Surface Modification of a MOF-based Catalyst with Lewis Metal Salts for Improved Catalytic Activity in the Fixation of CO2 into Polymers

Abstract

The catalyst zinc glutarate (ZnGA) is widely used in the industry for the alternating copolymerization of CO2 with epoxides. However, the activity of this heterogeneous catalyst is restricted to the outer surface of its particles. Consequently, in the current study, to increase the number of active surface metal centers, ZnGA was treated with diverse metal salts to form heterogeneous, surface-modified ZnGA-Metal chloride (ZnGA-M) composite catalysts. These catalysts were found to be highly active for the copolymerization of CO2 and propylene oxide. Among the different metal salts, the catalysts treated with ZnCl2 (ZnGA-Zn) and FeCl3 (ZnGA-Fe) exhibited ~38% and ~25% increased productivities, respectively, compared to untreated ZnGA catalysts. In addition, these surface-modified catalysts are capable of producing high-molecular-weight polymers; thus, this simple and industrially viable surface modification method is beneficial from an environmental and industrial perspective.

Engineering Nanoscale Metal‐Organic Frameworks for Heterogeneous Catalysis

“…In general, PSM routes include covalent PSM, metal ions exchange (known as transmetalation), post‐synthetic metalation, dative PSM, solvent‐assisted linker exchange (SALE), post‐synthetic metal exchange (PSME) and post‐synthetic deprotection (PSD). [ 148–151 ] Some low‐connected MOFs can transform into more stable MOFs with increasing coordination numbers through post‐synthetic installation (PSI).…”

Metal Organic Frameworks for Advanced Applications

“…The optimum material was a bimetallic (Fe,Sc) form of MIL-88B, which provides~70% conversion of glucose with 35% selectivity towards 5-HMF after 3 h at 140 • C, which was a higher conversion compared to other heterogeneous catalysts reported in the same solvent. Padmanaban and Yoon [12] studied the surface modification of an MOF-based catalyst with Lewis metal salts for improved catalytic activity in the fixation of CO 2 into polymers.…”

Surface activated zinc-glutarate for the copolymerization of CO2 and epoxides

“…For example, introducing ethylsulfinate, Lewis acid (MCl n ), or hydroxy groups to ZnGA, increased catalytic activity, which is likely due to the increased number of active zinc sites for polymerization. [16][17][18][19] In this paper, we present a protocol for increasing the active zinc sites, the Fig. 1 Generation of active zinc sites using surface modification in previous studies compared to this study.…”

“…For example, introducing ethylsulfinate, Lewis acid (MCl n ), or hydroxy groups to ZnGA, increased catalytic activity, which is likely due to the increased number of active zinc sites for polymerization. 16–19 In this paper, we present a protocol for increasing the active zinc sites, the surface area, and porosity of ZnGA using the reaction of thin plate ZnGA (two-dimensional (2D) ZnGA) with H 3 Co(CN) 6 . The synthesis and characterization of 2D ZnGA, the modification of 2D ZnGA by H 3 Co(CN) 6 to form Co-modified ZnGA (Co-ZnGA), and the polymerization results using Co-ZnGA are presented.…”