Hydrothermal synthesis and characterization of indium containing beta zeolite

Abstract

The hydrothermal synthesis of indium containing beta zeolite has been reported. The efficiency of the synthesis depends mainly on the concentration of indium, synthesis temperature, and pH of the gel. Beta indium has been synthesized in a range of different SiO₂/In₂O₃ ratios using tetraethylammonium ion as a template. For SiO₂/In₂O₃ ratio around 40, beta indium was obtained as a pure phase with a good yield. The product was contaminated with ZSM-5 in case of low In₂O₃ content. If the synthesis is carried out at higher temperatures the possibility of the formation of ZSM-5 increases, whereas lowering the temperature takes longer, about 10-14 days. Upon calcination to remove the organic template, some demetallation occurs which lowers the crystallinity. Indium species present in the beta zeolite framework were characterized by IR NMR. The extra framework indium species probably exist in a cationic state. The catalytic activity of the sample was tested by the benzoylation reaction of naphthalene.