Processing and characterization of porous electrochemical cells for flue gas purification

He, Zeming; Andersen, Kjeld Bøhm; Keel, Li; Nygaard, Frederik Berg; Menon, Mohan; Hansen, Kent Kammer

doi:10.1007/s11581-008-0286-0

Cited by 19 publications

(16 citation statements)

References 11 publications

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“…The porous composite electrode layers were manufactured by mixing LSM15, CGO10, solvent (mixture of ethanol and butanone), binder (polyvinylbuyral), dispersant (polyvinylpyrrolidone) and pore former (graphite) into a slurry, ball mill the slurry and thereafter tape caste the slurry into green tapes of approximately 40 μm thickness, for more details see Hee et al 20 . The porous CGO10 layers were prepared in a similar manner, and subsequent the green electrode and electrolyte layers were laminated together and round cell stacks were stamped out.…”

Section: Methodsmentioning

confidence: 99%

NOx conversion on LSM15-CGO10 cell stacks with BaO impregnation

Traulsen

Andersen

2012

J. Mater. Chem.

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The electrochemical conversion of NO x on non-impregnated and BaO-impregnated LSM15-CGO10 (La 0.85 Sr 0.15 MnO 3 -Ce 0.9 Gd 0.1 O 1.95 ) 5 porous cell stacks has been investigated, and extensive impedance analysis have been performed to identify the effect of the BaO on the electrode processes. The investigation was conducted in the temperature range 300-500 °C, a polarisation range from 3 V to 9 V and in atmospheres containing 1000 ppm NO, 1000 ppm NO + 10% O 2 and 10% O 2 . On the non-impregnated cell stacks no NO x conversion was observed at any of the investigated conditions. However, BaO impregnation greatly enhanced the NO x conversion and at 400 °C and 9 V polarisation a BaO-impregnated cell stack showed 60% NO x conversion into N 2 with 8% current efficiency in 1000 ppm NO + 10% 10 O 2 . This demonstrates high NO x conversion can be achieved on an entirely ceramic cell without expensive noble metals. Furthermore the NO x conversion and current efficiency was shown to be strongly dependent on temperature and polarisation. The impedance analysis revealed that the BaO-impregnation increased the overall activity of the cell stacks, but also changed the adsorption state of NO x on the electrodes; whether the increased activity or the changed adsorption state is mainly responsible for the improved NO x conversion remains unknown. IntroductionIn Europe the NO x -emission from the road transport has been significantly reduced during the last 10 years, mainly due to the introduction of the three-way-catalyst on gasoline vehicles 1 . Due to the negative impact of NO x -emissions on both human health and the environment 2 , a further reduction in the NO x emissions from the car fleet is desirable. However a major challenge in that connection is the increased number of diesel vehicles, as the conventional three-way-catalyst is incapable of removing NO x from diesel exhaust. For this reason much research is currently focused on NO x -removal technologies for diesel exhaust, the most heavily investigated technologies being selective catalytic reduction with ammonia (NH 3 -SCR), selective catalytic reduction with hydrocarbons (HC-SCR) and the NO x -storage and reduction (NSR) catalyst 3 . In all these three technologies there is the need for a reducing agent, either coming from operating the engine occasionally in an excess fuel to air-ratio (HC-SCR and NSR) or supplied by a separate system (NH 3 -SCR). A NO x removal technology without the need for the addition of a reducing agent would be simpler and therefore advantageous compared to the aforementioned technologies.A suggestion for such a technology is electrochemical NO x removal, where the NO x is reduced to N 2 and O 2 by electrons supplied to a polarised electrode 4 . The technology is inspired by the finding in 1975 by Pancharatnam et al. 5 that NO can be reduced to N 2 during polarisation of a zirconia based cell in the absence of oxygen, and later it was shown by Cicero et al. 6 and Hibino et al. 7 that NO x also could be electrochemically reduced in the...

