Cationic surfactant-directed synthesis of hollow Beta zeolite with hierarchical structure

Abstract

Hollow Beta zeolite with hierarchical meso/microporous has been synthesized via one-step hydrothermal method by using a designed cationic surfactant of N2-p-N2 as soft-template. The structure-directing ability of N2-p-N2 was studied by the DFT calculations. The hollow Beta zeolite with a hierarchical structure was characterized by a combination of X-ray diffraction, Fourier transform infrared spectroscopy, nitrogen adsorption-desorption isotherms, scanning electron microscopy and transmission electron microscopy. The structural characterization suggested that the positively charged quaternary ammonium group can interact with the anionic aluminosilicate species to induce the formation of Beta zeolites. The hollow zeolites possess the large inner cavity and hierarchical structure, which can significantly reduce diffusion limitations and facilitate accessibility of the active sites. FTIR spectra of 2,6-di-tertbutylpyridine results indicated that the hollow Beta zeolite with hierarchical structure provided increased external surface acid sites and exhibited superior catalytic property in the benzylation of benzyl alcohol with mesitylene. Such hollow zeolite with hierarchical structure has great potential in catalysis involving large molecules.