CO₂ Cycloaddition to Epoxides by using M‐DABCO Metal–Organic Frameworks and the Influence of the Synthetic Method on Catalytic Reactivity

Abstract

A series of high‐quality M2(BDC)2(DABCO) metal–organic frameworks (abbreviated as M‐DABCO; M=Zn, Co, Ni, Cu; BDC=1,4‐benzene dicarboxylate; DABCO=1,4‐diazabicyclo[2.2.2]octane), were synthesized by using a solvothermal (SV) method, and their catalytic activity for the cycloaddition of CO2 to epoxides in the absence of a co‐catalyst or solvent was demonstrated. Of these metal–organic frameworks (MOFs), Zn‐DABCO exhibited very high activity and nearly complete selectivity under moderate reaction conditions. The other members of this MOF series (Co‐DABCO, Ni‐DABCO, and Cu‐DABCO) displayed lower activity in the given sequence. Samples of Zn‐DABCO, Co‐DABCO, and Ni‐DABCO were recycled at least three times without a noticeable loss in catalytic activity. The reaction mechanism can be attributed to structural defects along with the acid–base bifunctional characteristics of these MOFs. Moreover, we illustrate that the synthetic method of M‐DABCO influences the yield of the reaction. In addition to the SV method, Zn‐DABCO was synthesized by using spray drying due to its industrial attractiveness. It was found that the synthesis procedure clearly influenced the crystal growth and thus the physicochemical properties, such as surface area, pore volume, and gas adsorption, which in turn affected the catalytic performance. The results clarified that although different synthetic methods can produce isostructural MOFs, the application of MOFs, especially as catalysts, strongly depends on the crystal morphology and textural properties and, therefore, on the synthesis method.

MIL-101(Cr) for CO2 Conversion into Cyclic Carbonates, Under Solvent and Co-Catalyst Free Mild Reaction Conditions

“…However, a co-catalyst and solvent are required to participate in the reaction as basic sites. Consequently, amino-bearing ligands and nitrogen-containing ligands to construct MOFs, for example, UiO-66-NH 2 , Zn-DABCO were reported also exhibiting a catalytic activity comparable to their parent MOFs [7,31,35]. Additionally, binary MOFs such as UiO-66@HKUST-1 and Co@MOF-5 were described as a bimetallic catalyst for the cycloaddition reaction of carbon dioxide with epoxides.…”

“…In this regard, the coupling reaction of CO 2 with epoxides to produce cyclic carbonates that are further useful in the production of polycarbonate is currently perceived as being friendlier than the industrial production of polycarbonates from bisphenol A, which requires the highly toxic reagent phosgene [3][4][5]. A catalyst needed for in the cycloaddition of CO 2 into epoxides due to the inactivity of CO 2 [6,7]. Also, the critical reaction conditions, such as high temperature and pressure of CO 2 , are required to proceed with the reaction.…”

“…Besides, several reports are describing a surface area for MIL-101(Cr) between 2000-3000 m 2 •g −1 [8,23,24,26,27]. Here, the complicated procedure described by Sun et al to synthesize and to activate materials was applied to obtain a large surface area [7].…”

“…Epichlorohydrin 9.2mmol,2 Blank means no catalyst present in reaction,3 Cr(NO 3 ) 2 •9H 2 O 0.125 mmol,4 1-benzene 1,4-dicarboxylate (BDC) 0.3 mmol, 5 second cycle,6 third cycle,7 fourth cycle, 8 fifth cycle, 9 Yields (isolated) were determined by 1 H NMR and using 1,3,5,-trioxane as the internal standard.…”

Three Component Controls in Pillared Metal-Organic Frameworks for Catalytic Carbon Dioxide Fixation

“…Under the optimized reaction conditions (100 °C, 1 mol% TBABr) with a shortened reaction time (2 h) to display reactivity differences better, DMOF(Zn) showed the best conversion (entry 8, Table 1), and the catalytic efficiency decreased according to the following sequence: DMOF(Co) > DMOF(Ni) > DMOF(Cu) (entries 9-11, Table 1), which is exactly the same trend recently reported by Verpoort's group. In their study, DMOFs from different metals were employed for CO2 cycloaddition without co-catalysts [19]. With DMOF(Zn) and the optimized conditions, the effect of the functional group on the BDC ligand was studied next ( Table 2) With DMOF(Zn) and the optimized conditions, the effect of the functional group on the BDC ligand was studied next ( Table 2).…”