AlCl3-Promoted MCM-41-Supported Platinum Catalysts with High Activity and Sulfur-Tolerance for Tetralin Hydrogenation: Effect of Al/Pt Ratio

AlCl3-promoted MCM-41-supported Pt catalysts with different Al/Pt mole ratios (0, 1, 2, 4, 8) were prepared for tetralin (THN) hydrogenation. Py-FTIR results show that the acid amount of catalysts increases with the increase of Al/Pt ratio. XRD, TEM and CO-FTIR results indicate that platinum dispersion changes with Al/Pt ratio and is highest at Al/Pt = 2. The specific rate constant of THN hydrogenation under sulfur-free condition is roughly proportional to platinum dispersion. Thermogravimetric analysis of the adsorbed THN and benzothiophene (BT) indicates that BT is more tightly adsorbed on the catalysts than THN, which is the main reason for catalytic deactivation. The introduction of aluminum enhances both THN and BT adsorptions. All Al-containing catalysts have better sulfur-tolerance than the Al-free one, which is attributed to that (1) high catalytic activity reduces the proportion of BT-deactivated catalyst; (2) Al3+ site might provide additional active sites; (3) electron-deficient Pt delta+ promotes the BT competitive hydrogenation activity.