有机-无机杂化L-Rh/SiO_2氢甲酰化催化剂的研究 Ⅱ.L-Rh/SiO_2的催化性能及表征

Study on Organic-Inorganic Hybrid L-Rh/SiO_2 Catalysts for Hydroformylation of Olefins Ⅱ. Catalytic Performance and Characterization of L-Rh/SiO_2 Catalysts

以具有不同电子结构的有机膦直接修饰Sh/SiO2 制备了有机 无机杂化L Rh/SiO2 催化剂 ,并考察了催化剂对 1 己烯氢甲酰化反应的催化性能 .结果表明 ,P(OPh) 3 Rh/SiO2 催化剂上 1 己烯氢甲酰化反应的TOF可高达 4 111h-1,而PCy3 Rh/SiO2 催化剂上生成醛的选择性为 10 0 % .不同催化剂活性的顺序为P(OPh) 3 Rh/SiO2 >PPh3 Rh/SiO2 >PCy3 Rh/SiO2 ,其选择性的顺序则与之相反 .TG表征结果表明 ,有机膦与Rh之间相互作用强度的顺序为PCy3 Rh/SiO2 >PPh3 Rh/SiO2 >P(OPh) 3 Rh/SiO2 .因此 ,有机膦给电子的能力越强 ,则与Rh之间相互作用的能力越强 ,催化剂体系越稳定 ,1 己烯氢甲酰化反应的活性越低 ,而庚醛的选择性越高 .

The organic triphenyl-phosphine ligand was directly used to modify the Rh/SiO 2 catalyst to prepare PPh 3-Rh/SiO 2 catalyst for hydroformylation of olefins. The results showed that its catalytic activity for hydroformylation of 1-hexene under the mild conditions of 1.0 MPa and 373 K was higher than that of Rh/SiO 2 catalyst, and comparable to that of the corresponding homogeneous HRhCO(PPh 3) 3 catalyst. The PPh 3-Rh/SiO 2 catalyst possessed the advantages of both heterogeneous catalysis and homogeneous catalysis, such as high activity, high selectivity and easy separation. By means of 31 P MAS NMR and XPS techniques for characterization of PPh 3-Rh/SiO 2 catalyst, it was found that the coordination bond between Rh metal and PPh 3 with lone-pair electron was formed on the catalyst. The PPh 3-Rh/SiO 2 catalyst could be used in hydroformylation of olefins from C = 2 to C = 12 .