Addition Of Ru Research Articles

Catalytic oxidation of dichloromethane co-promoted by RuO2 and V2O5 supported on nano-CeO2

The catalytic oxidation of chlorinated volatile organic compounds is a hot and difficult area of research. Ru-V/CeO2 catalyst constructed in this paper had enhanced catalytic performance for dichloromethane (DCM), and the conversion of DCM reached about 94 % at 300 °C with no by-products generated. The DCM conversion of Ru-V/CeO2 catalyst at 300 °C remained above 90 % in a 48 h stability test. The catalytic activity and structural properties were explored through experimental comparisons and related characterizations. The presence of V increased the surface acidity and thus improved the low-temperature stability, and the addition of Ru increased the oxygen species on the surface of Ru-V/CeO2 catalyst, which greatly enhanced the CO2 mineralization. A possible mechanism for the promotion of DCM oxidation by Ru-V/CeO2 catalyst was proposed by in situ DRIFTS.

Boosted photothermal synergistic CO2 methanation over Ru doped Ni/ZrO2 catalyst: From experimental to DFT studies

The hydrogenation of CO2 to CH4 presents a captivating and challenging avenue for CO2 reutilization. In this study, we explored the potential of photo-thermal catalytic (PTC) reactions for CO2 conversion to CH4. Herein, we employed a novel catalyst, NiRu/ZrO2, for photothermal CO2 methanation. Remarkably, the Ru-doped Ni/ZrO2 catalyst demonstrated significantly higher catalytic activity compared to the Ni monometallic catalyst. The optimized Ru doping conditions led to decreased temperature requirements and promoted CO2 conversion rates, achieving an impressive 100% CH4 selectivity. Detailed characterizations of the catalyst revealed several advantageous properties of NiRu/ZrO2, including superior optical absorption performance, a higher temperature of CO2 resolved peak, and an increased binding energy of the Ni2+ peak. Furthermore, density functional theory (DFT) calculations demonstrated that the addition of Ru positively influenced CO2 adsorption, thereby lowering the energy barrier for CO2 decomposition and C species hydrogenation. This research sheds light on the potential of the Ru-doped Ni/ZrO2 catalyst for efficient CO2 conversion to CH4 through photothermal catalysis. These findings offer valuable insights for the development of advanced catalysts in CO2 reutilization strategies.

The widening of the solution heat treatment window by the addition of Ru in Ni-based single crystal superalloy

This work investigates the effect of Ru on the solution heat treatment window of the Ni-based single crystal superalloy. The addition of the Ru influences the solidification microstructure and widens the window. The solidification process is established to occur in the sequence of γ (dendrite) → γ + γ' grid eutectic (inter-dendrite) → γ + γ' lamella eutectic (inter-dendrite) → γ' (inter-dendrite). This is followed by the γ → γ + γ' decomposition of the γ dendrite into the common channel-cuboid structure upon cooling. The solvus of γ' and the solidus of the alloy define the window. In alloys containing inter-dendrite eutectic, the window is in principle zero. In this case, only the dynamic window created by homogenization diffusion may allow heat treatment. Adding Ru decreases the elements' partition ratios between the dendrite core and dendrite edge regions. It also promotes the enrichment of Re at the γ/γ' phase interfaces, which helps to refine the γ + γ' channel-cuboid structure and reduce the differences in both the size and volume fraction of the γ' phase between dendrite core and dendrite edge. Ru is found to inhibit the formation of (Ta, X)C carbide. These help widen the solution treatment temperature window of the Ni-based single crystal alloy.

