Equilibrium of the protonic species in hydrates of some heteropolyacids at elevated temperatures

Mioč, U.B.; Davidović, M.; Tjapkin, N.; Colomban, Philippe; Novák, A.

doi:10.1016/0167-2738(91)90136-y

Cited by 113 publications

(45 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The DTA record of pure PTA shows endothermic peaks at 45, 82, 119 and 219 C. The peak at 45 C is attributed to the removal of physioadsorbed water molecules and the rest of the peaks correspond to the removal of water of crystallization from the PTA lattice. In pure PTA, it has been reported [15] that at T > 120-130 C, PTA Á 6H 2 O phase remains after the removal of the rest of water molecules. In the composite electrolyte with x ¼ 0.8, the endothermic peaks appear at 48, 72, 128 and 217 C. At x ¼ 0.5, exothermic peaks appear at 61 and 85 C whereas the peaks at 40 and 223 C are endothermic.…”

Section: Dta/tga Studiesmentioning

confidence: 99%

“…The band at %1700 cm --1 appears as a shoulder in pure PMA but can be seen more clearly in the composites. Kearley et al [17] and Pavia and Giguere [18] [15]. In the composites of PMA dispersed with Al 2 O 3 this shoulder at %1700 cm --1 grows into a more prominent peak as x is decreased whereas the bending vibration of H 2 O (i.e.…”

Section: Ir Studiesmentioning

confidence: 99%

“…A broad band in the region 3600-3100 cm --1 and a band at %1615 cm --1 in PTA and its composites are assigned to 392 N. Lakshmi and S. Chandra: Proton Conducting Composites of Heteropolyacid Hydrates -OH stretching and HOH bending mode, respectively [16]. Similar to the PMA : Al 2 O 3 system, a shoulder appears at %1700 cm --1 in PTA and its composites assigned to the asymmetric stretching of O-H-O in H 5 O þ 2 [17,18], nH 3 O þ [15] or deformation of H 2 O group in H 5 O þ 2 [19]. A weak shoulder appears at %1404 cm --1 in pure PTA assigned to H-O-H asymmetric deformation mode [17,20] and gradually disappears at higher alumina concentrations.…”

Section: Ir Studiesmentioning

confidence: 99%

See 2 more Smart Citations

Proton Conducting Composites of Heteropolyacid Hydrates (Phosphomolybdic and Phosphotungstic Acids) Dispersed with Insulating Al2O3

Lakshmi

Chandra

2001

phys. stat. sol. (a)

View full text Add to dashboard Cite

Section: Dta/tga Studiesmentioning

confidence: 99%

Section: Ir Studiesmentioning

confidence: 99%

Section: Ir Studiesmentioning

confidence: 99%

See 1 more Smart Citation

Proton Conducting Composites of Heteropolyacid Hydrates (Phosphomolybdic and Phosphotungstic Acids) Dispersed with Insulating Al2O3

Lakshmi

Chandra

2001

phys. stat. sol. (a)

View full text Add to dashboard Cite

“…7a), heating leads immediately to dehydration according to a two-step process in the 25-100 and 120-230°C temperature ranges. It is wellknown that heteropolyacid hydrates lose water molecules even at room temperature and are transformed to lower hydrates [46]. The corresponding DTA curves showed two endothermic peaks at 40-60 and 185°C which probably involve the loss of crystallisation (lattice water) and constitution water (structure water) [47].…”

Section: Thermal Characterization Of Powdered Pta-ssa Complexesmentioning

confidence: 99%

Heteropolyacid/saponite-like clay complexes and their blends in amphiphilic SEBS

Vuillaume

Mokrini

Siu

et al. 2009

European Polymer Journal

View full text Add to dashboard Cite

“…Asimismo, la conductividad protónica se relaciona con la red inorgánica debido a la capacidad de retención de moléculas de agua en los grupos hidroxilo superficiales (6-11). Un modo de mejorar la conductividad protónica es dopar las membranas híbridas con heteropoliácidos (HPAs) como el ácido fosfowolfrámico, H 3 (P(W 3 O 10 ) 4 ) (PWA) (8)(9)(12)(13)(14)(15)(16)(17)(18)(19)(20). La utilización de heteropoliácidos como dopantes en membranas para pilas de combustible permite alcanzar elevados valores de conductividad, aunque se han apreciado problemas de lixiviación de los HPA en el agua generada en el cátodo (12).…”

Section: Introductionunclassified

Membranas híbridas basadas en estireno-metacrilato-sílice y ácido fosfowolfrámico obtenidas por sol-gel para pilas de combustible de intercambio protónico (PEMFC)

Mosa¹,

Durán²,

Aparicio³

2007

Bol. Soc. Esp. Ceram. Vidr.

