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Miroslav Zdražil - One of the best experts on this subject based on the ideXlab platform.

  • Water-assisted spreading of MoO3 onto SiO2–Al2O3 supports for preparation of sulfide CoMo hydrodesulfurization catalysts
    Fuel, 2013
    Co-Authors: Luděk Kaluža, Zdeněk Vít, Daniela Gulková, Miroslav Zdražil
    Abstract:

    Catalysts with various MoO3 and Al2O3 contents were prepared by a reaction of acidic SiO2–Al2O3 supports with Aqueous Slurry of MoO3. The saturated adsorption amount of MoO3 corresponded with the amount of Al2O3 in the supports. The deposited and sulfided Mo species were accessible for promotion of the activity and selectivity in benzothiophene hydrodesulfurization reaction by Co. The acidity of the SiO2–Al2O3 supports modified by dealumination by leaching with nitric acid in terms of cyclohexene isomerization and cumene cracking were preserved after deposition of the CoMo sulfide phase.

  • Deposition of NiO onto MoO_3/γ-Al_2O_3 extrudates by Slurry impregnation method
    Reaction Kinetics and Catalysis Letters, 2009
    Co-Authors: Luděk Kaluža, Miroslav Zdražil, Zdeněk Vít
    Abstract:

    NiO-MoO_3/γ-Al_2O_3 catalysts were prepared by the reaction of γ-Al_2O_3 extrudates with an Aqueous Slurry of MoO_3, followed by the reaction of the MoO_3/γ-Al_2O_3 catalyst with an Aqueous Slurry of NiO, Ni(OH)_2, NiCO_3·2Ni(OH)_2· x H_2O, or 2NiCO_3·3Ni(OH)_2·4H_2O and by subsequent drying. The NiO deposition was examined with electron probe microanalysis. The deposited Ni efficiently increased the activity in benzothiophene hydrodesulfurization.

  • Deposition of NiO onto MoO3/γ-Al2O3 extrudates by Slurry impregnation method
    Reaction Kinetics and Catalysis Letters, 2009
    Co-Authors: Luděk Kaluža, Miroslav Zdražil, Zdeněk Vít
    Abstract:

    NiO-MoO3/γ-Al2O3 catalysts were prepared by the reaction of γ-Al2O3 extrudates with an Aqueous Slurry of MoO3, followed by the reaction of the MoO3/γ-Al2O3 catalyst with an Aqueous Slurry of NiO, Ni(OH)2, NiCO3·2Ni(OH)2·xH2O, or 2NiCO3·3Ni(OH)2·4H2O and by subsequent drying. The NiO deposition was examined with electron probe microanalysis. The deposited Ni efficiently increased the activity in benzothiophene hydrodesulfurization.

  • Slurry Impregnation of ZrO_2 Extrudates: Controlled EggShell Distribution of MoO_3, Hydrodesulfurization Activity, Promotion by Co
    Catalysis Letters, 2009
    Co-Authors: Luděk Kaluža, Miroslav Zdražil
    Abstract:

    Catalysts with eggshell/uniform Mo concentration profiles were prepared by a reaction of ZrO_2 and ZrO(OH)_2 extrudates with an Aqueous Slurry of MoO_3. The thickness of the shell was regulated by the amount of MoO_3. CoCO_3 was adsorbed onto MoO_3/ZrO_2 from its Aqueous Slurry. The ZrO_2-supported catalysts were compared to their TiO_2-supported and industrial reference Al_2O_3-supported counterparts in a model reaction of benzothiophene hydrodesulfurization.

  • Preparation of alumina supported molybdena catalysts by new Slurry impregnation method: MoO_3/Al_2O_3 sulfide hydrodesulfurization catalyst
    Catalysis Letters, 1994
    Co-Authors: Miroslav Zdražil
    Abstract:

    A new Slurry impregnation method (SIM) of the preparation of a catalyst or catalyst precursor MoO_3/Al_2O_3 is described. Aqueous Slurry of powdered MoO_3 is mixed with alumina extradátes and the mixture is refluxed. A low solubility of MoO_3 is sufficient for transport of MoO_3 from powder form via solution to the surface of the support. The catalysts were tested by hydrodesulfurization of thiophene at 1.6 MPa and 280–400°C. Their activity was similar to the activity of industrial and laboratory MoO_3/Al_2O_3 samples prepared by conventional impregnation with solution of ammonium heptamolybdate. The advantage of the SIM method is that calcination, producing nitrogeneous waste gases, is not required and that all deposited molybdenum species are adsorbed and not precipitated.

Ramin Farnood - One of the best experts on this subject based on the ideXlab platform.

  • Effect of Hydrogen Peroxide on the Photocatalytic Degradation of Methyl tert-butyl Ether
    Topics in Catalysis, 2006
    Co-Authors: Yujing Zang, Ramin Farnood
    Abstract:

    The photocatalytic degradation of methyl tert -butyl ether (MTBE) was investigated in the Aqueous Slurry of titanium dioxide (TiO_2) particles irradiated with xenon lamp in a batch reactor, in the presence and absence of hydrogen peroxide. The reaction was found to follow a pseudo -first-order kinetics and the initial reaction rate constant increased by raising the TiO_2 loading and reached an apparent optimum value at 0.5 g TiO_2/L. The addition of small amounts of hydrogen peroxide to the TiO_2 Slurry, which is generally known to enhance the oxidation process in treating organic pollutants, decreased the initial MTBE degradation rate by as much as nearly 50%. However, this trend was reversed and reaction rate approached a plateau at higher concentration levels of hydrogen peroxide.