Application fischer-tropsch synthesis: a review

This work was to evaluate the catalytic properties Ru/Cobalt/SBA-15 catalyst for Fischer-Tropsch synthesis (FTS). The molecular sieve SBA-15 synthesized by hydrothermal method with rice husk ashes (RHA) and with tetraethyl orthosilicate (TEOS). The Ru promoted Co/SBA-15 catalyst was prepared by wet impregnation method and was characterized by X-ray diffraction, X-ray energy dispersion spectrophotometer, N2 adsorption-desorption, temperature-programmed reduction and transmission electron microscopy. The Fischer-Tropsch synthesis using the catalysts were carried out to evaluate the catalysts activities and its effect on FTS product distribution. The synthesis was carried out in a slurry reactor operating at 513 K, 20 atm, CO : H2 molar ratio of 1 : 2. X-ray diffraction showed that the calcined cobalt catalyst did not modify the structure of SBA-15, proving that Co was present under the form of Co3O4 in the catalyst. The addition of cobalt in SBA-15 decreased the specific superficial area of the molecular sieve. By RTP results was found the ranges of temperature reduction typical of iron oxides phases. Fischer-Tropsch synthesis activity and C5+hydrocarbon selectivity increased with the addition of Ru. The increases in activity and selectivity were attributed to the increased number of active sites resulting from higher reducibility and the synergetic effect of Ru and Co. The most interesting fact to be pointed out is that the use of this catalytic system for the catalyst prepared with alternative source of silica and cheap (rice hull ash) showed high selectivity in liquid products, that is, in hydrocarbons with C5+ (88.2% w/w), higher than the catalyst prepared with conventional silica source.

New insights into effects of Ru on the oxidation behaviour of Ni-based single-crystal superalloys at 1150 °C

This study provides new insights into Ru-effects on the oxidation resistance of some fourth-generation single-crystal Ni-based superalloys at 1150 °C. No apparent evaporation of Ru-oxides was observed. On the contrary, HCP-structured Ru-Re solid solution ((Ru,Re)ss) particles were found to be embedded in the oxide scale for the Ru-added alloys. Local evaporation of Re-oxides from the (Ru,Re)ss particles, as well as the internal stress at their boundaries, gives birth to micro-pores and cracks and increased the spallation of oxide scales upon cooling. Despite the inhibition of undesirable TCP phase precipitation, Ru additions degrade the high-temperature oxidation resistance of the alloys considerably.

High-temperature mechanical performance of Ru doped cermets

The mechanical properties degradation of cermets under high temperatures greatly limits their applications. In this paper, the compressive yield strength of WC-Co based cermets at high temperatures was significantly improved by the addition of Ru. Based on the detailed microstructure analyses, the contribution of Ru to the plastic deformation of the cermets was disclosed. The addition of Ru would stabilize the fcc-Co structure, leading to an increase in the proportion of the coherent WC/Co phase boundaries. The coherent phase boundaries are beneficial to avoid stress concentration across the interface and premature crack initiation, inducing higher dislocation densities and larger plastic deformation in both Co and WC phases. The solid solution strengthening effect of Ru and the Ru cluster in the Co phase can inhibit the softening of the binder phase at high temperatures. The synergy of solid solution strengthening and dislocation strengthening is responsible for the higher yield strength of WC-Co cermets with Ru at high temperatures.

On the constitution and cobalt alloy formation in WC-1.4 wt% Ru-9.5 wt% Co cemented carbides

Our work confirms that the addition of Ru to Co-based cemented carbides significantly broadens the carbon processing window. Using a WC-10.9 wt% (Co-12.8Ru) alloy, the width of the two-phase window is extended from about 0.16 wt% C (Ru-free) to about 0.21 wt% C on addition of Ru.According to semi-quantitative EDS analysis, the amount of W dissolved in the Co binder is significantly higher in Ru-containing materials at all carbon contents. This higher degree of solubility is also reflected in the lattice parameter. When decreasing the carbon content (from precipitation of graphite to the formation of eta carbides), the lattice parameter increases steadily from 3.585 Å to 3.609 Å respectively. In contrast, Ru-free materials present 3.548 Å in equilibrium with graphite, and 3.576 Å in equilibrium with eta carbides.The relative magnetic saturation value of the alloys with Ru was significantly lower when compared to Ru-free alloys (from 80.2% at graphite precipitations to 41.4% with dendritic eta phase), which is also in agreement with the higher W solubility observed in these alloys.DTA measurements of WC-4.4 wt% Ru-30 wt% Co samples (same Ru to Co ratio in the nominal composition) demonstrated a similar melting and solidification regime as compared to Ru-free WC-30 wt% Co materials.

