甲苯/甲醇在碱性沸石上侧链烷基化反应的研究 Ⅲ.X型沸石添加稀土元素La、Ce改性

添加稀土元素Ｌａ、Ｃｅ均能提高甲苯和甲醇的侧链烷基化反应催化活性，但添加量有最佳值，Ｌａ的质量分数为０．５％左右，Ｃｅ为１％左右。Ｌａ的碱性比Ｃｅ强，因而它对活性的促进作用更明显。添加Ｌａ和Ｃｅ可以有效地抑制骨架脱铝作用，增大电负性，使相应的［ＡｌＯ４－］的分电荷值增大，给电子能力减小，则沸石的碱性减弱，较好地维持了其热稳定性。

Investigation on side Chain alkylation of toluene with methanol over a basic zeolite catalyst Ⅲ.Modification of KX zeolite with La or Ce

Modification of basic zeolite KX with La or Ce salt can improve its catalytic activity for side chain alkylation of toluene with methanol. The optimum content of La is about 0.5%(La/KX) and that of Ce about 1.0%(Ce/KX).Experiments show that the La modified zeolite is more active than the Ce modified one because of the basicity of the former higher than that of the latter. A possible explanation of the above phenomena is that addition of La or Ce can restrain the loss of aluminium ion from zeolite frame work, increase zeolites electronegativity and partial electropositivity of groupAlO 4 ], thus decrease the groups ability to supply electron and the basicity of zeolite, and additionally improve the heat stability of the zeolite.