Zeolite Membranes for Gas/Vapor Separation

Zeolites are porous, crystalline structures with uniform molecular-sized pores ranging from 0.35 to 1.3 nm.  Zeolite crystals have been assembled into continuous membranes by hydrothermal synthesis onto porous supports for chemical separation. Because of the complex crystallization and crystal intergrowth processes and complicated interaction between zeolite crystals and porous supports, which may be affected by gel composition, aging time, and hydrothermal synthesis conditions, it is very challenging to prepare high quality zeolite membranes with negligible defects. Our research in this direction is focused on optimizing zeolite membrane growth processes and developing novel synthesis methods and exploring the potential of these membranes for mixture separations.

Under the support by DOE/ARPA-E, we obtained the following key results and reported them in peer-reviewed journals:

·         We found a Na⁺-gated water-conducting zeolitic nanochannel that only allows water to permeate through while blocking molecules as small as H₂.

·         We showed high-aspect-ratio seeds were effective for high quality zeolite membrane growth.

·         We designed a novel process to selectively block non-selective defects in zeolite membranes.

·         We developed a gel-modulated growth process to improve the equality of zeolite membranes.

Recently, we found surprisingly fast zeolite crystallization rate by contacting the “clean” seeds with synthesis gel only at the actual synthesis temperature; using this new strategy, we can grow high quality zeolite membranes within 1 min, which is 2 to 3 orders of magnitude faster than traditional methods.  We are conducting more detailed research work to understand the crystallization mechanism and exploring its potential for initiating the second-generation zeolite and zeolite membrane synthesis. We built a startup company, E2H2Nano LLC, to explore the potential of Na⁺-gated water-conducting nanochannel membrane for renewable methanol production, ammonia separation, and food drying.

• Huazheng Li, Chenglong Qiu, Shoujie Ren, Qiaobei Dong, Shenxiang Zhang, Fanglei Zhou, Xinhua Liang, Jianguo Wang, Shiguang Li, and Miao Yu, “Na⁺-gated Water-conducting Nanochannels for Boosting CO₂ Conversion to Liquid Fuels”, Science (impact factor: 41.063), 367, 667 (2020)
• Yi Huang, Lei Wang, Zhuonan Song, Shiguang Li, and Miao Yu, “Growth of High Quality, Thickness-Reduced Zeolite Membranes towards N₂/CH₄ Separation Using High-Aspect-Ratio Seeds”, Angewandte Chemie International Edition (impact factor: 12.257), 127, 10993-10997 (2015)
• Rongfei Zhou, Huamei Wang, Bin Wang, Xiangshu Chen, Shiguang Li, and Miao Yu, “Defect-Patching of Zeolite Membranes by Surface Modification Using Siloxane Polymers for CO₂ Separation”, Industrial & Engineering Chemistry Research (impact factor: 3.37), 54, 7516-7523 (2015)
• Ji Jiang, Qiaobei Dong, Fanglei Zhou, Weiwei Xu, Shiguang Li, and Miao Yu, “Synthesis Gel-Modulated Growth of High-quality Zeolite Membranes”, ACS Applied Materials & Interfaces (impact factor: 8.456), in press, 2020