焙烧对HZSM－5分子筛结构的影响

运用魔角自转固态核磁共振谱（ＭＡＳ－ＮＭＲ），研究了焙烧对ＨＺＳＭ－５分子筛结构的影响．结果表明，高温焙烧将引起ＨＺＳＭ－５分子筛骨架的脱铝，当焙烧温度从５００℃增加到７００℃时，ＨＺＳＭ－５的骨架Ｓｉ／Ａｌ比由１６．７增加至２２．７；而当焙烧温度由７００℃到８００℃时，骨架Ｓｉ／Ａｌ比则由２２．７增加到了４８．５．２７Ａｌ－ＭＡＳＮＭＲ结果表明，从骨架上脱下来的铝，部分地形成了ＮＭＲ不可见的无定形态．随着焙烧温度的升高，ＮＭＲ不可见铝增多

The Influence of Calcination on the Structure of HZSM 5

The influence of calcination temperature (from 773 K to 1073 K) on the structure of HZSM 5 zeolite has been studied using 29 Si , 27 Al MAS NMR. It is found that calcination has caused partial dealumination of the framework of HZSM 5. From 773 K to 973 K, the framework Si/Al ratios of the zeolite change from 16.7 to 22.7. Furthermore, after calcination at 1073 K, the framework Si/Al ratio increases to 48.5. It suggests that the samples calcined at temperature higher than 973 K will suffer severe dealumination. 27 Al MAS NMR results imply that the Al out from HZSM 5 framework is only partially NMR visible. The NMR invisible Al increases with the increase of calcination temperature.