Anatase–rutile transformation in TiO2–V2O5 catalyst coatings for ceramic foams

Bucharsky, Ethel C.; Schell, Karl G.; Oberacker, R.; Hoffmann, Michael J.

doi:10.1016/j.jeurceramsoc.2008.12.007

Cited by 37 publications

(16 citation statements)

References 39 publications

(37 reference statements)

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“…O processo pelo qual impurezas são introduzidas na estrutura do semicondutor é conhecido por dopagem [63]. As impurezas/dopantes geralmente são elementos metálicos ou não-metálicos que se alojam na estrutura do TiO 2 na forma intersticial ou substitucional [40,64]. A fotoatividade depende muito da presença dos dopantes, além da presença de substâncias como sílica amorfa na interface e/ou contornos de grã o que tem grande infl uência sobre a taxa de transferência de massa, difusão e crescimento de cristalito da titânia [6].…”

Section: Estabilização Térmica Da Fase Anataseunclassified

“…A fotoatividade depende muito da presença dos dopantes, além da presença de substâncias como sílica amorfa na interface e/ou contornos de grã o que tem grande infl uência sobre a taxa de transferência de massa, difusão e crescimento de cristalito da titânia [6]. O próprio processo de formação das fases via solução sólida favorece a inclusão de impurezas e o surgimento de defeitos [40,64].…”

Section: Estabilização Térmica Da Fase Anataseunclassified

“…Ao aumentar a quantidade de V 2 O 5 há uma menor área superfi cial específi ca a uma determinada temperatura [64].…”

Section: +unclassified

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Superfícies fotocatalíticas de titânia em substratos cerâmicos: Parte I: Síntese, estrutura e fotoatividade

et al. 2013

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ResumoA fotocatálise é um processo de oxidação avançada capaz de transformar uma grande variedade de poluentes orgânicos tóxicos em substâncias inofensivas em condições ambientes. Porém, a utilização do dióxido de titânio na fase anatase em produtos cerâmicos é limitada devido à transformação para fase rutilo em temperaturas superiores a 400 °C. As pesquisas apontam caminhos promissores para inibir a formação da fase rutilo através da introdução de dopantes na estrutura do semicondutor. Neste trabalho, foi realizada uma revisão dos principais aspectos encontrados na literatura especializada sobre fotocatálise com dióxido de titânio, em particular a relação entre estrutura química e atividade fotocatalítica. Palavras-chave: fotocatálise, dióxido de titânio, superfícies cerâmicas. Abstract Photocatalysis has been considered as an advanced oxidation process capable of transforming a large variety of toxic organic

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Section: Estabilização Térmica Da Fase Anataseunclassified

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Superfícies fotocatalíticas de titânia em substratos cerâmicos: Parte I: Síntese, estrutura e fotoatividade

et al. 2013

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“…Those RPC are cellular structures composed of a three-dimensional interconnected pores network of struts, are know for high porosity, high strength, acid and alkali resistant [3][4][5][6]. These highly porous materials have a lot of applications as filters for molten metal, hot gas and diesel engine exhausts filters, catalyst carriers, biomaterials, thermal insulators for furnaces and aerospace applications, gas combustion burners and lightweight building materials [7][8][9][10][11][12][13][14]. Also the RPC were tried to immobilizing microalgae or saccharomyces cerevisiae [15][16].…”

Section: Introductionmentioning

confidence: 99%

Preparation of large effective specific surface area reticulate porous ceramics by polymeric foam replication process using recoating technique

et al. 2011

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Large effective specific surface area reticulate porous ceramics (RPC) were fabricated by a polymeric foam replication process using of two-step route (presintering-recoating). The coating slurries used clay as the major material and silica sol etc. as a binder, while the recoating slurries consisted of lower concentration coating slurries and pore-forming materials such as starch or graphite. The solids-content of the recoating slurries which could effect on the porosity and the coating amount of sintered bodies was optimized in our work. Specific surface area and the pore size distribution of the RPC were measured by intrusive mercury curve. Morphological characteristics of the RPC were investigated by SEM. Comparing with the uncoated RPC, the recoated RPC had still highly porosity (80%) and a higher compressive strength. A lot of pores and apertures left on the surface of the sintered RPC's after those starch/graphite pore-forming materials were burned out, thus lead to a remarkable increase in the specific surface area. The maximal effective specific surface area (ignore the pores size below 10 microns) of the recoated RPC is 0.52 m 2 /g, as over ten times as the uncoated RPC.

