Conclusions
In this work, we have employed a flexible Mn-bpdc MOF featuring distinct gate-opening and reversible switch behavior for C4H6 purification. The intrinsic flexibility is confirmed by VT-XRD with gradient temperature control. In addition, the different polarity guest-depended molecule can lead to structure transformation with different gate-opening pressure points at different temperatures, such as C2H4 and C3H6. Importantly, it exhibits prominent gate-opening and abrupt adsorption for C4H6 at very low pressure (0.13 bar) but no stimulus-response behavior for all n-C4H8,iso-C4H8, n-C4H10 and iso-C4H10 even at 1 bar and ambient conditions. Notably, the uptake selectivities of Mn-bpdc MOF for both C4H6/n-C4H8and C4H6/iso-C4H8surpass whole the reported adsorbents. Furtherly, four dynamic breakthrough experiment results of C4H6/n-C4H8, C4H6/iso-C4H8, C4H6/n-C4H10and C4H6/iso-C4H10mixtures verifies that this Mn-bpdc MOF can practically separate C4H6 from other C4paraffins and mono-olefins. In addition, the unexpected water stability, benign regeneration ability, signifies that this MOF has great potentiality for industrial C4H6 purification and makes it a new benchmark of flexible adsorbent for the separation of C4H6 over other C4hydrocarbons.