Direct synthesis of hierarchical ferrierite nanosheet assemblies via an organosilane template approach and determination of their catalytic activity

Abstract

Hierarchical ferrierite (FER) nanosheet assemblies with a ball-shaped morphology were prepared via a direct hydrothermal synthesis by using an organosilane surfactant, 3-(trimethoxysilyl) propyl octadecyl dimethyl ammonium chloride (TPOAC) as structure directing agent (SDA). The prepared nanosheet assemblies not only have a different morphology (micro-spherical nanosheet assemblies) but also a higher hierarchy factor (HF) (0.11) compared with that obtained in the case of conventional FER (plate-like products with HF value of 0.03). The enhanced HF of the FER nanosheet assemblies corresponds to an increase in mesopore surface area as they preserve the microporous zeolitic features in terms of crystallinity and acidity. This results in an improvement of the catalytic activities (82% and 14% conversion efficiency in the cases of the FER nanosheet and the conventional FER, respectively) for the benzylation of toluene with benzyl chloride. We demonstrate a simple way to create hierarchical FER nanosheet assemblies with a 2D pore system by a direct synthesis via an organosilane-SDA approach. This is complementary to the nanosheet design on other types of zeolites besides MFI and FAU nanosheets and opens up the catalytic applications involving bulky molecules like in the case of benzylation.