²⁹Si²⁷Al and ¹H Solid-State NMR Study of the Surface of Zeolite MAP

Abstract

Zeolite MAP (maximum aluminum P) is a zeolite of the gismondine family that has recently found utility as an ion exchanger for water softening in detergents applications. It is composed of spherical agglomerates of small crystallites which have appreciable external surface area. A combination of 27 Al and 29 Si single-pulse and cross-polarization MAS NMR experiments have been used to elucidate the nature of the surface of zeolite MAP. The 29 Si experiments given an external surface area of approximately 8% of the total, which is consistent with that expected based the calculated particle size. The T cp is similar to amorphous aluminosilicates while the T 1 ρ values are significantly different, indicating protons with a different type of mobility. The 1 H NMR is consistent with the silanols being located on the external surface of the crystallites.