Ruthenium Nanoparticle Catalysts Research Articles

Ruthenium nanoparticle immobilised on ionic liquid polymer as efficient catalyst for the hydrolysis of NaBH4

Development of heterogeneous catalyst is significant key for achieving high performance of NaBH4 hydrolysis to produce hydrogen. The stability of sodium borohydride in the presence of suitable catalyst is the efficient method to generate hydrogen. In this work, styrene-imid PIILP, polymer 1 decorated styrene, imidazolium ionic liquid, and cross-coupling is successfully synthesised by AIBN initiated radical polymerisation, then precipitation with 3,3′,3″phosphinetriyltribenzene sulfonate with ratio (1:0.3) to isolate the first styrene-imid- sulphonated PIILP, polymer 2. RuNP@styrene-imid-sulphonated PIILP, RuNPs catalyst 3 was synthesised by impregnation with RuCl3, then reduction by NaBH4. Moreover, several analytical techniques such as, 31P, 1H, 13C solid-state NMR, CHN, IR, XPS, TEM, TGA-DTA, and SEM were examined to explore the obtained catalyst 3. The hydrogen generation from NaBH4 utilizing catalyst 3 was exhibited the catalytic behaviour studying several parameters such as, temperature, catalytic loading, and NaBH4 concentrations this work was deducted the activation energy (30.32 kJmol-1), and the turnover frequency (TOF) reached up 134.9, 112.77, and 98.38 moleH2.molcat−1.min−1 at 40, 35 and 30 °C. The effectiveness of Ruthenium nanoparticle catalyst 3 for the hydrolysis reaction of NaBH4 was examined in H2O and D2O resulting kinetic isotope effect (KIE) kH/kD = 3. In addition, RuNPs demonstrated a promising efficient for reuse catalyst 3 after five cycles for the catalytic hydrolysis.

Construction of heterophase MoOx/Ru assisted by self-assembled carboxymethylcellulose-Ru3+ nanosheet for improved alkaline hydrogen evolution

The hydrogen evolution reaction (HER) in alkaline medium is much sluggish than that in acidic medium due to the limited water dissociation step, thus accelerating the water dissociation kinetics is critical. Herein, we designed a MoOx species-modified ruthenium nanoparticle catalyst (MoOx/Ru/C-3) based on the unique electrostatic interaction between carboxymethylcellulose sodium salt (CMC) and metal ions, where an heterophase structure is formed between MoOx and Ru. The obvious electronic interaction between them allows the formation of synergistic promotion relationship involving the water dissociation on MoOx and the adsorbed hydrogen recombination on Ru. At a metal loading of 6.98 μgRu cm-2 geo, the overpotential of 82 mV is just required to reach a current density of 10 mA cm−2, exhibiting a significantly better apparent electrochemical activity than Ru/C (98 mV) without introduction of MoOx, which demonstrates superior or comparable alkaline HER activity to the recently reported Ru-based electrocatalysts. Meanwhile, the overpotential for Ru/C increased by 113 mV after 24 h of chronopotentiometric test, whereas only 61 mV elevates for MoOx/Ru/C-3, and even just 98 mV generates after 120 h. Thereof, introduction of MoOx species into Ru matrix can also markedly improve the electrochemical stability. The proposed material construction strategy in this study provides a feasible idea for the rational design of highly cost-performance alkaline hydrogen evolution catalysts.

Selective Hydrogen Production from Glycerol over Ruthenium Catalyst

AbstractGlycerol – one of the prominent by‐products of biodiesel is also an important source of hydrogen gas. Herein, the efficient and selective production of hydrogen gas from glycerol in water at 90–120 °C over a ruthenium nanoparticle (∼2.7 nm) catalyst is demonstrated. Notably, high yield of hydrogen gas (n(H2)/n(glycerol); 0.96–1.61) was achieved from the glycerol‐water solution, where the reaction temperature and base concentration played crucial role in achieving high yield of H2. Advantageously, under the studied reaction conditions, the ruthenium catalyst also exhibited appreciably high long‐term stability for over 36 h while generating ca. 70 L H2 per gram of Ru with H2 yield of 350 L per L of glycerol. Moreover, high yield for lactic acid is also achieved during the production of hydrogen gas from glycerol.

N,N-Dimethylformamide-stabilized ruthenium nanoparticle catalyst for β-alkylated dimer alcohol formation via Guerbet reaction of primary alcohols.

