PHYSICOCHEMICAL AND CATALYTIC PROPERTIES OF POLYANILINE PROTONATED WITH 12-MOLYBDOPHOSPHORIC ACID

Using acid-base-type doping of polyaniline with H3PMo12O40, two series of catalyst samples were prepared. In series Sl the doping and polyme rization were carried out simultaneously, leading to a uniform distrib ution of the dopant over the whole volume of the polymer. In series SI I the doping was achieved by protonation of already formed polyemerald ine base with H3PMo12O40. Since this process must involve diffusion in the solid matrix, the surface becomes enriched in heteropolyanions (K eggin units) due to their limited diffusivity. The examination of phys icochemical properties of the samples by XP, EPR and FTIR spectroscopi es indicated that the Keggin units incorporated into the polymer matri x retain their identity and represent catalytically active centres. Th e insertion of the dopant species increases the electrical conductivit y of the polymer by several orders of magnitude. The catalytic activit y was tested in ethyl alcohol conversion and both the products of acid -base [C2H4 and (C2H5)2O] and redox (CH3CHO) type reactions were obser ved. Owing to the surface enrichment of the SII series of catalysts th eir catalytic activity was much higher than that of samples of the Sl series nominally doped to the same level. In both types of catalysts t he selectivity to the redox reaction product (CH3CHO) was greatly enha nced in comparison with unsupported H3PMo12O40.