DIFFERENTIAL REACTIVITY AND STRUCTURE OF MONOALKOXIDES AND DIALKOXIDES - THE REACTIONS OF ETHYLENE-GLYCOL ON MO(110)

The reactions of ethylene glycol on Mo(110) were studied using tempera ture-programmed reaction, infrared reflection absorption, high-resolut ion electron energy loss, and X-ray photoelectron spectroscopies. The major reaction pathway is double C-O bond scission to evolve gas-phase ethylene at 350 and 390 K. Both X-ray photoelectron and infrared spec tra demonstrate the existence of two surface intermediates, a bidentat e (-OCH2CH2O-) and a monodentate (-OCH2CH2OH) species, at saturation c overage of ethylene glycol. We demonstrate that all ethylene glycol in the mixed overlayer of mono- and bidentate species reacts via a biden tate surface intermediate. Furthermore, in contrast to previous studie s on other surfaces, the dialkoxide ethylene glycol intermediate is sh own to be more reactive than similar monoalkoxides on Mo(110). Finally , analysis of the infrared spectra demonstrates that the bidentate spe cies adsorbs with C-2 (or lower) symmetry at 300 K.