Studies on gamma-Al2O3 supported Cr promoted SO42-/ZrO2 solid superacid catalysts

The Cr-SZ/Al2O3 series solid superacid catalysts were prepared first by sup porting Cr promoted SO42-/ZrO2(SZ) solid superacid catalysts, Cr-SZ, on gam ma -Al2O3 support, The variation rules of their superacidities, medium stro ng acidities and weak acidities were investigated by using model reactions, The surface area, sulfur content and zirconia crystallization as well as t he catalytic activity of samples for n-butane isomerization at low temperat ure were also studied in detail. It was shown that the both introducing Cr species and supporting Cr-SZ on gamma -Al2O3 were beneficial to stabilize t he tetragonal ZrO2 crystal phase that are supposed to be one of the basic c onditions of superacidity, Moreover the SO3 contents of the supported sampl es were much larger than those of both Cr-SZ and SZ sample, The catalytic a ctivities of some Cr-SZ samples for n-butane isomerization were improved gr eatly after supporting them on gamma -Al2O3. The improvement of both acidit y and dehydrogenation ability of samples containing Cr makes contribution t o the increasing of their catalytic activities for n-butane isomerization, Cr-SZ/Al2O3 sample with proper acidity and dehydrogenation ability shows a high activity for n-butane isomerization.