Effects of niobium addition on ZSM-5 studied by thermal and spectroscopy methods

Barros, Ivoneide C.L.; Braga, Vítor; Pinto, Daniel S.; Macedo, Julio L. de; Filho, Geraldo N. Rocha; Dias, José A.; Dias, Sílvia C.L.

doi:10.1016/j.micromeso.2007.05.050

Cited by 35 publications

(28 citation statements)

References 39 publications

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“…28 XRD ( Figure S1 in the Supplementary Information (SI) section), IR and Raman (not shown) spectroscopic analyses were thus used to confirm the prepared materials.…”

Section: Resultsmentioning

confidence: 99%

Characterization of ZSM-5 modified with niobium pentoxide: the study of thiophene adsorption

Cavalcanti

Barros

Dias

et al. 2013

J. Braz. Chem. Soc.

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Adsorventes ZSM-5 impregnados com Nb 2 O 5 foram aplicados na remoção de enxofre sob a forma de tiofeno, substância refratária de difícil remoção dos combustíveis líquidos. Para tanto, foi preparado um combustível modelo contendo iso-octano contaminado com tiofeno nas concentrações de 877,5 a 1155 ppmw. As amostras foram caracterizadas por difratometria de raios X (XRD), espectroscopias no infravermelho (FTIR) e Raman (FT-Raman) por transformada de Fourier para confirmação dos adsorventes obtidos, sendo priorizado o estudo de adsorção com aquele contendo 5% de pentóxido de nióbio, que apresentou uma maior capacidade de remoção de tiofeno. Os melhores resultados de adsorção foram alcançados a 353 K, sendo observado um maior tempo para atingir o equilíbrio. Sob essas condições, o melhor ajuste cinético foi alcançado utilizando a equação de pseudo-segunda ordem, evidenciando o domínio do fenômeno de quimissorção. Por outro lado, sob menores temperaturas, o modelo de difusão apresentou uma melhor aproximação dos resultados experimentais. O aumento da temperatura também favoreceu os processos espontâneos.ZSM-5 adsorbents impregnated with Nb 2 O 5 were applied in the sulfur removal in the form of thiophene, refractory substance of difficult removal of liquid fuels. For this purpose, a model fuel containing iso-octane contaminated with thiophene in concentrations of 877.5 to 1155 ppmw was prepared. The samples were characterized by X-ray diffractometry (XRD), Fourier transform infrared (FTIR) and Fourier transform-Raman (FT-Raman) spectroscopies for confirmation of the adsorbents, being prioritized the adsorption study with that containing 5 wt.% of niobium pentoxide, because it showed a greater capacity for removal of thiophene. The best results of adsorption were achieved at 353 K, a longer time to reach equilibrium was observed. Under these conditions, the best kinetic fitting was achieved using the equation of pseudo-second order, demonstrating the domain of the phenomenon of chemisorption. While under lower temperatures, the diffusion model presented a better approximation of the experimental results. Also, the increasing of temperature did enhance spontaneous processes.

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“…28 XRD ( Figure S1 in the Supplementary Information (SI) section), IR and Raman (not shown) spectroscopic analyses were thus used to confirm the prepared materials.…”

Section: Resultsmentioning

confidence: 99%

Characterization of ZSM-5 modified with niobium pentoxide: the study of thiophene adsorption

Cavalcanti

Barros

Dias

et al. 2013

J. Braz. Chem. Soc.

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Section: Caracterización De Los Catalizadoresunclassified

“…4, para el N b 2 O 5 · 3H 2 O, se aprecio una banda principal alrededor de los 650 cm −1 correspondiente a octaedros de N bO 6 [37]. La región de los 500 cm −1 y 700 cm −1 presentó una serie de bandas de mediana intensidad, debidos a estiramientos N b − O, una banda débil y poco definida alrededor de los 290 cm −1 ,se asignó al enlace Nb-OH [37], [38]. La muestra de N b 2 O 5 · 3H 2 O puso a la vista una señal intensa y amplia cerca de 650 cm −1 que fue asignada a los estiramientos simétricos de los poliedros del enlace N b − O [39], ligeramente distorsionados.…”

Section: Caracterización De Los Catalizadoresunclassified

Estudio catalítico comparativo de los sistemas TiO2 y Nb2O5 en la degradación de cianuro en función del tipo de oxidante

López

Sierra

2012

ing.cienc.

