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The growing emphasis on decarbonization and the use of renewable energy has sparked considerable interest in ammonia (NH3) synthesis under mild conditions, accompanied by the ...concurrent development of catalysts. Among these catalysts, BaO-promoted Ru has often been reported as a highly efficient catalyst for this reaction. Despite MgO being traditionally regarded as an optimal support for this catalytic system, its precise role has remained ambiguous. This study aims to elucidate the specific role of MgO as a support for Ru-BaO catalysts. Using pure MgO and MgO-Al2O3 mixed oxide (MgAlOx) with different MgO contents (MgO wt% = 5, 30, and 70) as supports, catalysts impregnated with equal amounts of Ba and Ru were prepared and analyzed to explore their NH3 synthesis activity and structural properties. Our observations reveal that while MgO does not directly promote Ru, it maintains robust basicity of BaO, enabling BaO to effectively function as an electronic promoter. In contrast, BaO supported on AlOx domain shows suppressed basicity, resulting in inertness as a promoter. Consequently, the Ru-Ba/MgO catalyst forms highly active Ru-BaO-MgO interfacial sites, leading to significantly higher activity, lower activation energy, and a distinct reaction mechanism compared to Ru-Ba/MgAlOx catalysts. This work sheds light on the importance of sequential interactions, i.e. support–promoter and promoter–active center interactions, in facilitating catalytic activity, thereby providing valuable insights essential for the design of advanced catalysts.
Ru sites acted as conductors rather than reductive activators to transfer electrons between pyridine N and PMS, resulting in the PMS activation for O2•- generation. Then 1O2 species were obtained via ...hydrolysis of O2•- and responsible for DCF degradation.
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•DCF was completely removed within 10 min in a wide pH range of 3.00–9.00.•1O2 was responsible for DCF removal and showed high tolerance to matrix effects.•The toxicity of almost all intermediates/products was significantly reduced.•CNRu showed high stability and reusability, and few Ru was leached in seven runs.
Metals doped carbon nitride (CN) is considered as a class of promising efficient catalysts for peroxymonosulfate (PMS) activation in water purification. Herein, ruthenium doped carbon nitride (CNRu) was synthesized via a facile one-pot method, and CNRu was in form of Ru–N2 that could efficiently activate PMS for DCF degradation and detoxification via nonradical pathway. DCF was completely removed within 10 min under the optimized condition in a wide working pH range of 3.00–9.00, while other traditional transition metals (e.g. Fe, Co, Ni, Cu) doped CN showed negligible removal of DCF due to adsorption rather than activation of PMS, which was demonstrated by DFT calculations. CNRu showed high stability and reusability after seven cycles and very few Ru leaching was detected in DCF degradation process. Ru was highly dispersed in form of Ru–N bond via coordinating to pyridine nitrogen, and the electron defect transfer between Ru and coordinated N, rather than redox cycle of Ru, mediated superoxide radicals (O2•−) evolution, which was further hydrolyzed into singlet oxygen (1O2) and responsible for DCF removal. Thus, the CNRu/PMS system showed high tolerance to inorganic anions. Much lower toxic intermediates/products than DCF were obtained via the strong electrophilic attack reaction between 1O2 and DCF in CNRu/PMS system. This study displayed a new practical application prospect of ruthenium-based materials for high-efficient removal and detoxification of DCF from wastewater.
Palladium and platinum–ruthenium nanoparticles supported on multi-walled carbon nanotubes (MWCNT) are prepared by the impregnation-reduction procedure. The materials obtained,
Pd/
MWCNT and
Pt–Ru/
...MWCNT, are characterized by TEM, ICP-AES and XRPD. Electrodes coated with
Pd/
MWCNT are scrutinized for the oxidation of methanol, ethanol or glycerol in 2
M KOH solution in half cells. The catalyst is very active for the oxidation of all alcohols, with glycerol providing the best performance in terms of specific current density and ethanol showing the lowest onset potential. Membrane-electrode assemblies have been fabricated using
Pd/
MWCNT anodes, commercial cathodes and anion-exchange membrane and evaluated in both single passive and active direct alcohol fuel cells fed with aqueous solutions of 10
wt.% methanol, 10
wt.% ethanol or 5
wt.% glycerol.
Pd/
MWCNT exhibits unrivalled activity as anode electrocatalyst for alcohol oxidation. The analysis of the anode exhausts shows that ethanol is selectively oxidized to acetic acid, detected as acetate ion in the alkaline media of the reaction, while methanol yields carbonate and formate. A much wider product distribution, including glycolate, glycerate, tartronate, oxalate, formate and carbonate, is obtained from the oxidation of glycerol. The results obtained with
Pt–Ru/
MWCNT anodes in acid media are largely inferior to those provided by
Pd/
MWCNT electrodes in alkaline media.
