Efficient and sustainable production of p-xylene from biomass-derived 2,5-dimethylfuran and ethylene using alkali metal doped phosphotungstic acid catalysts

Abstract

A series of alkali metals (K, Rb, and Cs) doped phosphotungstic acid (H₃PW₁₂O₄₀, HPW) catalysts were prepared by an ion-exchange method. These catalysts were characterized by various techniques and applied for the renewable production of p-xylene (PX) from biomass-derived 2,5-dimethylfuran (DMF) and ethylene. The effects of the types and amounts of the alkali metals on the catalytic activity of these catalysts were evaluated, and the relationship between the catalytic activity and acidity was established. Among these catalysts, the Cs₁H₂PW exhibited the best activity and PX yield. The influences of the reaction conditions i.e. the ethylene pressure, catalyst dosage, reaction temperature, and reaction time were investigated. Under the optimum reaction conditions, a high DMF conversion of 91.8% along with PX yield of 64.0% was obtained over Cs₁H₂PW. Also, the Cs₁H₂PW catalyst could be re-used at least five times with slight losses in activity. Moreover, the kinetics of the conversion of DMF to PX over Cs₁H₂PW was studied using a pseudo-first-order kinetic model, and a lower activation energy (57.9 KJ mol⁻¹) was obtained.