Al-promoted Pt/SO42−/ZrO2 with low sulfate content for n-heptane isomerization

To reduce the occurrence of cracking reactions and obtain high activity for n-heptane isomerization, we performed this study, aimed at improvements of the Al-promoted Pt/SO42−/ZrO2 (Pt/SZ) catalyst. The effect of sulfur content was studied and it was found that lowering sulfate content in the Al-promoted Pt/SZ resulted in remarkably enhanced selectivity towards iso-C7 formation from 25% up to 83% compared with Pt/SZ without a loss of activity. The results of catalyst characterizations revealed that the tetragonal phase of ZrO2 and its acidity were responsible for the higher activity, and that aluminum helped to stabilize the tetragonal phase in Al-promoted Pt/SZ and hence maintained catalytic activity at low sulfate content, while the low acidity and high Pt dispersion resulted in a high ratio of metal sites to acid sites and hence benefited a higher selectivity for iso-C7.

Figure optionsDownload high-quality image (96 K)Download as PowerPoint slideResearch highlights▶ The sulfur content in Pt/SZA catalyst greatly affected its performance. ▶ Lowering sulfate content resulted in remarkably enhanced iso-C7 selectivity. ▶ The selectivity could increase from 25% up to 83% without a loss of activity. ▶ Pt/SZA catalysts with low sulfur content had low acidity and high Pt dispersion. ▶ High Pt dispersion in Pt/SZA with low sulfur content benefited a higher selectivity.