hattori, Osamu Takahashi, Mikako Takagi, Kozo Tanabe,
Tópico(s)Catalysis and Oxidation Reactions
ResumoPreparation of solid super acid catalysts was attempted by treatment of metal oxides with NH4F, FSO3H, SbCl5, SbF5, and FSO3H-SbF5. All treatments with these reagents enhanced the acidic properties of the metal oxides. Among them, SbF5 was the most effective. Conversions of several alkanes proceeded at room temperature or below, over the metal oxides treated with SbF5. The conversion rates of alkanes were in the order: cyclohexane ∼- methylcyclopentane > hexane > pentane ∼- 2-methylbutane > butane ∼- 2-methylpropane > propane ⪢ 2,2-dimethylpropane ∼-ethane ∼- methane. The acid strengths were −13.75 ≥ H0 > −14.52 for SbF5-SiO2-Al2O3 and −13.16 ≥ H0 > −13.75 for SbF5-TiO2-SiO2 and SbF5-Al2O3. The ir spectra of pyridine adsorbed on SbF5-SiO2-Al2O3 showed that both Brönsted and Lewis acid sites were present on the surface when SiO2-Al2O3 was treated with SbF5 at low temperatures below 100 °C, but only Lewis acid sites when treated at 300 °C. The reaction mechanisms are discussed on the basis of the acidic properties, product distributions, and a tracer study.
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