Structures of niobium pentoxide and their implications on chemical behavior

Ko, Edmond I.; Weissman, Jeffrey G.

doi:10.1016/0920-5861(90)87005-n

Cited by 179 publications

(117 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Figure 1 Figure 1-f, where the most intense peaks appear at 2θ angles of 27.3° (100%), 23.3° (55%) and 25.7° (44%). In previous studies, Ko and Weissman (1990) reported that, when calcined at 500°C, the forms of the TT and Tphases of Nb 2 O 5 have a similar XRD pattern. Other authors (Chary et al, 2002) The temperature-programmed reduction (TPR) profiles of bulk V 2 O 5 , Nb 2 O 5 and catalysts are presented in Figure 2.…”

Section: Resultsmentioning

confidence: 99%

Characterization and catalytic behavior of MoO3/V2O5/Nb2 O5 systems in isopropanol decomposition

Paiva

Monteiro

Zacharias

et al. 2006

Braz. J. Chem. Eng.

View full text Add to dashboard Cite

-The influence of molybdenum oxide as a promoter on the V 2 O 5 /Nb 2 O 5 system was investigated. A series of MoO 3 /V 2 O 5 /Nb 2 O 5 catalysts, with MoO 3 loading ranging from 1 to 3 wt% MoO 3 and fixed V 2 O 5 content (21 wt%), were prepared by impregnation of the Nb 2 O 5 support with an aqueous solution of ammonium metavanadate and ammonium molybdate. The acid-base properties of the catalysts were investigated to determine of the selectivity of the isopropanol decomposition reaction. The X-ray diffraction results showed the presence of the β-(Nb,V) 2 O 5 phase. The temperature-programmed reduction profiles showed that the reducibility of vanadium was affected by the presence of molybdenum oxide. Activity results for isopropanol decomposition revealed that the acid-base properties of V 2 O 5 /Nb 2 O 5 catalysts are affected upon incorporation of MoO 3 , specifically for loadings of 3 wt %. For this catalyst composition both propylene and acetone formation rates decreased.

show abstract

Section: Resultsmentioning

confidence: 99%

Characterization and catalytic behavior of MoO3/V2O5/Nb2 O5 systems in isopropanol decomposition

Paiva

Monteiro

Zacharias

et al. 2006

Braz. J. Chem. Eng.

View full text Add to dashboard Cite

show abstract

“…Figure 1 shows the XRD patterns of the samples. The structure of the samples and the crystallinity of niobium containing TS-1 (based on the highest diffraction line of TS-1) • , indicating that the sample is crystalline niobium oxide phase (T-Nb 2 O 3 ) with orthorhombic structure [20]. Similar orthorhombic phase of niobium oxide has been prepared by Paulis et al [21] for the preparation of niobium oxide from a precursor solution of niobium chloride in ethanol, and calcined at 700…”

Section: Catalysts Characterizationmentioning

confidence: 88%

Characterization and Catalytic Performance of Niobic Acid Dispersed over Titanium Silicalite

Prasetyoko

Ramli

Endud

et al. 2008

Advances in Materials Science and Engineering

View full text Add to dashboard Cite

Niobic acid, Nb 2 O 5 ·nH 2 O, has been supported on the titanium silicalite by impregnation method. The obtained materials were characterized by X-ray diffraction, infrared, and ultra-violet-visible diffuse reflectance spectroscopy, temperature programmed reduction, pyridine adsorption, and field emission scanning electron microscopy techniques. It was demonstrated that the tetrahedral titanium species still retained after impregnation of niobic acid. The results revealed that niobium species interacted with hydroxyl groups on the surface of TS-1. The niobium species in the catalysts are predominantly polymerized niobium oxides species or bulk niobium oxide with the octahedral structure. All catalysts showed both Brønsted and Lewis acid sites. The catalysts have been tested for epoxidation of 1-octene with aqueous hydrogen peroxide. It was found that the presence of niobic acid in the catalysts enhanced the rate of the formation of epoxide at the initial reaction time. Diol as a side product was also observed due to the acidic properties of the catalysts.

show abstract

“…As (TERAO, 1965;MCCONNELL et al, 1976;KO e WEISSMAN, 1990;NOWAK e ZIOLEK, 1999 : (A) 90Si-10Nb tratada termicamente a 900°C, (B) 70Si-30Nb tratada termicamente 900°C, (C) 70Si-30Nb tratada termicamente a 1000°C, (D) 70Si-30Nb tratada termicamente a 1100°C, (E) 50Si-50Nb tratada termicamente 900°C, (F) 50Si-50Nb tratada termicamente 1000°C, e (G) 50Si-50Nb tratada termicamente 1100°C por 10 horas. Detalhe: difração de elétrons mostrando a cristalização dos nanocompósitos.…”

Section: Microscopia Eletrônica De Transmissão De Alta Resolução (Metunclassified

“…A fase M, que foi identificada nos materiais do presente trabalho, cristaliza-se a 800°C, tem sido descrita na literatura como uma fase H mal cristalizada e muitos autores tem reconhecido que os polimorfos são essencialmente os mesmos. A discussão sobre essas duas fases cristalinas será retomada nas seções referentes à caracterização estrutural (TERAO, 1965;MCCONNELL et al, 1976;KO e WEISSMAN, 1990;NOWAK e ZIOLEK, 1999 (TANABE, 1990;ZIOLEK, 2003;NAKAJIMA et al, 2010;DI SERIO et al, 2012;SREETHAWONG et al, 2013), eletrocromismo (AEGERTER, 2001;BUENO et al, 2001;ROSARIO e PEREIRA, 2005;ROMERO et al, 2009), sensores (CHAMBON et al, 1997FANG et al, 2011;WANG et al, 2012;RANI et al, 2013) e materiais biocompatíveis para próteses (VELTEN et al, 2004;OCHSENBEIN et al, 2008;NASCIMENTO et al, 2011;RAMÍREZ et al, 2011), além das aplicações fotônicas que serão discutidas a seguir.…”

Section: Introductionunclassified

Desenvolvimento de materiais nanoestruturados à base de óxido de nióbio para aplicação em fotônica

Aquino¹

View full text Add to dashboard Cite

Structures of niobium pentoxide and their implications on chemical behavior

Cited by 179 publications

References 24 publications

Characterization and catalytic behavior of MoO3/V2O5/Nb2 O5 systems in isopropanol decomposition

Characterization and catalytic behavior of MoO3/V2O5/Nb2 O5 systems in isopropanol decomposition

Characterization and Catalytic Performance of Niobic Acid Dispersed over Titanium Silicalite

Desenvolvimento de materiais nanoestruturados à base de óxido de nióbio para aplicação em fotônica

Contact Info

Product

Resources

About