The dealumination of Na-Y zeolite with silicon tetrachloride vapor is a product-inhibited reaction because of the formation of sodium tetrachloroaluminate, which is nonvolatile at the reaction temperature. However, starting from Li,Na-Y prepared by ion exchange in aqueous solution, a nearly complete substitution of framework aluminum by silicon proceeds as evidenced by magic-angle spinning of NMR and IR spectrometry. Also after contact-induced ion exchange performed by grinding a mechanical mixture of hydrated Na-Y and crystalline LiCl, the framework dealumination is not prematurely stopped by product inhibition. In contrast to Na[AlCl4], the corresponding Li compound dissociates at the reaction temperature, the decomposition product (AlCl3) volatilizes, and only minor amounts of solid products not affecting the progression of the dealumination reaction are deposited in the zeolite pores.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry