Ethanol conversion over GaO-ZrO solid solution: empirical evidence of the reaction pathway, the surface acid-base properties, and the role of gallium ions

Ethanol conversion over Ga 2 O 3 -ZrO 2 solid solution was examined in the temperature range of 573-773 K, and acetone/isobutene formation was confirmed under cofeeding of H 2 O vapor. The reaction pathway was empirically investigated with the contact time dependency and reactivity of the five possible intermediates. The surface acid-base properties were discussed with 1-butene isomerization, 2-butanol decomposition and the poisoning experiment, the dehydration/dehydrogenation selectivity of C3-C4 primary and secondary alcohols, and CO 2 -TPD. The Ga 2 O 3 -ZrO 2 catalyst was less basic than ZrO 2 itself and exhibited a stronger dehydrogenation property. Alcohol dehydrogenation over Ga 2 O 3 -ZrO 2 was suggested to be promoted by the specific dehydrogenation property of isolated Ga 3+ species. Acetaldehyde formed by ethanol dehydrogenation was converted into acetone, mainly via acetate species in the presence of H 2 O. Coexistence of ZrO 2 , doped elements with dehydrogenation capability, surface acid-base properties, and H 2 O vapor is important for ethanol to acetone/isobutene reaction. The reaction pathway of ethanol conversion to acetone/isobutene over Ga 2 O 3 -ZrO 2 solid solution was investigated. Acetaldehyde formation is promoted at the atomically dispersed Ga 3+ species due to its dehydrogenation capability rather than solid basicity of a catalyst.