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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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Hydrotreating over Silica-Alumina Supported Catalysts
Gulková, Daniela ; Vít, Zdeněk ; Kaluža, Luděk
They are studied for possible use in deep hydrodesulfurization (HDS)1 while they have not been investigated for the HDS parallel with hydrodeoxygenation (HDO)2. The aim was to find the effect of active phase and support of Pd and PdPt catalysts on activity and selectivity in HDS of 4,6-dimethyldibenzothiophene (DMDBT) and HDS/HDO of l-benzothiophene/octanoic acid (BT/OA).
Plný tet: 00206B6C274C191104130820 -  DOC
Plný text: content.csg - DOC
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The Novel Preparation of Hydrotreating Catalysts Using Machanochemical Activation of Aluminum Nitrate and NiMo Complexes.
Kaluža, Luděk ; Jirátová, Květa ; Tyuliev, G. ; Gulková, Daniela ; Balabánová, Jana ; Palcheva, R. ; Koštejn, Martin ; Spojakina, A.
The novel Al2O3 synthesis by mechanochemical activation of aluminum nitrate hydrate was applied to prepare hydrodesulfurization (HDS) NiMo catalysts. Impregnation techniques using the complex made by dissolution of nitrilotriacetic acid (NTA), ammonium heptamolybdate and nickel nitrate and the Anderson-type heteropolyoxymolybdate ((NH4)4Ni(OH)6Mo6O18) complex were compared with conventional impregnation using subsequent deposition of ammonium heptamolybdate (first) and nickel nitrate (second) with calcination in between. Properties of the support and HDS catalysts were studied by N2 physisorption, Raman spectroscopy, H2 temperature-programmed reduction (H2-TPR), O2 chemisorption and X-ray photoelectron spectroscopy (XPS).
Plný text:  PDF
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Hydrodesulfurization NiMo Catalysts over Mechanochemically Prepared Gamma-Alumina.
Kaluža, Luděk ; Jirátová, Květa ; Tyuliev, G. ; Palcheva, R. ; Koštejn, Martin ; Spojakina, A.
The aim of the present work is to explore optimum preparation route of NiMo catalysts for the novel mechanochemically prepared Al2O3 in order to achieve high HDS activity. Specifically, the goals are: i) to up-scale the support synthesis to provide sufficient amount ofAl2O3, ii) to deposit NiMo from solutions of highly soluble precursors by conventional impregnation techniques (I), i.e. sequential impregnation using Mo (first) and Ni (second), and by co-impregnation (Ni+Mo together), i.e. using chelating agent NTA or nickel heteropolyoxomolybdate (HPO), iii) to deposit NiMo from solutions ofslightly soluble precursors by slurry impregnation (SI).\n
Plný tet: SKMBT_C22018100509420 - PDF
Plný text: content.csg - PDF
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