Investigation of reusability and deactivation mechanism of supported platinum catalysts in the practical isomerization of allylic esters

Metal oxides supported platinum catalysts with residual chloride are known to be reusable soft Lewis acid catalysts for the isomerization of allylic esters. To deepen the understanding of the industrial application of the catalytic system and optimize the catalyst design, an investigation on the reusability and deactivation mechanism of supported platinum catalysts in the isomerization of but-3-ene-1,2-diyl diacetate was conducted. A great reactivation effect was observed by treating the used catalysts with HCl, rather than that of calcination. Pt-Cl/CeO2 showed the best reusability among the catalysts prepared with other metal oxides, and it was uncovered that the reduction of PtOxCly species should be the main reason for deactivation with the assistance of X-ray absorption fine structure (XAFS) analysis. Besides, a relatively stable state was also observed from the XAFS spectra of Pt-Cl/CeO2 catalysts in the reusing test, and it could effectively prevent the active species from further deactivation. Furthermore, in an extended evaluation of the stability of the catalysts, reusability, and a limited deactivation were also verified through a 10-run batch reaction. Additionally, the continuous flow reaction was also proven to be feasible.