Temperature-programmed desorption study of Re/gamma-Al2O3 catalysts prepared from Re-2(CO)(10) precursor

Alumina supported rhenium catalysts were prepared by gas-phase sublimation technique from carbonyl based precursor. Temperature-programmed desorption (TPD) profiles measured at different rhenium loadings suggested the formati on of a new rhenium phase when the rhenium content reached a certain level. Acidic properties of the catalysts were investigated by temperature-progra mmed desorption of ammonia. Total acidity of the samples increased until th e metal loading reached 4.1 wt.%, and afterwards decreased. As the metal lo ading increased, the portion of the middle strength acid sites increased at the expense of the lower strength acid sites which dominated in the pure s upport sample and samples with low rhenium content. (C) 2001 Elsevier Scien ce B.V. All rights reserved.