Ruthenium Loading Research Articles

Sequential conversion of lignite in alkaline water by oxidative degradation, dissolution and catalytic gasification

We have demonstrated a sequence of degradation, dissolution and catalytic hydrothermal gasification (CHTG) of lignite in alkaline water. A Victorian lignite was subjected to hydrothermal treatment (HT) in an aqueous solution of NaOH at 250 °C, and then oxidation with pressurized O2 at 100 °C. The sequential HT and oxidation solubilized a 95% portion of the lignite on mass/carbon bases. The resulting solution was further converted by CHTG in a flow reactor at 350 °C for 10 h, employing a ruthenium/activated-charcoal catalyst (ruthenium loading; 16 wt%). The initial carbon conversion to gas was as high as 98% while CH4, CO2 and H2 were produced. The conversion gradually decreased due to coke deposition over the catalyst but was near steady around 83% at 8–10 h. The solubilized lignite consisted of compounds with molecular mass up to 5,000. The heavier portion (molecular mass > 1,000) was responsible for the coke formation and accumulation that caused the catalyst deactivation.

Stable and Efficient PtRu Electrocatalysts Supported on Zn-BTC MOF Derived Microporous Carbon for Formic Acid Fuel Cells Application.

Highly efficient, well-dispersed PtRu alloy nanoparticles supported on high surface area microporous carbon (MPC) electrocatalysts, are prepared and tested for formic acid oxidation reaction (FAOR). The MPC is obtained by controlled carbonization of a zinc-benzenetricarboxylate metal-organic framework (Zn-BTC MOF) precursor at 950°C, and PtRu (30 wt.%) nanoparticles (NPs) are prepared and deposited via a polyol chemical reduction method. The structural and morphological characterization of the synthesized electrocatalysts is carried out using powder X-ray diffraction (PXRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), an energy dispersive X-ray (EDX) technique, and gas adsorption analysis (BET). The FAOR performance of the catalysts is investigated through cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS). A correlation between high electrochemical surface area (ECSA) and high FAOR performance of the catalysts is observed. Among the materials employed, Pt1Ru2/MPC 950 with a high electrochemical surface area (25.3 m2 g−1) consequently showed superior activity of the FAOR (Ir = 9.50 mA cm−2 and Jm = 2,403 mA ) at room temperature, with improved tolerance and stability toward carbonaceous species. The superior electrochemical performance, and tolerance to CO-poisoning and long-term stability is attributed to the high surface area carbon support (1,455 m2 g−1) and high percentage loading of ruthenium (20 wt.%). The addition of Ru promotes the efficiency of electrocatalyst by offering FAOR via a bifunctional mechanism.

Enhance photocatalytic of hydrogen production from water-glycerol solution over RuO2-loaded

Study of hydrogen production from aqueous glycerol solution on RuO2-loaded LaNaTaO3 has been studied. This research aim is to investigate the influence of co-catalyst RuO2 and glycerol as a sacrificial reagent on the photocatalytic process of hydrogen production. La-doped NaTaO3 was prepared via sol-gel route. The RuO2 was loaded onto the LaNaTaO3 surface by impregnation method. The sample was characterization by Scanning Electron microscopy (SEM) and X-ray Diffractometer (XRD). From XRD spectrum shows that the La-NaTaO3 photocatalyst has high crystallinity. The SEM analysis indicates that the size of La-NaTaO3 photocatalyst is ranging from 100 to 250 nm without agglomeration and RuO2 as a co-catalyst is well loaded into the La-NaTaO3 surface. The rate of hydrogen production increased significantly with a glycerol concentration. Loading RuO2 on La-NaTaO3 photocatalyst is proved to increase the rate of hydrogen production of 3.2 times with the addition of glycerol as a sacrificial reagent. The highest hydrogen production activity was obtained for 0.3 wt.% ruthenium loading. The role of co-catalyst RuO2 and glycerol as a sacrificial reagent has enhanced the performance of La-NaTaO3 photocatalyst since both play an active role in the separation efficiency of electrons and holes and the reaction of hydrogen formation.

