| 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. |
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| 3. |
- Messmer, E. R., et al.
(författare)
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In situ mesa etching and immediate regrowth in a HVPE reactor for buried heterostructure device fabrication
- 2000
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Ingår i: Journal of Crystal Growth. - 0022-0248 .- 1873-5002. ; 210:4, s. 600-612
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Tidskriftsartikel (refereegranskat)abstract
- Mesa etching in a hydride vapour-phase epitaxy (HVPE) reactor has been studied. Etched depth. underetching and shape of the mesas have been analysed as a function of partial pressures of active gases (HCl, PPI, and InCl) stripe orientation and etching temperature. The experimental results show that the depth and undercut can be etched independently. We propose qualitative mechanisms for etching each of the emerging crystallographic planes ((0 0 1), ( 1 1 0) and {1 1 1}). In situ mesa etching with immediate regrowth was applied to the fabrication of buried heterostructure Fabry-Perot lasers. No surface contamination due to exposure to ambient and low process time are advantages of this technique.
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| 4. |
- Moraisde Carvalho, Danila, et al.
(författare)
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Assessment of chemical transformations in eucalyptus, sugarcane bagasse and straw during hydrothermal, dilute acid, and alkaline pretreatments
- 2015
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Ingår i: Industrial crops and products (Print). - : Elsevier BV. - 0926-6690 .- 1872-633X. ; 73, s. 118-126
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Tidskriftsartikel (refereegranskat)abstract
- The impact of hydrothermal, dilute acid, and alkaline pretreatments on the chemical structure of eucalyptus, sugarcane bagasse, and straw were compared with a view to their subsequent bioconversion into ethanol. Sugarcane bagasse and straw contain high amounts of extractives (15.0% and 12.2%, respectively), ash (2.3% and 7.9%, respectively), and silica (1.4% and 5.8%, respectively). If not properly corrected, the presence of silica would lead to the overestimation of the lignin, while high amounts of extractives would cause the overestimation of the content of sugars in biomass. Applying a novel approach through the use of complete mass balance, bagasse and straw were proven to contain lower amounts of lignin (18.0% and 13.9%, respectively) than previously reported for these raw materials, and certainly a much lower amount of lignin than eucalyptus (27.4%). The syringyl to guaiacyl units ratio (SIG) for lignin in bagasse and straw (1.1 and 0.5, respectively) was lower than that for eucalyptus (2.7), indicating a different reactivity during chemical pretreatments. The xylan content in sugarcane bagasse and straw was much higher than that in eucalyptus, with a significantly lower degree of substitution for uronic acids and acetyl groups. The sugarcane straw showed the highest mass loss during the investigated pretreatments, especially under alkaline conditions, with a total biomass yield of only 37.3%. During the hydrothermal and dilute acid treatments, mostly hemicelluloses were removed, followed by the formation a significant amount of pseudo-lignin structures, while the alkaline pretreatment affected the lignin content. With eucalyptus, the formation of structures similar in their behavior to extractives (i.e., soluble in toluene and ethanol, subsequently referred to as "pseudo-extractives") was observed during all three pretreatments, with 12.4% for hydrothermal, 18.9% for dilute acid, and 8.7% for alkaline pretreatment. This information, combined with actual yields, should be taken into account when assessing the impact of pretreatments on the chemical composition and structure of biomass.
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| 5. |
- Rabinovich, Mikhail L., et al.
(författare)
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Carbon adsorbents from industrial hydrolysis lignin : The USSR/Eastern European experience and its importance for modern biorefineries
- 2016
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Ingår i: Renewable & sustainable energy reviews. - : Elsevier. - 1364-0321 .- 1879-0690. ; 57, s. 1008-1024
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Forskningsöversikt (refereegranskat)abstract
- This paper reviews the origin, distribution and composition of hydrolysis lignin, a large-scale by-product of the hydrolysis industry that operated in the Soviet Union and several eastern European countries from 1930s to the end of 1990s. The fundamental and industrial aspects of the production of various types of powdered and granular carbon adsorbents from hydrolysis lignin are considered through the prism of future large-scale production of biofuels and platform chemicals from renewable lignocellulosic resources. The advantages and drawbacks of hydrolysis lignin as a feedstock for the production of carbon adsorbents are compared with other types of feedstock, and the application of lignin-based carbons is discussed.
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