Cycloaddition-dehydration continuous flow chemistry for renewable para-xylene production from 2,5-dimethylfuran and ethylene over phosphorous-decorated zeolite beta

Abstract

We demonstrate highly selective production of para-xylene (pX) from ethylene and 2,5-dimethylfuran (DMF) in a packed bed microreactor using phosphorous-decorated zeolite beta (P-BEA), with pX selectivity up to 97% at 80% DMF conversion. We map the effect of reactor temperature, space velocity, concentration, gas-to-liquid ratio, and process pressure. Time-on-stream (TOS) and in situ regeneration studies show minimal productivity degradation over ~5 h TOS and full productivity restoration upon regeneration for multiple cycles. Most non-selective Brønsted acidity occurs at low TOS and is attributed to the remaining trace Al bridge site. External mass transfer limitations are implicated at low space velocities. We combine the TOS data with NMR, XRD, and Raman to develop structure-performance insights into the catalyst behavior. Comparison to mesoporous P-supported materials illustrates that P-BEA is an excellent catalyst for size selectivity and long-term stability.