Pure vs ultra-pure γ-alumina: A spectroscopic study and catalysis of ethanol conversion

• Spectroscopic and catalytic properties of “pure” and ultrapure g-Al2O3 are compared.
• Impurities of Fe3 +, Ti4 + in pure Al2O3 produce evident effects in UV and Raman.
• Surface Na + and silanols in “pure” Al2O3 are revealed by IR experiments.
• “Ultrapure” sample is more selective for the production of ethylene from ethanol.
• “Ultrapure” sample is less active in oxidizing ethanol to COx and oxygenates.

Spectroscopic and catalytic properties of “pure” and “ultrapure” γ-Al2O3 samples, both from Sasol, are compared. The “pure” sample has additional absorption in the UV region, much stronger luminescence in the Raman scattering experiments, slightly different skeletal surface OH groups IR spectra, and more evident features of weakly adsorbed pyridine. These effects are attributed to small amounts of Fe3 +, Ti4 +, surface silanol groups and Na+ ions. The “ultrapure” sample is more selective for the production of ethylene from ethanol at total conversion, while in the presence of oxygen is less active in oxidizing ethanol to other oxygenates and to COx.