Ruthenium Carbon Research Articles

Preparation of Ru/C hydrogen evolution catalyst by mixed salt co-electroreduction of RuCl3*nH2O and CO2

Ruthenium carbon (Ru/C) catalyst is obtained by co-electroreduction of carbonate and ruthenium ions in mixed sodium carbonate, sodium chloride, calcium oxide molten salts (Na2CO3-NaCl-CaO) from carbon dioxide (CO2) and hydrated ruthenium chloride (RuCl3*nH2O). Irregular particles with Ru loaded on carbon, Ru particles coated by carbon and nanocarbon fibers filled with Ru are prepared. Ru/C catalysts with different Ru content of 16.0 wt%, 36.5 wt% and 76.8 wt% are obtained. With the increase of Ru content, the overpotentials (-10 mA cm−2) for HER are respectively 110.8 mV, 198.4 mV, 31.9 mV in strong acid electrolyte (0.5 M H2SO4) and 50.2 mV, 197.9 mV, 16.8 mV in strong alkaline electrolyte (1.0 M KOH). Ru/C prepared at 800 °C, 3.0 V and RuCl3*nH2O content of 1.0 wt% for electrolysis 6 h are of more advantageous for application. The stability of Ru/C catalyst still needs to be improved in 1.0 M KOH. In final, Ru/C electrocatalysts for HER can be successfully prepared by a green route of molten mixed salt from RuCl3*nH2O and CO2.

Ru@C as a safety‐release RuO3@C catalyst precursor for selective oxidative cleavage of alkenes to aldehydes or ketones and alkynes to 1, 2‐diketones

High‐performance and recyclable high valence oxides of ruthenium catalyst had been released safely from commercially available ruthenium carbon catalyst in situ. They could selectively oxidize C=C bonds to corresponding aldehydes or ketones in 78%–99% yields and C ≡ C bonds to α‐diketones in 93%–99% yields. The cheap availability, recyclability, safety, and low toxicity of ruthenium carbon might endow the catalyst with great potential in industrial scale unsaturated bond oxidation cleavage applications.

Overcharge to Remove Cathode Passivation Layer for Reviving Failed Li–O 2 Batteries

Overcharge to Remove Cathode Passivation Layer for Reviving Failed Li–O ₂ Batteries

First Observation of Superconductivity in Molybdenum–Ruthenium–Carbon Alloy Nanoparticles

Abstract We report the synthesis of molybdenum–ruthenium–carbon alloy nanoparticles with molybdenum-rich composition by an annealing treatment following a thermal decomposition. We first found its superconductivity with a transition temperature at around 5 K through the observation of zero resistivity and Meisner effect.

Structure Function Relationships in Ruthenium Carbon Dioxide Reduction Catalysts with CNC Pincers Containing Donor Groups

Seven ruthenium catalysts with the general formula [(CNC)Ru(CH3CN)2Cl]OTf have been used to understand structure function relationships in the sensitized photocatalytic CO2 reduction reaction. Herein, CNC is a pincer ligand containing imidazole‐based N‐heterocyclic carbenes (NHCs) attached to a central pyridyl ring with R groups at the 3‐ or 4‐position. Two new complexes (R = 3‐OMe, 4‐NPh2) have been fully characterized by analytical and spectroscopic methods and single‐crystal X‐ray diffraction. Furthermore, three previously synthesized complexes (R = 4‐Me, 4‐NMe2, and 4‐OH) are used for photocatalysis for the first time. Methoxy and methyl donor groups in the 4‐position lead to durable catalysts (TON up to 1000) with high TOFs (up to 174 h–1) for CO production. In contrast, R = 4‐NPh2, 3‐OMe, and 4‐H substituents lead to modest TOF values (up to 32 h–1), yet these systems are still robust and achieve up to 565 TON. In contrast, low activity is observed with 4‐NMe2 and 4‐OH substituents, which resemble sacrificial donors and may be leading to side reactions. Thus, remote substituents were found to greatly influence catalyst activity and longevity.

