Ultra-high selectivity COF-based membranes for biobutanol production

For the biofuel production industry, the implementation of membrane-based processes has great potential for significantly reducing energy consumption relative to thermodynamic separation methods such as distillation. However, to achieve this goal, the key issue is developing new membrane materials with higher selectivity, permeability and stability than available at present. Here, we report composite materials consisting of crystalline porous polymers of hydrazone-linked covalent organic-frameworks (COFs) dispersed within commercial polydimethylsiloxane. The resultant COF-based membrane shows ultra-high selectivity for n-butanol over water with improved permeate flux, due to the increased preferential pathways for n-butanol and hindrance to water diffusion from COFs in the selective layer. By coupling the COF-based membrane with a commercial dehydration membrane, a 5 wt% feed solution could be first concentrated and then directly purified to over 99.2 wt% n-butanol. The developed ultra-high selectivity COF-based membranes could provide a possible non-distillation way for biobutanol production in the future.