Molecular sieving membrane development for syngas purification

Synthesis gas (syngas) purification technologies become more crucial as the demand for high-grade hydrogen (H2) increases. Due to its energy efficiency, membrane technology is highly promising to replace or complement existing syngas purification techniques. However, conventional membrane materials (polymers, ceramics, and metals) fail at tolerating syngas purification conditions or are costly. This chapter introduces the fundamentals, current status, and future potential of molecular sieving membranes for syngas purification. We first explain the basics of membrane technology and major classes of molecular sieving membranes, which are zeolites, reticular materials (i.e., metal-organic frameworks, covalent-organic frameworks), and laminated two-dimensional materials. Then, we summarize the materials’ characteristics and fabrication methodologies of molecular sieving membranes. We later brief the progress made in utilizing molecular sieving membranes for syngas purification, with particular emphasis on H2 separation. Lastly, we propose future directions for the industrialization of advanced molecular sieving membranes for producing H2 from syngas.