添加镧的羟基铝柱化粘土的合成与表征

报道了添加镧的羟基铝拄化粘土(Pillared Clays,简称PILC)的合成。用~(27)Al-NMR、XRD、DTA、IR、吡啶吸附-IR、正丁胺吸附-TPD等手段表征了柱结构、热稳定性和表面酸性。利用脉冲反应技术,考察了异丙苯裂化和重芳烃1,2,4-三甲苯的转化。试验表明,利用取代法和共聚法,都可以合成出高底面间距(d_(001)=1.8nm)的添加镧的羟基铝柱化粘土(LaAl-PILC),并且未破坏其热稳定性。LaAl-PILC具有较高的裂解活性(76.8％)和1,2,4-三甲苯转化活性(74.9％)。镧的引入,使其表面酸性有所降低,裂解活性和偏三甲苯的歧化选择性却有所增加。

Synthesis and Characterization of Lanthanum Doped Hydroxy-Alumina Pillared Clay

A series of lanthanum doped hydroxyalumina pillared clays with basal spacing (1.84nm) were first prepared by two method. The pillar structure, thermal stability and surface acidity of the pillared clays were investigated by ~(27)Al-NMR, XRD, DTA, IR, Py-IR, TPD. The results suggest that the thermal stability of the pillared clays is improved by doping lanthanum (Ⅲ) and the pillars have Keggin structure, but surface acidity is slightly decreased. Cracking of cumene, disproportionation and alkylation of 1,2,4-trimethylbenzene were carried out in a pulse reaction system at 400℃ over the pillared clays. Lanthanum(Ⅲ) plays an important role in increasing the cracking activity of cumene and selectivity of disproportionation of 1,2,4-trimethylbenzene.