Ruthenium Complexes Immobilized on an Azolium Based Metal Organic Framework for Highly Efficient Conversion of CO₂ into Formic Acid

Abstract

A series of efficient heterogenized ruthenium catalysts designated as Rux‐NHC‐MOF (x=1, 2, 3; NHC=N‐heterocyclic carbene; MOF=metal organic framework) were successfully synthesized by the immobilization of different ruthenium complexes RuCl3, [RuCp*Cl2]2 (Cp*=pentamethylcyclopentadienyl) and [Ru(C6Me6)Cl2]2 (C6Me6=hexamethylbenzene) on an azolium based MOF through post‐synthetic metalation. The heterogenized catalysts were subsequently accessed for the catalytic hydrogenation of CO2 to formic acid. The resulting Ru3‐NHC‐MOF catalyst exhibited the highest activity because of its stronger electron‐donating ability of C6Me6 ligand of [Ru(C6Me6)Cl2]2 complex, which is favorable for CO2 hydrogenation reaction. A high turnover number (TON) value up to 3803 was obtained at 120 °C under a total pressure of 8 MPa (H2/CO2=1) for 2 h with K2CO3 additive in N,N‐Dimethylformamide (DMF) solvent. Furthermore, the heterogenized Ru3‐NHC‐MOF catalyst was effectively recovered through filtration without significant loss of catalytic activity.

A Facile Method for Preparing UiO-66 Encapsulated Ru Catalyst and its Application in Plasma-Assisted CO2 Methanation

“…Among these elements, carbon, oxygen, and zirconium constitute the catalysts. It is noted in Figure 5b that the peak appearing at 462.4 eV is attributed to 3p 3/2 of Ru 0 [36]. This reveals that the Ru 3+ ions from RuCl 3 have been reduced into metallic Ru 0 directly, without extra reduction processes.…”

“…Ru-based catalysts, due to their efficient activity, have been applied in CO 2 methanation extensively. This is because, in the process of CO 2 hydrogenation, the active Ru sites are more selective to the formation of methane, which can promote the reaction of CO 2 along the methanation path in the hydrogen-rich environment [34,35,36,37].…”

Enabling storage and utilization of low-carbon electricity: power to formic acid

“…pyridinethiolate (161), the TOF of 178 s −1 was achieved but at the cost of highly negative cathodic potential, making the overall reaction less energy efficient (Fig. 46).…”

Homogeneous hydrogenation of saturated bicarbonate slurry to formates using multiphase catalysis

“…The latter have recently been addresses by immobilizing homogeneous catalysts on solid supports 43 and encapsulating them into porous carriers. 44,45 While this approach greatly simplifies catalyst separation, it has a drawback of consistently lower activity of immobilized catalyst compared to its free molecular predecessor.…”