Abstract:

The Pt-sulfated zirconia catalysts (PtSZ) were prepared by extrusion method with the addition of binder. The influence of the binder type, binder content and the addition order of binder on the isomerization performance and mechanical strength of catalyst were studied. The crystalline structure and sulfur content of the catalysts were characterized by XRD and TG techniques. The experimental results demonstrate that the PtSZA(a) catalyst prepared with pseudo bohemite powder as the binder has a higher catalytic activity and higher mechanical strength than that with aluminum sol and silica sol as binder added into sulfated Zr(OH)4 powder. The increase of Al2O3 content from 5 wt % to 30 wt% leads to an obvious decrease in the isomerization activity of PtSZA(a). However, the isomerization activity of PtSZA(b) catalyst prepared by the addition of pseudo bohemite to Zr(OH)4 powder before sulfation of Zr(OH)4 did not change with Al2O3 content increasing up to 20%. And the further increase of the Al2O3 content up to 30% results in a very slight decrease in the activity of PtSZA(b). Both mechanical strength and sulfur content of catalyst are improved with the increase of Al2O3 whatever the addition order of binder is. The PtSZA(b) catalyst prepared by the addition of pseudo bohemite prior to the sulfation of Zr(OH)4 possesses both high activity and high mechanical strength.

Key words: Pt/SO42-/ZrO2, hydroisomerization, binder, extrusion