Hydrothermal synthesis and characterization of iridium containing beta zeolite

Abstract

The hydrothermal synthesis of iridium containing beta zeolite has been reported. The cffcicncy of the synthesis depends mainly on the concentration of indium. synthesis temperature, and pH of the gel. Beta iridium has been sylrthesized in a range of different Si02’ln,0, ratios using tetr~eth~l~~mmonium ion as a template. For SiO,:‘ln,O, ratio around 30, beta indictm was obtained as a pure phase with a good yietd. The product was contaminated with ZSM-5 in case of low In,O, content. If tht 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 crystallinit?;. Iridium species present in the b&a reolitc framea,ork were char;tcteriLed by IR NMR. The extra framework indium specicr probably exist in :I catiomc state. The catalytic activity elf the sample was tested by the benroylation reaction ol‘ naphthalene