Effect of the sequence of impregnation on the activity and sulphur resistance of Pt-Ni/AL2O3 bimetallic catalysts for the selective hydrogenation of styrene

C.P. BETTI; J. BADANO; M. JULIANA MACCARRONE; V.A. MAZZIERI; C. VERA; M. QUIROGA

APPLIED CATALYSIS A-GENERAL

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2012

0926-860X

The effect of the impregnation sequence and the use of different nickel precursors on the activity and sulphur resistance of bimetallic Pt-Ni catalysts was studied during styrene semi-hydrogenation. Catalysts were characterized by ICP, TPR, XPS and TPD of pyridine techniques. All the catalysts presented high selectivities (> 98%). Bimetallic catalysts were more active than the monometallic one, the following activity order of the catalysts was found: Pt @  NiClPt < NiNPt < PtNiCl < PtNiN. After poisoning with 100 ppm of thiophene the following order of sulphur resistance was found: PtNiCl < Pt < PtNiN < NiClPt < NiNPt. Differences on activities and sulphur resistances between the catalysts could be associated to electronic effects due to the presence of different electron- rich and deficient species of Pt and Ni on the surface interacting between the metals or with the support with different kind of forces. The bimetallic with highest Cl/Pt atomic ratio on the surface (obtained by XPS) proved to be the most sulphur resistant catalyst; the higher poison resistance might be caused by steric and / or electronic effects.