| The synthesis of zeolite UZM-5 by the dynamic hydrothermal method in tetraethylammonium hydroxide (TEAOH)-tetramethylammonium chloride (TMAC1) two-organic component system was studied, crystallization temperature, time, organic templates, Na+ were important to synthesis, which were investigated, the optimum calcining conditions and decomposition mechanism of templates were then involved, finally, exploratory research of templates removal of zeolite UZM-5 was studied.The results indicated that the UZM-5 zeolite could be synthesized when the initial mixture was n(SiO2):n(Al2O3):n(H2O)=1:0.25:18, n(TEAOH):n(SiO2)=0.4～1.2, n(TMACl):n(SiO2)=0.064-0.160, with the temperature range of 413-423K. A small amount of Na+ ions resulted in the crystallization of UZM-9 zeolite.High-temperature calcination was used to remove the templates in UZM-5, ammonia atmosphere was found to be the best calcining atmosphere, air atmosphere took the second place, N2 atmosphere was worst; the effect of persistent overheating was better than stage heating; the crystallinity of UZM-5 was falling as the temperature grow higher, the zeolite had been amorphous when it reached 800℃. In zeolite, template tetramethylammonium chloride (TMAC1) exists in two forms, TMAC1 and TMA+, the latter can be decomposed in lower temperature, when UZM-5 was calcining in high temperature, TMAC1 and TMA+ located outside the canal were decomposed first, with the reaction went on, TMA+ and TEA+ located inside the canal begun to be decomposed, part of the framework collapsed, gaseous products escaped from the broken window; Oxidizing reaction and decomposition reaction took place in the meantime in the presence of oxygen, massive amounts of heat was one reason for the structural change.The methods of solvent extraction and UV/H2O2 were used to remove the templates from zeolites, nitric acid and hydrochloric acid had certain effect, 21% of the templates were removed by UV/H2O2. So these two methods were worth further exploration and research. |
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