Pt-Al₂O₃-Cl触媒の2,3-ジメチルブタン異性化活性

抄録

The catalyst activity for the isomerization of 2, 3-dimethylbutane has been investigated in relation with both acidity and acid strength of a series of Pt-Al₂O₃-Cl catalysts activated in a stream of hydrogen at different temperatures ranging from 300 to 660°C.
The rate of the isomerization increases as the temperature of the activation is elevated, passing through a maximum at activation temperatures between 500 and 550°C, and then decreases. The acidity also shows a similar trend but a maximum between 450 and 500°C. These results suggest that the metal site of the catalyst plays a certain role in the isomerization mechanism and there exist some interactions between metal and acid sites of the dual functioning catalyst. With the catalysts activated at temperatures between 440 and 550°C, highly selective isomerization takes place. Whereas dehydrogenation and hydrogenolysis to lower molecular weight hydrocarbons are observed with the catalysts activated at lower temperatures and dehydrogenation with the catalysts activated at higher temperatures. The acid strengths of the catalysts as measured by the Hammett's acidity function are in the range between +4.8 and +6.8 for all the catalysts used in the present study.