无胺法合成高硅丝光沸石的表征  

Characterization of High Silica Mordenite Synthesized from Amine-free System Using Fluoride as Structure-directing Agent

作　　者：祁晓岚[1,2] 王战[3] 李士杰[1] 李斌[1] 刘希尧[1] 林炳雄[1] 

机构地区：[1]北京大学化学与分子工程学院物理化学研究所 [2]中国石油化工股份有限公司上海石油化工研究院,上海201208 [3]北京燕山石油化工公司研究院

出　　处：《物理化学学报》2006年第2期198-202,共5页Acta Physico-Chimica Sinica

基　　金：国家自然科学基金(20373002)资助项目

摘　　要：采用XRD、SEM、FT-IR、MASNMR等表征手段,对以氟离子为结构导向剂无胺法合成的高硅丝光沸石进行了表征.结果表明:高硅丝光沸石结构属立方晶系,晶胞参数小于传统低硅丝光沸石,但b、c值要比相近硅铝比非氟体系合成的丝光沸石样品的大;样品形貌及粒径与其硅铝比有关,表明晶化条件对产物形貌及粒径均有影响;随硅铝比的增大,FT-IR光谱中450、544、1053cm-1谱带向高频移动,720cm-1谱带强度减弱,表明骨架中铝减少而硅增多;采用含氟无胺体系合成高硅丝光沸石时基本上不会产生非骨架铝.A series of high silica mordenite samples synthesized from amine free system using fluoride as structuredirecting agent were characterized by XRD, SEM, FF-1R, and MAS NMR. The results confirmed that the samples were truly mordenite with high SiO2/Al2O3 molar ratio, The unit cell constants a, b, c and the unit cell volume （axbxc） of M-36 sample were smaller than those of mordenite with silica alumina molar ratio （SAR）=10 reported in the literature, which indicated the unit cell contraction caused by the replacement of Al atoms by smaller Si atoms. However, compared with the sample with SAR=31.5 synthesized from free-fluoride system, the lattice parameters of M-36 were somewhat increased in the a and c directions, but elongated obviously in b direction, which indicated some influences on 8-membered ring parallel to the b axis of mordenite structure should be brought by using fluoride as structuredirecting agent. As the SAR of mordenite samples increased, a variety of crystal morphologies （cuboids, hexagonal prismatic crystals, rectangular parallelepiped crystals） was observed and a wide variation in the crystallite size was presented, As the SAR changed from 14 to 55, in the infrared spectra of the samples, the band attributed to T--O bending vibration shifted from 434 cm^-1 to 450 cm^-1, and its absorption intensity also increased. The band at 720 cm^-1 which corresponded to the internal symmetric stretching vibration of the AlO4 tetrahedral in the mordenite from a weak band developed into a broad band and nearly disappeared at last, indicating that the number of SiO4 in the framework was increased. In ^27Al MAS NMR spectra, ahnost all high silica mordenite samples presented a peak at 6（55,6） and no non-framework Al species peak at about δ（0）, which was different from steamed or acid-leached siliceous mordenite.

关 键 词：氟离子 高硅丝光沸石 表征 

分 类 号：O611.3[理学—无机化学]