Effective Conversion of Cellulose to Sorbitol Catalyzed by Mesoporous Carbon Supported Ruthenium Combined with Zirconium Phosphate

The selective conversion of cellulose to sorbitol is a promising route to valorize biomass. A binary catalyst ZrP-Ru/MC was constructed by mesoporous carbon supported ruthenium (Ru/MC) combined with zirconium phosphate (ZrP). It was found that ZrP-Ru/MC was an excellent catalyst for the conversion of cellulose with high sorbitol yield. Under the optimal reaction condition, a high sorbitol yield of 66.4% was obtained in just 1.5 h if cellulose was mix-milled together with ZrP. The characterizations results indicated that the high dispersion of Ru and macroporous–mesoporous structure were the key factor to determine the excellent catalytic activity of Ru/MC. In addition, the Ru TOF of 220 h−1 in the Ru/MC was much higher than that of commercial ruthenium carbon, indicating the high Ru utilization in Ru/MC.

Hydrothermal Synthesis of Ruthenium Nanoparticles with a Metallic Core and a Ruthenium Carbide Shell for Low-Temperature Activation of CO2 to Methane.

Ruthenium nanoparticles with a core-shell structure formed by a core of metallic ruthenium and a shell of ruthenium carbide have been synthesized by a mild and easy hydrothermal treatment. The dual structure and composition of the nanoparticles have been determined by synchrotron X-ray photoelectron spectroscopy (XPS), near-edge X-ray absorption fine structure (NEXAFS) analysis, and transmission electron microscopy (TEM) imaging. According to depth profile synchrotron XPS and X-ray diffraction (XRD) analysis, metallic ruthenium species predominate in the inner layers of the material, ruthenium carbide species being located on the upper surface layers. The ruthenium carbon catalysts presented herein are able to activate both CO2 and H2, exhibiting exceptional high activity for CO2 hydrogenation at low temperatures (160-200 °C) with 100% selectivity to methane, surpassing by far the most active Ru catalysts reported up to now. On the basis of catalytic studies and isotopic 13CO/12CO2/H2 experiments, the active sites responsible for this unprecedented activity can be associated with surface ruthenium carbide (RuC) species, which enable CO2 activation and transformation to methane via a direct CO2 hydrogenation mechanism. Both the high activity and the absence of CO in the gas effluent confer relevance to these catalysts for the Sabatier reaction, a chemical process with renewed interest for storing surplus renewable energy in the form of methane.

Low-Cost Ru/C-Catalyzed Depolymerization of the Polymeric Proanthocyanidin-Rich Fraction from Bark To Produce Oligomeric Proanthocyanidins with Antioxidant Activity.

A new method has been developed for the high-value utilization of larch bark, which is regarded as a low-value byproduct of the logging industry. Polymeric proanthocyanidins (PPCs) were extracted from the Larix gmelinii bark and depolymerized by catalytic hydrogenolysis, using ruthenium/carbon (Ru/C) as the catalyst. The method has been found that although the molecular weight of the depolymerized product was significantly lower, the basic structural units were not destroyed, and the product retained a condensed flavanol polyphenol structure; the depolymerized product contains very little Ru metal and thus complies with food safety standards; the antioxidant properties of both the depolymerized products and PPCs were better than those of the commonly used antioxidant 2,6-di-tert-butyl-4-methylphenol. The relative molecular weight and steric hindrance of the depolymerized products were lower than those of the PPCs, leading to better antioxidant performance. A new technical route for the depolymerization of PPCs from the L. gmelinii bark is provided. The route offers practical and commercial advantages, and the product could have many applications as an antioxidant.

Ultralong Cycle Life Li-O2 Battery Enabled by a MOF-Derived Ruthenium-Carbon Composite Catalyst with a Durable Regenerative Surface.

