Shaping of a Metal–Organic Framework–Polymer Composite and Its CO₂ Adsorption Performances from Humid Indoor Air

Abstract

Diamine-functionalized metal−organic frameworks (MOFs) are known as desirable adsorbents that can capture CO 2 even at low pressures, but the humidity instability of bare MOF powders as well as their shaping have not yet adequately addressed for practical applications. Herein, we report an effective synthetic strategy for fabricating millimeter-sized MOF/poly(vinylidene fluoride) (PVDF) composite beads with different amounts of PVDF binders (30, 40, and 50 wt %) via a phase inversion method, followed by the postfunctionalization of 1-ethylpropane-1,3-diamine (epn). Compared with the pristine MOF powder, the diamine-grafted bead, epn-MOF/PVDF40, upon mixing with 40% binder polymers, exhibited a superior long-term performance without structural collapse for up to 1 month. The existence of the hydrophobic PVDF polymer in the composite material is responsible for such durability. This work provides a promising preparative route toward developing stable and shaped MOFs for the removal of indoor CO 2 .

From metal–organic framework powders to shaped solids: recent developments and challenges

“…Park et al [152] shaped diamine-functionalized epn-Mg 2 (dobpdc) MOF (dobpdc = 4,4′dioxido-3,3′-biphenyldicarboxylate, epn = 1-ethylpropane-1,3-diamine) into beads using poly(vinylidene fluoride) (PVDF). For this, the pristine MOF powder was dispersed in a DMF solution containing the polymer dissolved.…”

Recent advances in direct air capture by adsorption

“…188 In addition, MOF spheres with diameters of 2-3 mm prepared using a hydrophobic polymer binder, PVDF (poly(vinylidene fluoride)), and functionalized with epn follow the same CO 2 insertion mechanism, showing one-month stability at 25 1C at 60% RH. 433 A deeper understanding of the unprecedented cooperative adsorption mechanism of mmen-M 2 (dobpdc) was first reported by McDonald et al 423 in 2015. The mechanisms of diamine-M 2 (dobpdc) materials such as the dmen-M 2 (dobpdc) series 434 and mmen-M 2 (dobpdc) series 435 were investigated using more advanced experimental and simulation tools such as van der Waals (vdW)-corrected density functional theory calculations, single-crystal X-ray diffraction experiments, and quantum chemical methods.…”

Direct air capture: process technology, techno-economic and socio-political challenges

“…, pressure drop and handling during application. 248 Finally, it has been suggested that the current cost of MOFs makes their use in DAC prohibitively expensive. 173 Notably, however, Mosaic Materials are developing CO 2 capture and indoor air quality control technologies based upon the use of MOFs (Table 1).…”

“…247 Furthermore, the stability of powders under humidity is an issue, although strategies related to preparing composites with hydrophobic binders are beginning to appear, which may also help address issues related to e.g., pressure drop and handling during application. 248 Finally, it has been suggested that the current cost of MOFs makes their use in DAC prohibitively expensive. 173 Notably, however, Mosaic Materials are developing CO 2 capture and indoor air quality control technologies based upon the use of MOFs (Table 1).…”