Effect of the solvent used during preparation on the properties of Pt/Al2O3 and Pt-Sn/Al2O3 catalysts

The influence of the solvent (water, acetone, and ethanol) used during alum ina impregnation on the properties of Pt/Al2O3 and Pt-Sn/Al2O3 catalysts wa s studied. Catalysts were characterized by H-2 chemisorption, TEM, temperat ure-programmed reduction, ammonia temperature-programmed desorption, UV-vis spectroscopy and cyclohexane dehydrogenation, n-pentane isomerization, and n-octane reforming reactions. It was found that the catalysts prepared in ethanol has the highest metallic dispersion. The results are explained cons idering the Pt-Sn complex stability in the different solvents used during t he preparation. Pt/Al2O3 (acetone) is the most active catalyst for isomeriz ation while the activity of Pt-Sn/Al2O3 catalysts decreases in the order et hanol > acetone > water. The selectivity to aromatic hydrocarbons is relate d to isomerization activity, but there also exits a competition between hyd rocracking and dehydrocyclization.