The cycling performance of Li-O2 batteries (LOBs), which is an important parameter determining the practical use of this advanced energy technology with ultrahigh energy density, is strongly affected by the nature of the oxygen electrocatalyst. As a good oxygen electrode, it should possess good activity for both the oxygen evolution reaction and the oxygen reduction reaction and superior stability under operating conditions. During the past, oxygen electrodes for LOBs were generally fabricated by loading noble metal nanoparticles on the surface of a porous carbon support. However, the nanoparticles could easily lose contact with the carbon support during the reversible liquid-gas-solid reactions that involve lithium ions, oxygen gas, and Li2O2. Herein, we reported a novel Ru-metal-organic framework (MOF)-derived carbon composite, characterized by stereoscopic Ru nanoparticle distribution within the carbon matrix, as an alternative oxygen catalyst of LOBs, enabling superior operational stability and favorable activity. More specifically, the battery demonstrated stable charge-discharge cycling for up to 800 times (∼107 days) at a current density of 500 mA g-1 with low discharge/charge overpotentials (∼0.2/0.7 V vs Li). A mechanism of regenerative surface was further proposed to explain the excellent cycling stability of the LOBs through the use of the Ru-MOF-C catalyst. These encouraging results imply an accessible solution to address issues related to the oxygen catalyst for the realization of practical LOBs.

PRODUCTION OF HYDROGEN BY WATER-GAS SHIFT REACTION ON Ru/C CATALYST

This work explores the catalytic performance of a 2% ruthenium carbon (Ru/C) catalyst in the low temperature water-gas shift reaction (WGSR). The catalyst synthetized was characterized with X-ray diffraction (XRD) and specific surface area (BET) methods. The gas mixture of 15% carbon monoxide + argon and water were used as reagents. The operations catalytic were performed in a fixed bed reactor over a temperature range of 453–553 K. A numerical fitting algorithm was developed for the estimation of the kinetic parameters in a power-law model for the rate velocity. At 553K, 80% CO conversion was achieved, under steady state. For the empirical rate equation, the activation energy determined from the experimental data, was 190 kJ/mol.

Production of γ-valerolactone from levulinic acid over a Ru/C catalyst using formic acid as the sole hydrogen source

Conversion of levulinic acid (LA) to γ-valerolactone (GVL) over a ruthenium-carbon (Ru/C) catalyst using formic acid (FA) as the sole hydrogen source in cellulose hydrolysis process was investigated. The reaction was accelerated using Ru(5wt%)/C as the catalyst and by adding triethylamine. The highest LA conversion (87.26%) and GVL yield (80.75%) were obtained using 10g/mol (LA) catalyst and 150mL/mol (LA) triethylamine at 160°C for 180min. In this reaction, the hydrogenation process can only be accomplished in the presence of FA, which is the byproduct of LA production from cellulose hydrolysis. The application of this new route not only improves the economy of the process, but also avoids the energy-costly separation of LA from the LA and FA aqueous mixture. A new reaction pathway for the conversion of LA and FA into GVL over Ru/C with triethylamine was proposed.

Hydrogenation of Succinic Acid to Tetrahydrofuran Over Ruthenium–Carbon Composite Catalyst: Effect of Catalyst Preparation Condition

Hydrogenation of Succinic Acid to Tetrahydrofuran Over Ruthenium–Carbon Composite Catalyst: Effect of Catalyst Preparation Condition

Carbon Nanotube–Ruthenium Hybrids for the Partial Reduction of 2‐Nitrochalcones: Easy Access to Quinoline N‐Oxides

AbstractA ruthenium–carbon nanotube nanohybrid was employed as a catalyst in the tandem transformation of nitrochalcones into quinoline N‐oxides. Partial reduction of the nitro group to a hydroxylamine, followed by in situ intramolecular condensation to the carbonyl afforded the quinoline‐N‐oxides in satisfactory to good yields. Reduction of the nitro group was selective and independent of changes in the reaction conditions. Highlights of this method include a very low catalyst loading relative to that required for conventional methods for the synthesis of quinoline N‐oxides and mild reaction conditions.

