Effect of hydrazine hydrate on the Ru-Zn/SiO2 catalysts performance for partial hydrogenation of benzene

Ru-Zn/SiO2 catalysts were prepared in a water-in-oil microemulsion for partial hydrogenation of benzene. Hydrazine hydrate was added during the preparation to obtain Ru particles with controllable size. The results indicated that, the addition of hydrazine hydrate led to Ru particles with larger size, and the amount of hydrazine hydrate did not show obvious influence on the size of Ru particles. However, the catalytic activity changed significantly with addition of hydrazine hydrate, even if the Ru particle size, obtained by Scherrer equation, remained constant. This is attributed to the formation of a highly dispersed Ru species and crystalline Ru simultaneously. The former favored benzene conversion, and the latter was beneficial for increasing cyclohexene selectivity by contrast. (C) 2009 Elsevier B.V. All rights reserved.