THE GALLIATION OF ZEOLITE-BETA

The process of galliation of zeolite beta, a highly siliceous zeolite with a Si/Al ratio of about 10, was investigated, and a mechanism is proposed on the basis of the characterization of the galliated product and as a result of monitoring the process using a combination of X-ray diffraction, infrared spectroscopy, magic angle spinning n.m.r., X-ray photoelectron spectroscopy, and chemical analysis. The process occurs on the framework sites of the zeolite through insertion of gallium species into the vacancies created during prior thermal treatment of the zeolite and through substitution of framework Si atoms removed by basic leaching. The galliation starts preferentially at the external surfaces of the zeolite particles and then proceeds to their interior. The aluminum (if present) and gallium species present in the liquid phase behave similarly during the process. The effects of factors such as alkalinity, gallium concentration, and temperature on the galliation were also investigated.