摘要
对Y型沸石原粉及几种不同脱铝样品进行了几种不同NMR方法的测量,确定了不同处理过程的脱铝机制和骨架内外铝状态的变化, ̄(29)SiMASNMR谱给出了骨架Si、Al分布的信息,反映了不同方法处理样品其脱铝机制的差异,据此可以控制Y沸石脱铝过程获得更高的硅铝比, ̄(27)AlMAsNMR谱、二维章动NMR及 ̄1H- ̄(27)AlCP/MAsNMR测量表明:水热处理的Y沸石中存在4种不同的铝状态。综合 ̄(29)Si和 ̄(27)AlMASNMR观测,可相当程度地推断Y型沸石分子筛脱铝改性所发生的内部过程。
ealuminated Y zeolites after mild steaming and (NH_4)_2SiF_6 treatments were studiedby ^(29)Si ,^(27)Al MAS NMR, ^(27)Al-~1H cross polarization MAS NMR and 2D nutationNMR. ^(29)Si MAS NMR shows that the Si, Al framework distributions of ultrastableY zeolites and Y zeolites dealuminated by (NH_4)_2SiF_6 isomorphous substitution are dif-ferent, even if they have almost the same framework Si/Al ratio. The reason is due totheir different dealumination experience. Y zeolites with high Si/Al framework ratio canbe obtained by a coorperation of isomorphous substitution and hydrothermialdealumination . Based on ^(27)Al MAS NMR, ^(27)Al-~1H CP/MAS NMR and 2D nutation^(27)Al NMR observations, four aluminuous species, i.e. framework tetrahedral Al(Al^(FT)),distortcd framework tetrahedral Al(Al^(FDT)), penta - coordinated non framework Al(Al^(NFP))and non framework octahedral Al(Al^(NFO)), in dealununated Y zeolites are supposedSi/Al frame ratios of dealuminated Y zeolites determined by ^(27)Al MAS NMRsimulations are in good agreement with whose results of ^(29)Si MAS NMR
出处
《波谱学杂志》
CAS
CSCD
1995年第2期119-125,共7页
Chinese Journal of Magnetic Resonance
关键词
沸石
分子筛
核磁共振
二维章动
铝配位态
Zeolite, NMR, 2D nutation, Cross polarization, Al coordination