Insight into the Mechanism of Selective Catalytic Reduction of NO by CO over a Bimetallic IrRu/ZSM-5 Catalyst in the Absence/Presence of O2 by Isotopic C13O Tracing Methods.

The development of efficient catalysts for the selective catalytic reduction of NO by CO (CO-SCR) in the presence of O2 is highly desirable for controlling the emission of toxic gases from tailpipes. Here, a bimetallic IrRu/ZSM-5 catalyst was prepared for the selective catalytic reduction of NO by CO in the presence of O2 (5%) for the low-temperature treatment of exhaust gas. IrRu/ZSM-5 afforded 90% NOx conversion in the range of 225-250 °C and maintained 90% NOx conversion after 12 h of reaction. Ru addition inhibited agglomeration of the Ir particles during the reduction process and provided more active sites for NO adsorption. Isotopic C13O tracing and in situ diffuse reflectance infrared Fourier-transform spectroscopy experiments were used to elucidate the CO-SCR mechanism in the absence or presence of O2. NCO could easily form on the surface of catalysts in the absence of O2, whereas NCO formation has been inhibited owing to the quick consumption of CO in the presence of O2. Moreover, some byproducts such as N2O and NO2 are generated in the presence of O2. Finally, a possible mechanism for CO-SCR under different conditions was proposed based on in situ experiments and physicochemical analyses.

Improving the Stability of Ru-Doped Ni-Based Catalysts for Steam Methane Reforming during Daily Startup and Shutdown Operation

In this study, a Ru-doped Ni pellet-type catalyst was prepared to produce hydrogen via steam methane reforming (SMR). A small amount of Ru addition on the Ni catalyst improved Ni dispersion, thus affording a higher catalytic activity than that of the Ni catalyst. During the daily startup and shutdown (DSS) operations, the CH4 conversion of Ni catalysts significantly decreased because of Ni metal oxidation to NiAl2O4, which is not reduced completely at 700 °C. Conversely, the oxidized Ni species in the Ru–Ni catalyst can be reduced under SMR conditions because of H2 spillover from the surface of Ru onto the surface of Ni. Consequently, the addition of a small quantity of Ru to the Ni catalyst can improve the catalytic activity and stability during the DSS operation.

Ni/Ru@NC-CeO2 composite for hydrogen evolution reaction in alkaline media: Effect of CeO2 decoration with Ru@NC on the catalytic activity

The design of composites with controlled interfaces has proven to be an efficient approach to obtaining highly active electrocatalysts for the hydrogen evolution reaction with improved stability. In this work, we report the preparation of Ni-based composites by co-depositing commercial CeO2 nanoparticles and Ru nanoparticles with N-doped carbon patches supported onto CeO2 (Ru@NC-CeO2) using a facile electrodeposition method. The Ru@NC-CeO2 nanoparticles were obtained through the impregnation of CeO2 with Ru organometallic precursor and subsequent pyrolysis. A comprehensive chemical, structural and morphological characterization of the synthesized nanoparticles and co-deposit composites is presented. The cyclic voltammetry analysis showed that the composites exhibit a higher current density in comparison to the conventional nickel Watts catalyst; specifically a ∼ 48 % increase for the CeO2-containing composite, and ∼ 105 % for the Ru@NC-CeO2 based composite. This study demonstrates that the small addition of Ru to the CeO2 nanoparticles on the nickel matrix can improve drastically the performance towards HER in alkaline media.

Combined effect of Ru on the oxidation behavior and microstructure stability of a single crystal superalloy

The isothermal oxidation behavior and the microstructure stability was studied at 900 °C, 1000 °C and 1100 °C of the two alloys with and without Ru. The curves of oxidation weight gain show that the oxidation resistance decreases sharply with the addition of Ru. A multi-layered scale formed on the alloy surface, and it generally consisted of an external layer of NiO, an intermediate layer of spinel and an Al2O3 inner layer. The oxidation rate at 1100 °C is significantly higher than that at the other two temperatures due to more serious cracking and peeling of oxide scale. Compared with Ru-free alloy, the oxide layer of Ru-containing alloy is thicker and the oxide layer spallation more seriously. The oxide of Ru was found in the spinel layer and the vaporization of the oxide makes the scale spallation. Surprisingly, a large number of TCP phases were found in alloy matrix, especially in 2Ru alloy. This indicates that poor oxidation resistance will lead to a decline in microstructure stability.

