Thermal stability and catalytic properties of the Wells-Dawson K6P2W18O62 center dot 10H(2)O heteropoly compound in the oxidative dehydrogenation of isobutane to isobutene (vol 3, pg 387, 1996)

The thermal stability of the Wells-Dawson heteropoly compound K6P2W18O62. 10H(2)O was examined under both reducing and oxidizing conditions, and its structural and morphological evolution was characterized by several complementary solid state techniques. It is shown that the primary structure of the title compound remains intact up to 770 K, while at higher temperature structural changes and rearrangements are observed. These modifications depend considerably on the treatment conditions and catalyst composition. Under oxidizing conditions the Wells-Dawson compound rearranges with formation of a mixed phase containing the Keggin-type unit K3PW12O40 and the hexatungstate K2W6O19. Furthermore, the catalytic activity in the oxidation of isobutane is affected considerably by these changes. The best catalytic performance was shown by the rearranged Wells-Dawson compound.