Structure and decomposition pathways of vinyl acetate on Pd(111)

CALAZA, FLORENCIA C.; STACCHIOLA, DARIO J.; NEUROCK, MATTHEW; TYSOE, WILFRED T.

SURFACE SCIENCE

ELSEVIER SCIENCE BV

Año: 2005 vol. 598 p. 263 - 275

0039-6028

The surface chemistry of vinyl acetate on clean Pd(111) is explored experimentally in ultrahigh vacuum using reflection absorption infrared spectroscopy (RAIRS) and temperature-programmed desorption (TPD) combined with density functional theory (DFT) calculations. The relative intensities of the vibrational features of a vinyl acetate overlayer are in good agreement with the structure calculated by DFT. Furthermore, the calculated heat of adsorption of vinyl acetate (63.4 kJ/mol) is in excellent agreement with the measured desorption activation energy (65 +/- 7 kJ/mol). The thermal decomposition pathways of adsorbed vinyl acetate are relatively complex involving initial cleavage of the O-acetyl or O-vinyl bonds to form either vinyloxy and acetyl, or acetate and vinyl species, respectively on the surface. The acetate thermally decomposes to desorb methane at similar to 260 K, while the acetyl and vinyloxy species isomerize and react to form acetaldehyde or methane. Ethylidyne is formed, and adsorbed CO either desorbs or oxidizes to CO2 at similar to 450 K.