Dispersing small Ru nanoparticles into boron nitride remodified by reduced graphene oxide for high-efficient electrocatalytic hydrogen evolution reaction

Ruthenium (Ru) electrocatalysts suffer from excessive aggregation during the hydrogen evolution reaction (HER), which hinders their practical application for hydrogen production. Hexagonal boron nitride (h-BN) is a potential carrier that could solve the above problem, but its wide band gap and low conductivity become obstacles. Herein, we provide a new, facile, low-cost, and effective strategy (killing two birds with one stone) to overcome the above issues. After modifying h-BN with reduced graphene oxide (rGO), a small amount of Ru nanoparticles (NPs) (2.2 %) are dispersed into BN with approximately uniform distribution and size control of Ru nanoparticles (∼3.85 nm). The strong synergy between Ru NPs and BN@C in the optimal Ru/BN@C (Ru wt.% = 2.22 %) electrocatalyst endows it an outstanding HER activity, with small HER overpotentials (η10 = 32 mV, 35 mV) and low Tafel slopes (33.89 mV dec−1, 37.66 mV dec−1) in both 1 M KOH and 0.5 M H2SO4 media, respectively, along with good long-term stability for 50 h. Based on density functional theory (DFT) calculations, the addition of Ru to BN has been successful in creating fresh active sites for H*, with good possible adsorption/desorption ability (ΔGH* = −0.24 eV) while preserving low water dissociation (ΔGb = 0.46 eV) in an alkaline environment. As a result, the Ru/BN composite exhibits outstanding HER activity in both acidic and alkaline conditions. Furthermore, this study provides, for the first time, a template-free strategy to develop a good and low-cost supporter (BN) for dispersing other noble metals and the formation of highly efficient HER/OER electrocatalysts.

Effect of Ru on Deformation Mechanism and Microstructure Evolution of Single-Crystal Superalloys under Medium-Temperature and High-Stress Creep.

In this work, the effect of the Ru element on the γ'-phase evolution and deformation mechanism in the fourth-generation Ni-based single-crystal superalloy was investigated. Results show that the Ru element alters the distribution coefficient of other elements in the alloy to produce reverse partitioning behavior, which leads to a difference in microstructure between 0Ru and 3Ru. The addition of Ru triggered the incubation period before the beginning of the primary creep stage, which depends on the creep temperature and stress during creep deformation. TEM results revealed that Ru addition inhibits the slip system {111}<112> at medium-temperature (760-1050 °C) and high-stress (270-810 MPa) creep, which brings a considerably low creep rate and high creep life to the Ru-containing alloy.

Selective hydrogenation of phenol to cyclohexanone over small amount of Ru-promoted Pd/ZrHP catalysts

Selective hydrogenation of phenol to cyclohexanone is a vital step in the manufacture of fiber (nylon), which is currently carried out over expensive Pd catalyst with low productivity. In this work, a series of Ru-promoted Pd catalysts were synthesized in a facile microwave-assisted method and tested in the hydrogenation of phenol to cyclohexanone. It was found that small amount of Ru in Ru-Pd alloy can increase the conversion of phenol obviously without loss of cyclohexanone selectivity. The selectivity of cyclohexanone over Ru0.15Pd4.85/ZrHP remained higher than 99%, while the conversion of phenol increased from 20.5% (over Pd5/ZrHP) to 97.9% at 100 °C and 1 MPa. And the highest turnover frequency (TOF) of surface metal in Ru0.15Pd4.85/ZrHP at 100 °C and 2 MPa reached 1605 h−1. Characterization results revealed that the addition of Ru can improve the dispersion of Ru-Pd alloy and enhance its electron density. In addition, the activated hydrogen on Ru-Pd alloy and acid sites in ZrHP played a synergistic effect for the selective formation of cyclohexanone from phenol.

