Thermal properties of new catalysts based on heteropolyanion-doped polyaniline

Thermal properties of a new family of catalysts, namely, heteropolyanion-doped polyaniline, have been studied by thermogravimetry (TG) and differential thermal analysis (DTA). Two types of samples have been tested: bulk-doped and surface-doped polyaniline. It has been found that all systems exhibit good thermal stability in the temperature of their catalytic application (up to 250 °C) in both oxidative and inert reaction atmospheres. Thermal stability varies significantly with the dopant used, being the highest for 12-tungstosilicic acid and the lowest for 12-molybdophosphoric acid. Although the latter shows significantly lower thermal stability as compared with all other catalysts studied, it still can be used in ethyl alcohol conversion, giving predominantly redox activity products. On the basis of thermogravimetric data, Gram—Schmidt chromatograms and FT-IR spectra of volatile products, some preliminary conclusions about the mechanism of degradation have been formulated.