NiSO_4/γ-Al_2O_3催化剂中活性组分的分散度及与其叠合活性的关联

CORRELATION BETWEEN DISPERSION OF ACTIVE COMPONENTS IN NiSO_4/Υ-Al_2O_3 CATALYST AND ITS OLIGOMERIZATION ACTIVITY

NiSO_4/γ-Al_2O_3催化剂是一种新型、高效的混合烯烃叠合催化剂,其反应活性随活性组分Ni担载量的增加,呈单峰曲线的变化规律.应用XRD相定量法、TEM法研究了一组担载量不同的NiSO_4/γ-Al_2O_3催化剂中活性组分NiSO_4的表面分散度,测定了表面单层最大分散量——阈值.与用密置单层模型计算所得阚值接近.用吸附指示剂法测定了一组NiSO_4/γ-Al_2O_3催化剂的表面酸性,发现其酸性为最大值时试样的组成与阈值接近.

NiSO_4/γ-Al_2O_3 is a new type high active catalyst for the oligomerization of mixed olefins. Its catalytic activity varies with increasing amount of Ni supported in accordance with the mono peak rule.TEM and XRD phase quantitative analysis have been used to study the extent of surface dispersion for a series of NiSO_4/γ-Al_2O_3 catalysts with various nicked contents. The maximum monolayer dispersion capacity——threshold has been determined. The results obtaind agree with the value calculated from the model on the assumption that the NiSO_4 is despersed as a closely-packed monolayer on γ/-Al_2O_3 surface. The surface acidities of a series of catalysts have been determined by using the method of adsorptionindicator. It has been found that the composition is close to the threshold at maximum acidity.