Abstract
The hydrolysis of tetrafluoromethane (PFC-14) was studied over alumina-zirconia catalysts with varying alumina contents, prepared from boehmite. The initial PFC-14 conversion values were observed to increase with increasing catalyst alumina content. The alumina-zirconia catalyst used in this work possesses two types of acidity, termed (I) and (II), and previous work has shown that the hydrolysis of chloropentafluoroethane proceeds at a faster rate over acidity (I). The values of initial PFC-14 conversion in this work exhibited a positive correlation with the amount of acidity (I) in the catalyst. The hydrolysis of hexafluoroethane (PFC-116) was also investigated using these same catalysts and its initial conversion was found to peak at an alumina content of 90 wt% and to correlate with the total acidity (types (I) and (II) combined) of the catalyst. The catalytic cracking of isopropylbenzene is known to occur over the Brönsted acid sites of the catalyst, and the catalysis of isopropylbenzene in the presence of water vapor over two different catalysts indicated that acidity (I) corresponds to Lewis acidity and acidity (II) to Brönsted acidity. Accordingly, it is concluded that PFC-14 is decomposed by Lewis acid sites, whereas PFC-116 is decomposed by both Lewis and Brönsted acid sites.
