Synthesis of Single-Crystalline Mesoporous ZSM-5 with Three-Dimensional Pores via the Self-Assembly of a Designed Triply Branched Cationic Surfactant

A single-crystalline mesoporous ZSM-5 (SCMZ) with sheetlike pores, a uniform thickness of similar to nm, and a wide range of lengths (5-50 nm) along the a-axis and c-axis was synthesized using an amphiphilic template with three diquaternary ammonium-terminated alkyl chain branches that were bound to a benzene ring at positions 1, 3, and 5. The triply branched diquaternary ammonium head groups of the template broke the extension of the lamellar assembly along the a-axis and c-axis, which led to the formation of SCMZ with three-dimensional mesopores having abundant crystal faces along the a-axis, b-axis, and c-axis. By increasing the length of the hydrophobic chain, we obtained the mesoporous ZSM-5 with intercrossed nanosheets (MZIN) with only a-c planes, whose mesopores were maintained after calcination because of the structural connectivity around the crossed joints. The SCMZ exhibited catalytic efficiencies significantly higher than those of and unique selectivity compared with those of the conventional MFI and MZIN.