Study On Synthesis And Permeation Performance Of B-oriented ZSM-5 Membrane With High Al Contents

In recent years, the ZSM-5 zeolite membrane has attracted a lot of research interest due to its wide application prospect in catalytic raction and separation procedure. b-oriented molecular sieve membrane has important application value due to its shortest channel length and fastest diffusion. While the synthesis of ZSM-5 zeolite membrane with low Si/Al ratio and high b-orientation is still difficult. This paper mainly focuses on the controllable fabrication of b-oriented ZSM-5 zeolite membrane by in situ growth method and studies the influence of synthesis conditions, nature of the substrates, aluminum source, aluminum content and the synthesis mechanism of ZSM-5 membrane.We synthesized ZSM-5 membrane on TiO2?Al2O3?ZrO2 with different pore size and studied the influence of the nature and roughness of the substrates on the zeolite membrane. It was found that membrane synthesized on anatase TiO2 has the best b-orientation and highest continuity.We explored the influence mechanism of Al3+ by synthesizing zeolite membrane with different Si/Al ratio. It is found that the content of Al3+ directly affect the continuity of the membrane by inhibiting the nucleation process which was also proved by HP-DSC.We used NaAlO2?AlOOH·nH2O?Al(O-i-Pr)3 and(CH3COO)2(OH)Al as aluminum source and found that aluminum source can't affect the orientation of the membrane but influence the continuity. The use of NaAlO2 and AlOOH·nH2O in place of Al(NO3)3 induces the formation of high-aluminum b-oriented ZSM-5 membranes with framework Si/Al ratio of 57 and 19.Besides, we synthesized a&b, b&b, c&b oriented bi-layered ZSM-5 membrane. According to the result of nitrogen permeability, b&b-oriented ZSM-5 membrane has the highest permeability: 2.256?10-5molPa-1s-1m-2. And it was 0.448?10-5molPa-1s-1m-2 and 0.076?10-5molPa-1s-1m-2 higher than that of a&b, c&b-oriented bi-layered ZSM-5 membrane respectively.