Boosting oxygen evolution of single-atomic ruthenium through electronic coupling with cobalt-iron layered double hydroxides

Single atom catalyst, which contains isolated metal atoms singly dispersed on supports, has great potential for achieving high activity and selectivity in hetero-catalysis and electrocatalysis. However, the activity and stability of single atoms and their interaction with support still remains a mystery. Here we show a stable single atomic ruthenium catalyst anchoring on the surface of cobalt iron layered double hydroxides, which possesses a strong electronic coupling between ruthenium and layered double hydroxides. With 0.45 wt.% ruthenium loading, the catalyst exhibits outstanding activity with overpotential 198 mV at the current density of 10 mA cm−2 and a small Tafel slope of 39 mV dec−1 for oxygen evolution reaction. By using operando X-ray absorption spectroscopy, it is disclosed that the isolated single atom ruthenium was kept under the oxidation states of 4+ even at high overpotential due to synergetic electron coupling, which endow exceptional electrocatalytic activity and stability simultaneously.

Highly Selective, Iron‐Driven CO2 Methanation

AbstractCO2 methanation has gained traction for its potential in renewable energy storage, though the high cost of renewable hydrogen production and costly metals used in methanation catalyst synthesis remain a significant barrier to implementation. Herein we present a Ru−Fe@NCNT catalyst, consisting of ruthenium and iron nanoparticles on nitrogen‐doped carbon nanotubes, as a highly selective, hydrogen efficient, iron‐driven alternative to typical nickel and ruthenium catalysts used for CO and CO2 methanation. Ru−Fe@NCNT offer competitive CO2 conversion and methane selectivity, and a reduction of up to 80 % in ruthenium loading versus similar literature and commercial catalysts. It is proposed that this desirable CO2 methanation performance, using an atypical optimal feed gas composition where PH2/PCO2=3, is the result of effective cooperation between the iron‐catalysed reverse water gas shift and methane‐selective Fischer‐Tropsch, and ruthenium‐catalysed CO methanation reactions.

Enhanced dry methane reforming over Ru decorated mesoporous silica and its kinetic study

Ru with variable loadings (0.5–2 wt.%) in nanoparticle form, were deposited over ceria, magnesia modified mesoporous silica by single step synthesis followed by urea hydrolysis of the metal precursor. The obtained materials were tested for methane reforming with CO2 (DRM). The catalysts were substantially exposed to different characterisation techniques both before and after the reaction to get an insight into the structure-activity relationship. Characterisation results and activity study confirmed, homogeneous dispersion of nanosized ruthenium particles over a high surface area of modified silica possess strong metal support interaction, which restricts metal sintering and enables coke free CO2 reforming of methane (DRM). Introduction of ceria and magnesia strongly enhanced the surface oxygen storage capacity (OSC) that readily oxidise the deposited coke over the active metal during the activity analysis. An in-detailed study was carried out to evaluate the effect of reaction parameters and long-term activity analysis on the material. The catalyst systems with lower Ru loading performs a better activity in comparison to higher loading. At a higher Ruthenium loading, the metal particle size gets increase and remains mainly over the surface rather than in the pores which enhances the rate of coke deposition and hence decreases the catalyst activity.

Benign-by-Design Orange Peel-Templated Nanocatalysts for Continuous Flow Conversion of Levulinic Acid to N-Heterocycles

In this work, two different strategies have been employed to explore the potential valorization of biomass waste. A TiO2-based sample was prepared by a dry-milling strategy, involving orange peel valorization toward nanostructured materials. Subsequently, ruthenium deposition was accomplished by a chemical reduction method to obtain different ruthenium loadings on the titania support. The prepared catalysts were characterized using a multitechnique approach in terms of chemical, structural, and morphological properties. Levulinic acid, a typical model molecule associated with lignocellulosic biomass, was subsequently converted into N-heterocycles in a continuous flow reactor. The prepared Ru-TiO2 systems exhibited outstanding catalytic performance in terms of conversion and selectivity in comparison with Ru/P25 and Ru/C catalytic references. Maximum activity (79% conversion, 85% selectivity to 1-ethyl-2-(ethylideneamino)-5-methylpyrrolidin-2-ol) was achieved for the sample containing 3 wt % Ru, homogeneou...

