Coating of uniform inorganic particles with polymers: III. Polypyrrole on different metal oxides

1995 ◽  
Vol 10 (5) ◽  
pp. 1327-1336 ◽  
Author(s):  
Chin-Lin Huang ◽  
Egon Matijevic
Keyword(s):  
Metal Oxide ◽  
Metal Ions ◽  
Metal Oxides ◽  
Dissolution Process ◽  
Reductive Dissolution ◽  
Inorganic Particles ◽  
Ethanol Medium ◽  
Oxide Particles ◽  
Coated Spheres

Five kinds of uniform metal oxide particles (α-Fe2O3, CeO2, CuO, NiO, and SiO2) were coated with polypyrrole by reacting the dispersed solids with pyrrole in a water/ethanol medium without the use of a soluble oxidant. When the process was carried out in air, all particles were coated with the polymer, although the thickness of the layer varied on different cores. In CuO dispersions, independent polypyrrole particles were produced in addition to coated spheres. While oxygen is the major oxidant that initiates the polymerization of pyrrole, some metal oxides may also affect the reaction both in terms of the amount and the composition of the shell. Thus, α-Fe2O3 and SiO2 were found to be inactive in the polymerization, while CeCh and CuO react with the adsorbed pyrrole molecules through a reductive-dissolution process, in which the monomers are oxidized, causing a release of reduced metal ions.

scholarly journals Technological Aspects of Vegetable Oils Transesterification with Ethanol in the Presence of Metal Oxides

2020 ◽  
Vol 69 (7-8) ◽  
pp. 365-370
Author(s):  
Yuriy Melnyk ◽  
Roman Starchevskyi ◽  
Stepan Melnyk
Keyword(s):  
Zinc Oxide ◽  
Catalytic Activity ◽  
Metal Oxide ◽  
Metal Oxides ◽  
Vegetable Oil ◽  
Vegetable Oils ◽  
Sunflower Oil ◽  
Mass Fraction ◽  
Oxide Catalyst ◽  
Oxide Particles

Transesterification of vegetable oil with ethanol in the presence of fine metal oxide particles as catalysts has been investigated. Zinc and nickel(II) oxides were shown to have the highest catalytic activity. In their presence, the conversion of sunflower oil triglycerides, after 150 min, reached 95.3 and 94.2 %, respectively. The optimal mass fraction of zinc oxide catalyst was found to be 0.25–0.31 %. In the presence of zinc oxide, with mass fraction of water in ethanol of 5 and 10 %, the conversion of triglycerides was 98.5 and 94.8 %, respectively.

scholarly journals A Moving Bed Reactor for Thermochemical Energy Storage Based on Metal Oxides

Energies ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1232 ◽  
Author(s):  
Nicole Carina Preisner ◽  
Marc Linder
Keyword(s):  
High Temperature ◽  
Energy Storage ◽  
Iron Oxide ◽  
Metal Oxide ◽  
Metal Oxides ◽  
Thermal Energy ◽  
High Energy ◽  
Heat Extraction ◽  
Moving Bed ◽  
Oxide Particles

High-temperature thermal energy storage enables concentrated solar power plants to provide base load. Thermochemical energy storage is based on reversible gas–solid reactions and brings along the advantage of potential loss-free energy storage in the form of separated reaction products and possible high energy densities. The redox reaction of metal oxides is able to store thermal energy at elevated temperatures with air providing the gaseous reaction partner. However, due to the high temperature level, it is crucial to extract both the inherent sensible and thermochemical energies of the metal-oxide particles for enhanced system efficiency. So far, experimental research in the field of thermochemical energy storage focused mainly on solar receivers for continuously charging metal oxides. A continuously operated system of energy storage and solar tower decouples the storage capacity from generated power with metal-oxide particles applied as heat transfer medium and energy storage material. Hence, a heat exchanger based on a countercurrent moving bed concept was developed in a kW -scale. The reactor addresses the combined utilization of the reaction enthalpy of the oxidation and the extraction of thermal energy of a manganese–iron-oxide particle flow. A stationary temperature profile of the bulk was achieved with two distinct temperature sections. The oxidation induced a nearly isothermal section with an overall stable off-gas temperature. The oxidation and heat extraction from the manganese–iron oxide resulted in a total energy density of 569 kJ/kg with a thermochemical share of 21.1%.

