| 1. |
- Dahlin, Sandra, et al.
(författare)
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Effect of biofuel- and lube oil-originated sulfur and phosphorus on the performance of Cu-SSZ-13 and V2O5-WO3/TiO2 SCR catalysts
- 2021
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Ingår i: Catalysis Today. - : Elsevier B.V.. - 0920-5861 .- 1873-4308. ; 360, s. 326-339
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Tidskriftsartikel (refereegranskat)abstract
- Two different SCR catalysts, V2O5-WO3/TiO2 and Cu-SSZ-13, were exposed to biodiesel exhausts generated by a diesel burner. The effect of phosphorus and sulfur on the SCR performance of these catalysts was investigated by doping the fuel with P-, S-, or P + S-containing compounds. Elemental analyses showed that both catalysts captured phosphorus while only Cu-SSZ-13 captured sulfur. High molar P/V ratios, up to almost 3, were observed for V2O5-WO3/TiO2, while the highest P/Cu ratios observed were slightly above 1 for the Cu-SSZ-13 catalyst. Although the V2O5-WO3/TiO2 catalyst captured more P than did the Cu-SSZ-13 catalyst, a higher degree of deactivation was observed for the latter, especially at low temperatures. For both catalysts, phosphorus exposure resulted in suppression of the SCR performance over the entire temperature range. Sulfur exposure, on the other hand, resulted in deactivation of the Cu-SSZ-13 catalyst mainly at temperatures below 300-350 °C. The use of an oxidation catalyst upstream of the SCR catalyst during the exhaust-exposure protects the SCR catalyst from phosphorus poisoning by capturing phosphorus. The results in this work will improve the understanding of chemical deactivation of SCR catalysts and aid in developing durable aftertreatment systems.
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| 2. |
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| 3. |
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| 4. |
- Zacharias, Savannah C., et al.
(författare)
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Exploring Supramolecular Gels in Flow-Type Chemistry-Design and Preparation of Stationary Phases
- 2021
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Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 0888-5885 .- 1520-5045. ; 60:28, s. 10056-10063
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Tidskriftsartikel (refereegranskat)abstract
- Two major challenges facing chemical synthesis are product isolation and catalyst recovery. One method to overcome these challenges is to perform the synthesis in a flow system with a catalytic stationary phase. However, the polymeric catalytic materials used in flow systems are often laborious to produce. In this study, we investigate a novel supramolecular gel as a catalytic stationary phase material. The gel is based on a modular, easy to synthesize, oxotriphenylhexanoate (OTHO) gelator comprised of a catalytic unit designed to catalyze the Knoevenagel reaction. The catalytic organogel enhances the rate of product formation and can be reused five times. Use of the OTHO to construct catalytic gels is a flexible technique that can be utilized to improve product isolation and reduce wastage of the catalyst.
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| 5. |
- Bauhn, Lovisa, 1981, et al.
(författare)
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The fate of hydroxyl radicals produced during H2O2 decomposition on a SIMFUEL surface in the presence of dissolved hydrogen
- 2018
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Ingår i: Journal of Nuclear Materials. - : Elsevier BV. - 0022-3115. ; 507, s. 38-43
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Tidskriftsartikel (refereegranskat)abstract
- Over geologic timescales hydrogen peroxide will be one of the most important radiolytic oxidants challenging the spent fuel integrity in a deep repository. Consequently, the reaction between hydrogen peroxide and different kinds of UO 2 based materials has been the subject of several studies over recent decades. Parts of these studies have investigated the effect of dissolved hydrogen on this reaction, as large amounts of hydrogen are expected to be produced by anoxic corrosion of iron in the deep repositories. In some of the studies hydrogen has been shown to offset the radiolysis-driven oxidative dissolution of the fuel despite the expected inertia of hydrogen at repository temperatures. However, the underlying mechanism is primarily based on the effect of the metallic particles contained in the spent fuel. One clue to the mechanistic understanding is whether or not a reaction takes place between dissolved hydrogen and hydroxyl radicals adsorbed to a fuel surface resulting from the decomposition of H 2 O 2 . In the study presented here this reaction could be confirmed in an autoclave system with SIMFUEL, a hydrogen peroxide spiked solution, and deuterium gas. The results show that the studied reaction does not only occur, but accounts for a substantial part of the hydrogen peroxide consumption in the system. Only a very minor part, 0.02%, of the total consumed hydrogen peroxide caused oxidative dissolution of the SIMFUEL. The conclusion is supported by quantitative measurements of HDO, dissolved U in solution and O 2 in the gas phase.