Support structure and reduction treatment effects on CO oxidation of SiO2 nanospheres and CeO2 nanorods supported ruthenium catalysts

The effects of support structure and reducibility, oxidation and reduction treatment and ruthenium loading amount were studied in SiO2 nanospheres and CeO2 nanorods supported ruthenium catalysts on CO oxidation. 0.4, 1.0 and 5.0 wt% Ru were impregnated on SiO2 nanospheres and CeO2 nanorods using precipitation method and then the samples were oxidized in air. Half of the oxidized samples were also further reduced under hydrogen atmosphere to compare the effect of reduction treatment on the catalytic activity. Detailed XRD, Raman, TEM, H2-TPR, and CO oxidation analyses were carried out to understand the effects of RuOx-support interaction, oxidation and reduction treatment and ruthenium loading amount on the catalytic performance. Compared to SiO2 nanospheres supported ruthenium catalysts, both the oxidized and reduced RuOx/CeO2 catalysts exhibited superior catalytic performance in terms of CO conversion and low-temperature hydrogen consumption. After the reduction treatment in H2, the RuOx/CeO2 catalysts is further activated for low-temperature CO conversion. Especially, the 5.0 wt% Ru/CeO2-reduction sample can achieve ∼9% CO conversion at near room temperature. The enhanced low-temperature activity of CeO2 nanorods supported ruthenium catalysts was correlated strongly to the surface defects on CeO2 nanorods, dispersion of RuOx, and interfacial structures between CeO2 and RuOx.

Asymmetric Hydrogenation of β-Keto Esters Catalyzed by Ruthenium Species Supported on Porous Organic Polymer

A porous organic polymer (POP) with chiral 2, 2'-bis(diphenylphosphino)-1, 1'-binaphthalene (BINAP) has been prepared and characterized by several techniques including 13 C CP/MAS NMR, 31 P CP/MAS NMR, fourier transform infrared spectroscopy, powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy and nitrogen adsorption. The material exhibits amorphous microporous structure. After loading of ruthenium(Ⅱ) species via coordination, the composite material Ru/POP-BINAP could be used as a heterogeneous catalyst for the asymmetric hydrogenation of β -keto esters with high activity, excellent enantioselectivity and recyclability.

RuCl3 Supported on N‐Doped Graphene as a Reusable Catalyst for the One‐Step Glucose Oxidation to Succinic Acid

AbstractImpregnation of RuCl3 on N‐doped graphenes results in the formation of well‐dispersed, small ruthenium oxyhydroxide nanoparticles supported on N‐doped graphene that may exhibit high selectivity (87 %) for the conversion of glucose into succinic acid under wet oxidation conditions (160 °C, 18 atm O2 pressure). Ruthenium loading and N‐atom distribution on graphene influence the catalytic activity, the best performing catalyst having 1 wt. % Ru loading on a graphene having a large population of graphenic N atoms. The high catalytic selectivity to succinic acid was correlated with the presence of small ruthenium nanoparticles. The present catalyst improves the best one previously reported because it does not require the continuous addition of an excess of amine to reach high succinic acid selectivity and reusability.

Ruthenium Dioxide Catalysts for the Selective Oxidation of Benzylamine to Benzonitrile: Investigating the Effect of Ruthenium Loading on Physical and Catalytic Properties

The oxidative dehydrogenation of benzylamine to benzonitrile was studied in batch and continuous flow processes using ruthenium dioxide catalysts with varying ruthenium loadings. Increased conversions were observed in the continuous flow process compared with the batch process (up to 100% in the flow process compared with up to 92% in the batch process), with increased selectivity to benzonitrile (82 and 65%, respectively) and benzonitrile yields (84 and 58%, respectively). The major by-product was N-benzylidenebenzylamine. The ruthenium loading in the catalyst was successfully optimised and the most active catalyst had a ruthenium loading of 2.5–3.5 wt%.

Catalytic Supercritical Water Gasification: Continuous Methanization of Chlorella vulgaris

Continuous catalytic supercritical water gasification (CSCWG; 400 °C, 28 MPa) of microalgal biomass (Chlorella vulgaris) was carried out at the microalgae production site of ZHAW in Wadenswil (Switzerland) nonstop over a period of 100 h. Microalgae slurries (3–15 wt %) were successfully gasified to a methane-rich gas for 55 h. The low total organic carbon of the reactor effluent (<400 mg L–1) recorded during that period demonstrated the high catalytic activity of the Ru/C catalyst for converting microalgae to the gaseous products. The addition of a sulfur removal step with a commercial zinc oxide adsorbent was essential for protecting the catalyst against sulfur poisoning. A brine effluent rich in nutrients (N, K, S, P, Na) was withdrawn continuously from a salt separator. In summary, the use of a zinc oxide adsorbent upstream of the catalyst bed, together with a higher ruthenium loading of the catalyst, improved the long-term performance of the CSCWG process significantly.

