CO₂ Hydrogenation to Formate Catalyzed by Ru Coordinated with a N,P-Containing Polymer

Abstract

Development of high-performance catalysts for carbon dioxide (CO2) hydrogenation is crucial for CO2 utilization. Herein, a heterogeneous catalyst for CO2 hydrogenation to formate was developed by coordinating the mononuclear Ru3+ center (Ru hereafter) with a N,P-containing polymer, which was synthesized from phosphonitrilic chloride trimer and 2,6-diaminopyridine. Multiple nitrogen functionalities in the polymer (N content: 25.9 wt %) containing pyridine nitrogen and phosphazene nitrogen not only provided an electron-rich coordination environment for stabilizing mononuclear Ru center but also facilitated CO2 conversion by interacting with CO2 molecules. The polymer-coordinated mononuclear Ru catalysts (Ru/p-dop-POMs) could promote the hydrogenation of CO2 to formate with a turnover number (TON) up to 25.4 × 103 in aqueous solutions, and the concentration of formate in the solution could reach 3.4 mol/L. DFT calculations revealed that the electron-rich mononuclear Ru site could promote H2 dissociation, which is the rate-determining step in the reaction, thereby enhancing the catalytic activity. Systemic studies demonstrated that the synergistic effect between individually electron-rich Ru centers and nitrogen-rich polymer enhanced catalytic efficiency.

Heterogeneous catalysts for CO2hydrogenation to formic acid/formate: from nanoscale to single atom

“…Han and co-workers prepared a pincer-like cyclophosphazene-containing polymer (p-dop-POMs) by the condensation of 2,6-diaminopyridine with phosphonitrilic chloride (Figure 18A). 160 RuCl 3 was subsequently immobilized onto p-dop-POMs by coordinating to triple N sites, i.e., two pyridinic N atoms and one phosphazene N atom, along with two hydride species and one chloride ligand forming an octahedral configuration (Scheme 5), as confirmed by EXAFS (Figure 18B and C). The resultant Ru@p-dop-POMs exhibited a TON up to 25400 at 120 °C and 80 bar H 2 /CO 2 (1/1) in H 2 O/NEt 3 in 24 h (Table 3, entry 26).…”

Revealing the Double‐Edged Behaviors of Heteroatom Sulfur in Carbonaceous Materials for Balancing K‐Storage Capacity and Stability

“…Recently, carbonaceous materials doped with heteroatoms also play an increasingly important role in the field of catalysis such as metal‐air batteries, [ 12 ] CO 2 hydrogenation, [ 13 ] CO 2 reduction, [ 14 ] oxygen reduction, [ 15 ] and hydrogen evolution reaction. [ 16 ] For example, Chen et al.…”

Homogeneous hydrogenation of saturated bicarbonate slurry to formates using multiphase catalysis

“…Secondly, the catalyst should be separable form the formate product that can easily be dehydrogenated once the hydrogenation reactor is decompressed. 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.…”