| 1. |
- Bjornbom, E., et al.
(författare)
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Reduction of NOx with NH3 in presence of pyrolysed macro-cycle catalyst
- 1991
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Reduction of NOx with NH3 in the presence of pyrolyzed cobalt-tetraphenylporphyrin, CoTPP 'macro-cycle black', was studied. Active carbon, Norit RBXS 1, was used as a carrier. The experimental conditions were varied as follows: temperature from 95 to 140°C, space velocity of the gas mixture 1000-5000 h-1 and catalyst content 0-1%. The results showed that, in the experimental range studied, the temperature has no significant effect on the conversion of NOx. The conversion of NOx at low space velocity of the gas (1000 h-1) was high (approx. 90%), both in the presence and absence of CoTPP black. This was explained by the fact that the active carbon used as a catalyst support also has a catalytic effect on the reduction of NOx. At low space velocity this effect is sufficient to achieve high conversion of NOx in the presence of active carbon only. The conversion decreased at higher space velocity, however. The presence of CoTPP black counteracted the negative effect of the increased space velocity. The effect of the 'macro-cycle black' on the conversion of NOx was significant at higher space velocitites.
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| 2. |
- Kiros, Yohannes, 1956-, et al.
(författare)
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Cobalt and cobalt-based macrocycle blacks as oxygen-reduction catalysts in alkaline fuel cells
- 1993
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Ingår i: Journal of Power Sources. - 0378-7753 .- 1873-2755. ; 45:2, s. 219-227
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Tidskriftsartikel (refereegranskat)abstract
- The electrochemical reduction of oxygen on high surface are carbons catalyzed by cobalt and pyrolyzed macrocycles has been studied in alkaline fuel cells. Tests were also carried out with 'green black', i.e., pyrolyzed phyto-biomass. Galvanostatic polarization curves show that cobalt from cobalt acetate and fine cobalt metal power exhibit a high catalytic activity. The activity of pyrolyzed cobalt tetraphenylporphyrin (CoTPP) is due to the combined effects of the cobalt additive and the charred residue of the macrocycle. 'Green black', with chlorophyll as macrocycle black precursor, has a similar effect. The dissolution of cobalt from the electrode surface has been established. Life tests with these electrodes are reported. © 1993.
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| 3. |
- Kiros, Yohannes, 1956-, et al.
(författare)
-
Pyrolyzed macrocycles on high surface area carbons for the reduction of oxygen in alkaline fuel cells
- 1991
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Ingår i: Journal of Power Sources. - 0378-7753 .- 1873-2755. ; 36:4, s. 547-555
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Tidskriftsartikel (refereegranskat)abstract
- Polarization characteristics and preparation methods of double-layer porous gas diffusion electrodes on various carbon materials in alkaline fuel cells were investigated. The electrodes with active carbon carriers were catalyzed with cobalt/iron tetraphonylporphyrin or silver. These electrodes show a potential of - 186 mV (versus Hg/HgO) at 1.0 A/cm2 when operated with oxygen at 40 °C and 5 M KOH. Various techniques such as surface area measurements, scanning (SEM) and transmission (TEM) electron microscopy in combination with energy dispersive spectroscopy (EDS) and electron energy loss spectroscopy (EELS) were used to characterize the structure and morphology of the catalyst layer.
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