Scalable synthesis of a low-cost Zn–MOF with a nonpolar pore surface for efficient separation of methanol-to-olefin products

Abstract

The pursuit of scalable metal–organic framework (MOF) adsorbents for efficient one-step purification of C₂H₄ and recovery of C₃H₆ holds significant importance for practical applications. It is desirable to incorporate high separation efficiency along with other key norms such as easy scalability, economic feasibility, and eco-friendliness into a single MOF structure. However, this presents a formidable challenge due to the high cost of specially designed ligands, rigorous synthetic conditions, and typically lengthy reaction times. Herein, we present a scalable MOF adsorbent denoted as Zn-hba decorated with a nonpolar pore surface, which successfully integrates all the aforementioned norms. Zn-hba exhibits selective uptake for C₂H₆ and C₃H₆ over C₂H₄ with exceptional selectivity and record-high C₃H₆ and exceptional C₂H₆ uptake at low pressure, allowing for one-step purification of C₂H₄ and recovery of C₃H₆ from a ternary mixture of C₂H₆/C₂H₄/C₃H₆. Importantly, Zn-hba is synthesized with a high yield of 42% using commercially available cheap reagents such as zinc acetate, 4-hydroxybenzoic acid, methanol and n-amyl alcohol in only 12 hours. The total cost for producing each gram of this adsorbent is as low as $0.14, comparable to that of commercial zeolites and nearly one-tenth the cost of the benchmark MOF MAC-4.