Phosphotungstic acid anchored on amine-functionalized MIL-101: An effective catalyst for the direct esterification of 1-butene to sec-butyl acetate

This article proposes a novel strategy for enhancing the dispersion and stability of supported H3PW12O40 (HPW) via the charge interaction between HPW anions and amino groups originating from ethylenediamine (ED) grafted on the unsaturated metal sites of MIL-101. Due to its larger specific surface area and pore volume as well as stronger interactions between HPW and the carrier, the as-prepared catalyst exhibited a higher sec‑butyl acetate (SBAC) yield for the direct esterification of olefins than did the catalyst prepared by the encapsulation of HPW in the mesoporous cages of MIL-101. In addition, the HPW content incorporated in the as-prepared catalyst was optimized, and the results showed that among the series of catalysts, the HPW/ED-grafted MIL-101 catalyst with 40 wt% HPW had the highest activity and good stability for olefin esterification. This investigation sheds light on the conversion of 1-butene into high-value SBAC via the amine-functionalized MIL-101-supported HPW catalysts.