Effect of transition metal (Cr, Mn, Fe, Co, Ni and Cu) on the hydrogenation properties of chloronitrobenzene over Pt/TiO2 catalysts

The influence of transition metal (Cr, Mn, Fe, Co, Ni and Cu) on the hydrogenation properties of chloronitrobenzene (CNB) over Pt/TiO2 catalyst has been studied in ethanol at 303 K and normal pressure. The hydrogenation of CNB can be carried out over Pt/TiO2 catalyst. The order of the hydrogenation rate of CNB is m > p > o, and the yield of chloroaniline (CAN) is p > m > o. The effect of transition metal may be interpreted by electronic effect. Electron deficient species of the second element promote the specific rate constant turnover frequency (TOF) expressed on a per surface Pt atom by activating the nitrogen-oxygen bond. The conversion of CNB is over 99% and chloroaniline is main product on the hydrogenation of CNB over PtM/TiO2 catalysts. PtFe/TiO2 catalyst shows the best selectivity of CNB to CAN, and 98.0 mol% for p-CAN, 98.5 mol% for m-CAN and 98.7 mol% for o-CAN, respectively. Both catalytic activity and yield of p-CAN increase with addition of Fe over Pt/TiO2 on the hydrogenation of p-CNB. (C) 2003 Elsevier B.V. All rights reserved.