Construction and Characterization of Mini-ruthenium–Carbon Eutectic Cells for Industrial Use

High-temperature eutectic fixed points have proved to be convenient tools for temperature scale dissemination and thermometer calibrations/checks at temperatures above \(1100\,^{\circ }\text {C}\). In order to investigate the feasibility of metal-carbon eutectic cells in industrial applications as a means for assessing the traceability of non-contact thermometers, a batch of cells was constructed at LNE-Cnam, NPL, and TUBITAK UME. Compared to the usual dimensions of high-temperature fixed point cells (45 mm in length \(\times \) 24 mm in diameter), a new cell design was created to fit with industrial applications. TUBITAK UME constructed and characterized five ruthenium–carbon (Ru–C) eutectic cells of dimensions 24 mm in length \(\times \) 24 mm in diameter. One of these cells has been selected and characterized at CEA premises. Ru–C eutectic cells have been evaluated in terms of short-term repeatability, reproducibility, furnace effect, sharp temperature ramps, and the effect of cell location. Measurements at TUBITAK UME have been performed with a transfer standard pyrometer calibrated at the copper point and a BB3500pg high-temperature blackbody furnace was used for construction and measurement. For the measurements at CEA, a Land Standard—HIMERT S1 radiation thermometer and a VITI induction furnace were used. In this article results of the measurements at TUBITAK UME and CEA will be presented. The possible use of these mini-eutectic cells as industrial temperature standards will be discussed.

Carbon coated face-centered cubic Ru-C nanoalloys.

Carbon-encapsulated ruthenium-carbon (Ru-C) nanoalloys were synthesized by dynamic shocks. The Ru-C alloy shows a new fcc structure different from the original hcp structure of metal Ru. This fcc phase is assigned to a Ru32C4 solid solution with a lattice parameter of 3.868(2) Å and a bulk modulus KT0 of 272(12) GPa. The small amount of carbon in the solid solution enhances the thermodynamic and chemical stabilities with respect to pure Ru, as well as induces changes in the electronic properties, which have direct applications in improving the material's catalytic activity and selectivity.

Hydrogenation of succinic acid to tetrahydrofuran (THF) over ruthenium–carbon composite (Ru–C) catalyst

Ruthenium–carbon composite (Ru–XC) catalysts prepared by a single-step surfactant-templating method were pre-graphitized at different temperature (X=200, 250, 300, 350, and 400°C), and they were applied to the liquid-phase hydrogenation of succinic acid to tetrahydrofuran (THF). The effect of pre-graphitization temperature on the catalytic performance of Ru–XC catalysts (X=200, 250, 300, 350, and 400°C) was investigated. It was observed that Ru–XC composite catalysts showed different textural properties depending on pre-graphitization temperature. In the liquid-phase hydrogenation of succinic acid to tetrahydrofuran (THF), conversion of succinic acid and yield for THF showed volcano-shaped trends with respect to pre-graphitization temperature. In other words, an optimal pre-graphitization temperature was required to achieve maximum catalytic performance of Ru–XC catalysts. Yield for THF in the hydrogenation of succinic acid increased with decreasing ruthenium particle size of Ru–XC catalysts. Among the catalysts tested, Ru-300C, which had the smallest ruthenium particle size, showed the highest yield for THF.

Platinum Ruthenium Catalysts Supported on Carbon Xerogel for Methanol Electro‐Oxidation: Influence of the Catalyst Synthesis Method

AbstractA high surface area, highly mesoporous carbon xerogel was synthesised and used as a support in the preparation of platinum–ruthenium catalysts by different synthetic routes. The platinum–ruthenium carbon xerogel catalysts were physico‐chemically characterised and used for the chemical electro‐oxidation of methanol. The synthetic routes pursued included: 1) impregnation with metal chloride precursors and reduction with two different reducing agents: sodium borohydride and formic acid; 2) a microemulsion‐based method and 3) a sulfite complex method, which led to catalysts with different physico‐chemical features that strongly influence their catalytic behaviour towards methanol oxidation. The electro‐oxidation of methanol was found to depend on both the crystal size and the extent of active phase reduction as well as on the platinum concentration on the catalyst surface, which were maximised for the impregnation method and reduction with formic acid.

