Catalytic behavior of Pt/SO42-/ZrO2 - Al2O3 in n-hexane isomerization

The catalytic behavior of Pt/SO42-/ZrO2 - Al2O3(PSZA) in n-hexane isomerization was evaluated in a continuous flow fixed bed micro-reactor. The acidity, reduction properties and sulfur content of PSZA were characterized by NH3-TPD, H2-TPR and TG technology, respectively. The experimental results demonstrated that the initial isomerization catalytic activity of PSZA was independent of the reaction temperature, while the stability of PSZA was closely related to the reaction temperature. The PSZA catalyst was quickly deactivated in short time at low reaction temperature. On the contrary, PSZA exhibited good reaction stability at relatively high temperature. In addition, the spent or deactivated catalyst possessed good regeneration performance. It was inferred that the deactivation of PSZA in short reaction time should be related with the creation mechanism of catalytic active sites and be independent of the sulfur loss or sulfur species reduction. In the process of the isomerization reaction the acid active centers in catalyst produced by hydrogen spillover were continuously consumed. At high reaction temperature, the catalytic active sites in the catalyst may be created in time by the spillover of the dissociated hydrogen atom, so the isomerization catalytic activity of the catalyst was relatively stable. At lower temperature, hydrogen spillover was difficult to occur and the new catalytic active centers of the catalyst could not be produced in time, resulting in the isomerization catalytic activity gradually decreased.