2024-06-30
06:40 |
Basic characteristics of sulfide catalysts for the direct decomposition of H2S
Bonnet, Florian ; Kaluža, Luděk
Sulfide catalysts are crucial in the hydrodesulfurization (HDS) of petroleum fractions, facilitating the hydrogenolysis of carbon-sulfur bonds. This process generates significant volumes of hydrogen sulfide (H2S), which is typically processed in the Claus unit. However, excess H2S can overwhelm the Claus process, creating both operational and environmental challenges. Researchers are now exploring sulfide catalysts for the direct thermo-catalytic decomposition of H2S to address this issue. Supported catalysts, like Mo/Al2O3, and commercial catalysts, considered typical monolayer-type well-dispersed catalysts, show the highest O2 uptake, ranging from 41.29 μmol/g for MoS2/Al2O3 (KLO) to 58.70 μmol/g for the commercial 715. Unsupported multilayer catalysts, such as Ni/MoWS2 (KKP), exhibit lower O2 uptake at 2.54 μmol/g, though it demonstrates high HDS activity with thiophene. Moreover, O2 uptake effectively describes the sintering of the Mo monolayer phase during the thermocatalytic reaction of H2S at 800°C. These O2 uptakes clearly correlate with the XRD patterns, where the MoS2 phase is X-ray amorphous with an O2 uptake of about 19.04 μmol/g, while the MoS2 phase in the spent catalyst shows certain crystallinity exhibiting an average particle size by Scherrer equation of about 6 nm and the O2 uptake of 1.63 μmol/g. O2 chemisorption thus serves as a valuable measure of the dispersion of Mo sulfides. The results obtain with the study of CoMo/Al2O3 (KJJ-family catalysts), highlight the correlation between the increasing amount of adsorbed O2 with the increasing nominal loading of MoO3 and the increasing rate constant of thiophene kTH. This research reveals the potential of these catalysts in hydrocarbon refining. The findings underline the connection between catalytic chemistry, process engineering, and environmental sustainability, with the objective to enhance industrial refining processes.
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2024-06-15
00:02 |
Measurements of New Particle Formation in the Atmosphere
Špalová, Anna
In this work, the formation of particles and their transformation to larger sizes will be studied by measuring the concentration of molecular clusters. The measurement will take place at a rural background site National Atmospheric Observatory Košetice. At the ground level, a Neutral and Air Ion Spectrometer (NAIS) able to measure both neutral and charged clusters or particles ranging from 0.8 to 40 nm in diameter will be used together with a Particle Size Magnifier (PSM) able to measure neutral clusters as small as 1 nm in diameter up to 12 nm. Larger particles will be measured by a Scanning Mobility Particle Sizer (SMPS). At a height of 230 m above ground level, there will be another SMPS and also a nanoSMPS able to detect particles as small as 1 nm in diameter.
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2024-06-15
00:02 |
Thin Film Photocatalysts on the Basis of g-C3N4
Schimon, Domonik
This study revolves around the synthesis of powder g-C3N4, fabricationof thin g-C3N4 films and their efficacy in degrading pollutants, assessed through experimentation in a batch photoreactor (BPR) and a slit geometry photomicroreactor (PMR)2. The photocatalytic activity of g-C3N4 was tested with 4 different model substances: fluorescent dye, rhodamine B, was used as a reference substance and three separate antibiotics, which are emerging wastewater pollutants, namely tetracycline, trimethoprim, sulfamethoxazole.
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2024-06-15
00:02 |
Bubble Breakup in Triton Solutions
Semlerová, Tereza
This work deals with investigation of the bubble breakup in surfactant Triton X-45 solutions and the results are compared with data measured in water and α-terpineol solutions as another type of surfactants.
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2024-06-15
00:02 |
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2024-06-15
00:02 |
Influence of Material Properties and Mixing Dynamics on Heat Transport in Granular Materials
Kokavcová, Anna
This study evaluates the effect of rotational speed on heat transfer and analyzes particle motion at different stirrer rotational frequencies to understand how primary and secondary flows affect heat transfer efficiency. It also examines the effect of Young’s modulus on heat transfer at different agitator\noperating speeds. Key simulation parameters and their influence 33 on heat transfer efficiency are detailed to improve the reproducibility and applicability of the results.
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2024-06-15
00:02 |
Exploring Bubble Dynamics with VOF Method Simulations: Insights from Two Fundamental Gas-Liquid Flow Case Studies
Harrandt, Václav
The present study focuses on the flow of Taylor bubbles, representing the interaction between the channel wall and the gas phase, and the collision of\na bubble with a vortex ring, serving as a model liquid-gas interaction. Understanding the former case can be essential to prevent the membrane\nfouling or the flow induced corrosion. The dynamics of the latter case is the predictive criterion for whether the initial mother bubble will break up into the daughter bubbles or not2 and this process can therefore be used as an idealized model of turbulent bubble flow.
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2024-06-15
00:02 |
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2024-06-15
00:02 |
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2024-06-15
00:02 |
Investigation of Mechanical Processing of Solar Photovoltaic Panels
Šperlich, Antonín
This work aims to describe the possibilities of mechanical treatment of solar photovoltaic panels. In the first part, the shredding and milling process for the transformation of the product (whole panel) into material that can be further processed, was investigated. Milled material was sieved and analyzed. It was observed that this shredding also works as a selective grinding because three main products were produced. The second part of this work was aimed at the physical concentration of silver in real samples of milled solar photovoltaic panels by Knelson separator. This device (type of centrifugal separator) showed the ability to significantly increase the amount of silver in the outcome stream.
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