合成云母蒙脱石的交联及其性能的研究

Preparation and Properties of Pillared Synthesis Mica-Montmorillonite

分别用十三铝低聚物和丙胺基三乙氧基硅烷与合成云母蒙脱石交联,制得了柱高分别为0.83和0.86 nm的交联云母蒙脱石Al-CLM和Si-CLM。按Si-O键长估算,硅柱可能由SiO_2的三聚物构成。IR、DTA研究结果表明,在交联蒙脱石焙烧时,因交联而使八面体层中羟基易于脱除。云母蒙脱石交联物的酸性与柱的性质有关。硅交联物的强酸点减少,弱酸点增多,B酸所占份额增加。铝交联物强酸点增加,弱酸点减少,L酸所占份额增大。裂解活性主要与催化剂强酸中心有关。活性衰减速率似受强L酸影响更多。

Pillared synthetic dioctahedral clays (designated SMM) are prepared by introducing hydrox-yl Al oligomer and hydrolysis material of CH3CH2CH2NH2Si(OCH2CH3)3 into SMM layers respectively. X-ray diffraction results show that the basal spacing of Si pillared SMM is larger than that of Al pillared SMM slightly. The Si and Al pillar's length are 0. 86 and 0. 83 nm respectively. According to the value of Si-O bond length, the Si pillar may be the tripolymer of silica.In the studies of DTA, IR, it is found that the dehydroxylation of octahedral hydroxyl group is easier at high temperature calcination because of pillaring. These indicate that bonding between the pillar and the layers may occur.The surface acidities of Si-CLM and Al-CLM determined by pyridine adsorbtion and NH8-TPD show some differences, there are more weak Bronsted acid sites on the former, however, more strong Lewis acid sites on the latter. The total surface acid amounts of the sampales are almost the same.Pillared SMM has a higher activity for cumene cracking and a lower delay rate compared with NH4-SMM. The initial activities of the catalysts are mainly related to the strong acid sites, however, the delay rates seem to be affected by strong Lewis acid sites.