Extraframework aluminium in steam- and SiCl4-dealuminated Y zeolite. A 27Al and 29Si nuclear magnetic resonance study

29 Si and 27Al m.a.s.n.m.r. techniques have been used to study the dealumination process of a Y zeolite. Dealumination by steaming or SiCl4 treatment leads to the formation of silica and/or silica–alumina type phases. Extraframework aluminium shows a different type of coordination (tetra-, penta- or octa-hedral) depending on the method of dealumination.