Ti functionalized hierarchical-pore UiO-66(Zr/Ti) catalyst for the transesterification of phenyl acetate and dimethyl carbonate

Abstract

Titanates are frequently used as precursors to prepare transesterification catalysts with Ti^IV species. Unfortunately, it is challenging to control the dispersity of Ti^IV active sites on supports. Herein, a series of Ti^IV species is anchored on abundant linker vacancy sites by introducing point and large scale defects in UiO-66(Zr/Ti) with hierarchical-pore structure. The catalyst functionalized by titanium(IV) oxide bis(2,4-pentanedionate) shows excellent catalytic performance in the transesterification of dimethyl carbonate with phenyl acetate. The catalysts are characterized by XRD, FT-IR, N₂ adsorption–desorption, XPS, SEM and STEM-HAADF techniques. The results demonstrate that the delicate mesopores in the support can not only exhibit a large surface area for the distribution of the active sites, but also provide better mass transfer performance. Meanwhile, the introduction of octahedral Ti^IV ions raises the activity of the catalyst via more coordinatively unsaturated Zr^IV sites. Furthermore, using titanium(IV) oxide bis(2,4-pentanedionate) as a Ti source can effectively prevent the condensation of tetrahedral Ti^IV species anchored on the hierarchical-pore UiO-66(Zr/Ti) support.