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| 6. |
- Corcoran, Angelica, 1988, et al.
(författare)
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Comparing the structural development of sand and rock ilmenite during long-term exposure in a biomass fired 12 MWth CFB-boiler
- 2018
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Ingår i: Fuel Processing Technology. - : Elsevier BV. - 0378-3820. ; 171, s. 39-44
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Tidskriftsartikel (refereegranskat)abstract
- Oxygen Carrier Aided Combustion (OCAC) is a novel combustion concept with the purpose to increase the overall efficiency in conventional circulating fluidized bed (CFB) boilers. By replacing the commonly used bed material with an oxygen carrier (OC), the conceptual idea is to utilize the fluid dynamics in a CFB and the inherent oxygen transport supported by the OC to increase the oxygen distribution within the furnace in time and space. The OCAC concept has been successfully validated and further reached long-term demonstration in full scale operation (75-MW th ). This work presents a first evaluation of how ilmenite particles are affected in regard to mechanical resistance during long-term exposure to OCAC conditions in Chalmers 12-MW th CFB-boiler. A sand and a rock ilmenite are evaluated with regard to their mechanical stability. For evaluation, samples of the fresh materials and samples collected during operation in the Chalmers boiler are investigated. The study shows that the two materials differ in how the mechanical degradation occurs with exposure time. The sand ilmenite form cavities which are held together by an ash layer before they are shattered into numerous pieces, whereas the rock ilmenite develops distinct cracks that cause splitting of the particles.
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| 7. |
- Maric, Jelena, 1983, et al.
(författare)
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Valorization of Automobile Shredder Residue Using Indirect Gasification
- 2018
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Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 1520-5029 .- 0887-0624. ; 32:12, s. 12795-12804
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Tidskriftsartikel (refereegranskat)abstract
- Dual fluidized bed (DFB) gasification offers the possibility to convert solid fuels into a valuable gas, comprised of syngas, and hydrocarbons that can be readily handled in petrochemical units. DFB gasifiers are especially suitable for nonhomogeneous fuels, such as waste fractions. In this work, the possibility to use DFB gasification as a recycling/valorization method of automobile shredder residue is investigated. The gasification tests were carried out in the Chalmers 2–4 MWth gasifier over 4 days. The effects of ash on the gas and tar compositions, as well as on the activity of the bed inventory, were evaluated. The results show that 60% of the total carbon in the fuel can be recovered in the form of a permanent gas, whereby the produced gas contains 12%mol of C2–3 hydrocarbons. The tar levels measured in the produced gas were high, although it was clear that decomposition into monomer-like compounds occurred in the reactor, which resulted in the production of valuable petrochemical compounds, corresponding to 8–9% of the carbon in the feed. Using a higher operating temperature was found to be beneficial in terms of obtaining a higher gas yield, regardless of the level of ash enrichment in the system. The high ash levels in the fuel feed did not negatively affect the technical operation of the fluidized bed. Possible routes of carbon recovery are discussed.
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| 8. |
- Wang, Kai, et al.
