Characterization of bimetallic PtSn catalysts supported on purified and H2O2-functionalized carbons used for hydrogenation reactions

The state of the metallic phase of PtSn/C catalysts prepared by coimpregnation and successive impregnation on purified and H2O2-functionalized carbons as supports was studied by TPD, TPR, H-2 chemisorption, XPS, and test reactions. Furthermore, the characteristics of the metallic structures were related with the catalytic behaviors in the selective hydrogenation reaction of carvone in liquid phase. In PtSn/C samples, most of the Sn would be in intimate contact with Pt, and the surface of the reduced bimetallic catalysts would be composed of metallic platinum, Sn(II), and/or Sn(IV) species, and small amounts of zerovalent tin, probably forming alloys with Pt-0. The high selectivity of these bimetallic PtSn/C catalysts for the production of unsaturated alcohols in the reaction of carvone hydrogenation would be due to the action not only of the promoter (Sn) but also of the support (carbon). (C) 1999 Academic Press.