Synthesis Method\nand Principle of Octahedral Hierarchical\nLTA Zeolite and Its Application to Enhance Catalytic Activity in Styrene\nEpoxidation

A 4 Å zeolite prepared under the synergistic effect\nof intense\nultrasound and a high-voltage electrostatic field had an octahedral\nstructure rather than a conventional hexahedral structure. XPS and\nXRD analyses showed that the ratio of silicon to aluminum, 2θ\npeak position, and the corresponding crystal planes were the same\nas those in traditional hexahedral 4 Å zeolite, but some crystal\nplanes were more prominent. SEM imaging showed that the octahedral\nzeolites had a larger particle size. Porosimetry (BET surface area\nand BJH analysis) showed that the octahedral zeolite had become a\nmesoporous zeolite, and its specific surface area increased and its\npore size expanded, which was conducive to loading catalytically active\nmaterials and thus improving its catalytic performance. In this paper,\nthe mechanism of formation of hierarchical LTA zeolite is discussed,\nand the octahedral hierarchical LTA zeolite is used to catalyze the\nepoxidation of styrene, giving very good results. It is concluded\nthat the (600), (622), (642), and (644) crystal planes played a decisive\nrole in the styrene epoxidation reaction, providing a realistic basis\nfor explaining the crystal plane catalysis effect of the 4 Å\nzeolite. This new zeolite prepared under the synergistic effect of\nintense ultrasound and a high-voltage electrostatic field, being the\nfirst time to prepare the octahedral hierarchical LTA zeolite, is\nsimple to produce, green, and environmentally friendly and has good\neconomic development prospects compared to the use of templating agents,\nwhich not only provides ideas and simpler methods for optimizing the\nperformance of traditional zeolites and developing new zeolites with\nbetter performance but also enhances the theoretical basis for preparing\nnew zeolites.