scholarly journals Semiconductive Properties of Anodic Niobium Oxides

2006 ◽  
Vol 24 (2) ◽  
pp. 305-311 ◽  
Author(s):  
A I de-Sá ◽  
C M Rangel ◽  
P Skeldon ◽  
G E Thompson
Keyword(s):  
Niobium Oxides

scholarly journals Glucose Conversion into 5-Hydroxymethylfurfural over Niobium Oxides Supported on Natural Rubber-Derived Carbon/Silica Nanocomposite

Catalysts ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 887
Author(s):  
Rujeeluk Khumho ◽  
Satit Yousatit ◽  
Chawalit Ngamcharussrivichai
Keyword(s):  
Natural Rubber ◽  
Lewis Acid ◽  
Value Added ◽  
Acid Sites ◽  
Superior Performance ◽  
Lewis Acidity ◽  
Lewis Acid Sites ◽  
Niobium Oxides ◽  
Silica Nanocomposite ◽  
Loading Amount

5-Hydroxymethylfurfural (HMF) is one of the most important lignocellulosic biomass-derived platform molecules for production of renewable fuel additives, liquid hydrocarbon fuels, and value-added chemicals. The present work developed niobium oxides (Nb2O5) supported on mesoporous carbon/silica nanocomposite (MCS), as novel solid base catalyst for synthesis of HMF via one-pot glucose conversion in a biphasic solvent. The MCS material was prepared via carbonization using natural rubber dispersed in hexagonal mesoporous silica (HMS) as a precursor. The Nb2O5 supported on MCS (Nb/MCS) catalyst with an niobium (Nb) loading amount of 10 wt.% (10-Nb/MCS) was characterized by high dispersion, and so tiny crystallites of Nb2O5, on the MCS surface, good textural properties, and the presence of Bronsted and Lewis acid sites with weak-to-medium strength. By varying the Nb loading amount, the crystallite size of Nb2O5 and molar ratio of Bronsted/Lewis acidity could be tuned. When compared to the pure silica HMS-supported Nb catalyst, the Nb/MCS material showed a superior glucose conversion and HMF yield. The highest HMF yield of 57.5% was achieved at 93.2% glucose conversion when using 10-Nb/MCS as catalyst (5 wt.% loading with respect to the mass of glucose) at 190 °C for 1 h. Furthermore, 10-Nb/MCS had excellent catalytic stability, being reused in the reaction for five consecutive cycles during which both the glucose conversion and HMF yield were insignificantly changed. Its superior performance was ascribed to the suitable ratio of Brønsted/Lewis acid sites, and the hydrophobic properties generated from the carbon moieties dispersed in the MCS nanocomposite.

Tellurium-Niobium Oxides

1980 ◽  
Vol 466 (1) ◽  
pp. 81-86 ◽  
Author(s):  
J. C. J. Bart ◽  
G. Petrini
Keyword(s):  
Niobium Oxides

Hydrothermal synthesis of octahedra-based layered niobium oxide and its catalytic activity as a solid acid

2014 ◽  
Vol 4 (12) ◽  
pp. 4250-4257 ◽  
Author(s):  
Toru Murayama ◽  
Junli Chen ◽  
Jun Hirata ◽  
Keeko Matsumoto ◽  
Wataru Ueda
Keyword(s):  
Catalytic Activity ◽  
Hydrothermal Synthesis ◽  
Hydrothermal Method ◽  
Layered Structure ◽  
Niobium Oxide ◽  
Solid Acid ◽  
Structure Type ◽  
Niobium Oxides

Layered-structure-type niobium oxides were synthesized by the hydrothermal method by using ammonium niobium oxalate as a precursor.

Niobium Oxides: A New Path to Achieving High-Power Batteries? the Case of H-Ti-Nb Oxide System

2021 ◽  
Vol MA2021-02 (4) ◽  
pp. 477-477
Author(s):  
Etienne Le Calvez ◽  
Camille Douard ◽  
Olivier Crosnier ◽  
Thierry Brousse
Keyword(s):  
High Power ◽  
Oxide System ◽  
Niobium Oxides ◽  
High Power Batteries

Harmonious Dual-Riveting Interface Induced from Niobium Oxides Coating Toward Superior Stability of Li-Rich Mn-Based Cathode

2021 ◽  
Author(s):  
Aipeng Zhu ◽  
Jinhua Wu ◽  
Boya Wang ◽  
Jinwei Zhou ◽  
Yin Zhang ◽  
...  
Keyword(s):  
Niobium Oxides

scholarly journals Mechanical High-Temperature Properties and Damage Behavior of Coarse-Grained Alumina Refractory Metal Composites

Materials ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 3927
Author(s):  
Anja Weidner ◽  
Yvonne Ranglack-Klemm ◽  
Tilo Zienert ◽  
Christos G. Aneziris ◽  
Horst Biermann
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Refractory Metals ◽  
Coarse Grained ◽  
Damage Behavior ◽  
Niobium Oxides ◽  
Alumina Refractory ◽  
Increasing Temperature ◽  
New Generation ◽  
Refractory Composites

The present study provides the mechanical properties of a new generation of refractory composites based on coarse-grained Al2O3 ceramic and the refractory metals Nb and Ta. The materials were manufactured by refractory castable technology and subsequently sintered at 1600 °C for 4 h. The mechanical properties and the damage behavior of the coarse-grained refractory composites were investigated at high temperatures between 1300 and 1500 °C. The compressive strength is given as a function of temperature for materials with two different volume fractions of the refractory metals Ta and Nb. It is demonstrated that these refractory composites do not fail in a completely brittle manner in the studied temperature range. The compressive strength for all materials significantly decreases with increasing temperature. Failure occurred due to the formation of cracks along the ceramic/metal interfaces of the coarse-grained Al2O3 particles. In microstructural observations of sintered specimens, the formation of tantalates, as well as niobium oxides, were observed. The lower compressive strength of coarse-grained Nb-Al2O3 refractory composites compared to Ta-Al2O3 is probably attributed to the formation of niobium oxides. The formation of tantalates, however, seems to have no detrimental effect on compressive strength.

scholarly journals Development of a process for the concentration of the strategic tantalum and niobium oxides from tin slags

2019 ◽  
Vol 134 ◽  
pp. 97-103 ◽  
Author(s):  
E. Allain ◽  
N. Kanari ◽  
F. Diot ◽  
J. Yvon
Keyword(s):  
Niobium Oxides
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