Examinando por Autor "Guerrero, Sichem"

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    A highly active Ca/Cu/YCeO2-TiO2catalyst for the transient reduction of NO with CO and naphthalene under oxidizing conditions
    (Royal Society of Chemistry, 2021-12) Sánchez, Luis; Aguila, Gonzalo; Araya, Paulo; Quijada, Sergio; Guerrero, Sichem
    The transient combustion of biomass leads to the evolution of a variety of pollutants (NO, CO, organic compounds, and many others) that can react with each other on a suitable catalyst to generate compounds of lower toxicity. Here, the transient reduction of NO with CO and naphthalene in the presence of oxygen was studied on a Ca/Cu/YCeO2-TiO2catalyst. Response surface methodology was used to identify the optimum amounts of calcium, copper, and cerium. The optimized Ca/Cu/YCeO2-TiO2catalyst was then extensively studied and characterized. The coupling of yttrium-stabilized ceria with TiO2provided an active support that effectively activated naphthalene. When calcium and copper were added to the support, the obtained Ca/Cu/YCeO2-TiO2catalyst achieved the full conversion of CO and naphthalene and 72% conversion of NO. The Ca/Cu/YCeO2-TiO2catalyst possessed labile oxygen species, which might be related to the high catalytic activity. © The Royal Society of Chemistry 2021.
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    Ítem
    Activity of alumina supported fe catalysts for N2O decomposition: Effects of the iron content and thermal treatment
    (Sociedad Chilena de Quimica, 2017) Alvarez, Pablo; Araya, Paulo; Rojas, Rene; Guerrero, Sichem; Aguila, Gonzalo
    The activity of Fe2O3/Al2O3 catalysts prepared by impregnation of Al2O3 with different amounts of Fe and calcination temperatures (650 and 900 °C) in the direct N2O decomposition reaction was studied. High calcination temperature was introduced to study the effect of "aging", which are the conditions prevailing in the process-gas option for N2O abatement. The catalysts were characterized by BET, XRD, UV-DRS, and H2-TPR. The incorporation of Fe promotes the alumina phase transition (g-Al2O3 to a-Al2O3) when the catalysts are calcined at 900 °C, which is accompanied by a decrease in the specifc area. The activity of the catalysts and the specifc surface area depend on Fe loading and calcination temperature. It was found that highly dispersed Fe species are more active than bulk type Fe2O3 particles. We conclude that Fe2O3/Al2O3 catalysts prepared by impregnation method are active in the decomposition of N2O, to be used at low or high reaction temperatures (tail-gas or process-gas treatments, respectively), as part of nitric acid production plant. © 2018 Sociedad Chilena de Quimica. All rights reserved.
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    ZrO2-supported alkali metal (Li, Na, K) catalysts for biodiesel production
    (Sociedad Chilena de Quimica, 2016) Aguila, Gonzalo; Salinas, Daniela; Jiménez, Romel; Guerrero, Sichem; Araya, Paulo
    We studied the effect of the alkali metal type (Li, Na, and K) and the calcination temperature (500, 600 and 700 °C) in the activity for biodiesel production of catalysts prepared by impregnation method, with constant metal content of 10%w/w using ZrO2 as support. The results of the catalytic activity allowed to find an activity sequence regarding the alkali tested metals: Na > Li > K, with this sequence remaining constant independent of the calcination temperature. The high activity of the Na/ZrO2 system, and slightly lower activity of Li/ZrO2 , can be explained by the fact that higher calcination temperatures promote the formation of alkali-based zirconate species, M2 ZrO3 (M = Na or Li). The presence of these species is correlated with the higher activity of these catalysts, specifically with the Na and Li-based catalyst calcined at high temperatures (600-700 °C). These M2 ZrO3 species show higher basicity respect to other alkali metal oxide species, as was demonstrated with CO2 -TPD results. The higher activity corresponded to 10% Na supported on ZrO2 and calcined at 700 °C, which reached full conversion within just 30 minutes of reaction, which makes this system a promising heterogeneous replacement for the regular homogeneous systems.