Diaminopropane-Functionalized MOF-PVDF Composite Beads for Indoor CO₂ Adsorption with Improved Humidity Tolerance

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• Elevated indoor carbon dioxide (CO2) levels necessitate efficient capture sorbents.
• Amine-functionalized metal-organic frameworks (MOFs) show promise but suffer from water instability and amine loss.
• Propylene-linked diamines offer improved stability over ethylene-linked analogues for MOF functionalization.

Purpose of the Study:

• To develop stable and efficient sorbents for indoor CO2 capture.
• To enhance the water resistance and practical applicability of amine-functionalized MOFs.

Main Methods:

• Mg2(hob) was used as a platform and functionalized with propylene-linked diamines, specifically N-methyl-1,3-propanediamine (mpn-MOF).
• Mg2(hob) was blended with poly(vinylidene fluoride) (PVDF) to create bead-shaped composites.
• Composites underwent postsynthetic mpn functionalization to improve CO2 capture and water resistance.

Main Results:

• The mpn-MOF exhibited high CO2 uptake (10.3 wt % at 1000 ppm and 25 °C) with a cooperative adsorption step.
• The mpn-MOF@PVDF25 composite maintained significant CO2 uptake after 15 days at 40% relative humidity.
• Propylene-linked diamine functionalization and hydrophobic polymer shaping enhanced sorbent stability and performance.

Conclusions:

• A practical strategy combining propylene-linked diamine functionalization with hydrophobic polymer shaping was demonstrated.
• The developed MOF composites offer a promising solution for long-term indoor CO2 capture.
• This approach addresses the stability limitations of traditional amine-functionalized MOFs in humid environments.