View full text Add to dashboard Cite

Membranas híbridas basadas en estireno-metacrilato-sílice y ácido fosfowolfrámico obtenidas por sol-gel para pilas de combustible de intercambio protónico (PEMFC)J. Mosa, a. Durán, M. aPariCio Instituto de Cerámica y Vidrio (CSIC). Campus de Cantoblanco, Madrid, EspañaComparadas con los motores de combustión interna, las pilas de combustible de intercambio de protones (PEMFC) son capaces de operar sin emisiones de agentes contaminantes. El aumento de la temperatura de operación de la pila de combustible por encima de 100ºC es uno de los grandes objetivos en este campo ya que facilitaría el desarrollo comercial de los vehículos eléctricos impulsados por pilas de combustible. Las membranas híbridas orgánico-inorgánicas nanoestructuradas combinan las propiedades necesarias para este tipo de aplicación. Se obtuvieron membranas híbridas dopadas con ácido fosfowolfrámico (PWA) por copolimerización radicálica a partir de alquilalcóxidos y monómeros de estireno y metacrilato, y por reacción sol-gel vía catálisis ácida. La conductividad protónica se logra realizando un proceso de sulfonación de anillos aromáticos para producir grupos SO 3 H unidos al anillo. Se ha estudiado el efecto de la sulfonación y el dopado de las membranas con PWA sobre las propiedades de la membrana, tales como la estabilidad química y térmica, retención de agua, capacidad de intercambio iónico y conductividad protónica. Las medidas de conductividad muestran aumento al aumentar la temperatura y la cantidad de grupos SO 3 H, hasta valores de 3.2 10 -3 S/ cm a 130ºC y 100%HR. Palabras clave: PEMFC; heteropoliácidos; sol-gel; membranas híbridas; sulfonación; conductividad protónicaHybrid styrene-methacrylate-silica sol-gel membranes combining sulfonation and tungstophosphoric acid doping for PEMFC Contrary to internal combustion engines, proton-exchange membrane fuel cells (PEMFC) used in transportation operate with zero emissions of environmental pollutants. The increase of the operation temperature in PEMFC above 100°C is a great concern for the application of this type of cells in electric vehicles. Hybrid organic-inorganic membranes with nanosized interfaces can combine the main properties of their components to meet this objective. Styrene-methacrylate-silica membranes doped with phosphotungstic acid (PWA) were prepared through acid catalyzed sol-gel process and free-radical copolymerization. Additionally, sulfonation processes of aromatic rings to produce attached SO 3 H groups were applied to increase the proton conductivity. The effect of sulfonation degree and PWA doping on the membrane properties such as chemical and thermal stability, water uptake, ion exchange capacity, and proton conductivity were investigated. The measurement of conductivity shows a general increase with rising temperatures and with the increasing of SO 3 H groups density, reaching a maximum value of 3.2 10 -3 S/cm at 130ºC and 100%HR.Keywords: PEMFC; heteropoly acids salts; sol-gel; hybrid membrane; sulfonation; proton conductivity INTRODUCCIóNLas pilas de combustible...

show abstract

Equilibrium of the protonic species in hydrates of some heteropolyacids at elevated temperatures

Cited by 113 publications

References 8 publications

Proton Conducting Composites of Heteropolyacid Hydrates (Phosphomolybdic and Phosphotungstic Acids) Dispersed with Insulating Al2O3

Proton Conducting Composites of Heteropolyacid Hydrates (Phosphomolybdic and Phosphotungstic Acids) Dispersed with Insulating Al2O3

Heteropolyacid/saponite-like clay complexes and their blends in amphiphilic SEBS

Membranas híbridas basadas en estireno-metacrilato-sílice y ácido fosfowolfrámico obtenidas por sol-gel para pilas de combustible de intercambio protónico (PEMFC)

Contact Info

Product

Resources

About