FTIR study of isopropanol reactivity on calcined layered double hydroxides

Abstract

A FTIR spectroscopy study on the surface reactivity of calcined layered double hydroxides (LDH), with different cations in the interlayer space (namely, carbonate, nitrate, silicate, and borate), for isopropanol oxidation is reported. The LDHs were previously calcined at 600°C and then their surface acidity was quantitatively determined ia volumetric determination of ammonia adsorption. Surface Lewis and/or Brönsted acid and basic sites were qualitatively studied by FTIR monitoring of the adsorption of pyridine and boric acid trimethyl ester. Carbonate and nitrate samples show surface acidity and basicity and hence the maximum activity for acetone formation through dehydrogenation of isopropanol. In contrast, although the silicate sample displays maximum surface acidity, the lack of an appreciable amount of surface basic sites gives rise to a lower activity in the named reaction, of the same order as that shown by the borate sample.