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La viabilidad del uso de otros agentes fotocatalizadores como el niobio, radicaen disminuir las energías altas de la banda prohibida para hacerlo competitivo frente al TiO2, sin embargo la presencia de coayudantes de oxidación, talescomo H2O2 y O3 podrían presentar resultados sorprendentes en el desempeño catalítico, debido a una mayor generación del radicales OH. La obtención de óxidos de mayor área y propiedades texturales diferentes al oxido de niobio comercial, mejoran su actividad catalítica en la remoción de cianuro libre. El trabajo presenta resultados experimentales de fotodegradación de cianuro 100mg=l sobre TiO2 Degussa P- 25 y Nb2O5 · 3H2O, usando un fotorreactor CPC con una capacidad de 4L de solución, usando como fuente de radiación la luz solar, tomando una inclinación igual a la latitud de Cartagena 10.45°, los resultados indicaron un claro efecto del pH, el tipo de catalizador y el coayudante de oxidación. La reducción de ion cianuro del efluente contaminado aumento por la adición del agente oxidante (O3 y H2O2). Sugiriendo una mayor susceptibilidad del cianuro libre, para oxidarse a cianato de forma indirecta, por una mayor generación de radicales hidroxilos, inducidos por la presencia de H2O2 o del O3 bajo radiación solar. Se obtuvo porcentajes de oxidación fotocatalítica de cianuro libre, entre el 64% y 72% usando Nb2O5 · 3H2O y un rango entre 67% y 71% usando TiO2 Degussa P - 25. Los catalizadores fueron caracterizados estructuralmente usando DRX, BET,Raman e FT-IR, con la finalidad de correlacionar los cambios morfológicos con el desempeño catalítico.

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“…The same reaction was studied using Fe-ZSM-5 [5]. Barrows et al [6] found the effects of Nb on ZSM-5 where it was observed the change of structural property of HZSM-5 at different percentage of Nb impregnation. The characterization and catalytic performance of niobic acid dispersed over titanium silicate was investigated in 1-octene epoxidation [7].…”

Section: Introductionmentioning

confidence: 99%

Application of La-ZSM-5 Coated Silicon Carbide Foam Catalyst for Toluene Methylation with Methanol

Ghosal

Basu

Sengupta

2015

Bull. Chem. React. Eng. Catal.

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The performance of toluene methylation reaction was studied by H-ZSM-5 modified with La, Ce and Nb at different percentage loading and found that 10% metal loading is producing the best performance in the reaction in terms of toluene conversion. The catalyst was coated on silicon carbide foam support which showed better conversion than the pelleted catalyst. Again, among the treated and untreated H-ZSM-5, the La-ZSM-5 catalyst is chosen for the reaction for its highest selectivity towards xylene, the main product. All catalysts were characterized in terms of surface properties, SEM, XRD and NH3-TPD. Kinetic study was done by La-ZSM-5 with 10% loading. Langmuir Hinshelwood kinetic model with surface reaction as rate controlling step was selected as the rate equation. The activation energy was found to be 47 kJ/mol.

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Effects of niobium addition on ZSM-5 studied by thermal and spectroscopy methods

Cited by 35 publications

References 39 publications

Characterization of ZSM-5 modified with niobium pentoxide: the study of thiophene adsorption

Characterization of ZSM-5 modified with niobium pentoxide: the study of thiophene adsorption

Estudio catalítico comparativo de los sistemas TiO2 y Nb2O5 en la degradación de cianuro en función del tipo de oxidante

Application of La-ZSM-5 Coated Silicon Carbide Foam Catalyst for Toluene Methylation with Methanol

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