Aimed at highly selective production of p-xylene (PX) from biomass-derived 2,5dimethylfuran with a high carbon balance, SiO 2 supported with sulfonic acid was especially designed and prepared. As one kind of the most widely used Brønsted acid, sulfonic acid groups were chosen as the active sites of probes. The density of sulfonic acid groups in the whole composite was highly adjustable, ranging from 4.7−540.6 μmol/g. The catalytic activity was strongly related to the acid concentration and location: the one with active sites mainly on the exterior surface exhibited much better catalytic activity by facile mass transfer through mesopores. The suitable acid species and structures of the as-prepared catalyst contributed to the improved activity: a selectivity of 89% and a carbon balance of 95% were achieved at 523 K. Overall, this new reusable catalyst provided an alternative for highly efficient production of biobased PX.
A hierarchical NbO
x
-based catalyst
with both Brønsted acid and Lewis acid sites was synthesized
in the absence of corrosive hydrofluoric acid, exhibiting high catalytic
activity for biobased p-xylene (PX) production from
2,5-dimethylfuran (DMF). The as-prepared composite was composed of
Nb2O5 and NbOPO4 crystals, and the
densities of Brønsted acid and Lewis acid were determined to
be 232.9 and 80.4 μmol/g, respectively. The well-balanced Brønsted/Lewis
acidity and the hierarchical structure with small mesopores (3 nm)
and large mesopores (48 nm) contributed to the high activity and stability:
a conversion of 87.2% with the PX selectivity of 92.7%, and a carbon
balance of 94.6% was achieved after 6 h of reaction at 523 K. In comparison
with Sn-Beta, NbO
x
-based catalyst prepared
in this work showed obvious advantages in suppressing carbon deposition:
90.9 and 54.7 mmol of PX were obtained over the NbO
x
-based catalyst and the Sn-Beta, respectively, after 24 h.
Spent catalysts were regenerated through calcination at high temperature
and they proved to be recyclable: a decrease of 3.7% in DMF conversion
and no loss in PX selectivity could be evidenced over five consecutive
runs. Overall, NbO
x
-based catalyst which
is synthesized through the green and sustainable approach is sufficiently
stable, active, and regenerable, and provides an alternative candidate
for efficient PX production.
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