Study on the Mechanism of Water Poisoning Pt-Promoted Sulfated Zirconia Alumina in n‑Hexane Isomerization

In present work, the water poisoning mechanism was investigated since a rapid deactivation was observed in n-hexane isomerization over the Pt-promoted sulfated zirconia alumina (termed as PtSZA) catalyst with a high-moisture-content feed (111 ppm). It was concluded that with the presence of hydrogen, the hydrogen molecules dissociated to hydrogen atoms on Pt sites and the partial hydrogen atoms spilled over to Zrδ+ to form acid sites which were the catalytic sites for isomerization. When the water in the feed adsorbed on the catalyst, it could combine Zrδ+ to form Zr–OH groups. In this way, the generation of acid sites was suppressed and the catalyst deactivated due to the lack of catalytic sites.