F. Coloma et al., Crotonaldehyde hydrogenation over alumina- and silica-supported Pt-Sn catalysts of different composition. In situ DRIFT study, PHYS CHEM P, 2(13), 2000, pp. 3063-3069
Alumina- and silica-supported bimetallic Pt-Sn catalysts with different Pt/
Sn atomic ratios have been prepared by using the bimetallic complex cis-[Pt
Cl(SnCl3)(PPh3)(2)], the monometallic complex cis-[PtCl2(PPh3)(2)] and SnCl
2 as metal precursors. Catalysts have been characterised by X-ray diffracti
on and transmission electron microscopy techniques, including energy-disper
sive X-ray microanalysis, electron diffraction experiments and lattice-frin
ge microanalysis. The phase composition of the different catalysts has been
related to the catalytic behaviour in the vapour phase hydrogenation of cr
otonaldehyde (but-2-enal). Results show that catalysts containing platinum-
tin alloy phases with large particles are more selective towards the hydrog
enation of the carbonyl bond to yield crotyl alcohol. The presence of oxidi
sed tin species on the surface of the large alloy particles promotes the hy
drogenation of the carbonyl bond. In situ diffuse reflectance infrared spec
troscopy studies of crotonaldehyde adsorption under He or H-2 reveal differ
ences between bimetallic catalysts and monometallic, and these differences
have been related to the different catalytic behaviour of the catalysts.