N,N-Dimethylformamide-stabilized Ru nanoparticles (NPs) provide a highly efficient catalyst for the Guerbet reaction of primary alcohols. DMF-modified Ru NPs were synthesized, and characterized by transition electron microscopy, and X-ray absorption spectroscopy, X-ray photoelectronspectroscopy, and Fourier-transform infrared spectroscopy. The Ru NP catalyst was highly durable during catalytic reactions under external additive/solvent-free conditions.

Ruthenium nanoparticles supported on carbon oxide nanotubes for electrocatalytic hydrogen evolution in alkaline media

“Cracking” water is of great significance to develop (HER) catalysts with high catalytic performance for non-platinum hydrogen evolution under alkaline conditions. In this paper, we prepared a ruthenium nanoparticle catalyst on oxidized carbon nanotubes (Ru@OCNT) support. Electrochemical tests showed that Ru@OCNT-700 exhibited excellent catalytic performance and good stability under alkaline conditions (1 M KOH). When the current density reached 10 mA cm−2, it only needed an overpotential of 13.2 mV. The Tafel slope was 45.4 mV/dec−1. Due to its excellent HER performance, Ru@OCNT electrocatalyst could have broad applicability in large-scale hydrogen production.

Structural and electrochemical properties of B-site Ru-doped (La0.8Sr0.2)0.9Sc0.2Mn0.8O3-δ as symmetrical electrodes for reversible solid oxide cells

Reversible solid oxide cells could be energy transfer devices between electrical power and hydrogen energy due to their multi-functions, such as fuel cells and electrolysis cells. However, the traditional configuration of solid oxide cells induces the thermal mismatch among different components during the changing between different operating modes. Herein, we demonstrate that A-site deficient (La0.8Sr0.2)0.9Sc0.2Mn0.8-xRuxO3–δ can be used as an air electrode and a fuel electrode simultaneously in reversible solid oxide cells. Ruthenium nanoparticle catalysts are exsolved on the surface of (La0.8Sr0.2)0.9Sc0.2Mn0.8-xRuxO3–δ in the reducing atmosphere. The electronic conductivity in air and 5% H2/N2 are optimized via the substitution of manganese by ruthenium, which changes the distortion of BO6 octahedron and the integral overlap between d orbitals of B-site atoms and O-p orbitals. The electrochemical activity of air electrode and fuel electrode are significantly improved simultaneously after Ru-doing. In fuel cell mode, the maximum power density of the symmetrical single cell reaches 318 mW cm−2 at 800 °C. In electrolysis cell mode, the electrolysis current density is 0.536 A cm−2 at 750 °C with an applied voltage of 1.5 V at 50% H2O/H2. The synthesized (La0.8Sr0.2)0.9Sc0.2Mn0.8-xRuxO3–δ material is a promising symmetrical electrode for reversible solid oxide cells.

Synthesis of a highly active amino‐functionalized Fe3O4@SiO2/APTS/Ru magnetic nanocomposite catalyst for hydrogenation reactions

An amino‐functionalized silica‐coated Fe3O4 nanocomposite (Fe3O4@SiO2/APTS) was synthesized. The Fe3O4@SiO2 microspheres possessed a well‐defined core–shell structure, uniform sizes and high magnetization. An immobilized ruthenium nanoparticle catalyst (Fe3O4@SiO2/APTS/Ru) was obtained after coordination and reduction of Ru3+ on the Fe3O4@SiO2/APTS nanocomposite. The Ru nanoparticles were not only ultra‐small with nearly monodisperse sizes but also had strong affinity with the surface of Fe3O4@SiO2/APTS. The obtained catalyst exhibited excellent catalytic performance for the hydrogenation of a variety of aromatic nitro compounds, even at room temperature. Moreover, Fe3O4@SiO2/APTS/Ru was easily recovered using a magnetic field and directly reused for at least five cycles without significant loss of its activity.

Activity, Selectivity, and Durability of Ruthenium Nanoparticle Catalysts for Ammonia Synthesis by Reactive Molecular Dynamics Simulation: The Size Effect.

