| 1. |
- Kattge, Jens, et al.
(författare)
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TRY plant trait database - enhanced coverage and open access
- 2020
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Ingår i: Global Change Biology. - : Wiley-Blackwell. - 1354-1013 .- 1365-2486. ; 26:1, s. 119-188
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Tidskriftsartikel (refereegranskat)abstract
- Plant traits-the morphological, anatomical, physiological, biochemical and phenological characteristics of plants-determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait-based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits-almost complete coverage for 'plant growth form'. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait-environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives.
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| 2. |
- Bergman, Susanna, et al.
(författare)
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In-situ studies of oxidation/reduction of copper in Cu-CHA SCR catalysts:comparison of fresh and SO2-poisoned catalysts
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- SO2-poisoning results in deactivation of Cu-CHA SCR under standard SCR conditions; however regeneration at 700 ◦C completely restores the SCR performance. To understand the nature of these effects, Cu-species in the fresh and poisoned catalystswere characterized by in-situ temperature-dependent time-resolved Cu K-edge X-ray absorption spectroscopy using the multivariate curve resolution alternating least squares (MCR-ALS) approach and continuous Cauchy wavelet transforms. The extracted chemically-meaningful reference spectra of Cu-species were analyzed by DFT-assisted XANES calculations. Cu-bisulfates werefound as the most energetically favorable poisoned Cu-species. The response of Cu-species to a reducing environment differs inthe fresh and SO2-poisoned catalysts. Differences in reducibility are related to the formation of quasi-linear Cu-complexes in the SO2-poisoned catalyst formed during heating in H2/He. Heating in H2/He leads to partial desulfurization of the poisoned catalyst. Cooling in H2/He after heating results in more facile formation of Cu-metal clusters in fresh catalyst than in SO2-poisoned.
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| 3. |
- Bergman, Susanna L., et al.
(författare)
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In-situ studies of oxidation/reduction of copper in Cu-CHA SCR catalysts: Comparison of fresh and SO2-poisoned catalysts
- 2020
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Ingår i: Applied Catalysis B: Environmental. - : Elsevier BV. - 0926-3373 .- 1873-3883. ; 269
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Tidskriftsartikel (refereegranskat)abstract
- SO2-poisoning results in deactivation of Cu-CHA SCR under standard SCR conditions; however regeneration at 700 °C completely restores the SCR performance. To understand the nature of these effects, Cu-species in the fresh and poisoned catalysts were characterized by in-situ temperature-dependent time-resolved Cu K-edge X-ray absorption spectroscopy using the multivariate curve resolution alternating least squares (MCR-ALS) approach and continuous Cauchy wavelet transforms. The extracted chemically-meaningful reference spectra of Cu-species were analyzed by DFT-assisted XANES calculations. Cu-bisulfates were found as the most energetically favorable poisoned Cu-species. The response of Cu-species to a reducing environment differs in the fresh and SO2-poisoned catalysts. Differences in reducibility are related to the formation of quasi-linear Cu-complexes in the SO2-poisoned catalyst formed during heating in H2/He. Heating in H2/He leads to partial desulfurization of the poisoned catalyst. Cooling in H2/He after heating results in more facile formation of Cu-metal clusters in fresh catalyst than in SO2-poisoned.
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| 4. |
- Dahlin, Iris, et al.
(författare)
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Fishing cyprinids for food - Evaluation of ecosystem effects and contaminants in cyprinid fish
- 2021
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- We conclude that a coastal cyprinid fishery may have positive effects on the ecosystem and with regard to levels of toxic contaminants, the fish is safe for humans to eat. There is, however, a need to scale up the targeted cyprinid fishery in order to evaluate and quantify the effects on the ecosystem. Scaling up from the pilot scale fisheries requires a change in consumer’s attitude and product development, so that larger quantities of cyprinid fish can be harvested and sold. Several wild fish stocks in the Baltic Sea are in poor condition and today the supply of fish for human consumption in Sweden heavily relies on farmed and imported fish. At the same time, eutrophication and climate change has led to increasing populations of cyprinid fish (e.g. bream, roach, ide) in many coastal areas of the Baltic Sea, which threatens to violate Swedish and international environmental goals. During recent years, there has been an increased interest to fish cyprinids for human consumption in Finland and Sweden. This report evaluates potential ecosystem effects resulting from an increased cyprinid fishery, and how to monitor and assess these effects in the Baltic Sea. We also assess potential barriers to increased cyprinid fisheries for human consumption due to food safety issues resulting from environmental contaminants and market incentives for fishers. In a literature review on biomanipulation targeting cyprinids in lakes, we show that removing cyprinids as a measure to improve water quality has been successful in around 60% of the cases where it has been tested. In the Baltic Sea, however, there have only been a few pilot projects of biomanipulation of cyprinids. Differences between coastal areas and lakes makes it unlikely that the same success rate as in lakes would also apply to coastal areas, especially when considering lowering of nutrient concentrations. Still, we think that a sustainable fishery targeting cyprinids may promote at least positive effects on water transparency and macrophytes in the Baltic Sea on a longer time-scale. In line with results from our literature review, we suggest a monitoring program for evaluation of