(författare)
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A one-carbon chemicals conversion strategy to produce precursor of biofuels with Saccharomyces cerevisiae
- 2023
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Ingår i: Renewable Energy. - : Elsevier BV. - 0960-1481 .- 1879-0682. ; 208, s. 331-340
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Tidskriftsartikel (refereegranskat)abstract
- Utilization of one-carbon chemicals such as CO2, formate, and methanol by microorganisms can enable the sustainable production of fuels and chemicals. However, the low conversion efficiency of these chemicals by microorganisms is a major challenge. To address this, we designed a one-carbon strategy that can utilize CO2 and its derivative formate. Here, a platform yeast strain with improved formate utilization and NAD(P)H production was constructed and evaluated for its ability to produce free fatty acids (FFAs). Based on 13C-marked analysis, the one-carbon assimilation efficiency of the platform strain reached 11.24%. Through continuous optimization, under conditions of glucose feeding the formate utilization rate of the final strain reached 0.48 g/L/h, with the final titer of FFAs reached 10.1 g/L, which represented improvements of 21.8 times and 33.7 times, respectively. As such, the produced FFAs can be easily transformed into biodiesel by combining them with downstream technologies in future research.
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| 9. |
- Balachandran, Srija, et al.
(författare)
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Comparative study for selective lithium recovery via chemical transformations during incineration and dynamic pyrolysis of EV li-ion batteries
- 2021
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Ingår i: Metals. - : MDPI AG. - 2075-4701. ; 11:8
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Tidskriftsartikel (refereegranskat)abstract
- Selective leaching of Li from spent LIBs thermally pretreated by pyrolysis and incineration between 400 and 700 °C for 30, 60, and 90 min followed by water leaching at high temperature and high L/S ratio was examined. During the thermal pretreatment Li2CO3 and LiF were leached. Along with Li salts, AlF3 was also found to be leached with an efficiency not higher than 3.5%. The time of thermal pretreatment did not have a significant effect on Li leaching efficiency. The leaching efficiency of Li was higher with a higher L/S ratio. At a higher leaching temperature (80 °C), the leaching of Li was higher due to an increase in the solubility of present Li salts. The highest Li leaching efficiency of nearly 60% was observed from the sample pyrolyzed at 700 °C for 60 min under the leaching condition L/S ratio of 20:1 mL g−1 at 80 °C for 3 h. Furthermore, the use of an excess of 10% of carbon in a form of graphite during the thermal treatment did not improve the leaching efficiency of Li.
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| 10. |
- Bylin, Susanne, 1982
(författare)
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Mechanisms of Biopolymer Solvation: Development of a two-component ionic liquid solvent system
- 2014
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Ionic liquids are of potential interest in the processing of lignocellulosic biomass, and/or its components, for the purpose of producing renewable and value-added biomaterials. An understanding of how solvation can be achieved and the way in which the feedstock biopolymers are affected, however, needs to be gained prior to a viable implementation. In this thesis, the solvation of the wood biopolymers cellulose, xylan and lignin in the ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate (EMIMAc) in a novel combination with the second system component 1-methylimidazole (MIM) have been investigated:The solvation of dissolving pulp, beech xylan and LignoBoost lignin model materials, was studied using FBRM (focused beam reflectance measurements) particle characterization in combination with microscopic analysis (cellulose and xylan), determination of molecular weights (xylan and lignin) and 13C- and 31P-NMR (nuclear magnetic resonance spectroscopy) of lignin.It was concluded that the most efficient solvation of cellulose and xylan occurred using 3-4% and 9% IL (n/n anhydroglucose units and n/n anhydroxylose Units), respectively, while polymer integrity was maintained. Cellulose solvation was found to be greatly dependent on the IL to AGU ratio whereas xylan solvation varied greatly with temperature. Moreover, a theoretical model was developed for the solvation of cellulose in the present system. The solvation of lignin was achieved at ~20% lignin loading (w/w), in any combination of MIM/EMIMAc. Regeneration of lignin resulted in two sets of fractions; one exhibiting a general and higher apparent molecular weight (Mw) along with an enrichment of condensed/aliphatic ether linkages and aliphatic hydroxyls, and the other exhibiting a lower apparent Mw and an enrichment of carboxylic and phenolic groups. The knowledge of biopolymer solvation gained in the present solvent system provides future opportunities of tuning extraction and/or fractionation processes to suite the specifications of a particular biomass-derived product.
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