| 1. |
- Abiso, Ahmad Muhammad, et al.
(författare)
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Advances in copper-based catalysts for sustainable hydrogen production via methanol steam reforming
- 2024
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Ingår i: Chemical Engineering Journal Advances. - : Elsevier BV. - 2666-8211. ; 19
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Forskningsöversikt (refereegranskat)abstract
- Efficient hydrogen production through Methanol Steam Reforming (MSR) is an area of high importance due to its environmental suitability and superior energy efficiency compared to methane steam reforming. Therefore, we present a comprehensive investigation into the development of copper-based catalysts for MSR. Over the past decades, research in this domain has intensified, encompassing Cu-based catalysts that exhibit notable promise. Strategies to enhance catalytic activity and stability involve the utilisation of mesoporous support materials with tuneable properties, novel promoters, and the introduction of mixed oxides and metal organic framework amongst others. Furthermore, the paper underscores the significance of catalyst morphology and metal precursors in determining their final performance. Several new catalysts have shown remarkable selectivity for hydrogen while minimizing carbon monoxide production even at elevated temperatures, positioning them as strong candidates for environmentally friendly commercial hydrogen production through methanol steam reforming. Valuable insights into synthesis approaches and catalyst performance variations across different research groups are also presented.
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| 2. |
- Latham, Kenneth G., et al.
(författare)
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Self-generation of low ash carbon microspheres from the hydrothermal supernatant of anaerobic digestate : Formation insights and supercapacitor performance
- 2021
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Ingår i: Chemical Engineering Journal Advances. - : Elsevier. - 2666-8211. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- This work provides the first observations of and insights into the self-generation of carbon microspheres from the supernatant after hydrothermal carbonization of anaerobic digestate has been completed and the hydrochar removed. Solid State NMR and XPS revealed that the carbon microspheres were comprised of decomposed fragments of proteins, carbohydrates and lignin. The carbon microspheres were significantly lower in ash content (3.1%), compared to the hydrothermal solid (41.2%) and precursor (25.2%) and their formation reduced the total organic carbon load of the supernatant. The low ash content allowed them to be easily activated, achieving a surface area of 1711.0 m2 g−1, compared to 51.4 m2 g−1 for the activated hydrothermal solid and 12.8 m2 g−1 for the activated precursor. The microcarbon spheres achieved a specific capacitance from cyclic voltammetry of 86 F g−1 at 100 mV s−1 to 176 F g−1 at 1 mV s−1, while the gravimetric capacitance was 42 F g−1 at 25 A g−1 and 140 F g−1 at 0.5 A g−1 in 0.5 M Li2SO4 and a 1.8V potential window. Overall, this study highlights the importance of exploring this new product and its valorisation potential for the hydrothermal carbonization of ash-rich precursors.
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| 3. |
- Naveed, M. H., et al.
(författare)
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Torrefied biomass quality prediction and optimization using machine learning algorithms
- 2024
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Ingår i: Chemical Engineering Journal Advances. - : Elsevier. - 2666-8211. ; 19
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Tidskriftsartikel (refereegranskat)abstract
- Torrefied biomass is a vital green energy source with applications in circular economies, addressing agricultural residue and rising energy demands. In this study, ML models were used to predict durability (%) and mass loss (%). Firstly, data was collected and preprocessed, and its distribution and correlation were analyzed. Gaussian Process Regression (GPR) and Ensemble Learning Trees (ELT) were then trained and tested on 80 % and 20 % of the data, respectively. Both machine learning models underwent optimization through Genetic Algorithm (GA) and Particle Swarm Optimization (PSO) for feature selection and hyperparameter tuning. GPR-PSO demonstrates excellent accuracy in predicting durability (%), achieving a training R2 score of 0.9469 and an RMSE value of 0.0785. GPR-GA exhibits exceptional performance in predicting mass loss (%), achieving a training R2 value of 1 and an RMSE value of 9.7373e-05. The temperature and duration during torrefaction are crucial variables that are in line with the conclusions drawn from previous studies. GPR and ELT models effectively predict and optimize torrefied biomass quality, leading to enhanced energy density, mechanical properties, grindability, and storage stability. Additionally, they contribute to sustainable agriculture by reducing carbon emissions, improving cost-effectiveness, and aiding in the design and development of pelletizers. This optimization not only increases energy density and grindability but also enhances nutrient delivery efficiency, water retention, and reduces the carbon footprint. Consequently, these outcomes support biodiversity and promote sustainable agricultural, ecosystem, and environmental practices.
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| 4. |
- Otaru, A. J., et al.
