Synthesis Of Mordenite Type Zeolite And Study Of Pickling

Mordenite as one of the earliest zeolites known by people, its source is mainly from two aspects:natural mordenite and synthetic mordenite. In recent years, the synthesis of mordenite methods emerge in endlessly, providing a great convenience for the wide application of mordenite.As a result, mordenite are widely used in the fields of building materials, environmental protection and so on in addition to adsorption and catalysis. In this paper, mordenite has been synthesized using natural mineral diatomite and industrial sodium silicate as raw materials in a template-free system. Using of raw materials without organic species reduced the pollution problem of waste liquid caused by the hydrothermal reaction, the synthetic methods was green and environmental protecting. It has provided a new method for the synthesis of mordenite greenly and efficiently. The as-synthesized mordenite was pretreated by acid, in order to remove the impurities introduced by mineral raw material and improve its adsorption performance. Crystal phase, chemical composition, thermal stability, BET surface area and adsorption performance of samples were characterized by X-ray diffraction, scanning electron microscopy, X-ray fluorescence, infrared spectroscopy, thermal gravimetric analysis, nitrogen adsorption and water saturation adsorption. In addition, the optimal experimental condition and the optimum pickling pretreatment conditions have been determined. The main conclusious are as follows:1, Mordenite has been synthesized from natural mineral diatomite as the main raw material and industrial sodium silicate. The best molar composition of the resultant mixture was39Na2O:158SiO2:7Al2O3:1865H2O. Crystallization was carried out at170℃for18h after aging. The synthesized samples present the typical structure of mordenite, and the SEM image reveals an oval-shaped morphology with a length of about5μm. The static saturated adsorption amount of water is13.80, slightly smaller than commercial pure mordenite.2, After the post-treatment by acid, the impurities within pore which caused by mineral diatomite were removed. The framework of mordenite after acid pickling is remained as shown in X-ray diffraction pattern, and the thermal stability of the samples is improved.After acid pickling,the surface of mordenite is416.83cm3/g, and adsorption performance is improved.Pickling condition is determined by static adsorption of water, the best water saturated static adsorption quantity is18%. The optimal pickling process took4h under80癈, with1mol/L sulfuric acid pickling. The ratio of mordenite and acid is1g:20ml.