New insights into the microstructural stability based on the element segregation behavior at γ/γ′ interface in Ni-based single crystal superalloys with Ru addition

A new insight into the microstructural stability was proposed in Ni-based single crystal superalloys with Ru addition, and the element segregation behavior at γ/γ′ interface was investigated by three-dimensional atom probe technology (3D-APT). After standard heat treatment, it was found that Ru addition barely altered the element partitioning coefficient between γ matrix and γ′ phase, and no element-segregation layer was observed at γ/γ′ interface. During the heat exposure at 1100 °C, Ru addition obviously promoted the rafting of the γ′ precipitates and inhibited the precipitation of topological close-packed (TCP) phases. It was more important that an element-segregation layer containing Re, Co, and Cr was formed in the γ matrix close to the γ/γ′ interface due to an “uphill diffusion” effect, and its concentration was obviously reduced after Ru addition. Finally, the microstructural stability based on the element segregation behavior at γ/γ′ interface was discussed. This element-segregation layer increased the γ/γ′ interfacial energy by increasing the absolute value of the lattice misfit of γ/γ′ interface to promote the rafting of the γ′ precipitates after Ru addition. On the other hand, the decrease of the segregation concentration of Re, Co, and Cr elements as TCP phase-forming elements near the γ/γ′ interface due to a “reverse partitioning” effect inhibits the precipitation of TCP phases in Ni-based single crystal superalloys after Ru addition.

Enhanced Low-Temperature CO2 Methanation over Bimetallic Ni–Ru Catalysts

Nickel-based catalysts are the most promising selection for CO2 methanation. But, it is challenging for monometallic Ni to achieve high CO2 conversion at low temperature. This study develops ceria-supported bimetallic Ni–Ru catalysts that are highly efficient for low-temperature methanation. A small amount of Ru (0.2 wt %) addition to Ni enables the intermetal interaction, and enhances the dispersion of Ni particles with a more active surface, consequently boosting the catalytic capacity for hydrogen activation and CO adsorption. The bimetallic Ni–Ru catalysts exhibit a more than 3-fold rate enhancement at low temperature for selective methanation of CO2 relative to the monometallic Ni/CeO2. Operando IR spectroscopy identifies the formate route as the major reaction mechanism over the monometallic Ni, and the presence of Ru in the bimetallic catalysts can induce the *CO-intermediate mechanistic pathway, contributing to the enhanced production of methane.

Dealloying of an amorphous TiCuRu alloy results in a nanostructured electrocatalyst for hydrogen evolution reaction

AbstractDevelopment of an electrocatalyst that is cheap and has good properties to replace conventional noble metals is important for H2 applications. In this study, dealloying of an amorphous Ti37Cu60Ru3 alloy was performed to prepare a free‐standing nanostructured hydrogen evolution reaction (HER) catalyst. The effect of dealloying and addition of Ru to TiCu alloys on the microstructure and HER properties under alkaline conditions was investigated. 3 at.% Ru addition in Ti40Cu60 decreases the overpotential to reach a current density of 10 mA cm−2 and Tafel slope of the dealloyed samples to 35 and 34 mV dec−1. The improvement of electrocatalytic properties was attributed to the formation of a nanostructure and the modification of the electronic structure of the catalyst. First‐principles calculations based on density function theory indicate that Ru decreases the Gibbs free energy of water dissociation. This work presents a method to prepare an efficient electrocatalyst via dealloying of amorphous alloys.