We report a molecular dynamics (MD) simulation employing the reactive force field (ReaxFF), developed from various first-principles calculations in this study, on ammonia (NH3) synthesis from nitrogen (N2) and hydrogen (H2) gases over Ru nanoparticle (NP) catalysts. Using ReaxFF-MD simulations, we predict not only the activities and selectivities but also the durabilities of the nanocatalysts and discuss the size effect and process conditions (temperature and pressure). Among the NPs (diameter = 3, 4, 5, and 10 nm) considered in this study, the 4 nm NPs show the highest activity, in contrast to our intuition that the smallest NP should provide the highest activity, as it has the highest surface area. In addition, the best selectivity is observed with the 10 nm NPs. The activity and selectivity are mainly determined by the hcp, fcc, and top sites on the Ru NP surface, which depend on the NP size. Moreover, the selectivity can be improved more significantly by increasing the H2 pressure than by increasing the N2 pressure. The durability of the NPs can be determined by the mean stress and the stress concentration, and these two factors have a trade-off relationship with the NP size. In other words, as the NP size increases, its mean stress decreases, whereas the stress concentration simultaneously increases. Because of these two effects, the best durability is found with the 5 nm NPs, which is also in contrast to our intuition that larger NPs should show better durability. We expect that ReaxFF-MD simulations, along with first-principles calculations, could be a useful tool in developing novel catalysts and understanding catalytic reactions.

Efficient Conversion of D-Glucose into D-Sorbitol over Carbonized Cassava Dregs-Supported Ruthenium Nanoparticles Catalyst

A carbonized cassava dregs-supported ruthenium nanoparticles catalyst (Ru/CCD) was prepared by a simple impregnation-chemical reduction method. The synthesized Ru/CCD catalysts were characterized by X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The catalytic performances of the Ru/CCD catalysts were evaluated in the conversion of D-glucose into D-sorbitol under hydrogen atmosphere. Moreover, the effects of various parameters on glucose hydrogenation and the recyclability of the catalysts were investigated in detail. The optimized D-sorbitol yield reached up to 98.6% at 120 °C for 1.5 h with D-glucose conversion of 99.7%. The Ru nanoparticles played an important role in the hydrogenation of D-glucose into D-sorbitol, and the Ru particle was widely dispersed all over the support surface. In addition, the Ru/CCD catalyst was stable during the reaction and was reused for up to five successive runs with a slight decrease in D-sorbitol yield.

New Routes for Refinery of Biogenic Platform Chemicals Catalyzed by Cerium Oxide-supported Ruthenium Nanoparticles in Water

Highly selective hydrogenative carbon–carbon bond scission of biomass-derived platform oxygenates was achieved with a cerium oxide-supported ruthenium nanoparticle catalyst in water. The present catalyst enabled the selective cleavage of carbon–carbon σ bonds adjacent to carboxyl, ester, and hydroxymethyl groups, opening new eight synthetic routes to valuable chemicals from biomass derivatives. The high selectivity for such carbon-carbon bond scission over carbon-oxygen bonds was attributed to the multiple catalytic roles of the Ru nanoparticles assisted by the in situ formed Ce(OH)3.

Revisiting alternative pathways in the Fischer–Tropsch process: Accurate density functional theory calculations on “magic” Ru12 clusters

AbstractModels of the Fischer–Tropsch reaction typically focus on two proposed mechanisms for the initial carbon monoxide dissociation: unassisted dissociation (carbide mechanism), and hydrogen‐assisted dissociation via an adsorbed oxymethylidene (HCO*) intermediate. Much evidence for hydrogen‐assisted dissociation comes from density functional theory calculations modeling ruthenium nanoparticle catalysts as infinite, periodic metal slabs. However, the generalized gradient approximations (GGAs) used in these calculations can make significant errors in reaction barrier heights. How these errors affect the predicted selectivity to unassisted vs. hydrogen‐assisted dissociation is not well understood. We address the problem by considering a different regime, applying GGA and beyond‐GGA approximations to CO dissociation on a “magic” nonmagnetic Ru12 cluster modeling supported nanoparticle catalysts. Both approximations concur that hydrogen‐assisted dissociation is facile on this cluster, providing additional support for its potential role in real catalysts.

Understanding the molecular basis for the controlled design of ruthenium nanoparticles in microporous aluminophosphates

Highly active ruthenium nanoparticle catalysts for C–H activation of hydrocarbons.

Conversion of Levulinic Acid to γ-Valerolactone over Few-Layer Graphene-Supported Ruthenium Catalysts

Few-layer graphene (FLG) supported ruthenium nanoparticle catalysts were synthesized and used for the hydrogenation of levulinic acid (LA), one of the “top 10” biomass platform molecules derived from carbohydrates. FLG-supported ruthenium catalyst showed 99.7% conversion and 100% selectivity toward γ-valerolactone (GVL) at room temperature in a batch reactor under high-pressure hydrogen. This catalyst showed 4 times higher activity and exceptional stability in comparison with traditional activated carbon supported ruthenium catalysts (Ru/C). X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) studies suggest that the superior catalytic properties of Ru nanoparticles supported on FLG in LA hydrogenation could be attributed to the greater metallic Ru content present in the Ru/FLG in comparison to that in Ru/C.

