The Experts below are selected from a list of 309 Experts worldwide ranked by ideXlab platform
F J Urbano - One of the best experts on this subject based on the ideXlab platform.
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influence of the preparation method on the structural and surface properties of various Magnesium Oxides and their catalytic activity in the meerwein ponndorf verley reaction
Applied Catalysis A-general, 2003Co-Authors: M A Aramendia, V Borau, C Jimenez, J M Marinas, Jose Rafael Ruiz, F J UrbanoAbstract:Abstract The Meerwein–Ponndorf–Verley (MPV) reaction of cyclohexanone with isopropyl alcohol, which yields cyclohexanol, was studied by using basic catalysts consisting of Magnesium oxide. The Oxides were prepared using various synthetic procedures including calcination of commercially available Magnesium hydroxide and carbonate, calcination of Magnesium hydrOxides obtained from Magnesium nitrate and sulphate, the sol–gel technique and precipitation by decomposition of urea. The solids thus obtained were characterized structurally by X-ray diffraction spectroscopy and their surface properties determined using gas adsorption measurements (of nitrogen for textural properties and carbon dioxide for basic properties). Based on the results, the most active catalyst was the solid prepared by rehydration and subsequent calcination of a Magnesium oxide that was previously obtained from commercially available Magnesium hydroxide.
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characterization of various Magnesium Oxides by xrd and1h mas nmr spectroscopy
IEEE Journal of Solid-state Circuits, 1999Co-Authors: M A Aramendia, V Borau, C Jimenez, J M Marinas, Jose A Benitez, Jose Rafael Ruiz, F J UrbanoAbstract:Abstract A Magnesium oxide obtained by thermal decomposition of commercially available Magnesium hydroxide was refluxed in water and acetone in order to improve its chemical and textural properties with the purpose of using it as a support for metals in heterogeneous catalysts. X-ray diffraction, CO2chemisorption, and1H magic-angle spinning nuclear magnetic resonance were used to identify crystal phases, the number of basic sites, and the nature of OH groups in the oxide, respectively.
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Magnesium Oxides as basic catalysts for organic processes study of the dehydrogenation dehydration of 2 propanol
Journal of Catalysis, 1996Co-Authors: M A Aramendia, V Borau, C Jimenez, J M Marinas, A Porras, F J UrbanoAbstract:Abstract The reactivity of various Magnesium Oxides in the gas-phase dehydrogenation–dehydration of 2-propanol was studied by using a tubular flow reactor. The Oxides were synthesized from different precursors by using various methods. The influence of the precursor used, in vacuo calcination and B 2 O 3 doping was analyzed in the light of the results obtained in the above-mentioned test reaction. Potential correlations between the surface acid–base properties of the Oxides and the kinetic constants of dehydrogenation and dehydration obtained for the test reaction were sought. Also, potential sources of deactivation for the catalysts were investigated. Carbon deposits observed by temperature-programmed oxidation and the presence of strongly adsorbed species following an isothermal reaction, which were detected by temperature-programmed desorption, were found to be the two primary sources. Finally, the reaction mechanism was studied; the two proposed pathways are consistent with the results obtained.
Isabel Cabrita - One of the best experts on this subject based on the ideXlab platform.
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effect of catalysts in the quality of syngas and by products obtained by co gasification of coal and wastes 2 heavy metals sulphur and halogen compounds abatement
Fuel, 2008Co-Authors: Filomena Pinto, Helena Lopes, Rui Neto Andre, Ibrahim Gulyurtlu, Isabel CabritaAbstract:This paper analyses the formation of sulphur and halogens compounds during co-gasification of low grade coals with different types of wastes that include: pine, petcoke and polyethylene (PE) with the aim of taking profit of waste energy value with the smallest possible impact on the environment. The influence of different types of catalysts or sorbents was studied: calcined dolomite, dolomite enriched with nickel, olivine, nickel and Magnesium Oxides, zinc oxide and cobalt and molybdenum Oxides. The presence of dolomite led to the lowest HCl, HF and H2S concentrations in the syngas produced. ZnO also gave rise to significant decrease in H2S concentration, though higher concentrations were obtained than those with dolomite. It was found that when catalysts or sorbents were used, a significant fraction of sulphur, halogens and heavy metals were trapped in the solid residue left behind in the bed and cyclone. Higher temperatures increased the volatility of some metals and sulphur. Leachability assays of solids showed that small quantities of SO42- and Cl− could be released and most metals were not leachable, although the use of dolomite slightly increased metals leachability, because of the higher alkaline nature of residual solids produced.
