N-pentane isomerization over Pt-Al promoted sulfated zirconia nanocatalyst

Abstract

Platinum containing sulfated zirconia (Pt-SZ/Al) catalyst was prepared by precipitation method. Characterization of the prepared catalyst was performed using XRD and SEM, and catalytic activity was studied for isomerization of nC5 at atmospheric conditions and temperatures of 180-240°C in a flow reactor. The effects of reaction temperature, H2/nC5 ratio, and WHSV were investigated. As revealed by SEM and XRD, the prepared sulfated zirconia was of nanoscale size and had predominantly tetragonal crystalline phase. n-pentane conversion increased with increasing temperature and selectivity decreased. The optimal reaction temperature was 220°C where n-pentane conversion and isopentane selectivity were 70% and 94%, respectively. The positive effect of H2/nC5 ratio was observed on nC5 conversion and iC5 selectivity in the investigated H2/nC5 ratio range. This trend of variation was related to the role of acid and metallic sites on the reaction pathway. As expected, increase in the WHSV, which reduces contact time between reactant and catalyst, decreased nC5 conversion and increased selectivity toward iC5. The RON of the product increased with increasing temperature; then, it showed slight decrease at higher temperature. The decrease in the activation energy was observed, which can be attributed to the different reaction mechanisms or different rate-determining steps.