LAUSR

Abstract Desilication and recrystallization of a low-silica NaK-form ferrierite (NaKFER) were conducted by one-step hydrothermal method in sodium hydroxide solution containing cetyltrimethylammonium bromide (CTAB). The attack by NaOH induced unprecedented mesopore formation in highly stable ferrierite crystals through framework desilication. Interestingly, the generated mesopores are parallelepiped-shaped and oriented along the [001] directions (10 MR) of the FER structure. The CTAB surfactant could be inserted between the layers of ferrierite crystals under the assistance of NaOH. This process was associated with the formation of occluded mesopores and led to partial delamination of layered crystals. Under severe treatment conditions, NaKFER transformed to GIS and SOD phases, successively. The samples were characterized by XRD, N 2 sorption, SEM, TEM, EDS, TG, etc. The influence of NaOH concentration, temperature, reaction time, CTAB and cation form of the parent zeolite was investigated in order to study the mechanism of mesopores formation, delamination process and phase transformation of ferrierite. Phase diagrams were established to show the transformation process of NaKFER as a function of NaOH concentration, reaction time and temperature.