Metal Oxide Particles: Multi Ball-In-Ball Hybrid Metal Oxides (Adv. Mater. 15/2011)

2011 ◽  
Vol 23 (15) ◽  
pp. 1687-1687 ◽  
Author(s):  
Won Cho ◽  
Yun Hee Lee ◽  
Hee Jung Lee ◽  
Moonhyun Oh
Keyword(s):  
Metal Oxide ◽  
Metal Oxides ◽  
Oxide Particles

scholarly journals The Model of Metal Oxide Particle Formation from Water Solutions of Salts

2010 ◽  
Vol 4 (2) ◽  
pp. 95-100 ◽  
Author(s):  
Volodymyr Kislenko ◽  
◽  
Liliya Oliynyk ◽  
Svyatoslav Ivanyshyn ◽  
◽  
...  
Keyword(s):  
Metal Oxide ◽  
Metal Ions ◽  
Metal Complexes ◽  
Oxide Particle ◽  
Ionization Constants ◽  
Primary Metal ◽  
Metal Hydroxides ◽  
Water Solutions ◽  
Inorganic Acids ◽  
Oxide Particles

The model describing the formation of metal oxide particles from water solutions of salts was suggested. Dependence of instability constants of metal complexes and ionization constants of oxygen containing inorganic acids on the electron density upon the central ion or atom allows to calculate these values for metal hydroxides. Equations describing the number of metal ions in polyion, the concentration of polyions in solution, the number of metal ions in primary metal oxide particles and their concentration in the system were suggested.

scholarly journals Effects of Metal Ions, Metal, and Metal Oxide Particles on the Synthesis of Hydrochars

ACS Omega ◽  
2020 ◽  
Vol 5 (11) ◽  
pp. 5601-5607
Author(s):  
Vahid Saadattalab ◽  
Xia Wang ◽  
Anthony E. Szego ◽  
Niklas Hedin
Keyword(s):  
Metal Oxide ◽  
Metal Ions ◽  
Oxide Particles

HREM Study of electron-induced surface radiation damage in ReO3

1991 ◽  
Vol 49 ◽  
pp. 636-637
Author(s):  
R. Ai ◽  
H.-J. Fan ◽  
L. D. Marks
Keyword(s):  
Transition Metal ◽  
Metal Ions ◽  
Metal Oxides ◽  
Electron Irradiation ◽  
Transition Metal Oxides ◽  
Carbon Film ◽  
Transition Metal Ions ◽  
Surface Radiation ◽  
Valence Transition ◽  
Electron Microscopes

It has been known for a long time that electron irradiation induces damage in maximal valence transition metal oxides such as TiO2, V2O5, and WO3, of which transition metal ions have an empty d-shell. This type of damage is excited by electronic transition and can be explained by the Knoteck-Feibelman mechanism (K-F mechanism). Although the K-F mechanism predicts that no damage should occur in transition metal oxides of which the transition metal ions have a partially filled d-shell, namely submaximal valence transition metal oxides, our recent study on ReO3 shows that submaximal valence transition metal oxides undergo damage during electron irradiation.ReO3 has a nearly cubic structure and contains a single unit in its cell: a = 3.73 Å, and α = 89°34'. TEM specimens were prepared by depositing dry powders onto a holey carbon film supported on a copper grid. Specimens were examined in Hitachi H-9000 and UHV H-9000 electron microscopes both operated at 300 keV accelerating voltage. The electron beam flux was maintained at about 10 A/cm2 during the observation.