(författare)
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On the hydrodynamics of macroporous structures : Experimental, CFD and artificial neural network analysis
- 2023
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Ingår i: Chemical Engineering Journal Advances. - : Elsevier. - 2666-8211. ; 16
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Tidskriftsartikel (refereegranskat)abstract
- Porous metallic structures play a critical role in mass and heat transfer processes due to their high surface areas, fixed porosity, and high stiffness – so understanding their fluid flow behaviour is crucial in designing materials that perform efficiently in mass and heat transfer. In view of this, a multi-disciplinary approach is employed to study the hydrodynamics of aluminium foams produced by a liquid melt infiltration technique using experimental, computational fluid dynamics (CFD) modelling and simulation, as well as artificial neural network (ANN) machine learning backpropagation. X-ray computed tomography datasets were used to characterize pore-structure-related properties of replicated materials, followed by three-dimensional advanced imaging of workable representative volume elements. Hydraulic flow information was acquired for the porous matrices using the constant-head permeameter technique. Experiments showed the permeability and Forchheimer coefficient dependence on pore-structure-related properties for fluid-flowing within the pre-Forchheimer and fully developed Forchheimer regimes. Flow permeability of 8.479 × 10−09m2 was highest in the material with the widest mean pore openings (0.212 mm) and lowest (1.291 × 10−09m2) in the material with the narrowest mean pore openings (0.106 mm). Conversely, Forchheimer coefficients were higher for materials with lower porosities and lower for materials with higher porosities. CFD calculations accurately predicted the fluid properties of metallic foams, as well as the influence of intrinsic foam properties on permeability and the Forchheimer coefficient. The ANN model framework was also able to provide valuable information about the hydrodynamics of these materials. Convolution and non-linearity of the ANN model were improved by adding supplementary neurons to the hidden layers allowing deviations within 0.3 and 9.0 percent to be attained.
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| 5. |
- Sörengård, Mattias, et al.
(författare)
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Fly ash-based waste for ex-situ landfill stabilization of per- and polyfluoroalkyl substance (PFAS)-contaminated soil
- 2022
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Ingår i: Chemical Engineering Journal Advances. - : Elsevier BV. - 2666-8211. ; 12
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Tidskriftsartikel (refereegranskat)abstract
- In response to world-wide soil and groundwater contamination per- and polyfluoroalkyl substances (PFAS), stakeholders require immediate mitigation. Soil deposition in landfill is a common mitigation scheme, but PFAS losses occur via landfill leachate. These leaching losses can be reduced by strategically utilizing other deposited waste materials for ex-situ contaminant stabilization. This screening study tested activated carbon (AC) and eight types of wastes (compost, rubber granulate, bentonite clay, industrial sludge, incineration slag, incineration bottom ash (n=4), incineration fly ash-based air pollution control residue (FA-APC) (n=16)) in amending (adding 4%, 5%, 10% or 25% sorbent) field-contaminated (n=19) and PFAS-fortified (n=11) soils. A subset of FA-based residue types, all originating from grate-fire incineration (G-F-I) plants, achieved extraordinarily high removal of PFAS. The removal was up to 98% (25% addition) of the sum of six dominant PFAS for field-contaminated soil and >99% of the sum of 11 PFAS for fortified soil (10/25% addition) (>99.9% for PFOS). Calculated partitioning coefficient revealed significant trends between sorption strength and perfluorocarbon chain length (0.21-0.47 log units per CF2-moiety), indicating high importance of hydrophobic sorption (R2>0.98). However, with incremental G-F-I FA-APC addition this relationship disappeared, indicating an alternative sorption mechanism. The exceptional PFAS sorption by G-F-I FA-APC was not explained by G-F-I surface area, surface charge, soil mineral- and metal composition, or solution DOC, metal, or ion composition (H+, Ca2+, Mg2+, Al3+ and Ba2+). Although the mechanism remains unknown, this study showed that landfill sites can utilize G-F-I FA-APC for ex-situ stabilization at negative cost, thus preventing PFAS-containing leachate.
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| 6. |
- Yang, Shuo, et al.
(författare)
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Mass transfer and modeling of deformed bubbles in square microchannel
- 2023
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Ingår i: Chemical Engineering Journal Advances. - 2666-8211. ; 16
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Tidskriftsartikel (refereegranskat)abstract
- Understanding of mass transfer in gas-liquid slug flow is imperative to design and optimize micro-reactors. There exist extensive studies on symmetric bubbles by the phase volume monitor technique, whereas deformed bubbles are rarely studied due to the limitation of volume calculation methods. In this work, CO2-water and N2-water two-phase flows were investigated in a square microchannel, obtaining annular flow, slug flow, and bubbly flow. A flow pattern map was then proposed and compared with the literature. A 3D slicing technique was developed to measure the volume and interfacial area of bubble, including symmetric bubbles and deformed bubbles, by slicing the bubble along the streamwise direction. Scaling laws of the important parameters that characterize the micro-reactors were proposed. Mass transfer coefficients kLa were quantified from the time-changing volume. The empirical correlation involving dimensionless numbers were fitted, which shows accurate predictive performance for mass transfer coefficients in this study and literatures. The bigger index of Reynolds number ReG indicated that gas flow condition is the main influencing factor during mass transfer process. To have a better universality, a new semi-theoretical model involving the ratio of the size of the liquid and gas phases LL/LG was developed based on the Pigford and Higbie penetration theory because experimental data confirms that the degree of bubble deformation is related to LL/LG. The semi-theoretical model shows a satisfactory agreement over the whole range of slug flow in this study.
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