John Gelves | Universidad Libre de Colombia (original) (raw)
Papers by John Gelves
Microporous and Mesoporous Materials, 2019
A natural zeolite presents in rocks of volcanic origin located in Colombia was characterized and ... more A natural zeolite presents in rocks of volcanic origin located in Colombia was characterized and tested for the isomerization of β-pinene epoxide. The material was characterized by TPD-NH 3 , BET, SEM, FRX, FTIR of adsorption-desorption of pyridine, TPD-CO 2 and TPR-H 2. It was found that 65% of the acidity was strong and 75% was Lewis type; the material also had low basicity, and a surface area of 34.9 m 2 g-1. The effect of different parameters such as kind of solvent (ethanol, THF, dioxane, acetone and toluene), concentration of catalyst, temperature and time on catalysts activity was evaluated in the ring-opening reaction of β-pinene epoxide. The maximum conversion (97%), selectivities to perillyl alcohol (46%), myrtanal (23%) and myrtenol (12%) were obtained with toluene (70°C, 1 h). A reaction mechanism was proposed based on the experimental and theoretical results for explaining the formation of the products synthetized from the catalytic reaction over Brönsted and Lewis acid sites. The catalyst was reused five times without apparent loss of conversion, but with a slight decreasing of selectivity to perillyl alcohol and increase of selectivity to myrtanal and myrtenol.
Boletín de la Sociedad Española de Cerámica y Vidrio, 2018
El área metropolitana de Cúcuta (Colombia) se caracteriza por contar con un conglomerado de empre... more El área metropolitana de Cúcuta (Colombia) se caracteriza por contar con un conglomerado de empresas dedicadas a la fabricación de materiales cerámicos de construcción. La zona de * Autor para correspondencia.
Catalysis Today, 2019
The Selective Catalytic Reduction of NOx by ammonia (NH 3-SCR of NOx) was studied over an iron Co... more The Selective Catalytic Reduction of NOx by ammonia (NH 3-SCR of NOx) was studied over an iron Colombian natural zeolite (Nat-zeo) based geo-catalysts after several treatments (H-zeo-Fe 3+ and H-zeo-Fe 2+) under lean, dry and wet conditions. Nat-zeo from the Combia geological formation in Colombia (South America) was treated with NH 4 NO 3 , calcined in air for obtaining H-zeo-Fe 3+ and then reduced with hydrogen to obtain the H-zeo-Fe 2+ catalyst. Catalysts were characterized by XRD, FTIR, Mössbauer spectroscopy, SEM/EDX, XRF BET, H 2-TPR, NH 3-TPD, and NOx-TPD. H-zeo-Fe 3+ showed better catalytic performance than Nat-zeo and H-zeo-Fe 2+ in the NOx conversion. The presence of Fe 3+ ions and the acidity in the catalyst explains partially the high activity towards NOx reduction. Water inhibits the NO and improves the NO 2 adsorption on the catalyst H-zeo-Fe 3+ surface according with the NOx-TPD analysis. After 30 h on-stream, under wet conditions, the Hzeo-Fe 3+ catalyst showed a decreased in the NOx conversion. The decrease of activity could be related with the loss of catalyst surface acidity detected by NH 3-TPD analysis after reaction and with the contraction of the zeolite channels due to the metaheulandite phase formation that was confirmed by XRD, BET and FTIR analysis.
Journal of Physics: Conference Series, Nov 1, 2019
Direct synthesis of methanol and other oxygenated compounds (ethanol, propanol, acetaldehyde, for... more Direct synthesis of methanol and other oxygenated compounds (ethanol, propanol, acetaldehyde, formic acid, acetic acid and propanoic acid) was carried out through the partial oxidation of methane process using carbon dioxide (greenhouse gas) and water in liquid phase (water has only been used in the form of steam). The activation process was carried out with dielectric barrier discharge plasma (sinusoidal power) and in the presence of a catalyst. A Colombian natural zeolite, glass wool and a material composed of magnesium oxide and alumina were used in this scientific investigation as catalysts. Tests in the presence/absence of catalyst, presence/absence of liquid water and combinations of the previous tests were carried out in order to establish which conditions allow to obtain the highest conversion of reagents and selectivity to oxygenated compounds. It was evidenced that the glass wool allows to obtain the highest levels of reagent conversion, followed by the magnesium catalyst and finally the natural zeolite. Regarding selectivity, the natural zeolite showed to be efficient for the obtaining of oxygenated compounds. It was also established that the presence of liquid water in the reactor decreases the conversion of the reactants, but favors the formation of carbon monoxide, hydrogen and especially oxygenated compounds.
