Dehydration of 2-octanol over zirconia catalysts: Influence of crystal structure, sulfate addition and pretreatment

Two phases of zirconia, monoclinic (m-ZrO2) and tetragonal (t-ZrO2), and their sulfated forms (m- or t-ZrO2-S) were evaluated for 2-octanol conversion. Unsulfated zirconia resembles thoria for both dehydration and I-alkene selectivities for 2-ol conversions. Its catalytic properties differ greatly from two other members of the group 4B family, titania and hafnia. Independent of crystal structure, sulfated and oxygen pretreated zirconia catalysts exhibit high activity for dehydration reaction. The sulfated and hydrogen pretreated and the unsulfated (both H-2 and O-2, pretreated) zirconia catalysts were less active for 2-octanol conversion. Hydrogen pretreated sulfated zirconia catalysts show high selectivity for 1-octene compared to oxygen pretreated and sulfated zirconia catalysts. The results show that the pretreatment influences the dehydration selectivity but the activity and selectivity are essentially independent of zirconia crystal phase.