Nanoscale surface study and reactions mechanism of 2-butanol over the γ-alumina (1 0 0) surface and nanochannel: A DFT study

The mechanism of adsorption, dissociation, hydrogen-shift, dehydration and dehydrogenation of adsorbed (R)- and (S)-2-butanol over the dehydroxylated (1 0 0) surface and nanochannel of γ-alumina defect spinel structure was computed by density functional theory (DFT). To test the asymmetric property of this surface by conformational analysis of adsorbed (R)- and (S)-2-butanol was investigated. Computed conformational analysis indicates that the (S)-isomer bond with the surface is stronger than the (R)-isomer. Steric interactions between adsorbed alcohol and catalyst surface appear to be more important than intramolecular steric constraints present within the alcohol conformations. Mulliken atomic charges predict that selected basic sites (Oa–h) play a major role in elimination reactions. E2 elimination with synclinal transition state was comparable with E2 antiperiplanar transition state. The activation energy for elimination of a β-hydrogen from the 2-butanol conformers increases with increasing the distance between β-hydrogen and basic sites. The formation of alkenes (thermodynamic products) is favored over the formation of ketone (kinetic product).

The mechanism of adsorption, dissociation, dehydration, dehydrogenation and hydrogen-shift of adsorbed (R)- and (S)-2-butanol over the (1 0 0) surface and nanochannel of γ-alumina was computed by DFT.Figure optionsDownload high-quality image (136 K)Download as PowerPoint slideResearch highlights▶ Mechanism of adsorption, dissociation, hydrogen-shift, dehydration and dehydrogenation of adsorbed (R)- and (S)-2-butanol over the dehydroxylated (1 0 0) surface and nanochannel of γ-alumina defect spinel structure. ▶ Density functional theory (DFT). ▶ Asymmetric property of dehydroxylated (1 0 0) surface and nanochannel of γ-alumina defect spinel structure. ▶ Conformational analysis of adsorbed (R)- and (S)-2-butanol over the dehydroxylated (1 0 0) surface and nanochannel of γ-alumina defect spinel structure. ▶ Computation of Mulliken atomic charges of selected basic sites.