Cyclometalated Ruthenium Sensitizers Bearing a Triphenylamino Group for p-Type NiO Dye-Sensitized Solar Cells

We report the synthesis, photophysical, and electrochemical studies of a series of cyclometalated ruthenium sensitizers carrying triphenylamino linkers for p-type NiO dye-sensitized solar cells (DSSCs). The general structure of these ruthenium sensitizers is Ru[N∧N]2[N∧C], where [N∧N] is a diimine ligand and [N∧C] is a cyclometalated ligand. The triphenylamino group is attached to the -para position of the ruthenium-carbon bond of the [N∧)] ligand as a linker to bridge the ruthenium chromophore and the NiO surface and to enhance the electronic coupling for hole injection. As a result, cells made with these sensitizers generate higher short-circuit currents (Jsc) than cells sensitized with our prior sensitizers with phenylene linkers. Morever the N∧N ligands are systematically tuned from 2,2'-bipyridine (O3), to 1,10-phenanthroline (O13), and to bathophenanthroline (O17). Following the series, the conjugation of the N∧N ligand is increased, which results in the enhancement of extinction coefficient and the red shift of light absorption. However the solar cell sensitized with O3 still gives the largest Jsc of 3.04 mA/cm2. The large Jsc highlights the promising potential of using these cyclometalated ruthenium sensitizers for NiO DSSCs. In addition, the carrier dynamics of these solar cells has been systematically studied by intensity-modulated photovoltage spectroscopy (IMVS) and intensity-modulated photocurrent spectroscopy (IMPS). The results suggest that the O3 solar cell giving the largest Jsc is likely caused by the slow geminate charge recombination and efficient dye regeneration.

Hydrogenation and Silylation of a Double-Cyclometalated Ruthenium Complex: Structures and Dynamic Behavior of Hydrido and Hydridosilicate Ruthenium Complexes

A double-cyclometalated ruthenium complex containing a chiral tripodal phospholane has been prepared by reaction with [Ru(η4-COD)(η3-methylallyl)2] via elimination of isobutene. The ruthenium–carbon bonds of this compound were reversibly cleaved by H2, resulting in an equilibrium between a tri- and a tetrahydride (4 and 5). T1 relaxation time measurements revealed the nonclassical nature of the fluctuating hydrides. Release of the gas led to complete re-formation of the cyclometalated compound. Reaction of 3 with D2 afforded D10-5, in which six ortho-phenyl protons and four hydrides were replaced by deuterium. Furthermore, diphenylsilane was found to readily insert into one Ru–C bond to form 6, containing a κ3-dihydridosilicate fragment. On the basis of deuterium labeling experiments, the fast exchange between the two hydrides was shown to include a reductive elimination/oxidative addition step involving the remaining metalated phenyl group. Again, pressurization of 6 with H2 resulted in reversible cleavage of the remaining Ru–C bond, yielding the corresponding trihydride 7.

Techno-economic analysis of dimethylfuran (DMF) and hydroxymethylfurfural (HMF) production from pure fructose in catalytic processes

Techno-economic studies of processes for production of dimethyl-furan (DMF) and hydroxymethyl-furfural (HMF) from fructose are performed based on published laboratory results. The early stage of technology development necessitates use of simplified process models to analyze a conceptual bio-refinery producing fuel and chemical intermediates. HMF and DMF production processes are divided into four and six processing areas respectively that include synthesis and purification sections. The HMF process employs a biphasic (aqueous–organic phases) continuously stirred tank reactor (CSTR), and the DMF process has an additional 3-train fixed bed catalytic plug flow tubular reactor (PFTR). The processing capacities are 300 metric ton/day of fructose and the plants will operate for 20 years. Installed equipment costs are estimated (US$2007) as $102.4 million for the HMF and $121.9 million for the DMF process, respectively. The DMF process uses a copper–ruthenium–carbon (Cu–Ru/C) catalyst. Catalyst cost is estimated as $36.4 million for the first charge with replacement cost of $258,500/2-years. Cost analysis is performed following the discounted cash flow method. The minimum selling prices for HMF and DMF are estimated as $1.33/l ($5.03/gal) and $2.02/l ($7.63/gal), respectively. Sensitivity analyses are performed to assess the relative importance of key assumptions on minimum HMF and DMF selling prices. The most significant parameters are feedstock cost, product yields, by-product prices, catalyst cost and total purchased equipment costs. Process and economic uncertainties can be reduced by incorporating better performance (through laboratory and pilot trials) and cost data.