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effect of catalysts in the quality of syngas and by products obtained by co gasification of coal and wastes 1 tars and nitrogen compounds abatement
Fuel, 2007Co-Authors: Filomena Pinto, Helena Lopes, Rui Neto Andre, Ibrahim Gulyurtlu, Isabel CabritaAbstract:Abstract The aim of this work is to analyse the possibility of using co-gasification technology to process coal mixed with wastes to take profit of its energy content and at the same time to minimize the environmental impact associated with the use of wastes and to diminish the costs of flue gas treatment. The addition to coal of different types of materials, like: pine based waste, petcoke and polyethylene (PE), was not found to give rise to any operational problems, regarding both the feeding system and gasification process and led to higher energy conversions, however, the gas presented higher tars and hydrocarbons content. Several catalysts were tested, such as, dolomite, olivine, nickel and Magnesium Oxides, zinc Oxides and cobalt and molybdenum Oxides. Catalyst action was analysed in tars release and also in ammonia compounds reduction. The presence of catalysts allowed increasing hydrogen release, whilst there was a decrease in hydrocarbons and tars contents. A nickel–Magnesium oxide was the catalyst that led to the highest reduction in hydrocarbons and tars. This catalyst also led to the lowest NH 3 content in the fuel gas produced, due to the catalyst efficiency in NH 3 destruction.
M A Aramendia - One of the best experts on this subject based on the ideXlab platform.
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influence of the preparation method on the structural and surface properties of various Magnesium Oxides and their catalytic activity in the meerwein ponndorf verley reaction
Applied Catalysis A-general, 2003Co-Authors: M A Aramendia, V Borau, C Jimenez, J M Marinas, Jose Rafael Ruiz, F J UrbanoAbstract:Abstract The Meerwein–Ponndorf–Verley (MPV) reaction of cyclohexanone with isopropyl alcohol, which yields cyclohexanol, was studied by using basic catalysts consisting of Magnesium oxide. The Oxides were prepared using various synthetic procedures including calcination of commercially available Magnesium hydroxide and carbonate, calcination of Magnesium hydrOxides obtained from Magnesium nitrate and sulphate, the sol–gel technique and precipitation by decomposition of urea. The solids thus obtained were characterized structurally by X-ray diffraction spectroscopy and their surface properties determined using gas adsorption measurements (of nitrogen for textural properties and carbon dioxide for basic properties). Based on the results, the most active catalyst was the solid prepared by rehydration and subsequent calcination of a Magnesium oxide that was previously obtained from commercially available Magnesium hydroxide.
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characterization of various Magnesium Oxides by xrd and1h mas nmr spectroscopy
IEEE Journal of Solid-state Circuits, 1999Co-Authors: M A Aramendia, V Borau, C Jimenez, J M Marinas, Jose A Benitez, Jose Rafael Ruiz, F J UrbanoAbstract:Abstract A Magnesium oxide obtained by thermal decomposition of commercially available Magnesium hydroxide was refluxed in water and acetone in order to improve its chemical and textural properties with the purpose of using it as a support for metals in heterogeneous catalysts. X-ray diffraction, CO2chemisorption, and1H magic-angle spinning nuclear magnetic resonance were used to identify crystal phases, the number of basic sites, and the nature of OH groups in the oxide, respectively.
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Magnesium Oxides as basic catalysts for organic processes study of the dehydrogenation dehydration of 2 propanol
Journal of Catalysis, 1996Co-Authors: M A Aramendia, V Borau, C Jimenez, J M Marinas, A Porras, F J UrbanoAbstract:Abstract The reactivity of various Magnesium Oxides in the gas-phase dehydrogenation–dehydration of 2-propanol was studied by using a tubular flow reactor. The Oxides were synthesized from different precursors by using various methods. The influence of the precursor used, in vacuo calcination and B 2 O 3 doping was analyzed in the light of the results obtained in the above-mentioned test reaction. Potential correlations between the surface acid–base properties of the Oxides and the kinetic constants of dehydrogenation and dehydration obtained for the test reaction were sought. Also, potential sources of deactivation for the catalysts were investigated. Carbon deposits observed by temperature-programmed oxidation and the presence of strongly adsorbed species following an isothermal reaction, which were detected by temperature-programmed desorption, were found to be the two primary sources. Finally, the reaction mechanism was studied; the two proposed pathways are consistent with the results obtained.
Filomena Pinto - One of the best experts on this subject based on the ideXlab platform.
