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.