Selective Hydrogen Generation from Formic Acid with Well‐Defined Complexes of Ruthenium and Phosphorus–Nitrogen PN<sup>3</sup>‐Pincer Ligand

Pan, Yupeng; Pan, Cheng‐Ling; Zhang, Yufan; Li, Huaifeng; Min, Shixiong; Guo, Xunmun; Zheng, Bin; Chen, Hailong; Anders, Addison; Lai, Zhiping; Zheng, Junrong; Huang, Kuo‐Wei

doi:10.1002/asia.201600169

Cited by 109 publications

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“…This could be explained by our recent mechanistic studies of the homogeneous PN 3 P-pincer ruthenium complexes, which showed that the dearomatized complex is the catalytically active species. [10] Accordingly, we treated PPRu with potassium tert-butoxide in DMSO for 24 h, and again applied it to FA dehydrogenation under the same conditions. The reaction proceeded smoothly, producing gases after a short induction period, indicating the catalyst had been successfully activated.…”

Section: Accepted Manuscriptmentioning

confidence: 99%

“…Based on our previous mechanistic studies of t Bu-PN 3 P Ru-catalyzed homogeneous FA dehydrogenation [10] and the reverse reaction (hydrogenation of bicarbonate) using the Rupincer RuP, [12] we proposed a plausible mechanism, as shown in Scheme 2. The mechanism for the Ph-PNpreviously reported to be the catalytically active species.…”

Section: Accepted Manuscriptmentioning

confidence: 99%

“…The mechanism for the Ph-PNpreviously reported to be the catalytically active species. [10] The catalytic transformation involves three steps: protonation of the imine arm of the dearomatized pincer complex 3 to give the ruthenium formate intermediate 4, decarboxylation of 4 to generate the dihydride species 5 with the liberation of CO2, and the final elimination of H2 that regenerates the catalyst. Accordingly, the lower TOF with PPRu as compared to the homogeneous PN 3 P-pincer ruthenium complex in the first reaction cycle could presumably be a result of the slow dissociation of a PN 3 P ligand from the bimetallic ruthenium complex in the solid state to give the catalytically active species.…”

Section: Accepted Manuscriptmentioning

confidence: 99%

“…[10] The tridentate organic part of the coordinated pincer enforced a meridional geometry on the metal center upon complexation, resulting in a unique balance of stability versus reactivity.…”

mentioning

confidence: 99%

“…This process was favorable to the dehydrogenation pathway and as a result, the dehydrogenation/dehydration selectivity was greatly improved. [10] The promising activity of the t Bu-PN 3 P-Ru catalyst prompted us to employ a more economical ligand using phenyl to replace the t-butyl groups. While the resulting Ph-PN 3 P-pincer ruthenium complex demonstrated high catalytic activity to selectively converted CO2 captured from air and H2 to formate, [12] only far-fetched durability of the catalyst was observed in the selective decomposition of FA to H2 and CO2.…”

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Single‐Site Ruthenium Pincer Complex Knitted into Porous Organic Polymers for Dehydrogenation of Formic Acid

et al. 2018

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Owing to its capacity for reversible hydrogen storage, formic acid (FA) holds great promise as an alternative energy carrier to conventional fossil fuel systems. Whereas the decomposition of FA to hydrogen (H2) and carbon dioxide (CO2) through homogeneous catalysis is well established, the selective and efficient dehydrogenation of FA by a robust heterogeneous catalyst remains a challenge. A new heterogeneous ruthenium pincer framework with single‐atomic sites was prepared in one step by the direct knitting of a phosphorus–nitrogen PN3P‐pincer ruthenium complex in a porous organic polymer. The heterogeneous ruthenium complex efficiently dehydrogenates formic acid in both organic and aqueous media with remarkably enhanced stability. Notably, no detectable CO was generated and a turnover number (TON) of 145 300 was attained in a continuous experiment with no significant decline in catalytic activity (in sharp contrast, a total TON of only 5600 was obtained with the homogeneous analog under the same conditions). The single‐atomic sites in the porous framework combined the desirable attributes of high reactivity and selectivity of a homogeneous catalyst with the significantly enhanced catalyst stability and reusability benefits of heterogeneous catalysis.

