Mixed‐Linker Metal‐Organic Frameworks as Catalysts for the Synthesis of Propylene Carbonate from Propylene Oxide and CO₂

Abstract

A series of mixed-linker metal-organic frameworks (MIXMOFs) of the general formula Zn 4 O(BDC) x (ABDC) 3-x has been synthesized and tested as catalyst in the reaction of propylene oxide (PO) and carbon dioxide. Based on MOF-5 a new synthetic route was developed which allows the partial substitution of benzene-1,4-dicarboxylate (BDC) linkers in the material by functionalized 2-aminobenzene-1,4-dicarboxylate. In that way the number of catalytically active amino groups can be tuned using the desired BDC/ABDC ratio. The presence of MIXMOFs (instead of a mechanical mixture of MOF-5 and IRMOF-3) was proven by high-resolution X-ray diffraction and DTG. XRD and TG/MS analysis revealed that pure MIXMOF materials can be obtained up to an ABDC loading of 40 %. The thermal stability in air is decreasing with increasing ABDC content from 450°C for pure MOF-5 (0 % ABDC) to ca. 350°C for the 40 % MIXMOF Zn 4 O(BDC) 1.8 (ABDC) 1.2 . Consequently, MIXMOF materials represent a promising class of materials for catalytic applications in the temperature range at least up to 300°C which is

The Potential Applications of Nanoporous Materials for the Adsorption, Separation, and Catalytic Conversion of Carbon Dioxide

“…This research group has also compared the activity of selected MOF systems for the cycloaddition of CO 2 onto styrene oxide and among them, UIO-66-NH 2 MOF was found to be the most active, with 70% conversion in 1 h. [ 138 ] However, the reaction conditions remained at high pressure and temperature with the use of a toxic solvent. There are other examples showing the catalytic activity of MOFs (Ni(salphen)-MOF, [ 139 ] Mg-MOF-74, [ 140 ] ZIF-8 [ 141 ] and MIXMOF-5 [ 142 ] as catalysts for cycloaddition of CO 2 onto an epoxide. Compared with zeolite catalysts, the larger pores of MOF catalysts did promote cycloaddition of CO 2 on larger epoxides, but most of these systems were operated at high pressure (>5 atm) and temperature (100-140 °C), with quarternary ammonium ions as co-catalysts in some cases.…”

Synthesis, structural properties, and catalytic behavior of Cu-BTC and mixed-linker Cu-BTC-PyDC in the oxidation of benzene derivatives

“…In contrast to that, also the MOF structure itself can contain catalytically active centers at the organic linker molecules of the framework. In this case, organic molecules are utilized that feature functional side groups at the aromatic units which can act as active (e.g., basic) sites themselves [9,10] or which can be further transformed by post-synthetic modification. This allows for the introduction of additional organic functional groups [11][12][13] as well as the immobilization of transition metal complexes via covalent bonding (or covalent tethering) [14][15][16][17].…”

Single-atom active sites on metal-organic frameworks

“…This concept, called isoreticularity (Eddaoudi et al 2002;Cavka et al 2008;Garibay & Cohen 2010), allows one to tune the pore size of the material and adds the possibility of introducing functional groups within the framework. Moreover, if two or more isoreticular organic linkers are employed, frameworks bearing different functionalities that are randomly and homogeneously distributed within the framework are produced ( figure 1d) by exploiting the concept of multi-variable or mixed MOFs (MTV-MOFs or MIXMOFs; Burrows et al 2008;Kleist et al 2009;Deng et al 2010). In general, functionalization can further be obtained via postsynthetic modification (PSM) to give a large variety of materials with different chemical and physical properties Cohen 2011;Tanabe & Cohen 2011 Figure 2.…”