  • Photocatalytic decomposition of methyl tert-butyl ether in Aqueous Slurry of titanium dioxide
    Applied Catalysis B: Environmental, 2005
    Co-Authors: Yujing Zang, Ramin Farnood
    Abstract:

    Abstract The photocatalytic degradation of methyl tert -butyl ether (MTBE) was investigated in the Aqueous Slurry of titanium dioxide (TiO 2 ) particles irradiated with xenon lamp in a batch reactor. The reaction was found to follow a pseudo-first-order kinetics and the reaction rate increased by raising the TiO 2 loading and the UV light intensity. The reaction rate constant was proportional to the square root of the UV intensity. An upper plateau level was observed for the reaction rate constant, corresponding to a steady photoproduction of hydroxyl radicals at high catalyst concentrations. The experimental data was analyzed using a modified Turchi–Ollis model to account for changes in the catalyst loading. It was found that this model predicted the observed trend in the pseudo-first-order rate constant if the reaction pathway involves the interaction between adsorbed hydroxyl radicals and solvated molecules.

Ange Nzihou - One of the best experts on this subject based on the ideXlab platform.

  • Can biomass be satisfactorily gasified under pressure using an Aqueous Slurry feed? Examination by simulation
    Biomass and Bioenergy, 2017
    Co-Authors: Brian Stanmore, Ange Nzihou
    Abstract:

    A major hurdle for the gasification of biomass under pressure is the need to introduce a fibrous biomass feed material such as straw, switchgrass or miscanthus into a pressure vessel. One proposed solution is to prepare a dense Aqueous Slurry from the biomass and then use a conventional high pressure pump. The production of syngas from wheat straw and subsequent power generation is examined theoretically in an Australian context. A Slurry of concentration of 50% biomass by volume, which is regarded as the maximum pumpable value, is dried with superheated steam and the biomass gasified at 2 MPa with steam only in cyclones. It was found that the thermal deficiency of introducing excessive liquid water is considerable, rendering the process unsustainable. The problem can be overcome by employing a subsidiary fuel such as natural gas, but even with the minimal amount of water, the required energy input is equivalent to that of the straw. The net electrical efficiency of the process based on both fuels is 33.5%, so that the approach would be contemplated only if the over-riding consideration was the use of the straw for energy generation. The zero net present value cost of power production is 125 $ MWh-1 for 90 Gg of straw consumption per annum.

  • Can biomass be satisfactorily gasified under pressure using an Aqueous Slurry feed? Examination by simulation
    Biomass and Bioenergy, 2017
    Co-Authors: Brian Stanmore, Ange Nzihou
    Abstract:

    International audienceA major hurdle for the gasification of biomass under pressure is the need to introduce a fibrous biomass feed material such as straw, switchgrass or miscanthus into a pressure vessel. One proposed solution is to prepare a dense Aqueous Slurry from the biomass and then use a conventional high pressure pump. The production of syngas from wheat straw and subsequent power generation is examined theoretically in an Australian context. A Slurry of concentration of 50% biomass by volume, which is regarded as the maximum pumpable value, is dried with superheated steam and the biomass gasified at 2 MPa with steam only in cyclones. It was found that the thermal deficiency of introducing excessive liquid water is considerable, rendering the process unsustainable. The problem can be overcome by employing a subsidiary fuel such as natural gas, but even with the minimal amount of water, the required energy input is equivalent to that of the straw. The net electrical efficiency of the process based on both fuels is 33.5%, so that the approach would be contemplated only if the over-riding consideration was the use of the straw for energy generation. The zero net present value cost of power production is 125 $ MWh-1 for 90 Gg of straw consumption per annum

Yujing Zang - One of the best experts on this subject based on the ideXlab platform.

  • Effect of Hydrogen Peroxide on the Photocatalytic Degradation of Methyl tert-butyl Ether
    Topics in Catalysis, 2006
    Co-Authors: Yujing Zang, Ramin Farnood
    Abstract:

    The photocatalytic degradation of methyl tert -butyl ether (MTBE) was investigated in the Aqueous Slurry of titanium dioxide (TiO_2) particles irradiated with xenon lamp in a batch reactor, in the presence and absence of hydrogen peroxide. The reaction was found to follow a pseudo -first-order kinetics and the initial reaction rate constant increased by raising the TiO_2 loading and reached an apparent optimum value at 0.5 g TiO_2/L. The addition of small amounts of hydrogen peroxide to the TiO_2 Slurry, which is generally known to enhance the oxidation process in treating organic pollutants, decreased the initial MTBE degradation rate by as much as nearly 50%. However, this trend was reversed and reaction rate approached a plateau at higher concentration levels of hydrogen peroxide.

  • Photocatalytic decomposition of methyl tert-butyl ether in Aqueous Slurry of titanium dioxide
    Applied Catalysis B: Environmental, 2005
    Co-Authors: Yujing Zang, Ramin Farnood
    Abstract:

    Abstract The photocatalytic degradation of methyl tert -butyl ether (MTBE) was investigated in the Aqueous Slurry of titanium dioxide (TiO 2 ) particles irradiated with xenon lamp in a batch reactor. The reaction was found to follow a pseudo-first-order kinetics and the reaction rate increased by raising the TiO 2 loading and the UV light intensity. The reaction rate constant was proportional to the square root of the UV intensity. An upper plateau level was observed for the reaction rate constant, corresponding to a steady photoproduction of hydroxyl radicals at high catalyst concentrations. The experimental data was analyzed using a modified Turchi–Ollis model to account for changes in the catalyst loading. It was found that this model predicted the observed trend in the pseudo-first-order rate constant if the reaction pathway involves the interaction between adsorbed hydroxyl radicals and solvated molecules.

Luděk Kaluža - One of the best experts on this subject based on the ideXlab platform.