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Section: Accepted Manuscriptmentioning

confidence: 99%

Section: Accepted Manuscriptmentioning

confidence: 99%

Section: Accepted Manuscriptmentioning

confidence: 99%

mentioning

confidence: 99%

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confidence: 99%

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Single‐Site Ruthenium Pincer Complex Knitted into Porous Organic Polymers for Dehydrogenation of Formic Acid

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Recent Advances in Homogeneous Catalysts for Hydrogen Production from Formic Acid and Methanol

Onishi

Himeda

2021

CO2 Hydrogenation Catalysis

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Carbon Dioxide Hydrogenation and Formic Acid Dehydrogenation Catalyzed by Iridium Complexes Bearing Pyridyl‐pyrazole Ligands: Effect of an Electron‐donating Substituent on the Pyrazole Ring on the Catalytic Activity and Durability

et al. 2018

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Cp*Ir (Cp* = pentamethylcyclopentadienyl) complexes with an N,N-bidentate ligand such as 2,2'-bipyridine serve as catalysts for both carbon dioxide (CO 2 ) hydrogenation to formate and formic acid dehydrogenation in water. Previously, it was shown that the introduction of an electron-donating substituent on 2,2'-bipyridine is an effective method to improve the catalytic activity. Especially, the highly electron-donating hydroxyl (OH) substituent performs much better than other substituents such as methyl or methoxy under basic conditions. However, the introduction of an OH substituent on the ligand has been limited to six-membered rings such as pyridine or pyrimidine. These results prompted us to develop a new ligand comprising a pyridyl-pyrazole with an OH group on the pyrazole moiety for Cp*Ir-catalyzed CO 2 hydrogenation and formic acid dehydrogenation. The resultant catalyst showed high catalytic activity in CO 2 hydrogenation and excellent robustness in formic acid dehydrogenation with a turnover number of 10 million.New fuels without emission of air pollutants or greenhouse gases are being sought, and among them the use of hydrogen gas has drawn much attention. Safe and efficient utilization of hydrogen provides a convenient way to help combat the pressing challenge of global greenhouse gas emissions. However, significant technical and safety concerns regarding cryogenic liquid and compressed gaseous hydrogen together with its high flammability result in considerable barriers to widespread use. Therefore, rapid and controlled storage/ production of hydrogen in a safe and efficient manner is being extensively studied. Because of its relatively high gravimetric hydrogen content (4.3 wt%), its low toxicity toward the human body and the environment, and its easy accessibility by biomass processing, [1] formic acid (FA) has been widely considered as a liquid storage medium capable of releasing H 2 via its catalytic dehydrogenation. In addition, when FA is stored as an aqueous solution (< 85 wt%), it is not combustible. Toward the efficient production and storage of hydrogen, it is of considerable interest to develop highly active and durable catalysts that exhibit selective FA dehydrogenation to H 2 and CO 2 , and convert thermodynamically stable CO 2 and H 2 to formate.To date, much effort has been devoted to discover new and effective homogeneous catalysts [2] for both CO 2 hydrogenation to formate [3] and FA dehydrogenation. [3j,ae,4] Remarkable performance of catalysts for CO 2 hydrogenation has been achieved by many researchers. Nozaki and coworkers showed that an Ir complex coordinated by a PNP pincer ligand exhibited the high TOF (turnover frequency) of 150,000 h À1 and high TON (turnover number) of 3,500,000 at 200 8C

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Selective Hydrogen Generation from Formic Acid with Well‐Defined Complexes of Ruthenium and Phosphorus–Nitrogen PN³‐Pincer Ligand

Cited by 109 publications

References 64 publications

Single‐Site Ruthenium Pincer Complex Knitted into Porous Organic Polymers for Dehydrogenation of Formic Acid

Single‐Site Ruthenium Pincer Complex Knitted into Porous Organic Polymers for Dehydrogenation of Formic Acid

Recent Advances in Homogeneous Catalysts for Hydrogen Production from Formic Acid and Methanol

Carbon Dioxide Hydrogenation and Formic Acid Dehydrogenation Catalyzed by Iridium Complexes Bearing Pyridyl‐pyrazole Ligands: Effect of an Electron‐donating Substituent on the Pyrazole Ring on the Catalytic Activity and Durability

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Selective Hydrogen Generation from Formic Acid with Well‐Defined Complexes of Ruthenium and Phosphorus–Nitrogen PN3‐Pincer Ligand

Cited by 109 publications

References 64 publications

Single‐Site Ruthenium Pincer Complex Knitted into Porous Organic Polymers for Dehydrogenation of Formic Acid

Single‐Site Ruthenium Pincer Complex Knitted into Porous Organic Polymers for Dehydrogenation of Formic Acid

Recent Advances in Homogeneous Catalysts for Hydrogen Production from Formic Acid and Methanol

Carbon Dioxide Hydrogenation and Formic Acid Dehydrogenation Catalyzed by Iridium Complexes Bearing Pyridyl‐pyrazole Ligands: Effect of an Electron‐donating Substituent on the Pyrazole Ring on the Catalytic Activity and Durability

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Selective Hydrogen Generation from Formic Acid with Well‐Defined Complexes of Ruthenium and Phosphorus–Nitrogen PN³‐Pincer Ligand