Characterization of organic solvents adsorption/desorption on hydrophobic porous coordination polymers and their micro-crystals aggregation on mullite support

Equilibrium adsorption/desorption isotherms of organic vapor (MeOH, EtOH, i-PrOH, and Me2CO) at 298 K were measured on two hydrophobic porous coordination polymers, [Zn2(1,4-bdc)2(dabco)]n (1, 1,4-bdc ¼ 1,4-benzenedicarboxylate, dabco ¼ 1,4-diazabicyclo[2.2.2]octane) and [Zn2(1,4-ndc)2(dabco)]n (2, 1,4-ndc ¼ 1,4-naphthalenedicarboxylate). All adsorption isotherms exhibit immediate sharp increases at low relative pressures to attain saturated points, where adsorbed compounds were checked by X-ray powder diffraction (XRPD) confirming the maintenance of porous structure. In alcohol (MeOH, EtOH, i-PrOH) adsorption/desorption isotherms, several steps are observed, indicating that the adsorption processes are involved with the intermediated states. For each isotherm, adsorption parameters (W0 and  E0) were obtained based on Dubinin-Radushkevich (DR) equations. In addition, micro-crystals of 1 were grown on the mullite support, which were checked by XRPD and SEM analysis.

This work was devoted to the characterization of polar organic adsorption on hydrophobic porous coordination polymers, 1 and 2. In alcohol adsorption on both compounds, stepwise isotherms were observed, which are due to that the frameworks of coordination polymers are relatively flexible, indicating that each alcohol adsorption proceeds via several intermediate states. It was succeeded in aggregating 1 on the support.