Highly efficient catalytic conversion of biomass-derived 2,5-dimethylfuran into renewable p-xylene over zirconium phosphate catalysts

A series of zirconium phosphates (ZrP-x) with various P/Zr ratios were prepared. Among the catalysts, ZrP-2.5 with a high specific surface area of 410.9 m2·g−1 and abundant mesopores exhibited outstanding catalytic performance in the synthesis of p-xylene (PX) from 2,5-dimethylfuran (DMF) and ethylene. A high PX yield of 89.2% and a productivity of 72.3 mmolPX·gcat−1·h−1 were achieved at 250 °C using a small amount of catalyst. The excellent catalytic performance of ZrP-2.5 was attributed to the synergy between the large quantities of acidic sites with appropriate acid strength distribution, balanced Brønsted and Lewis acidity, and abundant mesopores. In addition, the catalyst had excellent recyclability and stability. In-situ FT-IR spectra of adsorbed DMF and ethylene revealed the crucial roles of P-OH and the coordinately unsaturated Zr(IV) in the adsorption and reaction process, which is beneficial to understanding the reaction mechanism and designing highly efficient catalysts.