One-pot synthesis of mesoporous ZrPW solid acid catalyst for liquid phase benzylation of anisole

Abstract

Mesoporous zirconium phosphotungstate (M-ZrPW), with large specific surface area (~170 m² g⁻¹), large pore volume (~0.25 cm³ g⁻¹), uniform pore size distribution (~6.5 nm) and tunable W/Zr ratios (0–0.2), was successfully prepared via a facile one-pot evaporation-induced self-assembly (EISA) strategy. Small-angle X-ray diffraction (SXRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) characterizations showed that these materials had a mesoporous structure even when the W/Zr ratio reached up to 0.2. The tungsten species introduced via this strategy highly were dispersed among the wall of mesoporous framework. More importantly, the tungsten species greatly improved the Brønsted acidic property and catalytic activity in the Friedel–Crafts benzylation reaction. The highest activity was obtained at a W/Zr ratio of 0.2 with the strongest Brønsted acidity. In addition, the influences of various reaction parameters such as reaction time, amount of catalyst and calcination temperature of the catalyst, systematically investigated in this paper. Furthermore, the M-ZrPW showed a higher catalytic activity than H-Beta, H-ZSM5 and ZrPW prepared by the sol–gel method. Meanwhile, M-ZrPW could be reused at least for five cycles in the benzylation reaction without any notable decrease of catalytic activity.