Effects of support on Naphthalene hydrogenation over the TiO_2 Supported Pd catalysts in the presence of a sulfur compound

摘要

Naphthalene hydrogenation was carried out over Pd/TiO_2 and Pd/A_2O_3 catalysts in the presence of a sulfur compound. Turnover frequency of Pd/TiO_2 was much higher than that of Pd/Al_2O_3. The Pd-S bond strength of Pd/TiO_2 was compared with that of Pd/A_2O_3 by temperature programmed reduction of adsorbed sulfur (H_2S-TPR), measurement of CO uptake and FT-IR after sulfidation. The Pd-S bond strength of Pd/TiO_2 was weaker than that of Pd/Al_2O_3. The effect of reduction temperature of Pd/ TiO_2 on the Pd-S bond strength was investigated. The sulfur adsorbed on Pd/TiO_2, which was reduced at low temperature, was easy to desorb. It was concluded that Ti~(4+) having high electronegativity decreased the electron density of Pd and reduced the Pd-S bond strength.