Vi. Parvulescu et al., SELECTIVE HYDROGENATION OF STYRENE ON PD-HO GAMMA-AL2O3 AND PD/GAMMA-AL2O3 CATALYSTS/, Bulletin des Societes chimiques belges, 102(6), 1993, pp. 391-399
Pd-Ho/gammaAl2O3 catalysts exhibit higher activity for styrene hydroge
nation than Pd/gammaAl2O3 ones. The addition of holmium to Pd catalyst
s changes the place of the palladium impregnation front depending on t
he state of the supported palladium. As a consequence of the interacti
on between holmium and Pd/gammaAl2O3 support, oxidized forms as holmiu
m aluminate were formed. These forms are catalytically inactive but re
present adsorption centers for styrene. On holmium containing catalyst
s, hydrogenation takes place between the styrene adsorbed on basic cen
ters and the hydrogen spilled over from palladium particles.