RAIRS AND TPD STUDY OF METHYL FORMATE, ETHYL FORMATE, AND METHYL ACETATE ON NI(111)

The thermal chemistry of methyl formate, ethyl formate, and methyl ace tate on Ni(111) was studied using infrared reflection absorption spect roscopy and temperature programmed desorption. The principal molecular decomposition products in each case were CO and H-2. Methane and acet aldehyde were also formed from ethyl formate. For each of the three mo lecules, adsorption occurred through the interaction of the carbonyl l one pair with the metal. The orientation of the molecular plane, in ea ch case, was approximately perpendicular to the surface. The molecular surface decomposition species were detected by RAIRS. Methoxy species were formed from methyl formate and methyl acetate. Ethoxy was produc ed by ethyl formate. Evidence was obtained for the formation of a stab le acetyl species during the decomposition of methyl acetate. The deco mposition of methyl acetate occurred above 170 K whereas the other two esters began to decompose at approximately 140 K. This study shows th at the adsorption induced shifts in the infrared spectra of esters are similar to those which occur on the formation of ester-Lewis acid add ucts.