【摘要】 采用水溶液中阴离子直接交换法合成了过渡金属单取代Keggin结构杂多阴离子SiW₁₁M（H₂O）O⁶-₃₉(M=Mn²⁺,Fe²⁺,Co²⁺,Ni²⁺,Cu²⁺,Zn²⁺柱撑水滑石.用元素分析、XRD和IR对产物的组成与结构进行了表征.XRD结果给出柱撑产物的底面间距达1.47nm.DTA结合不同温度下焙烧样品的XRD、IR研究表明,柱撑水滑石在低于250℃时脱除物理吸附水和层间水;在400～500℃之间脱除层上羟基,形成一个无定形的混合氧化物状态;在600℃以上无定形态结晶为晶态氧化物混合物.异丙醇探针反应表明,柱撑水滑石具有高于水滑石前驱体和相应杂多酸盐的催化活性.且同时存在酸碱两类催化活性中心,但酸中心明显较强.更多还原

【Abstract】 Layered Double Hydroxides (LDHs) pillared with heteropolyanions (POMs) SiW11M (H2O)O396- , were synthesized by direct anion exchange reactions in aqueous solution, and were characterized by elemental analysis, XRD and IR spectra. The XRD patterns give the d(oo1) value of 1. 47nm. Differential thermal analysis (DTA) combined with XRD and IR studies of samples calcined at different temperatures indicates that the thermal decomposition of the samples takes place in three steps: the elimination of water molecules from the interlayer space (less than250℃); the elimination of hydroxyl groups from the brucite - like layers (between 400 ~500℃) , then amorphous materials are obtained, which crystallize upon calcination at temperaturehigher than 600℃. The results from isopropanol conversion show that the pillared products are more catalytically active than that of the LDH precursor and the corresponding K+ salts of the POMs, and there exists two kinds of active sites (acid and base sites) on the surface of the samples.更多还原