Bimetallic Be/Cu Pillared-Layered Porous Coordination Polymer for Selective CO2 Removal via Adsorption

The rational exploration of new chemical configurations within the structural confinements of porous coordination polymers (PCPs) continues to play a major role in developing novel functional adsorbents. In this respect, a bimetallic beryllium/ copper [Cu2(pzdc)2(Be(pyac)2)]n [pzdc: pyrazine-2,3-dicarboxylate; Be(pyac)2: Bis[3-(4-pyridyl)pentane-2,4-dionato]beryllium(II)] pillared-layered PCP was synthesized for the first time. N2 (- 196 degrees C) and CO2 (-78 degrees C) equilibrium adsorption data confirmed a microporous complex with a surface area of about 284 m2 g-1. A thermal gravimetric analysis showed that the PCP is thermally stable to about 250 degrees C. Moreover, in situ high-temperature powder X-ray diffraction showed that the metal-organic structure reversibly contracts or expands upon the presence of a guest species (i.e., water) or temperature. The bimetallic Be/Cu complex also displayed strong CO2-adsorbent interactions, evidenced by a larger heat of adsorption (41 kJ mol-1) compared to similar but monometallic PCPs. Furthermore, the Be/Cu PCP exhibited an ideal adsorbed solution theory (IAST) selectivity >60 for separating CO2/N2 (15:85) mixtures at 25 degrees C and 1 atm, which is higher than the values obtained for monometallic PCPs.

Automated summary

A bimetallic Be/Cu coordination polymer with high stability and strong CO2 adsorption capacity was synthesized for the first time. It showed reversible changes in structure upon the presence of a guest species or temperature and exhibited higher selectivity for CO2/N2 separation compared to monometallic polymers.