Tuning Al Spatial Distribution in ZSM-5 Membranes: A New Strategy to Improve Separation Performance and Stability of Zeolite Membranes for Dehydration of Acetic Acid

Tuning Al spatial distribution in ZSM-5 membranes: a new strategy to improve separation performance and stability of zeolite membranes for dehydration of acetic acid

Liangqing Li ^a, Zan Chen^a, Jianhua Yang ^a,b*, Wanze Li ^a, Jinqu Wang ^a, Jinming Lu ^a ,Yan Zhang^a, Hongchen Guo^a

a:State Key Laboratory of Fine Chemicals, School of Chemical Engineering, Dalian University of Technology, Dalian, Liaoning,

116024, China.

 b: Department of Chemical Engineering and Materials Science, University of Minnesota, MN 55455;   

 *corresponding authors: Prof. Jianhua Yang, E-mail add.: yjianhua@dlut.edu.cn;

                              Abstract

Dehydration of acetic acid (AcOH) by the conventional distillation is particularly energy-intensive process. Membrane pervaporation is attracting great interest for this purpose because of the greatly reduced energy requirement. However, the dehydration of AcOH is very challenging because of the demanded high acid resistance and the membrane materials are very limited.  So far the water flux, selectivity and acid resistance of the both of polymer and zeolite membranes for the dehydration of AcOH are low.

   The fabrication of a high performance zeolite membrane significantly relies on the control of essential membrane microstructures including the membrane thickness¹, preferential grain orientation² and grain boundary defects³. In the present work, a new strategy through tuning the Al spatial distribution of ZSM-5 membrane was proposed to improve the acid resistance of zeolite membrane. The organic template-free synthesis route was designed to tune the spatial distribution of ZSM-5 membrane. A novel ZSM-5 membrane with a low Si/Al ratio and homogeneous aluminum spatial distribution was achieved from the designed synthesis route and the obtained ZSM-5 membrane high selectivity and flux and improved stability for dehydration of acetic acid in a wide AcOH content range. The work firstly demonstrates that the Al spatial distribution is a key factor for tuning the separation performance of the zeolite membranes⁴.

      

      Fig. 1 Schematic illustration of preparation of the ZSM-5 membrane preparation with uniform spatial distribution

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