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“…Under similar reaction conditions (5 ml of 2 wt% fructose solution, 0.1 g of resin, 150 °C and 10 min), fructose conversion and HMF yields by microwave heating (91.7% and 70.3%, respectively) were higher than those by conventional heating (22.1% and 13.9% respectively). Subsequently, Qi et al 68 observed that acetone-DMSO solvent mixture was an effective solvent for the dehydration of fructose to HMF owing to improved separation efficiency and highly selective product formation.…”

Section: Ionic Resinsmentioning

confidence: 99%

Catalytic conversion of biorenewable-carbohydrate sources to 5-Hydroxymethylfurfural: a platform molecule for future chemical and energy

Atanda¹

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Cellulosic biomass provides renewable alternatives to fossil-fuel resources for the sustainable production of liquid fuels and valuable chemicals. The challenge for the effective utilization of biomass resources is to develop cost-effective processing methods for the transformation of carbohydrates into value-added chemicals. Carbohydrates, predominantly cellulose, represent the largest fraction of biomass, and various strategies for their efficient use as a commercial chemical feedstock are currently being established with the aim to supplement and ultimately replace fossil fuels. To achieve this goal, it is pivotal to develop more efficient and environmental-friendly methods to convert cellulose into useful chemicals. One possible conversion route of cellulose is through the synthesis of 5-hydroxymethyfurfural (HMF), which the US Department of Energy has classified as one of the most promising renewable molecules.This thesis is aimed at advancing the potential application of heterogeneous catalysis and waterorganic biphase system for the synthesis of HMF directly from solid biomass. Firstly, we undertook a literature survey of the current strategies employed for HMF production with more attention on solid catalysis.Secondly, we explored the catalytic potential of non-toxic TiO 2 nanoparticle prepared by sol-gel technique on glucose conversion into HMF in an aqueous reaction system. Catalytic performance of TiO 2 was modified by introducing a second metal oxide (ZrO 2 ) to form binary oxides. Compared to pure TiO 2 , the binary oxide displayed better activity in terms of HMF yield, which was attributed to optimum balance of basic and acid sites for the tandem isomerization-dehydration reactions.Solvent effect was also studied in order to promote the reaction preferentially towards target product. Consequently, a biphase system of water-organic solvent mix was utilized and in combination with TiO 2 -ZrO 2 /Amberlyst 70 catalyst system, a remarkable yield of HMF can be produced from glucose Thirdly, catalytic properties of TiO 2 nanoparticle were fine-tuned to develop a single solid acid bifunctional (Lewis and Brønsted acidity) catalyst. To achieve this goal, TiO 2 was modified with phosphate anion and evaluated as catalysts for the conversion of glucose to HMF in a water-butanol biphasic system. Catalyst synthesis protocol was optimized by varying loading amount of phosphate anion and calcination temperature. X-ray spectroscopic analysis confirmed phosphorus incorporation into the TiO 2 framework giving rise to small-sized nanocrystals with high surface acidity. Pyridine-infrared (Py-IR) spectroscopy on the TiO 2 catalyst confirmed the presence of bifunctional Lewis and Brønsted acid sites as compared to pure TiO 2 with only Lewis acidity. The ii phosphate modified TiO 2 demonstrated excellent catalytic performance in terms of both activity and selectivity, as well as good recyclability.Fourthly, the robustness of phosphated TiO 2 catalyst to transform a variety of sugar moieties ranging from simple to ...

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Anatase–rutile transformation in TiO2–V2O5 catalyst coatings for ceramic foams

Cited by 37 publications

References 39 publications

Superfícies fotocatalíticas de titânia em substratos cerâmicos: Parte I: Síntese, estrutura e fotoatividade

Superfícies fotocatalíticas de titânia em substratos cerâmicos: Parte I: Síntese, estrutura e fotoatividade

Preparation of large effective specific surface area reticulate porous ceramics by polymeric foam replication process using recoating technique

Catalytic conversion of biorenewable-carbohydrate sources to 5-Hydroxymethylfurfural: a platform molecule for future chemical and energy

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