Catalytic Conversion of Isopropanol on a Heteropoly Acid–η-Aluminum Oxide System

The results from catalytic conversion of isopropanol on a heteropoly acid–η-aluminum oxide system are discussed. It is established that modification increases its activity and selectivity toward oxygen-containing products. Based on a comparative analysis of reaction products, it is shown that the active sites of unmodified η-aluminum oxide consist only of strong Lewis acid sites (LASes) and strong Lewis basic sites (LBSes), represented predominantly by Bronsted basic sites (BBSes) after modification with a heteropoly acid. The synthesized systems are characterized via X-ray diffraction, scanning electron microscopy, elemental analysis, and IR spectroscopy. The set of obtained results shows that the Keggin structure decomposes as it interacts with the basic oxide to form heteropoly anions. Due to their negative charge, these interact with the electron-accepting Lewis acid sites to form a surface–ligand complex. This then begins to act as a new Bronsted base, due to its uncompensated negative charge.