a targeted cyprinid fishery in coastal areas. Based on the potential ecosystem effects of a cyprinid fishery we suggest that monitoring should prioritize fish community composition, water transparency, chlorofyll α, and submerged macrophytes. For more thorough scientific evaluations, the monitoring program should also include abundance of phyto- and zooplankton, as well as and nutrient and oxygen levels. An increased use of cyprinids from the Baltic Sea as human food will also have societal impacts. To examine if human consumption of cyprinid fish entails any increased risk of exposure to contaminants, we analysed concentration levels of several toxins (mercury, cadmium, dioxins, PCBs, PFAS and PBDE) in bream, ide and roach from five sites along the Swedish coast of the northern Baltic Sea. Our results show that, based on the regulations in Sweden today, cyprinids meet all health regulations for human food. Based on recommendations of weekly intake there are no apparent health risks of consuming cyprinid fish from the Baltic Sea at least weekly. However, since knowledge and regulations of certain environmental toxins are poor or non-existent, we believe it is important to conduct a more comprehensive study, especially for PFAS. An increased fishery targeting cyprinids would diversify the small-scale coastal fishery in Sweden, but the currently low demand makes it risky for fishers to invest in equipment and distribution becomes relatively expensive.
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| 5. |
- Dahlin, Sandra, et al.
(författare)
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Chemical aging of Cu-SSZ-13 SCR catalysts for heavy-duty vehicles –Influence of sulfur dioxide
- 2018
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Ingår i: Catalysis Today. - Amsterdam : Elsevier. - 0920-5861 .- 1873-4308. ; 320, s. 72-83
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Tidskriftsartikel (refereegranskat)abstract
- Selective catalytic reduction of nitrogen oxides is an efficient technique for emission abatement in heavy-dutyvehicles. Cu-SSZ-13 SCR catalysts are more active than vanadium-based catalysts at low temperatures, but aremore sensitive to deactivation by sulfur. Consequently, there is a need to study poisoning by sulfur for thiscatalyst material. This experimental investigation focuses on the effect of sulfur on the low-temperature per-formance of Cu-SSZ-13 SCR catalysts. The effect of sulfur exposure temperature, and the influence of the NO 2 /NO x ratio, are considered and two different regeneration temperatures are compared. In addition, catalystsamples from an engine-aged catalyst are evaluated. The SO 2 exposure temperature is shown to have an im-portant impact on the deactivation of the Cu-SSZ-13 catalyst. The lowest sulfur exposure temperature (220 °C)results in the most severe deactivation, while the highest temperature during sulfur exposure (400 °C) results inthe lowest degree of deactivation. This was found to be related to the amount of sulfur on the catalyst.Additionally, SO 2 exposure was shown to decrease the N 2 O selectivity. The engine-aged catalyst has a decreasedperformance in terms of both decreased activity and increased N 2 O selectivity. For this catalyst, impurities fromfuel and engine-oil can play a role in the deactivation. Different deactivation mechanisms are seen for the lab-and engine-aged catalysts.
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| 6. |
- Dahlin, Sandra
(författare)
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Deactivation of emission control catalysts for heavy-duty vehicles : Impact of biofuel and lube oil-derived contaminants
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Catalytic emission control is used to reduce the negative impact of pollutants from diesel exhausts on our health and on the environment. For a heavy-duty truck, such a system consists of a diesel oxidation catalyst (DOC), a diesel particulate filter (DPF), a selective catalytic reduction (SCR) catalyst, and an ammonia slip catalyst (ASC). Due to greenhouse-gas induced global warming, it is necessary to decrease the emissions of such gases. Two strategies for this reduction are: 1) to produce engines that are more fuel efficient, 2) to use sustainably produced renewable fuels such as biodiesel and HVO. However, both these strategies may pose additional challenges for the emission control system: a colder exhaust due to the higher fuel-efficiency requires the use of highly active catalysts; catalyst deactivation related to impurities in biofuels, which requires very robust catalysts. The objective of this thesis was to study the impact of biofuel as well as lubrication oil-related contaminants on the performance of emission control catalysts (DOC and SCR catalysts) for heavy-duty diesel engines. The main focus has been on the low-temperature performance of V2O5-WO3/TiO2 (VWTi) and Cu-SSZ-13 SCR catalysts. Results from the project have shown that both Cu-SSZ-13 and VWTi catalysts capture and can be deactivated by phosphorus (P), while only the Cu-SSZ-13 is deactivated by sulfur (S). The degree of the P-related deactivation depends on the concentration in the catalyst, which depends on content of P in the exhaust and the exposure time, as well as the type of catalyst. S-deactivation of Cu-SSZ-13 is observed at low temperatures, where un-poisoned Cu-SSZ-13 are significantly more active than VWTi catalysts. As a contrast, the VWTi-performance can even be improved by sulfur; but alkali metals are severe poisons to VWTi catalysts. Partial performance-recovery of S-poisoned Cu-SSZ-13 can be obtained by exposing it to sulfur-free exhausts at elevated temperatures. The use of an upstream DOC, providing fast SCR conditions to the SCR catalyst, considerably improves the low-temperature performance of the VWTi, as well as sulfur-poisoned Cu-SSZ-13 catalysts. An upstream DOC also protects the SCR catalysts from phosphorus deactivation, as it can trap large amounts of P. However, if too much phosphorus is captured by the DOC, severe deactivation of this catalyst results, which lowers the overall performance of the exhaust treatment system. Insights from this project will guide the development of robust exhaust treatment systems for various applications. Additionally, it could aid in developing more durable emission control catalysts.