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Section: Methodsmentioning

confidence: 99%

NOx conversion on LSM15-CGO10 cell stacks with BaO impregnation

Traulsen

Andersen

2012

J. Mater. Chem.

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“…The LSF had been synthesized in house by the glycine-nitrate combustion synthesis [27] [28]. The porous CGO electrolyte was tapecasted like the electrode tape and afterwards the green electrode and electrolyte tapes were laminated 6 together with 6 electrode layers alternating with 5 electrolyte layers.…”

Section: Fabrication Of Porous Cell Stacksmentioning

confidence: 99%

NO x conversion on porous LSF15–CGO10 cell stacks with KNO3 or K2O impregnation

Traulsen

Bræstrup

2012

J Solid State Electrochem

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In the present work it was investigated how addition of KNO 3 or K 2 O affected the NO x conversion on LSF15-CGO10 (La 0.85 Sr 15 FeO 3 -Ce 0.9 Gd 0.1 O 1.95 ) composite electrodes during polarisation. The LSF15-CGO10 electrodes were part of a porous 11-layer cell stack with alternating layers of LSF15-CGO10 electrodes and CGO10 electrolyte. The KNO 3 was added to the electrodes by impregnation, and kept either as KNO 3 in the electrode or thermally decomposed into K 2 O before testing. The cell stacks were tested in the temperature range 300-500 °C in 1000 ppm NO, 10% O 2 and 1000 ppm NO + 10% O 2 . During testing the cells were characterized by electrochemical impedance spectroscopy (EIS) and the NO conversion was measured during polarization at -3 V for 2 h. The concentration of NO and NO 2 was monitored by a chemiluminiscence detector, while the concentration of O 2 , N 2 and N 2 O was detected on a mass spectrometer. A significant effect of impregnation with KNO 3 or K 2 O on the NO x conversion was observed. In 1000 ppm NO both impregnations caused an increased conversion of NO into N 2 in the temperature range 300-400 °C with a current efficiency up to 73%. In 1000 ppm NO + 10% O 2 no formation of N 2 was observed during polarisation, but the impregnations altered the conversion between NO and NO 2 on the electrodes. Both impregnations caused increased degradation of the cell stack, but the exact cause of the degradation has not been identified yet.

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“…In addition to the intrinsic pores in the matrix after sintering, the porous structure is mainly contributed by the added graphite pore-formers, which were burnt off at the temperature above 800°C and left flaky pores in the matrix [10]. The evolution of reactor microstructure with sintering temperature could also be seen from Figure 3.…”

Section: Resultsmentioning

confidence: 90%

“…Perovskite-type oxides (ABO 3 structure) are suitable electrode candidates because they are characterised by a mixed ionic-electronic conduction in solid electrolyte and could catalyse the simultaneous removal of NO x and soot particulates [1]. The electrolyte materials, such as gadolinia-doped cerium oxide (CGO) [10] and yttria stabilised zirconia (YSZ) [11], should possess high ion conductivity at exhaust gas temperatures for oxygen anion transportation. On the other hand, for practical application of the electrochemical cells, porous microstructures are required for electrode and electrolyte materials to facilitate the penetration and removal of gases and soot particles.…”

Section: Introductionmentioning

confidence: 99%

Sintering Effect on Material Properties of Electrochemical Reactors Used for Removal of Nitrogen Oxides and Soot Particles Emitted from Diesel Engines

Andersen

Keel

et al. 2010

Fuel Cells

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In the present work, 12‐layered electrochemical reactors (comprising five cells) with a novel configuration including supporting layer lanthanum strontium manganate (LSM)‐yttria stabilised zirconia (YSZ), electrode layer LSM‐gadolinia‐doped cerium oxide (CGO) and electrolyte layer CGO were fabricated via the processes of slurry preparation, tape casting and lamination and sintering. The parameters of porosity, pore size, pore size distribution, shrinkage, flow rate of the sintered reactors and the electrical conductivities of the supporting layer and the electrode in the sintered reactors were characterised. The effect of sintering temperature on microstructures and properties of the sintered samples was discussed, and 1,250 °C was determined as the appropriate sintering temperature for reactor production based on the performance requirements for applications. Using the present ceramic processing route, porous, flat and crack‐free electrochemical reactors were successfully achieved. The produced electrochemical reactors have the potential application in the removal of NOx and soot particles emitted from the diesel engines.

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Processing and characterization of porous electrochemical cells for flue gas purification

Cited by 19 publications

References 11 publications

NOx conversion on LSM15-CGO10 cell stacks with BaO impregnation

NOx conversion on LSM15-CGO10 cell stacks with BaO impregnation

NO x conversion on porous LSF15–CGO10 cell stacks with KNO3 or K2O impregnation

Sintering Effect on Material Properties of Electrochemical Reactors Used for Removal of Nitrogen Oxides and Soot Particles Emitted from Diesel Engines

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