Search results for "Catalyst"

Effect of the Raney alloy composition on activity of a skeletal nickel catalyst Wpływ składu stopu Raneya na aktywność niklowego katalizatora szkiele…

2015

Atomically Precise, Thiolated Copper–Hydride Nanoclusters as Single-Site Hydrogenation Catalysts for Ketones in Mild Conditions

2019

Copper-hydrides are known catalysts for several technologically important reactions such as hydrogenation of CO, hydroamination of alkenes and alkynes, and chemoselective hydrogenation of unsaturated ketones to unsaturated alcohols. Stabilizing copper-based particles by ligand chemistry to nanometer scale is an appealing route to make active catalysts with optimized material economy; however, it has been long believed that the ligand-metal interface, particularly if sulfur-containing thiols are used as stabilizing agent, may poison the catalyst. We report here a discovery of an ambient-stable thiolate-protected copper-hydride nanocluster [Cu25H10(SPhCl2)18]3- that readily catalyzes hydrogen…

Aqueous synthesis of Z-scheme photocatalyst powders and thin-film photoanodes from earth abundant elements

2018

Riga Technical University supported the preparation of this manuscript from the Scientific Research Project Competition for Young Researchers No. ZP 2017/8

The Hydrogen‐Storage Challenge: Nanoparticles for Metal‐Catalyzed Ammonia Borane Dehydrogenation

2021

International audience; Dihydrogen is one of the sustainable energy vectors envisioned for the future. However, the rapidly reversible and secure storage of large quantities of hydrogen is still a technological and scientific challenge. In this context, this review proposes a recent state-of-the-art on H 2 production capacities from the dehydrogenation reaction of ammonia borane (and selected related amine-boranes) as a safer solid-source of H 2 by hydrolysis (or solvolysis), according to the different developed nanoparticle-based catalysts. The review groups the results according to the transition metals constituting the catalyst according a special view to current cost/availability consid…

First-principles calculations on Fe-Pt nanoclusters of various morphologies

2017

Financial support provided by Scientific Research Project for Students and Young Researchers Nr. SJZ/2016/17 implemented at the Institute of Solid State Physics, University of Latvia, is greatly acknowledged. A.P. and R.E. express their gratitude to High-performance computer centers of ISSP (University of Latvia) and St. Petersburg University. This research was partially supported by Graphene Flagship GrapheneCore1-AMD-696656-4.

H2-TPR, XPS and TEM Study of the Reduction of Ru and Re promoted Co/γ-Al2O3, Co/TiO2 and Co/SiC Catalysts

2016

<p class="1Body">Effects of Ru and Re promoters on Co-CoO<sub>x </sub>catalysts supported on γ-Al<sub>2</sub>O<sub>3</sub>, TiO<sub>2</sub> and SiC were investigated to improve the understanding of the role of promoters of the active phase of Co-CoO<sub>x</sub>-Ru and Co-CoO<sub>x</sub>-Re. The influence of promoter addition on the composition and activity of the catalysts was characterized by several methods, such as H<sub>2</sub>-TPR, XPS, chemisorption and TEM. Furthermore, the role of support and metal-support interaction was especially studied and different support materials were compared.</p&g…

Enhanced kinetics of hole transfer and electrocatalysis during photocatalytic oxygen evolution by cocatalyst tuning

2016

Understanding photophysical and electrocatalytic processes during photocatalysis in a powder suspension system is crucial for developing efficient solar energy conversion systems. We report a substantial enhancement by a factor of 3 in photocatalytic efficiency for the oxygen evolution reaction (OER) by adding trace amounts (∼0.05 wt %) of noble metals (Rh and Ru) to a 2 wt % cobalt oxide modified Ta3N5 photocatalyst particulate. The optimized system exhibited high quantum efficiencies (QEs) of up to 28 and 8.4% at 500 and 600 nm in 0.1 M Na2S2O8 at pH 14. By isolation of the electrochemical components to generate doped cobalt oxide electrodes, the electrocatalytic activity of cobalt oxide …

Nanoparticles of AlTiZr mixed oxides as support of hydrodesulfurizaton catalysts: Synthesis and characterisation

2012

Abstract TiAlZr mixed oxides, synthesized using sol–gel method, were characterized and used as supports of hydrodesulfurization catalysts (12 wt% Mo) prepared by impregnation either with molybdenum heteropolyacid H3PMo12O40 or its cobalt salt Co1.5PMo12O40. Structure, morphology and textural properties of oxides and catalysts were characterized using X-ray powder diffraction (XRD), Raman spectroscopy, Nitrogen adsorption porosimetry, TEM-EDS, temperature-programmed desorption (TPD) and temperature-programmed reduction (TPR) techniques. Activity of the catalytic systems was tested in thiophene hydrodesulfurization (HDS). No formation of a new oxide phase was revealed in the synthesized mixed…

Ni-Based Catalysts for Low Temperature Methane Steam Reforming: Recent Results on Ni-Au and Comparison with Other Bi-Metallic Systems

2013

Steam reforming of light hydrocarbons provides a promising method for hydrogen production. Ni-based catalysts are so far the best and the most commonly used catalysts for steam reforming because of their acceptably high activity and significantly lower cost in comparison with alternative precious metal-based catalysts. However, nickel catalysts are susceptible to deactivation from the deposition of carbon, even when operating at steam-to-carbon ratios predicted to be thermodynamically outside of the carbon-forming regime. Reactivity and deactivation by carbon formation can be tuned by modifying Ni surfaces with a second metal, such as Au through alloy formation. In the present review, we su…

Electrochemistry and electrocatalysis of a Pt@poly(neutral red) hybrid nanocomposite

2015

Abstract Platinum nanoparticles have been deposited on a scaffold of electrosynthetized phenazine-type polymer, the poly(neutral red). This work discusses the role of poly(neutral red) in the electrochemistry and electrocatalysis properties of the hybrid nanocomposite. In situ combination of electrochemical quartz crystal microbalance and visible-near infrared spectroscopy (cyclic Vis-NIR spectroelectrogravimetry) and a combination of electrochemical impedance spectroscopy and mass impedance spectroscopy ( ac -electrogravimetry) were employed. Two electrochemical processes have been identified in our experimental conditions. On the one hand, the radical cations (polarons) localized in the i…