Unprecedented activity and stability on zirconium phosphates grafted mesoporous silicas for renewable aromatics production from furans

The selective production of aromatic chemicals such as benzene, toluene and xylenes from biomass-derived furans are quite challenging since zeolites and other supported heterogeneous catalysts are easily deactivated by trapping oligomeric species over their pores. Herein, a series of zirconium phosphates (ZrP) grafted on ordered mesoporous architectures of silicas was prepared by nonhydrolytic sol-gel method, and evaluated for the selective production of valuable para-xylene (pX) by catalytic reaction of 2,5-dimethylfuran (DMF) with gaseous ethylene through tandem Diels-Alder cycloaddition and dehydration reactions. The surface properties such as P/Zr ratio, Brönsted (B) to Lewis (L) acid sites and grafting layer thickness of the ZrP grafted silica catalysts were largely altered by changing P/Zr ratios and parent mesoporous silica surfaces. The amounts and strengths of acidic sites including B and L sites from the active (Zr–O)₂–PO(OH) and (Zr–O)₃–PO species were crucial factors for the differences in pX production rate on the ZrP grafted KIT-6, SBA-15 and fumed SiO₂.