Metal-oxide based ammonia gas sensors: A review

2020 ◽  
Vol 10 ◽  
Author(s):  
Priya Gupta ◽  
Savita Maurya ◽  
Narendra Kumar Pandey ◽  
Vernica Verma
Keyword(s):  
Metal Oxide ◽  
Metal Oxides ◽  
Gas Sensor ◽  
Gas Sensors ◽  
Review Paper ◽  
Gas Sensing ◽  
Gas Sensitivity ◽  
Ammonia Gas ◽  
Ammonia Sensing ◽  
Ammonia Gas Sensors

: This review paper encompasses a study of metal-oxide and their composite based gas sensors used for the detection of ammonia (NH3) gas. Metal-oxide has come into view as an encouraging choice in the gas sensor industry. This review paper focuses on the ammonia sensing principle of the metal oxides. It also includes various approaches adopted for increasing the gas sensitivity of metal-oxide sensors. Increasing the sensitivity of the ammonia gas sensor includes size effects and doping by metal or other metal oxides which will change the microstructure and morphology of the metal oxides. Different parameters that affect the performances like sensitivity, stability, and selectivity of gas sensors are discussed in this paper. Performances of the most operated metal oxides with strengths and limitations in ammonia gas sensing application are reviewed. The challenges for the development of high sensitive and selective ammonia gas sensor are also discussed.

scholarly journals Thermochemical Energy Storage Performance Analysis of (Fe,Co,Mn)Ox Mixed Metal Oxides

Catalysts ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 362
Author(s):  
Yabibal Getahun Dessie ◽  
Qi Hong ◽  
Bachirou Guene Lougou ◽  
Juqi Zhang ◽  
Boshu Jiang ◽  
...  
Keyword(s):  
Energy Storage ◽  
Metal Oxide ◽  
Metal Oxides ◽  
Redox Reaction ◽  
Gas Flow ◽  
Oxygen Exchange ◽  
Engineering Industry ◽  
Oxide Material ◽  
Oxide Materials ◽  
Uptake Ratio

Metal oxide materials are known for their ability to store thermochemical energy through reversible redox reactions. Metal oxides provide a new category of materials with exceptional performance in terms of thermochemical energy storage, reaction stability and oxygen-exchange and uptake capabilities. However, these characteristics are predicated on the right combination of the metal oxide candidates. In this study, metal oxide materials consisting of pure oxides, like cobalt(II) oxide, manganese(II) oxide, and iron(II, III) oxide (Fe3O4), and mixed oxides, such as (100 wt.% CoO, 100 wt.% Fe3O4, 100 wt.% CoO, 25 wt.% MnO + 75 wt.% CoO, 75 wt.% MnO + 25 wt.% CoO) and 50 wt.% MnO + 50.wt.% CoO), which was subjected to a two-cycle redox reaction, was proposed. The various mixtures of metal oxide catalysts proposed were investigated through the thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), energy dispersive X-ray (EDS), and scanning electron microscopy (SEM) analyses. The effect of argon (Ar) and oxygen (O2) at different gas flow rates (20, 30, and 50 mL/min) and temperature at thermal charging step and thermal discharging step (30–1400 °C) during the redox reaction were investigated. It was revealed that on the overall, 50 wt.% MnO + 50 wt.% CoO oxide had the most stable thermal stability and oxygen exchange to uptake ratio (0.83 and 0.99 at first and second redox reaction cycles, respectively). In addition, 30 mL/min Ar–20 mL/min O2 gas flow rate further increased the proposed (Fe,Co,Mn)Ox mixed oxide catalyst’s cyclic stability and oxygen uptake ratio. SEM revealed that the proposed (Fe,Co,Mn)Ox material had a smooth surface and consisted of polygonal-shaped structures. Thus, the proposed metallic oxide material can effectively be utilized for high-density thermochemical energy storage purposes. This study is of relevance to the power engineering industry and academia.

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