Ru nanoparticles confined in Zr-containing spherical mesoporous silica containers for hydrogenation of levulinic acid and its esters into γ-valerolactone at ambient conditions

Hydrogenation of levulinic acid and its esters to produce γ-valerolactone (GVL) was demonstrated over ruthenium nanoparticle (NP) catalyst supported on Zr-containing spherical mesoporous silicas as a bifunctional catalyst. The Ru NPs were found to be uniformly dispersed within the periodically ordered short mesopore channels with an average size of less than 1.5nm without any agglomeration. They exhibited superior activity for the hydrogenation of both levulinic acid and its esters under mild reaction conditions (70°C, 0.5MPa H2) compared to those supported on the conventional silica owing to their ultrasmall particle size and the acidity of Zr sites. In the hydrogenation of levulinate ester, addition of heterogeneous acids could afford a faster reaction rate in GVL production by accelerating the following intramolecular dealcoholation step. The catalyst was reusable over repeated catalytic cycles without a significant loss of catalytic performance, demonstrating its potential as a heterogeneous catalyst for GVL production under ambient reaction conditions.

Fischer–Tropsch Synthesis: Effect of Reducing Agent for Aqueous-Phase Synthesis Over Ru Nanoparticle and Supported Ru Catalysts

The effect of the reducing agent on the performance of a ruthenium nanoparticle catalyst was investigated during aqueous-phase Fischer–Tropsch synthesis using a 1 L stirred tank reactor in the batch mode of operation. For the purpose of comparison, the activity and selectivity of NaY zeolite supported Ru catalyst were also studied. NaBH4 and hydrogen were used as reducing agents in this study, and hydrogen reduced catalysts exhibited higher activities than the NaBH4 reduced catalysts, because of higher extent of reduction and a relatively lower tendency toward agglomeration of Ru particles. The Ru nanoparticle catalyst displayed higher activities than the NaY zeolite supported Ru catalyst for both reducing agents. NaBH4 reduced catalysts are less active and the carbon dioxide selectivity is higher than the hydrogen reduced catalysts. Nevertheless, the activity of the supported Ru catalyst (Ru/NaY) was 75 % of that of the Ru nanoparticle catalyst, and has the benefit of easy wax/catalyst slurry separation by filtration. The hydrogen reduced supported Ru catalyst exhibited superior selectivity towards hydrocarbons (higher C5+ selectivity and lower selectivity to methane) than all other catalysts tested.

Hydrogenation of Sulfoxides to Sulfides under Mild Conditions Using Ruthenium Nanoparticle Catalysts

The first demonstration of the hydrogenation of sulfoxides under atmospheric H2 pressure is reported. The highly efficient reaction is facilitated by a heterogeneous Ru nanoparticle catalyst. The mild reaction conditions enable the selective hydrogenation of a wide range of functionalized sulfoxides to the corresponding sulfides. The high redox ability of RuOx nanoparticles plays a key role in the hydrogenation.

Hydrogenation of sulfoxides to sulfides under mild conditions using ruthenium nanoparticle catalysts.

The first demonstration of the hydrogenation of sulfoxides under atmospheric H2 pressure is reported. The highly efficient reaction is facilitated by a heterogeneous Ru nanoparticle catalyst. The mild reaction conditions enable the selective hydrogenation of a wide range of functionalized sulfoxides to the corresponding sulfides. The high redox ability of RuO(x) nanoparticles plays a key role in the hydrogenation.

Improved Catalytic Reactor for the Electrochemical Promotion of Highly Dispersed Ru Nanoparticles with CeO2 Support

