Macroscopic shaping of coordination polymer via crystal–glass phase transformation as monolithic catalyst for efficient catalyst recovery

Abstract

To circumvent the difficult processability and recovery of catalytic materials in powder form, we herein report macroscopic shaping of 1D coordination polymer consisting of zinc ions, orthophosphate, and benzimidazole, namely ZnPBIm, motivated by the crystal–glass phase transformation. Glassy ZnPBIm monoliths with different shapes and sizes were prepared via a melt-quench process without using the secondary component. As a heterogeneous acid catalyst, the glassy ZnPBIm monoliths contribute to the esterification of levulinic acid with ethanol at 100 °C with recyclability for at least three consecutive cycles, and over 90% of catalyst mass was recovered. The macroscopic shape of the monoliths was retained after 24 h of reaction. Surface crystallization of glassy ZnPBIm was induced by the presence of water during esterification, and the glass domain serves as a macroscopic support for the crystallized domain.