Self-consistent charge density functional tight-binding (SCC-DFTB) parameterization and validation for Ti50Pd50-XRuX alloys

Titanium-palladium based systems are in high demand currently, particularly for the development of high-temperature shape memory alloys with a unique application in the aerospace industry. In particular, the Ti50Pd50-XRuX is found to be one of the promising alloys. This is due to their shape memory effect and superelasticity. Previous studies revealed that these alloys are mechanically stable above 25 at. % Ru with a positive C′ at 0 K. So, an understanding of its transformation temperature behavior is required, which is currently not clear. The self-consistent-charge density functional tight-binding (SCC-DFTB) approach was used to develop parameters for Ti50Pd50-XRuX employing the parameterization technique. The structural, electronic and elastic properties were determined to check their relative stability on derived potentials using DFTB + code. As part of the validation for the developed set, the results were reproducible to within 5 % agreement as compared with other theoretical findings. Furthermore, the SCC sets of parameters were also used to determine the lattice expansions and check the transformation temperature of ternary Ti50Pd50-XRuX. It was observed that the addition of Ru reduces the transformation temperature. The findings imply that the SCC-DFTB approach was able to predict the stability and transformation behavior of Ti50Pd50-XRuX alloys.

CO2 Hydrogenation to Renewable Methane on Ni/Ru Modified ZSM-5 Zeolites: The Role of the Preparation Procedure

Mono- and bimetallic Ni- and Ru-modified micro-mesoporous ZSM-5 catalysts were prepared by wet impregnation. The influence of the Ni content, the addition of Ru and the sequence of the modification by two metals on the physicochemical properties of the catalysts were studied. They were characterized by X-ray powder diffraction (XRD), N2 physisorption, temperature-programmed reduction (TPR-TGA), TEM and XPS spectroscopy. Formation of finely dispersed nickel and/or ruthenium oxide species was observed on the external surface and in the pores of zeolite support. It was found that the peculiarity of the used zeolite structure and the modification procedure determine the type of formed metal oxides, their dispersion and reducibility. XPS study revealed that the surface became rich in nickel and poorer in ruthenium for bimetallic catalysts. Ni had higher dispersion in the presence of ruthenium, and TPR investigations also confirmed its facilitated reducibility. The studied catalysts were tested in CO2 hydrogenation to methane. 10Ni5RuZSM-5 material showed the highest activity and high selectivity for methane formation, reaching the equilibrium conversion and 100% selectivity at 400 °C. Stability and reusability of the latter catalyst show that it is appropriate for practical application.

Corrosion Behaviour of Cemented Carbides with Co- and Ni-Alloy Binders in the Presence of Abrasion

More and more often, cemented carbides are employed for the production of wear resistant components and have to face highly demanding service conditions that combine different damage mechanisms. A key example is the range of tetraphasic (sea water, sand, liquid and gaseous hydrocarbons) flows encountered in the Oil and Gas extraction industry. Notwithstanding the importance of operating regimes of this type, the availability of fundamental and quantitative information on the corrosion performance of cemented carbides in the presence of abrasion is still limited. In this paper, we report a systematic study of the corrosion behaviour of cemented tungsten carbide grades with binders containing different amounts of cobalt (Co), nickel (Ni), chromium (Cr) and noble metal additions, subjected to controlled mechanical abrasion, impacting the stability and nature of pseudopassivation films. In this work, special attention is devoted to Cr, a classical of additive that inhibits the Ostwald ripening of tungsten carbide (WC) particles and notably improves the corrosion resistance of grades with ultrafine-to-fine WC grain size and low-to-medium binder content. We assessed the impact of binder composition on the anodic behaviour by means of linear-sweep voltammetry and chronopotentiometry as well as on the mechanical properties. The application of controlled abrasion conditions under electrochemical control is carried out with an in-house modified ASTM B611 apparatus, equipped with a three-electrode system, enabling the systematic investigation of the synergy of electrochemical and mechanical damaging conditions. Increased corrosion resistance in environments without and with added chloride—both in the absence and in the presence of abrasion—was observed in all the Co- and Ni-based grades to which growing quantities of Cr were added. Moreover, doping with ruthenium (Ru) further enhances corrosion resistance. Regarding corrosion in the presence of abrasion, the addition of Cr and Ru increases the ability of regenerating the pseudopassivation film. The optimized compositions of the binder have been highlighted that open up attractive opportunities of improved service behaviour and deployment in new applications.