Towards High Efficacy of Pd-Au/C Catalyst for Tetrachloromethane Hydrodechlorination

We present an efficient strategy for synthesising the PdAu catalysts with a homogeneous PdAu alloy phase for environmentally important hydrodechlorination of tetrachloromethane in the gas phase. The synthesis of carbon-supported catalysts involved two major steps: (i) incorporation of palladium and gold nanoparticles into carbon support and (ii) activation of the catalysts. The critical part of this work was to find the optimal conditions for both steps. Thus, the incorporation of the nanoparticles was carried out in two ways, by impregnation and direct redox reaction method using acetone solutions of metal precursor salts. The activation was performed either by a conventional thermal reduction in hydrogen or flash irradiation in a microwave oven. The homogeneity and structure of the PdAu alloy were found to depend on the catalyst activation method critically. In all cases, we observed better homogeneity for catalysts that were subject to microwave irradiation. Moreover, the flash microwave irradiation of prepared catalysts provided catalysts of better stability and selectivity towards the desired products (hydrocarbons) in the hydrodechlorination of tetrachloromethane as compared to the catalyst obtained by conventional thermal activation in hydrogen.

Download Full-text

Novel Carbon Structure as Highly Stable Support for Electro-catalyst in Acid Media: Regulating Oxygen Functionalization Behavior of Carbon

New Journal of Chemistry ◽

10.1039/d1nj01110c ◽

2021 ◽

Author(s):

Guokang Han ◽

Yongrong Sun ◽

Yuxin Liu ◽

Lingfeng Li ◽

Xudong Li ◽

...

Keyword(s):

Precious Metal ◽

Catalytic Properties ◽

Supported Catalysts ◽

Carbon Support ◽

Carbon Structure ◽

Acid Media

The nature of carbon support has huge effects on the catalytic properties of supported catalysts. When utilized for electrochemical purposes as support for precious metal in acid media, the oxygen...

Download Full-text

Laser electrodispersion as a new chlorine-free method for the production of highly effective metal-containing supported catalysts

Pure and Applied Chemistry ◽

10.1351/pac-con-11-07-12 ◽

2012 ◽

Vol 84 (3) ◽

pp. 495-508 ◽

Cited By ~ 23

Author(s):

Ekaterina S. Lokteva ◽

Anton A. Peristyy ◽

Natalia E. Kavalerskaya ◽

Elena V. Golubina ◽

Lada V. Yashina ◽

...

Keyword(s):

Gas Phase ◽

High Stability ◽

Heterogeneous Catalysts ◽

Supported Catalysts ◽

Promising Technique ◽

Wet Impregnation ◽

Oxide Supports ◽

Highly Active ◽

Specific Catalytic Activity ◽

Free Metal

Laser electrodispersion (LED) of metals is a promising technique for the preparation of heterogeneous catalysts as an alternative to wet impregnation of supports with the corresponding salt solutions. The LED technique can be used to deposit highly active chloride- and nitrate-free metal nanoparticles onto carbon or oxide supports. We report preparation and properties of new Ni-, Pd-, and Au-containing alumina-supported catalysts with low metal loadings (10–3–10–4 % mass) and their comparison with the previously studied carbon (Sibunit) supported systems. The catalysts demonstrate high stability and extremely high specific catalytic activity (by 2–3 orders of magnitude higher than for traditional catalysts) in the gas-phase hydrodechlorination (HDC) of chlorobenzene (CB).

Download Full-text

COHERENT SYNCHRONIZATION OF PYRIDINE DIMERIZATION REACTIONS AND DECOMPOSITION OF “GREEN OXIDANTS” – H2O2 AND N2O

Azerbaijan Chemical Journal ◽

10.32737/0005-2531-2021-4-6-11 ◽

2021 ◽

Vol 0 (4) ◽

pp. 6-11

Author(s):

I.T. Nagieva ◽

◽

N.I. Ali-zadeh ◽

T.М. Nagiev ◽

◽

...

