The adsorption and decomposition of ethanol was studied on clean, and
oxygen pre-covered Pt(331) surface by using mainly TPD, LEED and AES.
II was found that ethanol adsorbed molecularly on the Pt(331) surface
al low temperature. Upon heating, part of the ethanol desorbed molecul
arly from surface at 220 K, and part of the ethanol underwent C-C bond
scission to form methane and a variety of other products. There are t
wo distinct methane peaks at 240 K and 310 K in the desorption spectru
m suggesting that there are two different pathways for ethanol decompo
sition on this surface; both pathways-involve C-C bond scission since
methane is a major desorption product. CO adsorption experiments as we
ll as experiments with H-(ad) and O-(ad) suggest that the lower temper
ature pathway involves C-C bond scission at temperatures below that wh
ere the ethanol appreciably dehydrogenates, while the high temperature
pathway involves dehydrogenation of the ethanol followed by C-C bond
scission. O-(ad) additions suppress the low temperature pathway and en
hances the high temperature pathway presumably by speeding the dehydro
genation of the ethanol. H-(ad) additions slightly enhance the low tem
perature pathway. We also observe hydrogenolysis of the ethanol to yie
ld methanol at 180 K and methane at 240 K in the presence of excess hy
drogen. These results show that the step sites on the Pt(331) surface
have unusual activity for C-C bond scission in ethanol. (C) 1997 Elsev
ier Science B.V.