The activities of various supported catalysts were tested in a continuous flow reactor for production of CH4 and H2 from glucose via supercritical water gasification (SCWG) at a relatively low ...temperature (500°C). Based on this preliminary study, among all catalysts tested in this study Ni20%Ru2%/γ-Al2O3 catalyst was found to be the most active, achieving complete conversion of all carbon in glucose at 500°C and a weight-hourly space velocity (WHSV) of 3h−1. The addition of 2% Ru to Ni20%/γ-Al2O3 not only suppressed char/tar formation, promoted the carbon gasification efficiently, but also increased methane formation. Moreover, high stability of Ni20%Ru2%/γ-Al2O3 catalyst was demonstrated in the experimental runs for 20h on-stream. The roles of ruthenium as a co-catalyst in Ni/Al2O3 were found to be not only increasing nickel dispersion, enhancing nickel's reducibility, but also preventing leaching of Al and Ni metals in SCW. However, NiRu supported on either TiO2 and activated carbon led to lower catalytic activity and frequent plugging after only 3h on-stream.
•Renewable CH4/H2 efficiently produced by SCWG of glucose at 500°C.•Ni20%Ru2%/Al2O3 exhibited the highest activity/stability for CH4 yield.•Ru proved to be an excellent promoter to Ni catalyst for SCWG of biomass.•Ru promotes Ni catalysts by enhancing dispersion/reducibility of metals.
The effects of using fumed SiO
2, MCM-41, and SBA-15 as supports for Ru and Ni catalysts on ammonia decomposition were investigated. It was found that the supported catalysts on these siliceous ...materials are more active than those supported on ordinary silica. In general, the supported Ru catalysts are more active than the Ni catalysts, and MCM-41 is the best support material for Ru and Ni. Significant enhancement in activity was observed when the supported Ru catalysts were modified by KOH, but such effect was minimal in the cases of supported Ni catalysts. The results of N
2 adsorption and transmission electron microscopy studies revealed that the Ni particles of Ni/MCM-41(TIE) prepared by template-ion exchange (TIE) method are largely located inside the pores of MCM-41. Compared with the Ni/MCM-41(IMP) catalyst prepared by impregnation method, the Ni/MCM-41(TIE) catalyst exhibited appropriate Ni dispersion and weaker Ni/support interaction, and consequently higher catalytic activity. In terms of the remarkable changes in turnover frequency (TOF) with Ni dispersion on different catalysts, it was demonstrated that NH
3 decomposition over Ni is significantly structure sensitive. Some unique metal clusters similar to B5 active sites should be responsible for the catalytic activities. Preparation methodology has a substantial influence on metal dispersion. For the supported Ni catalysts prepared by the TIE method, the generated metal particles are very small and the constitution of unique active sites becomes unfavorable, which accounts for the apparently lower TOF values.
A ruthenium‐catalyzed formal anti‐Markovnikov hydroamination of allylic alcohols for the synthesis of chiral γ‐amino alcohols is presented. Proceeding via an asymmetric hydrogen‐borrowing process, ...the catalysis allows racemic secondary allylic alcohols to react with various amines, affording enantiomerically enriched chiral γ‐amino alcohols with broad substrate scope and excellent enantioselectivities (68 examples, up to >99 % ee).
Anti‐Markovnikov hydroamination of racemic allylic alcohols produces chiral γ‐amino alcohols, which are key intermediates for the synthesis of many drugs and biologically active molecules. Driven by a ruthenium catalyst via a hydrogen borrowing pathway, the reaction features a broad substrate scope (68 examples) and excellent enantioselectivities (up to >99 % ee).
A ruthenium‐catalyzed para‐selective alkylation of protected anilines to construct α‐arylacetonitrile skeletons has been reported. We firstly disclosed the ethyl 2‐bromo‐2‐cyanopropanoate was an ...effective alkylating reagent in ruthenmuim‐catalyzed remote‐selective C−H functionalization. A wide variety of α‐arylacetonitrile skeletons can be directly obtained with moderate to good yields. Importantly, the products contain both nitrile and ester groups guaranteeing its direct transformation into other useful synthetic units, indicating the synthetic importance of this method.
Herein, we report a ruthenium‐catalyzed para‐selective alkylation reaction with ethyl 2‐bromo‐2‐cyanopropanoate as the novel alkylating reagent to directly form an α‐arylacetonitrile skeleton with quaternary carbon center. Various protected anilines were tolerated, yielding the corresponding products in moderate to good yields.
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