PT-SO42--ZRO2 CATALYSTS - CORRELATION OF CATALYTIC ACTIVITY WITH SO42- XPS DATA

Increasing activity for the conversion of n-hexadecane is observed for 0.6% Pt-SO42--ZrO2 catalysts with increasing time of activation in ai r at 500 degrees C (773 K). XPS analysis suggests that, rather than a change in the crystal phase, this increase is due to a loss of water a nd/or an increase in surface concentration of SO42-. It is noted that there is a reasonably good correlation between the relative surface su lfate concentration and relative conversion of n-hexadecane with incre asing heating time, although there are minor differences. In spite of the many assumptions that were made to generate the two curves showing the relative XPS peak area and the catalytic activity, there is surpr ising agreement between the two. It is therefore inviting to relate th e catalytic activity for n-hexadecane conversion to that of the sulfat e group. Furthermore, it appears that the active site related to the s ulfate group is not one that contains water in its make-up.