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1 Polish Journal of Chemistry

1 2003

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Temperature Programmed Desorption of Triethylamine from Differently Pretreated Pd/Al2O3 Catalysts

Skotak M., Kijeński J., Karpiński Z.

Polish Journal of Chemistry

2003

Vol. 77 / nr 5

757-765

The temperature programmed desorption (TPD) of triethylamine from alumina and two alumina-supported palladium catalysts of different metal loadings (0.3 and 2.77 wt.% Pd) confirmed the presence of strong Lewis acid sites in the samples subjected to high temperature reduction at 600_C. With increasing temperature during thermodesorption, triethylamine adsorbed on Lewis acid sites of alumina undergoes transformation, leading to desorption of several products, among which hydrogen, ethylene and acetonitrile predominate. However, introduction of increasing amounts of palladium to alumina makes the acidity probing difficult, because a considerable part of adsorbed triethylamine is decomposed on metal sites. Temperature programmed oxidation (TPO) shows that the organic coke left after TPD of triethylamine is associated with acid sites of alumina, not with palladium sites. Another observation that pure alumina and 0.3 wt.% Pd/Al2O3 retained larger amounts of coke than the 2.77 wt.% Pd/Al2O3 catalyst reveals a beneficial role of palladium in desorbing organic material in the course of TPD runs.