The reactions of maleic anhydride (MA) have been investigated on the "near" stoichiometric and substoichiometric surfaces of TiO2 by temperature programmed desorption (TPD). Moreover, self-consistent field semiempirical PM3 calculations of MA over relaxed and unrelaxed Ti13O45H38 rutile clusters [simulating the rutile TiO2(011) surface] were conducted on two modes of adsorption. The dissociation of one C-O-C bond following adsorption on a Ti-5c(4+) - O2- Site results in a more stable adsorbed species (by 0.5 eV) than the nondissociatively adsorbed molecule. Desorption of a wide range of products in several temperature domains was observed during MA-TPD. In addition to the decomposition pathway to carbon monoxide (CO), carbon dioxide (CO2), acetylene (HC = CH), and ketene (H2C = C = O), the desorption of several coupling products is also seen: vinylacetylene (HC = CCH = CH2), butene, traces of butadiene (H2C = CHCH= CH2), and benzene (C6H6). Over the substoichiometric surfaces these coupling products are more accentuated while the decomposition pathway to ketene decreased. (C) 2000 American Vacuum Society. [S0734-2101(00)17404-4].
|Number of pages||6|
|Journal||Journal of Vacuum Science & Technology. A, Vacuum, Surfaces, and Films|
|Publication status||Published - 2000|
- REDUCED TIO2(001) SURFACES
- N-BUTANE OXIDATION
- VANADYL PYROPHOSPHATE
- BOND FORMATION