A Highly Stable Anion-Functionalized Cage-like Framework for Efficient Separation of MTO Products under Harsh Conditions

Separation of methanol-to-olefin products to obtain high-purity
C2H4 and C3H6 has been
deemed as one sustainable method for providing such indispensable
industrial feedstocks. To meet the practical separation conditions,
it is of critical significance to develop adsorbents that can separate
C3H6/C2H4 under high-temperature
and high-humidity conditions. Herein, we reported an anion-functionalized
cage-like MOF (SIFSIX-Cu-TPA) showing a high-stability structure and
huge distinction in C3H6 and C2H4 adsorption. Furthermore, C3H6- and
C2H4-loaded single-crystal structures clearly
reveal that more supramolecular interactions are generated between
the C3H6 molecule and SIFSIX-Cu-TPA. Breakthrough
experiments show that SIFSIX-Cu-TPA can efficiently separate C3H6/C2H4. After one separation
cycle, 3.5 mol kg–1 of high-purity C2H4 (>99.95%) and 2.5 mol kg–1 of
polymer-grade
C3H6 (>99.5%) can be obtained from a C3H6/C2H4 (50/50) mixture at 298 K. More importantly, even at 338 K and 100% relative humidity,
polymer-grade C2H4 (2.7 mol kg–1) and C3H6 (1.4 mol kg–1)
can also be collected.