ZIF-8 membranes for efficient C₃H₆ recovery from the Hydrogen Peroxide to propylene oxide process

The ZIF-8 membrane has emerged as a promising candidate for C₃H₆/C₃H₈ separation. However, the feasibility of ZIF-8 membranes for applications has rarely been investigated with gas provided directly by the industry sector. Herein, the C₃H₆/C₃H₈ mixture collected from the backend of the Hydrogen Peroxide to Propylene Oxide (HPPO) process was applied as feed gas to examine the separation performance of tubular ZIF-8 membranes. The membranes exhibited excellent separation performance and long-term stability under 9 bar and 50 °C. Noticeably, upon scaling up to a membrane area of 452.16 cm² by connecting six three-channel modules in series (multi-step membrane), its separation performance satisfied the C₃H₆ circulation requirements during the HPPO process (purity ≥97.5 % and recovery rate ≥85 %). Furthermore, a simulation of membrane operation under industrial working conditions (22 bar and 56.3 °C) was performed. By fixing the separation factor at 15, a minimum membrane area of 800 m² met the requirements at the cost of membrane permeance with 120 GPU. The corresponding economic calculation indicated a maximum of 91.8 % annual capital cost saving compared with the distillation process, paving the way for the practical application of membranes.