Keyword(s):

Hydrogen Peroxide ◽

Nitrous Oxide ◽

Gas Phase ◽

Atmospheric Pressure ◽

Raw Materials ◽

Oxidizing Agent ◽

Optimal Conditions ◽

Pyridine Bases ◽

Pharmaceutical Industries ◽

Oxidation By Hydrogen Peroxide

In recent years, hydrogen peroxide and nitrous oxide (1) "green oxidants" – have attracted much attention of researchers as a selective oxidizing agent for the catalytic oxidation of pyridine bases. In this regard, the reaction of pyridine oxidation by hydrogen peroxide and nitrous oxide under homogeneous conditions, in the gas phase, without the use of catalysts, at atmospheric pressure, has been experimentally investigated. Areas of selective oxidation of pyridine with hydrogen peroxide and nitrous oxide have been established, and optimal conditions have been found for obtaining valuable raw materials required in the petrochemical, chemical, and pharmaceutical industries

Download Full-text

Surfactant-Free Colloidal Strategies for Highly Dispersed and Active Supported IrO2 Catalysts: Synthesis and Performance Evaluation for the Oxygen Evolution Reaction

10.26434/chemrxiv.13643807.v1 ◽

2021 ◽

Author(s):

Francesco Bizzotto ◽

Jonathan Quinson ◽

Johanna Schröder ◽

Alessandro Zana ◽

Matthias Arenz

Keyword(s):

Supported Catalysts ◽

Active Phase ◽

Carbon Support ◽

Colloidal Dispersions ◽

Catalyst Design ◽

Transition Electron Microscopy ◽

Highly Active ◽

X Ray Scattering ◽

And Performance ◽

Transition Electron

Supported Ir oxide catalysts obtained from surfactant-free colloidal Ir nanoparticles (NPs) synthesized in alkaline methanol (MeOH), ethanol (EtOH), and ethylene glycol (EG) are investigated and compared. The comparison of independent techniques such as transition electron microscopy (TEM), small angle X-ray scattering (SAXS), and electrochemistry allows shedding light on the parameters that affect the dispersion of the active phase as well as the catalytic activity. The colloidal dispersions obtained are suitable to develop supported catalysts with little NP agglomeration on a carbon support leading to highly active catalysts with more than 400 A g-1Ir reached at 1.5 VRHE for the OER. While the more common surfactant-free alkaline EG synthesis requires flocculation and re-dispersion leading to Ir loss, the main difference between methanol and ethanol as solvent is related to the dispersibility of the support material. The choice of the suitable monoalcohol determines the maximum achieved Ir loading on the support without detrimental particle agglomeration. This simple consideration on catalyst design can readily lead to significantly improved catalysts.

Download Full-text

XRD characterization of highly dispersed metal catalysts on carbon support

Journal of Materials Research ◽

10.1557/jmr.1993.1829 ◽

1993 ◽

Vol 8 (8) ◽

pp. 1829-1835 ◽

Cited By ~ 15

Author(s):

Paolo Scardi ◽

Pier Luigi Antonucci

Keyword(s):

Particle Size ◽

Supported Catalysts ◽

Profile Analysis ◽

Rietveld Method ◽

Carbon Support ◽

Lattice Parameter ◽

Microstructural Parameters ◽

Transmission Electron ◽

Supported Pt Catalysts ◽

Highly Dispersed

Carbon-supported Pt catalysts were prepared from H2PtCl6 or K2PtCl6 aqueous solutions. Particle size and structure after several thermal activation treatments were studied by X-Ray Diffraction (XRD), Transmission Electron Microscopy (TEM), and Cyclic Voltammetry (CV), and the results of the three techniques were compared. As the catalysts were highly dispersed on an amorphous support, a conventional XRD profile analysis for crystallite size determination could not be performed properly, because of the strong overlapping between the broad Pt peaks superposed to the halos of the amorphous phase. Thus, a new procedure of whole XRD pattern fitting, based on the Rietveld method, was used to have reliable data of Pt particle size (surface area) and lattice parameter. All structural and microstructural parameters were refined within the same procedure, also considering the transparency of the carbon supported catalysts and minimizing the effect of the amorphous background. The method can also take into account the presence of bimodal particle size distributions, which is difficult to study by CV or TEM.

