摘要
用ＸＲＤ、ＴＧ、热重氨吸附法等手段，测定了Ａｌ_２（ＳＯ_４）_３／γ－Ａｌ_２Ｏ_３中单层分散相与Ａｌ_２（ＳＯ_４）_３担载量之间的关系，测定了表面单层最大分散量一阈值。其与用密置单层模型计算所得值接近，这为Ａｌ_２（ＳＯ_４）_３在γ－Ａｌ_２Ｏ_３上单层分散行为提供了证据，且将该催化剂的表面行为与其对丁烯齐聚反应活性进行了关联。
In this paper,the catalysis of Al_2 (SO_4)_3/γ-Al_2O_3 for butene oligomerization has been studied.It has been found that the change of Al_2(SO_4)_3 loading has a marked effect on activity.As the loading of Al_2(SO_4)_3 increased the coversion of butene rose sharply at first,then reached a maximum value ca.91.6%with 19.0wt%of Al_2(SO_4)_3.The conversion decreased as the loading further increased.We studied the relationship between the content of the monolayer dispersion phase and the loading of Al_2(SO_4) _3 in Al_2(SO_4)_3/γ-Al_2O_3 catalyst and the acidity by XRD,TG 、TG-adsorption of NH_3 methods.The results show that Al_2(SO_4)_3 on γ- Al_2O_3 surface has two states of monolayer dispersion and crystalline form,When the amount of Al_2(SO_4)3 loaded is low,the Al_2(SO_4)_3 will be dispersed onto γ-Al_2O_3 surface as monolayer.In case the amount is higher than the maximum monolayer dispersion capacity,the residual crystalline form of Al_2(SO_4)_3 will appear.The maximum monolayer dispersion capacity-the threshold has been determined,and the values obtained by XRD、TG、TG-adsorption of NH_3 are often very close. It has also been found that the threshold determined agrees with the value calculated ,when we assume the active compound Al_2(SO_4)_3 in the catalyst forms a close- packed monolayer on the surface of γ- Al_2O_3. Oxides or salts dispersed on the surface of γ- Al_2O_3 cause the acidity of surface to increase and the maximum acidity often appears at the point of threshold.It indicates that the surface acidity in the system originates from the salts of monolayer dispersion on the carriers surface.
出处
《分子催化》
EI
CAS
CSCD
1994年第6期443-448,共6页
Journal of Molecular Catalysis(China)
基金
北京大学分子动态及稳态实验室资助
关键词
XRD
TG
丁烯
齐聚
硫酸铝
氧化铝
Threshold,Monolayer dispersion,Oligomerization,XRD phase quantitatiue determination,TG,TG-adsorption of NH_3.
