b轴取向MFI分子筛膜的制备及应用研究进展

分子筛膜是一种新型的无机膜,具有孔道结构规整、化学和热稳定性好、机械强度高、抗污染性能好、易于改性等优点。b轴取向MFI分子筛膜因可以缩短传质路径、降低传质阻力、提高扩散效率,在膜分离和膜反应器领域有着广泛的应用前景,受到国内外学者的普遍关注。综述了b轴取向分子筛膜的制备方法及应用研究进展。详细介绍了原位水热合成法、二次生长法、微波辅助合成法、无凝胶法、固相转化法及纳米片法等。二次生长法可以控制分子筛膜的微观结构,且受载体表面性质的影响较小;微波辅助法可以缩短结晶时间,降低能耗,对工业化生产具有重要意义;无凝胶法具有制备工艺简单、环境友好等优点。在上述方法的基础上,将纳米片作为晶种可以降低膜厚。最后,展望了b轴取向MFI分子筛膜的发展前景,在制备b轴取向连续无缺陷MFI分子筛膜方面仍面临许多挑战,包括提高膜的机械强度和长期运行稳定性、实现粗糙或弯曲以及大尺寸载体表面取向膜层的制备等。

Research progress on preparation and application of b-axis oriented MFI zeolite membranes

Zeolite membrane is a new type of inorganic membrane,which has the advantages of regular pore structure,good chemical and thermal stability,high mechanical strength,good pollution resistance and easy modification.b-axis oriented MFI zeolite membrane has wide application prospect in membrane separation and membrane reactor,because it can shorten the mass transfer path,reduce the mass transfer resistance and improve the diffusion efficiency,which has been widely con-cerned by scholars at home and abroad.In this paper,the preparation and application of b-axis oriented zeolite membranes were reviewed.The in-situ hydrothermal synthesis,secondary growth,microwave-assisted synthesis,gel-free method,powder conversion method and nanosheet method were introduced in detail.The secondary growth method could control the micro-structure of zeolite membrane,which was less affected by the surface properties of support.Microwave-assisted method could shorten crystallization time and reduce energy consumption,which was of great significance for industrial production.The gel-free method had the advantages of simple preparation process and environmental friendliness.On the basis of the above meth-ods,the membrane thickness could be reduced by using nanosheets as crystal seeds.Finally,the development prospect of b-axis oriented MFI zeolite membrane was prospected.There were still many challenges in the preparation of b-axis oriented continuous and defect-free MFI zeolite membranes.It included improving the mechanical strength and long-term stability of membranes and achieving the preparation of oriented membranes on the roughness or bending and large-scale support surface.