MgAl-PdCl4 水滑石的合成与表征

Intercalation of PdCl42- in MgAlNO3 hydrotalcite was carried out by coprecipitation. The asprepared MgAl-PdCl4 hydrotalcite was characterized by XRD, IR, DTA and nitrogen sorption. The effects of palladium concentration in the intercalation solution, intercalation time, Mg/Al mol ratio and calcination temperature on the structure of asprepared hydrotalcite were investigated. The results illustrated that PdCl42- and NO3- coexist between layers and the intercalation of PdCl42- may reduce the interlayer spacing. Longer intercalation time is beneficial to the intercalation of PdCl42- and 8h is enough to forming MgAl-NO3HLTcs with good crystalline. MgAl-NO3HLTcs can be formed at Mg/Al = 2~4; the interlayer spacing decreases with the increase of the Mg/Al mol ratio. At high Pd content or high Mg/Al mol ratio, the decomposition temperatures for PdCl42- (to PdO) and NO3- is about 370℃ and 410℃, respectively; however, at low Pd content or low Mg/Al mol ratio, the decompositions of PdCl42- and NO3- change from a continuous process to a discrete one. The destruction of hydrotalcite structure to MgO-Al2O3PdO phase starts at 400℃ and is nearly completed at 600℃. The surface area of hydrotalcite increases with the calcination temperature at first, reaches a maximum at 600℃, and then decreases when further increase of the calcination temperature due to the aggregation of particles and formation of spinel MgAl-2O4.