Synthesis and Characterization of Hierarchical Mordenite Zeolite

Hierarchical MOR zeolite nanocrystallines with mesoporous architecture composed of 2 similar to 4 nm pores were synthesized via a simple hydrothermal route by adding surfactant CTAB as mesoporous template in the absence of organic co-solvent and zeolite seeds, in which the mesoporous volume and external surface area could be adjusted by changing the amount of CTAB. The largest external surface area and mesoporous volume were 191 m(2)/g and 0.17 cm(3)/g. Adsorption of mesitylene on the MOR zeolitic samples showed that only a small amount of adsorption could be found in the microporous mordenite, but a large amount of adsorption in hierarchical mordenite which presented the characteristics of typical IV isotherm indicating a mesoporous structure. Catalytic properties of the MOR zeolitic samples were investigated by benzylation reaction of mesitylene and benzyl chloride. Compared with the traditional microporous mordenite, the reaction conversion on the hierarchical mordenite increased similar to 7 times and the reaction apparent rate constant increased similar to 19 times. This property is due to the expansive external surface areas and mesopores volume in the hierarchical mordenite zeolite which can effectively improve accessibility of the bulky reactants to acid sites and mass transfer rate of big products, and greatly promote the catalytic efficiency of bulky molecules.