Characterization and study on performance of the Ru-La-B/ZrO2 amorphous alloy catalysts for benzene selective hydrogenation to cyclohexene under pilot conditions

Various characterizations of Ru-La-B/ZrO2 catalysts were carried out by means of XRD, TEM, SEAD, XPS and N-2-physisorption, and the activity and selectivity of the catalysts were measured. XRD results showed that Ru-La-B/ZrO2 catalysts were considerable stable and no significant peaks corresponding to Ru crystal were observed for the catalysts treated below 673 K and ran for 500 h under pilot conditions. The study on N-2-physisorption showed that with extending of the reaction time the most probable pore diameters, specific surface areas and pore volumes became smaller supposed to be relative to the adsorption of substances in the reaction mixture and to be one of the reasons for decreasing of the activity and selectivity of the catalysts. XPS showed that ruthenium exists in metallic state; lanthanum exists in La3+ or in metallic state. One of the most remarkable features of Ru-La-B/ZrO2 catalysts is the high activity and good selectivity for benzene selective hydrogenation to cyclohexene. On the other hand, the catalysts can be regenerated and have a long life under pilot conditions. (C) 2008 Published by Elsevier B.V.