Ruthenium(0) nanoparticles supported on nanohafnia: A highly active and long-lived catalyst in hydrolytic dehydrogenation of ammonia borane

Ruthenium(0) nanoparticles supported on nanohafnia (Ru0/HfO2) were prepared by impregnation of ruthenium(III) cations on the surface of hafnia followed by their reduction with sodium borohydride at room temperature. Ru0/HfO2 samples were isolated from the reaction solution by centrifugation and characterized by a combination of advanced analytical techniques including ICP-OES, BET, XRD, SEM-EDS, TEM, XPS. The catalytic activity of Ru0/HfO2 samples with various ruthenium loading in the range 0.5–5.0%wt Ru was tested in hydrogen generation from the hydrolysis of ammonia borane (AB) at room temperature. The highest catalytic activity was achieved by using 4.0%wt ruthenium loaded nanohafnia providing a turnover frequency of 170min−1 and an unprecedented catalytic life time (175,600 turnovers) in hydrogen generation from the hydrolysis of AB at 25.0±0.1°C. Ru0/HfO2 is reusable catalyst preserving 75% of the initial catalytic activity even after the fifth reuse in hydrogen generation from the hydrolysis of AB at room temperature. Our report also includes the results of kinetic studies depending on the catalyst concentration and temperature to determine the activation energy (Ea=65±3kJ/mol) for hydrolytic dehydrogenation of AB.

Catalytic supercritical water gasification: Interaction of sulfur with ZnO and the ruthenium catalyst

Continuous catalytic supercritical water gasification (CSCWG; 400°C, 28MPa) of microalgal biomass (Chlorella vulgaris) was carried out at the microalgae production site of ZHAW in Wädenswil (Switzerland) non-stop over a period of 100h. Characterization of the spent catalyst showed that mainly sulfur poisoning, and to a lesser extent coking, salt deposits, and some sintering of the Ru nanoparticles were responsible for the deactivation of the catalyst after 55h of time on-stream. The commercial zinc oxide adsorbent exhibited a high mechanical stability and good sulfur adsorption performance under supercritical water conditions although its specific surface area collapsed. In summary, the use of a zinc oxide adsorbent upstream of the catalyst bed, together with a higher ruthenium loading of the catalyst, improved the long-term performance of the CSCWG process significantly.

Robust ruthenium catalysts for the selective conversion of stearic acid to diesel-range alkanes

Triglycerides represent a type of sustainable energy source and robust catalysts for triglycerides refining to biofuels are very challenging. Herein, we report supported ruthenium catalysts, optimized from group VIII metal catalysts, for the selective conversion of triglycerides to diesel-range alkanes under mild conditions. The catalyst supports and ruthenium loadings show significant impacts on the performance of ruthenium catalysts, and Ru/TiO2 with ruthenium weight loading of 1.68% is optimized for the reaction. Typically, the platform compound stearic acid could be directly converted, or via 1-octadecanol as an intermediate product, to n-heptadecane and n-octadecane in n-heptane solvent using the optimized Ru/TiO2 catalyst at 473K and under 3MPa H2. On the basis of catalytic and spectroscopic characterization results, large ruthenium metal particles are established as the preferred active sites for stearic acid conversion. The complete reaction network of stearic acid deoxygenation on flat Ru (0001) is investigated by theoretical calculations. It is revealed that different pathways run simultaneously during the reaction and the adsorbed acyl species C17H35CO* are the key reaction intermediates for the catalytic deoxygenation on Ru (0001). The removal of adsorbed CO by hydrogenation is the rate-controlling step contributing to the highest energy barrier within the reaction network.

Catalytic Supercritical Water Gasification of Refuse Derived Fuel for High Energy Content Fuel Gas

Refuse derived fuel (RDF) was processed using hydrothermal gasification at high temperature to obtain a high energy content fuel gas. Supercritical water gasification of RDF was conducted at a temperature of 500 °C and 29 MPa pressure and also in the presence of a solid RuO2/γ-Al2O3 catalyst. The effect of residence time (0, 30 and 60 min) and different ruthenium loadings (5, 10, 20 wt% RuO2/γ-Al2O3) were investigated. Up to 93 % carbon gasification efficiency was achieved in the presence of 20 wt% RuO2/γ-Al2O3 catalyst. The fuel gas with the highest energy value of 22.5 MJ Nm−3 was produced with the 5 wt% RuO2/γ-Al2O3 catalyst after 30 min reaction time. The results were compared with the use of NaOH as a homogeneous catalyst. When NaOH was used, the maximum gross calorific value of the product gas was 32.4 MJ Nm−3 at 60 min reaction time as a result of CO2 fixation. High yields of H2 and CH4 were obtained in the presence of both the NaOH and RuO2/γ-Al2O3 catalysts.

