酒石酸钛配合物在MCM-41上的组装和催化苯乙烯环氧化

采用表面模板组装途径合成了MCM-41介孔材料,研究了这类载体上键合钛酸异丙酯+酒石酸二乙酯(Ti(OiPr)4+DET)和TiCl4+DET两类钛配合物的组装方法。XRD和FT-IR分别被使用来表征载体的晶体结构和载体与钛配合物的键合作用,结果表明:MCM-41在焙烧过程中,其介孔长程有序结构会发生退化,这种结构退化将导致1219和580cm-1红外带的消失,并诱发载体产生强的Si-OH畸变振动。在催化苯乙烯环氧化反应中,用焙烧载体组装钛催化剂显示了最好的氧化活性;而用含模板剂载体组装钛催化剂则显示出最高的环氧化选择性。胺基模板剂和DET配体对钛活性中心的调变作用将造成其活性下降,而环氧选择性上升。

Titanium Tartrate Complex Assembled MCM-41 Catalysts for Styrene Epoxidation

MCM-41mesoporous silicas were synthesized by the cooperative assembly of silica and surfactants. The assembled method of two Ti tartrate complexes over the untreated and calcined mesoporous carriers was firstly reported here. XRD and FT-IR were used to characterize the carrier's mesostructures and the binding of the carriers with Ti complexes. The results indicated that the MCM-41's mesostructure with long-range order would be deteriorated. This deterioration of the mesostructure resulted in the disappearance of 1219 and 580 cm-1, and then also caused a stronger aberrance of MCM-41's Si-OH groups and leaded to the appearance of 960 cm-1.In catalyzing the epoxidation of styrene, the assembled Ti catalysts with the calcined mesoporous carriers exhibited the highest oxidative activity, and the assembled Ti catalysts with untreated mesoporous carriers possessed the best epoxidative selectivity. The adjustment of the templating agents and diethyl tartrate (DET) ligand on the Ti active centers would cause the decreases in the catalytic activity and the increases in the selectivity.