微波场中T型分子筛的合成及晶化研究(英文)

Synthesis and Crystallization of Zeolite T by Microwave Heating

研究了微波场中T型分子筛的结晶过程。考察了微波加热体系中合成参数如合成时间、溶胶组成、反应压力和模板剂用量对分子筛晶化的影响。微波加热的主要优点是减少合成时间,无模板剂的溶胶在普通加热条件下的晶化时间需要120h,而在微波场中则仅需要20～25h。另一方面,由于微波的快速加热特性促进了稳定相钙十字沸石的生成,从而减小了次稳定相T型分子筛的结晶区间。在未添加模板剂条件时,100℃下微波水热合成T型分子筛的结晶区间为:20≤nSiO2/nAl2O3≤22和0.31≤nM2O/nSiO2≤0.33(其中M2O=Na2O+K2O,nNa/nK=3和nSiO2/nH2O=11.70)。在普通加热和微波加热合成体系中,添加模板剂均能扩大结晶区间,同时还可以进一步减少合成时间。

The crystallization of Zeolite T under microwave-heating system was studied. The effects of synthesis parameters such as synthesis time, gel composition, reaction pressure and template on crystallization were investigated. The results show that the crystalline zeolite T is obtained in 20-25 h without template under the microwave hydrothermal treatment in contrast to more than 120 h by conventional heating method. The crystallization fields of the metastable phase of zeolite T is narrowed due to the favored formation of the stable phase of phillipsite by the fast heating of microwave irradiation. The formation fields of zeolite T without template under microwave hydrothermal synthesis are： 20≤nSiO2/nAl2O3≤22 and 0.31≤nM2O/nSiO2≤0.33 （where M2O=Na2O＋K2O,nNa/nK=3 and nSiO2/nH2O=11.70） at 100 ℃. The addition of template（tetramethylammoninm（TMA） cation） will broaden the crystallization field of zeolite T and further reduce the synthesis time in both of the microwave-heating system and the conventional-heating system.