Facile Green Synthesis of New Copper-Based Metal–Organic Frameworks: Experimental and Theoretical Study of the CO₂ Fixation Reaction

Abstract

Two new entangled Cu(II)-based metal-organic frameworks (MOFs) have been synthesized, namely [Cu(BDC)(BPDB) 0.5 ] n (PNU-25) and [Cu(NH 2 -BDC)(BPDB) 0.5 ] n (PNU-25-NH 2 ), using a H 2 O-MeOH solvent mixture. Both the PNU-25 and PNU-25-NH 2 MOF materials were characterized by various analytical techniques and their catalytic potential of CO 2 fixation into cyclic carbonates at an atmospheric pressure, a low reaction temperature, and in the neat conditions were demonstrated. The amine-functionalized PNU-25-NH 2 exhibited a significant high conversion of epichlorohydrin (ECH) at the 1 bar of CO 2 pressure, at 55 °C, and a moderate catalyst amount (1 mol%), with over 99% selectivity toward the corresponding cyclic carbonate of ECH. The superior catalytic activity of PNU-25-NH 2 may be attributed to its high amount of acidic-basic sites and large BET surface area in comparison with the PNU-25. The PNU-25-NH 2 catalyst could be reused up to four cycles without compromising its structural integrity and the ECH conversion. The reaction mechanism of CO 2 and ECH cycloaddition reaction mediated by the PNU-25-NH 2 was investigated in detail based on the experimental inferences and periodic calculations of density functional theory (DFT). The energy barrier of the rate-determining step of the PNU-25-NH 2 /TBAB-catalyzed reaction was significantly lower than those of the ratedetermining steps of un-catalyzed and TBAB-catalyzed reactions.

Guanidyl-implanted UiO-66 as an efficient catalyst for the enhanced conversion of carbon dioxide into cyclic carbonates

“…Its high CO 2 adsorption capacity can be attributed to the strong dipole–quadrupole interaction between the CO 2 and N–H groups in the Gua ligand. 25,45 To further investigate their isosteric enthalpy ( Q st ) for CO 2 adsorption, the Clausius–Clapeyron equation was applied to their corresponding experimental isotherm at 273 and 298 K. The Q st value of UiO-66-Gua 0.2 ( s ) for CO 2 was found to be 29.0 kJ mol −1 , which is higher by ca . 5% than that of UiO-66( s ) (Fig.…”

Double Cationization Approach toward Ionic Metal–Organic Frameworks with a High Bromide Content for CO2 Cycloaddition to Epoxides

“…In the hope of further increasing the catalytic activity, mixed-linker MOFs with functional groups in addition to the ionic ingredients (pmtz + -Br – or pmtzm ++ -Br – ) were tested. It has been reported that the amino group can promote the CEC reaction by activating CO 2 . − This encouraged us to investigate the mixed-linker MOFs with amino groups. The catalytic activities of these multifunctional MOFs follow a trend similar to that observed for the MOFs without amino groups: MIL-101-NH 2 /pmtzm-TfO (very low conversion) ≪ MIL-101-NH 2 /pmtz-TfO (medium conversion) ≪ MIL-101-NH 2 /pmtz-Br (high conversion) ≪ MIL-101-NH 2 /pmtzm-Br (Table , entries 9–12).…”

Catalytic Performance of CPM-200-In/Mg in the Cycloaddition of CO2 and Epoxides

“…A plausible reaction mechanism based on the experimental results and our previous DFT studies [31,33,37] is proposed, for the cycloaddition of epoxide and CO 2 catalyzed by CPM-200-In/Mg and co-catalyst (Scheme 2). In the first step, Lewis acidic metal centers interact with the O atom of the epoxide ring.…”

“…High conversion of propylene oxide (87.3%), epichlorohydrin (90.3%), and allylglycidyl ether (82.1%) might be ascribed from the effective size of the epoxides, facilitating their access to the active sites. Very low conversion (14.3%) was obtained for cyclohexene oxide since the sterically hindered cyclohexene ring may prevent its approach to the Lewis acidic site [32,37,66]. In addition, it is well known that CO 2 -based polycarbonate is easily formed from the reaction of cyclohexene oxide and CO 2 [67].…”

“…The heterogeneous catalysts have higher catalytic performance, easier separation, and higher reusability than homogeneous ones [27,28]. It is well reported that heterogeneous catalysts based on metal-organic frameworks (MOFs) can efficiently proceed the topic reaction (Scheme 1) [31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50]. Porous MOFs composed of metal ions and ligands have been widely used as catalysts for many chemical reactions due to their crystalline nature, tunable structure, highly specific surface area, good thermal stability, and easier mass transfer of reactants [45,[51][52][53].…”