CATALYTIC PROPERTIES OF SULFATED AND NONSULFATED ZRO2-SIO2 - EFFECTS OF THE SULFATION SUBMITTED BEFORE OR AFTER THE CALCINATION PROCESS, INTHE CYCLOHEXENE ISOMERIZATION REACTION

Catalytic properties of sulfated and non-sulfated ZrO2-SiO2 (14% molar in ZrO2) for cyclohexene conversion (skeletal isomerization and hydro gen transfer) have been studied. The effects of the sulfation, submitt ed before or after the calcination process upon textural, morphologica l and surface acidity, have been studied. All these properties were co rrelated to explain catalytic behaviour of the non-sulfated and sulfat ed samples. It has been shown that catalytic activities were increased on sulfated samples, but at the same time products of the hydrogen tr ansfer reaction seem to increased too, lowering the selectivity of the reaction; isomerization always predominates. For a given temperature, when sulfation process' is submitted before calcination the catalytic activities are lower than those obtained when the sulfation is submit ted after the calcination process. In summary, the effect of calcinati on temperature, the presence of sulphate groups on the surface and the sequence of the sulfation procedure (before or after the calcination process) seem to be important parameters on the catalytic properties f or cyclohexene isomerization reaction exhibited by this kind of cataly sts. (C) 1998 Elsevier Science B.V. All rights reserved.