Catalytic Upgrading of Methane to Higher Hydrocarbon in a Nonoxidative Chemical Conversion

Discovery of large shale gas reserves in recent years resulted in the reduction of natural gas price. In order to convert methane in a direct and energy efficient route, nonoxidative catalytic conversion is a potentially attractive option which includes an activation of methane molecules at low temperature. The oxide of transition metals such as Mo, Fe, V, W, Cr, Zn, and Cu have been studied as catalysts for methane conversion, where usually the conversion is lower than 20% and the operating temperature needed is above 800 °C which causes coking, thus resulting in an early catalyst deactivation. In this work, a noble transition metal, ruthenium, has been chosen as the catalyst with the objective to decrease the methane activation temperature, increase the stability, and also achieve higher conversion than other transition metal catalysts. The catalyst was prepared as 1.5 or 3.0 wt % ruthenium loading on zeolite (i.e., ZSM-5) and silica supports separately to compare the effect of metal loading and metal–s...

Preparation of a high performance cobalt catalyst for CO2 reforming of methane

The novel silica supported cobalt catalysts powders promoted by ruthenium and zirconium (CRZS) were prepared via a coprecipitation method for the catalytic CO2 reforming. The optimum metals loadings and pH of solution were systematically investigated in order to obtain a high performance and coke resistant catalyst. The most active, stable, and coke resistance catalyst was found in the catalyst prepared at pH 1 with the combination of 14.68wt.%, 0.14wt.%, 5.00wt.%, and 80.00wt.%, respectively for cobalt, ruthenium, zirconium and silica. BET, XRD, TPR, and H2 chemisorption analyzer found that the phenomena of Co3O4 cluster enlargement as the increase of cobalt loadings, the higher reduction degree and pore diameter as the increase of ruthenium loadings, and the inhibition of strong Co–SiO2 interaction in the proper zirconium loading were confirmed as the variation of metals loadings. The variable of pH solution during catalysts preparation gave significant effects on the catalysts stability and coke formation. The deactivation of catalyst prepared in low pH was related with the presence of surface ZrO of catalyst without any relation with coke formation. The obtained parameters of methane consumption rate based on Eley–Rideal mechanism showed that the surface chemical reaction between methane and surface oxygen became the rate-determining step of the reaction.

Catalytic functionalities of nano Ru catalysts supported on TiO2–ZrO2 mixed oxide for vapor phase hydrogenolysis of glycerol to propanediols

Vapor phase hydrogenolysis of glycerol was studied over Ru catalysts supported on TiO2–ZrO2 binary oxide. Ru catalysts with various ruthenium loadings from 1.0 to 6.0 wt% were prepared by deposition–precipitation method on the TiO2–ZrO2 mixed oxide support. These catalysts were characterized by X-ray diffraction, H2 temperature-programmed reduction, NH3 temperature-programmed desorption, transmission electron microscopy, BET surface area, XPS and CO chemisorption measurements. The catalysts exhibited superior performance for the vapor phase hydrogenolysis of glycerol at moderate temperature and atmospheric pressure. The mixed oxide support plays a significant role in improving the catalytic activity for the production of propanediols. The glycerol conversion and the selectivity of various products depend on the catalyst preparation method and also on the Ru content. The influence of acidity of the catalyst and its correlation to the catalytic performance (selectivity and conversion) has been studied. The weak and strong acidic sites of the catalysts measured by NH3-TPD play a key role in selective formation of 1,2-propanediol and 1,3-propanediol. XRD, TEM, XPS and CO chemisorption studies revealed that ruthenium was well dispersed on TiO2–ZrO2 which further contributed to the superior catalytic activity for glycerol hydrogenolysis.

One-pot conversion of cellulose to isosorbide using supported metal catalysts and ion-exchange resin

One-pot conversion of cellulose to isosorbide was investigated by supported metal catalysts and ion-exchange resin in water. The maximum isosorbide yield using supported platinum catalysts and Amberlyst 70 was less than 30%. The isosorbide yield drastically increased with supported ruthenium catalysts instead of supported platinum catalysts and it also increased with the loading of ruthenium on carbon support. One-pot conversion of cellulose to isosorbide by 4wt.% ruthenium catalyst and Amberlyst 70 proceeded with isosorbide yield of 55.8%.