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. 1 0H(2)O was examined under both reducing and oxidizing conditions, and its s tructural and morphological evolution was characterized by several compleme ntary solid state techniques. It is shown that the primary structure of the title compound remains intact up to 770 K, while at higher temperature str uctural changes and rearrangements are observed. These modifications depend considerably on the treatment conditions and catalyst composition. Under o xidizing conditions the Wells-Dawson compound rearranges with formation of a mixed phase containing the Keggin-type unit K3PW12O40 and the hexatungsta te K2W6O19. Furthermore, the catalytic activity in the oxidation of isobuta ne is affected considerably by these changes. The best catalytic performanc e was shown by the rearranged Wells-Dawson compound.