Hydrodesulfurizace různých surovin na katalyzátoru CoMo/Al2O3 připraveným z heteropolyoxomolbdátu kobaltu

The CoMo/Al2O3 catalyst prepared from cobalt heteropolyoxomolybdate was evaluated in three different reactor systems in hydrodesulfurization of thiophene, 1-benzothiophene and light gas oil

Mechanical treatment of TiO2 and ZrO2 oxide mixtures

The mixed ZrO2–TiO2 system (5–50 wt% of ZrO2) has been studied to investigate the influence of the mechanical treatment on its physicochemical properties depending on the composition, time of milling (5, 10 and 20 min, r.p.m. 82) and temperature (400, 550 and 700 C). Samples were characterized by Raman spectroscopy, X-ray powder diffraction, Scanning Electron Microscopy coupled with Energy Dispersion X-ray analyzer, High Resolution-Transmission Electron Microscopy and nitrogen adsorption porosimetry. Results show that srilankite (TiZrO4) phase has been produced. No influence of the milling time and temperature on the phase composition is observed. The presence of zirconia increases the thermal stability of anatase phase up to 700 C hindering the anatase— rutile phase transformation

Phase formation in mixed TiO₂-ZrO₂ oxides prepared by sol-gel method

Pure titania, zirconia, and mixed oxides (3-37 mol.% of ZrO2) are prepared using the sol-gel method and calcined at different temperatures. The calcined samples are characterized by Raman spectroscopy, X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, and nitrogen adsorption porosimetry. Measurements reveal a thermal stability of the titania anatase phase that slightly increases in the presence of 3-13 mol.% of zirconia. Practically, the titania anatase-rutile phase transformation is hindered during the temperature increase above 700°C. The mixed oxide with 37 mol.% of ZrO2 treated at 550°C shows a new single amorphous phase with a surface area of the nanoparticles double with respect to the other crystalline samples and the formed srilankite structure (at 700°C). The anatase phase is not observed in the sample containing 37 mol.% of ZrO2. The treatment at 700°C causes the formation of the srilankite (Ti0.63Zr0.37Ox) phase

Hydrodesulfurization NiMo catalysts supported on Co, Ni and B modified Al2O3 from Anderson heteropolymolybdates

AbstractRecent catalysts of hydrodesulfurization (HDS) reaction consist of CoMo and NiMo phase supported on gamma-Al2O3 support. The support was modified with cobalt nitrate, nickel nitrate, or boric acid and high loadings of Anderson type heteropolyoxomolybdate (NH4)3[Ni(OH)6Mo6O18].7H2O were deposited. Surface area (SBET) and sulfide phase dispersion of the catalysts were determined by N2 physisorption and O2 chemisorption, respectively. Samples were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, infrared and UV-Vis spectrometry, and temperature programmed reduction. The activity of catalyst was measured in HDS of 1-benzothiophene. The preliminary incorporation of Co, Ni and B into the support increased the HDS activity of the deposited NiMo phase. IR and UV-Vis DR data revealed the partial decomposition of the initial Anderson type NiMo complex with a formation of new surface compounds, including heteropolymolybdates and separated polymeric oxomolybdenum compounds. X-ray photoelectron spectroscopy showed that the degree of Mo sulfidation is the smallest for the catalysts prepared over unmodified alumina and boron-modified alumina. The highest degree of sulfidation was found for the catalysts supported over Co-and Ni-modified alumina. The nickel-modified alumina increased the HDS activity and dispersion of the NiMo phase the most, which was associated with the formation of the largest number of active sites

Nanoparticles of AlTiZr mixed oxides as support of hydrodesulfurizaton catalysts: Synthesis and characterisation

TiAlZr mixed oxides, synthesized using sol–gel method, were characterized and used as supports of hydrodesulfurization catalysts (12 wt% Mo) prepared by impregnation either with molybdenum heteropolyacid H3PMo12O40 or its cobalt salt Co1.5PMo12O40. Structure, morphology and textural properties of oxides and catalysts were characterized using X-ray powder diffraction (XRD), Raman spectroscopy, Nitrogen adsorption porosimetry, TEM-EDS, temperature-programmed desorption (TPD) and temperature-programmed reduction (TPR) techniques. Activity of the catalytic systems was tested in thiophene hydrodesulfurization (HDS). No formation of a new oxide phase was revealed in the synthesized mixed materials. However the effect of separated oxides on the structure of ternary oxides was observed. Maximum in HDS activity of Mo containing samples was determined by optimum content of alumina in the mixed oxides. Incorporation of cobalt into the heteropolyacid increased the HDS activity about two times and masked the effect of the support composition

Phase formation in mixed TiO2-ZrO2 oxides prepared by sol-gel method

Pure titania, zirconia, and mixed oxides (3\u201437 mol.% of ZrO2) are prepared using the sol-gel method and calcined at different temperatures. The calcined samples are characterized by Raman spectroscopy, X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, and nitrogen adsorption porosimetry. Measurements reveal a thermal stability of the titania anatase phase that slightly increases in the presence of 3\u201413 mol.% of zirconia. Practically, the titania anatase-rutile phase transformation is hindered during the temperature increase above 700 C. The mixed oxide with 37 mol.% of ZrO2 treated at 550 C shows a new single amorphous phase with a surface area of the nanoparticles double with respect to the other crystalline samples and the formed srilankite structure (at 700 C). The anatase phase is not observed in the sample containing 37 mol.% of ZrO2. The treatment at 700 C causes the formation of the srilankite (Ti0.63Zr0.37Ox) phase