Study of the acidic properties of imogolite-based systems

Mg/Me mixed oxides, i.e. oxides containing both alkaline-earth metal ions and transition metal ions, have been reported to act as catalysts for many important reactions in fine chemicals industry. One such important reaction is phenol methylation. In situ FTIR spectroscopy, carried out using methanol and phenol to test the first step of reactivity of the two reactants, allowed us to identify the possible intermediates and products formed at the surface of the working catalyst. It can be evidenced that the nature of the main products obtained for the above reaction is actually ruled by the transformations occurring on methanol which, in turn, depend on the properties of the catalyst employed: if the favoured product is o-cresol (C-alkylation), catalysts with redox properties must be used (Mg/Fe or Mg/Cr); on the contrary, if O-alkylation (formation of anisole) is preferred, it is necessary to employ a non-redox system (Mg/Al).