Structural Behavior of Pt-Sn supported on MgO

Pt-Sn supported on magnesia and alumina were characterized, before and after treatment with hydrogen, by Mossbauer spectroscopy and X-ray diffraction. For the calcined samples on both supports tin is present as SnO2 and platinum as metal. After reduction with hydrogen, platinum and tin diffuse into the magnesia lattice to form a solid solution. On alumina Sn(IV), Sn(II), Sn(0), Pt, Pt3Sn, PtSn and PtSn2 alloys are formed. The SnO interacts strongly with the alumina support. The catalytic activity of both Pt-Sn catalysts is strongly affected by the support. On alumina the dehydrogenation of cyclohexane is very high, whereas that on magnesia is almost non-active.