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| 7. |
- 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
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Annan publikation (övrigt vetenskapligt/konstnärligt)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 ºC. The use of an oxidation catalyst upstream of the SCR catalyst during the exhaust-exposure could protect the SCR catalyst from phosphorus poisoning. The results in this work will improve the 2 understanding of chemical deactivation of SCR catalysts and aid in developing durable aftertreatment systems.
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| 8. |
- 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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| 9. |
- Dahlin, Sandra, et al.
(författare)
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Multivariate analysis of the effect of biodiesel-derived contaminants on V2O5-WO3/TiO2 SCR catalysts
- 2016
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Ingår i: Applied Catalysis B. - : Elsevier. - 0926-3373 .- 1873-3883. ; 183, s. 377-385
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Tidskriftsartikel (refereegranskat)abstract
- This study investigates the effect of biodiesel-derived contaminants on vanadia-based NH3-SCR catalysts in heavy-duty exhaust aftertreatment. The aim was to study, not only the effect of single contaminants on the catalyst performance, but also of possible interaction effects between poisons.The effect of six potential catalyst poisons (Na, K, Mg, P, S and Zn) was evaluated using an experimental design and multivariate data analysis. Monolithic V2O5-WO3/TiO2 catalysts were subjected to accelerated laboratory-scale aging, where the six contaminants were fed simultaneously using a wet impregnation method. In addition to NOx conversion tests, the catalysts were characterized by means of ICP-OES, SEM-EDX, XPS, N2 physisorption and NH3-TPD. The lab-aged samples were compared to fresh and vehicle-aged catalysts.The accelerated aging method showed good reproducibility and gave rise to surface compounds similar to those found in vehicle-aged catalysts. Despite plausible differences regarding penetration depth of the contaminants into the walls of the catalyst, the aging method appears to be an efficient way to point out significant chemical poisons.The model obtained from the experimental design was found to correlate well with the experimental data and can therefore be used to predict effects of the various poisons and poison interactions. Significant effects on the NO. x conversion were found for P, S, Na, Mg and K as well as for the interactions P. ×. Na, P. ×. K and S. ×. Na. A poisoning effect was found for Mg, Na, K, P. ×. K, and P. ×. Na, where Na and K exhibited the strongest poisoning effect. The deactivating effect of alkali was lowered in the presence of phosphorus and sulfur, which is explained by the formation of phosphates and sulfates, preventing the interaction of the alkali metals with the vanadia active sites.
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| 10. |
- Englund, Johanna, 1988, et al.
(författare)
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Deactivation of a Pd/Pt Bimetallic Oxidation Catalyst Used in a Biogas-Powered Euro VI Heavy-Duty Engine Installation
- 2019
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Ingår i: Catalysts. - : MDPI. - 2073-4344. ; 9:12
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Tidskriftsartikel (refereegranskat)abstract
- The reduction of anthropogenic greenhouse gas emissions is crucial to avoid further warming of the planet. We investigated how effluent gases from a biogas powered Euro VI heavy-duty engine impact the performance of a bimetallic (palladium and platinum) oxidation catalyst. Using synthetic gas mixtures, the oxidation of NO, CO, and CH4 before and after exposure to biogas exhaust for 900 h was studied. The catalyst lost most of its activity for methane oxidation, and the activity loss was most severe for the inlet part of the aged catalyst. Here, a clear sintering of Pt and Pd was observed, and higher concentrations of catalyst poisons such as sulfur and phosphorus were detected. The sintering and poisoning resulted in less available active sites and hence lower activity for methane oxidation.
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