Electrochemical promotion of catalysis (EPOC) is a promising method for enhancing catalytic activity through the application of a small electrical stimulus between the catalyst-working and counter electrode deposited on a solid electrolyte 1. The electronic properties of the catalyst can be modified resulting in a change in catalytic activity. In the case of yttria-stabilized zirconia (YSZ) as a solid electrolyte, the addition or removal of O2- species on the catalyst surface can be controlled in situ depending on the specified reaction conditions. Fully reversible and “permanent” or “persistent” EPOC has been reported for more than 70 various catalytic systems 1. In reversible EPOC experiments, the reaction rate returns to its initial value after the electrical stimulus is interrupted. For permanent EPOC (P-EPOC), the reaction rate remains at a higher value than the initial open circuit value 2,3. Despite receiving much attention, this phenomenon has not yet reached commercial application. One of the main technical factors preventing such development is the use of thick film catalysts with low surface areas and high material costs 4.Ceria, CeO2, is a mixed ionic-electronic conducting (MIEC) material that conducts O2- due to oxygen vacancies in the crystallographic structure in addition to conducting electrons at elevated temperatures. Furthermore, due to its non-stoichiometry, CeO2 has the ability to undergo conversion between Ce4+ and Ce3+ quite easily 5. These properties make the use of ceria-containing catalysts of interest for many applications. In heterogeneous catalysis, Pt group metals deposited on CeO2 show a metal-support interaction (MSI) effect associated with charge transfer between the two solids that are in contact. In EPOC studies, using a MIEC can also ensure electrical connectivity between highly dispersed nanoparticle catalysts 6.In this study, electrochemical enhancement of catalytic activity of a low particle size (1.9 nm) ruthenium nanoparticles catalyst for ethylene oxidation was investigated. Ru nanoparticles, synthesized using a modified polyol reduction method, were supported on CeO2 resulting in a 1 wt% Ru loading (RuNPs/CeO2) (i.e., typical in heterogeneous catalysis studies).The highly dispersed RuNPs/CeO2 catalyst powder was supported on a YSZ solid electrolyte in order to apply polarization. The discussion of this study includes the effect of the partial pressure of ethylene with constant partial pressure of oxygen, temperature, and applied positive and negative current on the catalytic activity of the RuNPs/CeO2 catalyst as well as the role of the cerium redox state in the observed persistent effect. In addition, the catalytic properties of the RuNPs/CeO2 catalyst is compared to that of larger Ru particles supported on CeO2 (TD-Ru/CeO2) (same metal loading) and blank CeO2, both supported on a YSZ solid electrolyte.Characterizations of the catalysts were carried out using TEM and SEM. In addition, XPS analysis was done for the RuNPs/CeO2catalyst as prepared and “spent” (after the reaction). Overall, it was observed that only the RuNPs/CeO2 catalyst could be catalytically enhanced, showing a pronounced enhancement (up to 2.5 times) of the catalytic rate for negative polarization. The opposite effect was observed for positive polarization. This effect of both positive and negative polarization is illustrated by Fig.1. Fig. 1.Transient effect of current application for C2H4 oxidation over Ru/CeO2 on YSZ electrolyte at 350°C for an applied current of -2 μA for 4 hours and +2 μA for 6 hours (0.012 kPa C2H4).Apparent Faradaic efficiencies up to 100 were also determined, indicating a non-Faradaic effect. In addition, a persistent effect was observed, showing stability up to 16 hours after current interruption. The modification of the cerium oxidation state (i.e., reduction from Ce4+ to Ce3+) is proposed to enhancethe catalytic performance of the Ru nanoparticles. This is due to the presence of more oxygen vacancies in the ceria interlayer causing a stronger metal-support interaction.These results demonstrate the feasibility of in-situ modification of the metal support-interaction between Ru nanoparticles and CeO2catalytic support.

Comparing Thermal-Cracking and Catalytic Hydrocracking in the Presence of Rh and Ru Catalysts to Produce Liquid Hydrocarbons from Vegetable Oils

We describe herein the production of liquid hydrocarbons through the catalytic hydrocracking of soybean, palm tree and castor oils, in the presence and absence of ruthenium and rhodium nanoparticle catalysts. The reaction at 200 oC leads to the hydrogenation of C=C double bonds only. However, at 400 oC, the decomposition of the triacylglycerides was observed, leading to hydrocarbons and oxygenated compounds. The catalyzed hydrocracking of vegetable oils in the presence of Rh and Ru strongly increased the amount of deoxygenated products and the formation of long-chain linear hydrocarbons, which are suitable for use as diesel fuel, when compared with pyrolysis reaction in the absence of the catalysts. The Ru catalyst is more effective than Rh, especially in the case of castor oil, probably due to its higher oxophilicity when compared to Rh.

Hydroxyapatite-nanosphere supported ruthenium(0) nanoparticle catalyst for hydrogen generation from ammonia-borane solution: kinetic studies for nanoparticle formation and hydrogen evolution

Nanohydroxyapatite-supported ruthenium(0) nanoparticles formed in situ during the hydrolysis of AB have been found to be a highly active catalyst in the generation of hydrogen from aqueous AB solution.