摘要
以聚环氧乙烷为诱导剂引发固-液两相分离形成以无定形水合羟基铝为骨架的三维贯通大孔氧化铝,经水热处理使水合羟基铝转化为拟薄水铝石(AlOOH),在温和焙烧条件下制备了具有贯穿大孔孔道的高结晶度γ氧化铝材料。采用XRD、SEM、N_2吸附-脱附和~(27)Al MAS NMR等测试手段对制备的大孔氧化铝材料的性质进行了表征。表征结果显示,所得材料不但具有300~600 nm之间的连续大孔孔道,大孔具有空间分布均匀且三维贯穿的结构特点,大孔氧化铝比表面积达到379 m~2/g;而且孔壁含有9.5 nm的介孔孔道,说明所得材料具有介孔/大孔多级孔道分布;焙烧后的试样铝物种具有四配位、五配位及六配位三种配位状态。实验结果表明,试样在500℃常规焙烧条件下即可转变为高结晶度的γ氧化铝,且抗压强度较高,基本满足多相催化对载体强度的要求。
Polyethylene oxide was used as inducer to initiate solid-liquid two-phase separation to form three-dimensional interconnected macroporous alumina with amorphous hydrated hydroxyl aluminium as framework. After hydrothermal treatment,the hydrated hydroxyl aluminium was converted into pseudo-boehmite(AlOOH). The AlOOH was transformed into high crystallinityγ-alumina materials with three-dimensional interconnected macropores under mild calcination condition. The samples were characterized by XRD,SEM,N_2 adsorption-desorption,and ~(27)Al MAS NMR. The results revealed that the alumima possessed continuous macropores(300-600 nm in size) with uniform spatial distribution and three-dimensional interconnected structure. The specific surface area of macroporous alumina reached 379 m~2/g. The pore wall contained 9.5 nm mesoporous channels,which indicated that the obtained material has mesoporous/macroporous multistage porous channel distribution. For the calcined sample,the three aluminium species of AlO_4,AlO_5,and AlO_6 had been formed by the result. The sample can be converted into high crystallinity γ-alumina by conventional calcination at 500 ℃,and the high crushing strength of alumina can meet the requirements of heterogeneous catalysis for carrier strength.
引文
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