ZSM-5 Monolithic Microreactors with Hierarchical Porosity: Maximizing Selective Production of para-Xylene
Résumé
ZSM-5 monoliths with Si/Al ∼40 were achieved by steam assisted conversion of micro-/macroporous silica-alumina monoliths synthesized by an optimized combination of spinodal decomposition and sol-gel process. ZSM-5 monoliths exhibit a homogeneous and interconnected network of macropores of ∼30 μm diameter, with a macropore volume of ∼1 mL g−1 and a micropore volume of 0.16 mL g−1, as waited for pure ZSM-5. The skeleton of ZSM-5 monoliths featured a 3D aggregation of spherical particles of 6 μm in diameter. The latter were composed by a stacking of thin plate-like shaped crystallites. The catalytic properties of the ZSM-5 monoliths were assessed through their use as catalytic microreactor in the continuous flow alkylation of toluene with methanol. An outstanding for para-xylene selectivity of 81 % was achieved possibly ascribable due to the maximization of pore openings of sinusoidal channels as a result of the plate-like morphology of the ZSM-5 crystallites