Highly acidic mesoporous aluminosilicates assembled from zeolitic subunits generated by controllable desilication of ZSM-5 in Na2SiO3 solution

Abstract

Mesoporous aluminosilicates (ZM) were hydrothermally synthesized by assembling zeolitic subunits, which were obtained by the controllable desilication of nano-sized ZSM-5 zeolite particles in Na2SiO3 aqueous solution, with cetyltrimethylammonium bromide (CTAB) as the template. The characterization results indicated that ZM possessed a mesoporous structure similar to MCM-41 and ZSM-5 subunits were present in the pore walls. Compared with conventional Al-MCM-41, ZM had less isolated silanol groups, larger pore wall thickness, and higher percentage of tetrahedrally coordinated Al species. The acidity site density, the proportion of strong acidity sites, and the B/L ratio of HZM, which was obtained by ion-exchange of ZM followed by calcination, were significantly higher than those of HAl-MCM-41, but slightly lower than HZSM-5 zeolite. In cumene cracking, HZM showed higher activity than HAl-MCM-41, and much better stability than HZSM-5. In the bulky molecules-involved Friedel–Crafts alkylation of benzene with 1-dodecene and in the liquid phase benzylation of benzene with benzyl alcohol, HZM exhibited higher catalytic performance than HAl-MCM-41 and HZSM-5.