Download Full-text

Gas phase synthesis of isopropyl chloride from isopropanol and HCl over alumina and flexible 3-D carbon foam supported catalysts

Applied Catalysis A General ◽

10.1016/j.apcata.2017.05.013 ◽

2017 ◽

Vol 542 ◽

pp. 212-225

Author(s):

Natalia Bukhanko ◽

Christopher Schwarz ◽

Ajaikumar Samikannu ◽

Tung Ngoc Pham ◽

William Siljebo ◽

...

Keyword(s):

Gas Phase ◽

Supported Catalysts ◽

Carbon Foam ◽

Phase Synthesis ◽

Gas Phase Synthesis

Download Full-text

Treatment of Acidic Wastewater by Microwave Irradiation Fenton’s Reagent

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.864-867.1680 ◽

2013 ◽

Vol 864-867 ◽

pp. 1680-1683

Author(s):

Xiao Tong Guan ◽

Da Wei Yu

Keyword(s):

Microwave Irradiation ◽

Microwave Power ◽

Irradiation Time ◽

Removal Rate ◽

Fenton’S Reagent ◽

Optimal Conditions ◽

Fenton's Reagent ◽

Secondary Pollution ◽

Cod Removal Rate ◽

Acidic Wastewater

Acidic wastewater was treated by microwave irradiation Fenton’s reagent, the effect factors: initial concentration of wastewater, dosage of H2O2, microwave irradiation time, microwave power and pH on Acidic wastewater were investigated. The optimal conditions of operation are determined as follows: microwave power is 480W, microwave irradiation time is 5min, H2O2 is 2.0mL and FeSO4 is 0.07g, pH=1. Under these conditions, the COD removal rate is 90.15% for 50mL Acidic wastewater（be diluted ten times）.The result of wastewater treated by microwave irradiation Fenton’s reagent is obvious, and without secondary pollution to environment.

Download Full-text

Preparation of Exfoliated Graphite by Microwave Using Natural Graphite with Different Particle Sizes

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.163-167.2333 ◽

2010 ◽

Vol 163-167 ◽

pp. 2333-2336 ◽

Cited By ~ 1

Author(s):

Kun Yu

Keyword(s):

Particle Size ◽

Microwave Irradiation ◽

Small Particle ◽

Graphite Particle ◽

Microwave Oven ◽

Raw Material ◽

Exfoliated Graphite ◽

Particle Sizes ◽

Natural Graphite ◽

Graphite Intercalation

Three natural graphite flakes (35, 50 and 80 mesh) were used as raw material. Exfoliated graphite (EG) was prepared by rapidly heating residue H2SO4-graphite intercalation compounds (RGIC) in a muffle and by irradiating it in a microwave oven, respectively. Results show that the exfoliation volume of EG decreases with decreasing the raw graphite particle size. Compared with muffle heating, microwave irradiation is more helpful for the exfoliation of RGICs, especially for the small particle samples.

Download Full-text

Synthesis of Hydrotalcites Using Microwave Irradiation

MRS Proceedings ◽

10.1557/proc-454-235 ◽

1996 ◽

Vol 454 ◽

Cited By ~ 1

Author(s):

G. Fetter ◽

P. Bosch ◽

F. A. Hernandez

Keyword(s):

Microwave Irradiation ◽

Exchange Capacity ◽

Microwave Oven ◽

Anion Exchangers ◽

Domestic Microwave Oven

ABSTRACTHydrotalcites are mineral anion exchangers whose exchange capacity is determined by the amount of structural magnesium atoms (octahedrally coordinated) substituted by aluminium atoms. In this work we study the synthesis of hydrotalcites using a domestic microwave oven at room pressure. The effect of the oven power on the composition and on the resulting structure of two hydrotalcites differing on their nominal Al/Al+Mg ratio is presented.

Download Full-text