Solid-state rubidium exchange of zeolite NH4Y

✍ Scribed by Michael F. Ciraolo; Jonathan C. Hanson; Clare P. Grey

• Publisher: Elsevier Science
• Year: 2001
• Tongue: English
• Weight: 320 KB
• Volume: 49
• Category: Article
• ISSN: 1387-1811
• DOI: 10.1016/s1387-1811(01)00409-7

✦ Synopsis

NH 4 Y has been ion exchanged by reaction with solid Rb 2 CO 3 to form RbY. This process has been followed with Xray powder diraction, mass spectrometry and NMR. Both 1 H and 87 Rb MAS NMR are very sensitive to the hydration level of the zeolite and have been used to investigate the solid-state exchange process. 87 Rb NMR shows that exchange begins instantaneously on grinding the two solids together: decomposition of Rb 2 CO 3 is observed, together with the migration of Rb into the zeolite pores. X-ray diraction indicates that the reaction proceeds to completion by 400 °C. The structure of the ®nal RbY product has been re®ned with Rietveld analysis and rubidium cations have been located at the SI H SII and SIII H positions. Residual sodium cations from the incomplete exchange of the ammonium starting material have been located at the SI position; this result was con®rmed by 23 Na MAS NMR. No evidence for Rb occupation of the SI positions was observed. Considerable disorder is observed in the cages of the zeolite during the ionexchange process, but re®nements of the structures, using the in situ data, indicate that Rb cations have entered the sodalite cages by 200 °C.