Facile and Rapid Preparation of Ag@ZIF-8 for Carboxylation of Terminal Alkynes with CO₂ in Mild Conditions

Abstract

Metal–organic frameworks (MOFs) are promising hosts for catalytic active sites due to their adjustable porosity and framework chemistry. Strategies to improve synergistic effects between the installed sites and the parent MOF are highly desired. Herein, a facile and rapid method for the preparation of xAg@ZIF-8 materials was reported. The materials were systematically characterized and used as catalysts for carboxylation of terminal alkynes via direct insertion of CO2 to the C­(sp)–H bond (CTACO2). It was found that the integrity of the ZIF-8 structure could be retained upon Ag loading, but short-range crystalline ordering was modified. Two types Ag species could be installed, namely, highly dispersed Ag­(I) in the backbone (AgHD) and aggregated Ag(0) nanoparticles on the outer surface (AgNP). The AgNP sites are highly effective for the activation of terminal alkynes due to its high accessibility, while the AgHD-modified ZIF-8 framework worked as a CO2 reservoir with enhanced affinity. Combination of these factors translated to high activity in the CTACO2 process, the measured turnover frequency and time yield are among the highest among most heterogeneous catalysts.

Induced CO2 Electroreduction to Formic Acid on Metal−Organic Frameworks via Node Doping

“…The strong peaks at 2θ = 7.4°, 10.4°, 12.7°, 18.0°, 26.7°, and 29.7°can be attributed to the typical (001), (002), (112), (222), (134), and (044) planes of ZIF-8, respectively. [20] All XRD patterns of the synthesized ZIF-8 and xSZ catalysts match those of the simulated ZIF-8 well, indicating the successful synthesis of ZIF-8 and the well-preserved framework structure after Sn doping. Furthermore, the detailed XRD analyses in the range of 9-14°show that the positions of the representative (002) and (112) peaks gradually down-shift with increasing Sn doping contents ( Figure S3B).…”

“…All catalysts exhibit three absorption bands at 600-800 cm À 1 , 900-1350 cm À 1 , and 1350-1500 cm À 1 , corresponding to out-of-plane vibration, in-plane vibration, and entire ring vibration of the MIm ring, respectively (Figure 1Da). [20] The sharp peaks at 419 and 996 cm À 1 are attributed to the stretching vibrations of ZnÀ N and CÀ N, respectively. [21] Variation of the relative peak intensity ratios of ZnÀ N/CÀ N in ZIF-8 and xSZ can be clearly seen in Figure 1Db.…”

“…The surface area (S BET ) of ZIF-8 reaches 1440 m 2 /g, in agreement with the previous reports well. [20,26] Sn 2 + competitive coordination may generate substantive amorphous phase defects in xSZ catalysts, [27] resulting in the higher S BET values of 1638-2193 m 2 / g (Table S2). The catalysts 0.4SZ and 0.6SZ exhibit the maximum surface areas of 2193 and 2011 m 2 /g, which are much higher than that of 0.8SZ (1681 m 2 /g), implying that excessive Sn introduction may destroy partial framework structures and cause the decreased surface area.…”

Recent Advances on Metal‐Organic Frameworks in the Conversion of Carbon Dioxide

“…In 2019, Wei et al . [ 103 ] prepared Ag@ZIF‐8 materials by contacting ZIF‐8 with AgNO 3 in methanol for 30 min (Scheme 11). The materials were employed as catalysts for carboxylation of terminal alkynes via direct insertion of CO 2 to the C(sp)–H bond.…”

Microwave‐assisted fabrication of a mixed‐ligand [Cu4(μ3‐OH)2]‐cluster‐based metal–organic framework with coordinatively unsaturated metal sites for carboxylation of terminal alkynes with carbon dioxide

“…Metal–organic frameworks (MOFs), built from the assembly of metal centers and multifunctional organic ligands through metal–ligand coordination bonds, are a relatively new class of crystalline porous materials, which can be directly adopted as heterogeneous catalysts or as catalyst supports/precursors in many important organic transformations. [ 22–26 ] Recently, a few MOFs, such as MIL‐101 [ 13 ] UiO‐66, [ 27 ] and ZIF‐8, [ 28 ] have been used as support of reactive silver nanoparticles to construct MOF‐supported silver nanoparticle catalysts for the coupling of alkynes with CO 2 . In contrast, the contribution involving the direct catalysis of such conversions by MOF catalysts is still scarce.…”