THEORETICAL-STUDIES OF THE INTERACTION OF PTSN SYSTEMS WITH H-2

The reaction of the PtSn system with the hydrogen molecule is studied theoretically. The results are compared with experimental reports of c ommercial-type catalysts and previous theoretical studies of Pt + H-2 and Pt-2 + H-2 reactions. All the calculations were made by the ab ini tio MC-SCF + MRCI method including relativistic core potentials approx imation. We consider two main geometrical approaches of the hydrogen m olecule to the SnPt system: parallel and perpendicular. The theoretica l and geometrical parameters were taken from our previous studies and from experiments. Many states were studied: Some of them are repulsive and others present weak capture of hydrogen; none scisse the H-2 mole cule. The main conclusion of this work is that the platinum activity, when Pt and Sn form alloys, is inhibited by the tin, suggesting that t he interaction between the two metals occurs through an oxygen atom of the support. (C) 1995 John Wiley & Sons, Inc.