Acid strength of sulfated zirconia inferred from catalytic isobutane conversion

The kinetics of the catalytic conversion of isobutane under gas-phase fixed -bed flow conditions over sulfated zirconia (SZ), when compared with those of other strong solid acids of known acidity, suggests that SZ may be a ver y strong solid superacid; this conclusion disagrees with recent reports cla iming that SZ is not a superacid, and supports older claims, based on acidi ty tests with Hammett indicators, that SZ may have H-O of < -16.