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effect of catalysts in the quality of syngas and by products obtained by co gasification of coal and wastes 2 heavy metals sulphur and halogen compounds abatement
Fuel, 2008Co-Authors: Filomena Pinto, Helena Lopes, Rui Neto Andre, Ibrahim Gulyurtlu, Isabel CabritaAbstract:This paper analyses the formation of sulphur and halogens compounds during co-gasification of low grade coals with different types of wastes that include: pine, petcoke and polyethylene (PE) with the aim of taking profit of waste energy value with the smallest possible impact on the environment. The influence of different types of catalysts or sorbents was studied: calcined dolomite, dolomite enriched with nickel, olivine, nickel and Magnesium Oxides, zinc oxide and cobalt and molybdenum Oxides. The presence of dolomite led to the lowest HCl, HF and H2S concentrations in the syngas produced. ZnO also gave rise to significant decrease in H2S concentration, though higher concentrations were obtained than those with dolomite. It was found that when catalysts or sorbents were used, a significant fraction of sulphur, halogens and heavy metals were trapped in the solid residue left behind in the bed and cyclone. Higher temperatures increased the volatility of some metals and sulphur. Leachability assays of solids showed that small quantities of SO42- and Cl− could be released and most metals were not leachable, although the use of dolomite slightly increased metals leachability, because of the higher alkaline nature of residual solids produced.
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effect of catalysts in the quality of syngas and by products obtained by co gasification of coal and wastes 1 tars and nitrogen compounds abatement
Fuel, 2007Co-Authors: Filomena Pinto, Helena Lopes, Rui Neto Andre, Ibrahim Gulyurtlu, Isabel CabritaAbstract:Abstract The aim of this work is to analyse the possibility of using co-gasification technology to process coal mixed with wastes to take profit of its energy content and at the same time to minimize the environmental impact associated with the use of wastes and to diminish the costs of flue gas treatment. The addition to coal of different types of materials, like: pine based waste, petcoke and polyethylene (PE), was not found to give rise to any operational problems, regarding both the feeding system and gasification process and led to higher energy conversions, however, the gas presented higher tars and hydrocarbons content. Several catalysts were tested, such as, dolomite, olivine, nickel and Magnesium Oxides, zinc Oxides and cobalt and molybdenum Oxides. Catalyst action was analysed in tars release and also in ammonia compounds reduction. The presence of catalysts allowed increasing hydrogen release, whilst there was a decrease in hydrocarbons and tars contents. A nickel–Magnesium oxide was the catalyst that led to the highest reduction in hydrocarbons and tars. This catalyst also led to the lowest NH 3 content in the fuel gas produced, due to the catalyst efficiency in NH 3 destruction.
Arjun Maity - One of the best experts on this subject based on the ideXlab platform.
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rapid high adsorption performance of hydrous cerium Magnesium Oxides for removal of fluoride from water
Journal of Molecular Liquids, 2018Co-Authors: Marko Chigondo, Hugues Kamdem Paumo, Madhumita Bhaumik, Kriveshini Pillay, Arjun MaityAbstract:Abstract A simple co-precipitation method was used to prepare a series of eco-friendly hydrous cerium-Magnesium bimetal Oxides (HCeMgO1:2, HCeMgO1:3, HCeMgO1:1 and HCeMgO2:1) adsorbents at different Ce/Mg molar ratio for fluoride removal from aqueous solution. The ideal adsorbent, HCeMgO1:1, not only demonstrated high adsorption efficiency but also rapid kinetics. Comprehensive characterization of HCeMgO1:1 before and after fluoride adsorption was performed using Scanning Electron Microscope (SEM), High Resolution Transmission Electron Microscope (HR-TEM), X-ray Photoelectron Spectroscopy (XPS), Fourier Transform Infrared Spectroscopy (FTIR), point-of-zero charge, Thermogravimetric-Differential Thermal Analysis (TG-DTA), Brunauer-Emmett-Teller (BET) and X-ray Diffraction (XRD) techniques. The BET surface area of HCeMgO1:1 was around 34.06 m2/g. The effect of various parameters such as adsorbent dosage, contact time, initial concentration, initial pH and co-existing ions was investigated in batch mode. Desorption study was explored to test the reusability of HCeMgO1:1. A pseudo-second-order model described the adsorption kinetics best with 5–20 minute rapid equilibrium adsorption. Fluoride uptake followed Langmuir model, with maximum adsorption capacities in the range of 66.23–80.00 mg/g from 25 to 45 °C at pH value 5.5. Both ion exchange and electrostatic interactions were found to dictate the process. The sorption was spontaneous and endothermic in nature. The revival study of the fluoride laden HCeMgO1:1 exhibited a high desorption efficiency up to four adsorption-desorption cycles. Further assay on underground water samples deep-rooted the potential use of HCeMgO1:1 as suitable candidate for defluoridation.