Microporous and Mesoporous Materials, 2019
A natural zeolite presents in rocks of volcanic origin located in Colombia was characterized and ... more A natural zeolite presents in rocks of volcanic origin located in Colombia was characterized and tested for the isomerization of β-pinene epoxide. The material was characterized by TPD-NH 3 , BET, SEM, FRX, FTIR of adsorption-desorption of pyridine, TPD-CO 2 and TPR-H 2. It was found that 65% of the acidity was strong and 75% was Lewis type; the material also had low basicity, and a surface area of 34.9 m 2 g-1. The effect of different parameters such as kind of solvent (ethanol, THF, dioxane, acetone and toluene), concentration of catalyst, temperature and time on catalysts activity was evaluated in the ring-opening reaction of β-pinene epoxide. The maximum conversion (97%), selectivities to perillyl alcohol (46%), myrtanal (23%) and myrtenol (12%) were obtained with toluene (70°C, 1 h). A reaction mechanism was proposed based on the experimental and theoretical results for explaining the formation of the products synthetized from the catalytic reaction over Brönsted and Lewis acid sites. The catalyst was reused five times without apparent loss of conversion, but with a slight decreasing of selectivity to perillyl alcohol and increase of selectivity to myrtanal and myrtenol.
Boletín de la Sociedad Española de Cerámica y Vidrio, 2018
El área metropolitana de Cúcuta (Colombia) se caracteriza por contar con un conglomerado de empre... more El área metropolitana de Cúcuta (Colombia) se caracteriza por contar con un conglomerado de empresas dedicadas a la fabricación de materiales cerámicos de construcción. La zona de * Autor para correspondencia.
Catalysis Today, 2019
The Selective Catalytic Reduction of NOx by ammonia (NH 3-SCR of NOx) was studied over an iron Co... more The Selective Catalytic Reduction of NOx by ammonia (NH 3-SCR of NOx) was studied over an iron Colombian natural zeolite (Nat-zeo) based geo-catalysts after several treatments (H-zeo-Fe 3+ and H-zeo-Fe 2+) under lean, dry and wet conditions. Nat-zeo from the Combia geological formation in Colombia (South America) was treated with NH 4 NO 3 , calcined in air for obtaining H-zeo-Fe 3+ and then reduced with hydrogen to obtain the H-zeo-Fe 2+ catalyst. Catalysts were characterized by XRD, FTIR, Mössbauer spectroscopy, SEM/EDX, XRF BET, H 2-TPR, NH 3-TPD, and NOx-TPD. H-zeo-Fe 3+ showed better catalytic performance than Nat-zeo and H-zeo-Fe 2+ in the NOx conversion. The presence of Fe 3+ ions and the acidity in the catalyst explains partially the high activity towards NOx reduction. Water inhibits the NO and improves the NO 2 adsorption on the catalyst H-zeo-Fe 3+ surface according with the NOx-TPD analysis. After 30 h on-stream, under wet conditions, the Hzeo-Fe 3+ catalyst showed a decreased in the NOx conversion. The decrease of activity could be related with the loss of catalyst surface acidity detected by NH 3-TPD analysis after reaction and with the contraction of the zeolite channels due to the metaheulandite phase formation that was confirmed by XRD, BET and FTIR analysis.
Journal of Physics: Conference Series, Nov 1, 2019
Direct synthesis of methanol and other oxygenated compounds (ethanol, propanol, acetaldehyde, for... more Direct synthesis of methanol and other oxygenated compounds (ethanol, propanol, acetaldehyde, formic acid, acetic acid and propanoic acid) was carried out through the partial oxidation of methane process using carbon dioxide (greenhouse gas) and water in liquid phase (water has only been used in the form of steam). The activation process was carried out with dielectric barrier discharge plasma (sinusoidal power) and in the presence of a catalyst. A Colombian natural zeolite, glass wool and a material composed of magnesium oxide and alumina were used in this scientific investigation as catalysts. Tests in the presence/absence of catalyst, presence/absence of liquid water and combinations of the previous tests were carried out in order to establish which conditions allow to obtain the highest conversion of reagents and selectivity to oxygenated compounds. It was evidenced that the glass wool allows to obtain the highest levels of reagent conversion, followed by the magnesium catalyst and finally the natural zeolite. Regarding selectivity, the natural zeolite showed to be efficient for the obtaining of oxygenated compounds. It was also established that the presence of liquid water in the reactor decreases the conversion of the reactants, but favors the formation of carbon monoxide, hydrogen and especially oxygenated compounds.