PNNL

Abstract

Product yields and selectivities, based on ultra high vacuum temperature programmed desorption, are compared for ten C2 to C8 aliphatic alcohols dosed at 100 K on highly-ordered TiO2(110) with a 3.5 % concentration of surface oxygen vacancies. Dehydration to form an alkene and water typically dominates while two other channels, dehydrogenation to form aldehydes, and reformation of alcohol, make detectable contributions for primary alcohols. Depending on the alcohol there are two distinct dehydration pathways, one operative at low temperature (LT, 300 to 425 K) and the other at high temperature (HT, 480 to 650 K). The HT dehydration pathway is common, while the LT channel is not observed for tertiary butanol and 3- and 4-octanol. The observed trends are accounted for in terms of the inductive and steric effects of the alkyl substituents.