摘要
研究了氮气气氛下于５００℃处理２ｈ后的Ｓｂ２Ｏ３／ＨＺＳＭ－５体系中Ｓｂ２Ｏ３在分子筛表面上的分散行为．发现处理后的体系中Ｓｂ２Ｏ３晶相消失，ＨＺＳＭ－５晶相减少，非晶相增加．经ＸＲＤ相定量、氮气吸附、正己烷吸附及ＮＨ３－ＴＰＤ实验可知，高温下酸性Ｓｂ２Ｏ３破坏了分子筛的部分骨架，生成无定形硅铝胶，同时Ｓｂ２Ｏ３高分散在其中．含Ｓｂ２Ｏ３的无定形硅铝胶修饰了分子筛表面，减小了孔口，提高了分子筛在甲苯烷基化反应中的择形性能。
The behavior of Sb\-2O\-3 on HZSM\|5 was
investigated by employing the techniques such as XRD, N\-2 and \%n\%\|hexane adsorption,
NH\-3\|TPD etc.. Mechanic mixture of Sb\-2O\-3 and HZSM\|5 was calcined at 500 under
nitrogen for two hours. XRD results showed that crystalline Sb\-2O\-3 disappeared while
HZSM\|5 framework suffered a noteworthy damage.Quantitative phase analysis indicate that the
crystalline HZSM\|5 amount in Sb\-2O\-3/HZSM\|5 shrank from 76% to 59% after calcination. The
Sb\-2O\-3/HZSM\|5 to HZSM\|5 ratios of pore volumes (derived from N\-2 adsorption experiment)
and \%n\%\|hexane saturated adsorption amount were 060 and 062, both corresponding to that
ratio of the crystalline HZSM\|5 amount(059/095=062). The fact suggests that in calcined
Sb\-2O\-3/HZSM\|5, nothing exists in the channels of the zeolite. Moreover, it is also found that
the \%n\%\|hexane saturated adsorption pressure of Sb\-2O\-3/HZSM\|5 is greater than that of
HZSM\|5. Based on the results above, a new mechanism of the interaction between Sb\-2O\-3
and HZSM\|5 was proposed. During calcination, the framework of HZSM\|5 is partly broken by
acidic Sb\-2O\-3, which in turn highly disperses into the silica\|alumina gel yielded from
framework collapse. This gel modifies the external\|surface of HZSM\|5 by diminishing its pore
openings, subsequently enhancing the shape\|selectivity of the zeolite. Toluene alkylation
reaction was applied to characterize Sb\-2O\-3/HZSM\|5, the \%para\%\|selectivity attained as
high as 89%.
出处
《高等学校化学学报》
SCIE
EI
CAS
CSCD
北大核心
1999年第4期616-619,共4页
Chemical Journal of Chinese Universities
