以MCM-22为原料合成高水热稳定性的介孔材料

以合成的微孔分子筛MCM-22为原料,将其与表面活性剂及氢氧化钠一起回流溶解,再调节溶液的pH值至7～9, 使MCM-22转化为高水热稳定性的介孔材料. 所得介孔材料具有蠕虫状的均匀孔道,骨架中不含有MCM-22的微观结构单元. 该介孔材料至少含有18%的表面活性剂,经823 K焙烧脱除表面活性剂后,其孔径为2 2 nm, 比表面积为 1 038 m2/g, 孔容为0 97 cm3/g. 焙烧后的介孔材料具有非常高的水热稳定性,经沸水回流100 h后其比表面积为896 m2/g, 孔容为0 90 cm3/g, 孔径为2 1 nm, 即使经过300 h的回流,该材料仍能保持698 m2/g的比表面积和0 90 cm3/g的孔容. 固体 29Si MAS NMR结果表明,该介孔材料的高水热稳定性与其高表面缩合度有关.

Synthesis of Mesoporous Materials with High Hydrothermal Stability from MCM-22

A microporous zeolite MCM-22 was synthesized and transferred to mesoporous materials with high hydrothermal stability by refluxing MCM-22 with surfactant in the presence of NaOH followed by adjusting the pH to 79.The obtained material exhibited uniform wormhole mesopores while had no primary structural units of MCM-22 in the mesoporous framework.The as-synthesized mesoporous material contained at least 18% surfactant,which can be removed by calcination at 823 K.The calcined mesoporous material had a pore diameter of 2.2 nm,a BET specific surface area of 1 038 m2/g,and a pore volume of 0.97 cm3/g.The calcined mesoporous materials exhibited excellent hydrothermal stability.After being refluxed in boiling water for 100 h,the material remained a BET specific surface area of 896 m2/g,a high pore volume of 0.90 cm3/g,and a pore diameter of 2.1 nm.Even after refluxing for 300 h,a high BET specific surface area of 698 m2/g and a high pore volume of 0.90 cm3/g could still be obtained.The remarkable hydrothermal stability of this mesoporous material was due to its highly polymerized pore walls ascribed by solid-state 29Si MAS NMR.