Browsing by Author "Alvarez, Pablo"

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    ACTIVITY OF ALUMINA SUPPORTED Fe CATALYSTS FOR N2O DECOMPOSITION: EFFECTS OF THE IRON CONTENT AND THERMAL TREATMENT
    (2017) Alvarez, Pablo; Araya, Paulo; Rojas Guerrero, René; Guerrero, Sichem; Aguila Avilés, Gonzalo Francisco
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    ACTIVITY OF ALUMINA SUPPORTED Fe CATALYSTS FOR N2O DECOMPOSITION: EFFECTS OF THE IRON CONTENT AND THERMAL TREATMENT
    (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 degrees 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 H-2-TPR. The incorporation of Fe promotes the alumina phase transition (gamma-Al2O3 to alpha-Al2O3 ) when the catalysts are calcined at 900 degrees C, which is accompanied by a decrease in the specific area. The activity of the catalysts and the specific 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.
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    Climate Change and Overuse: Water Resource Challenges during Economic Growth in Coquimbo, Chile
    (2022) Pizarro, Roberto; Garcia-Chevesich, Pablo A.; McCray, John E.; Sharp, Jonathan O.; Valdes-Pineda, Rodrigo; Sanguesa, Claudia; Jaque-Becerra, Dayana; Alvarez, Pablo; Norambuena, Sebastian; Ibanez, Alfredo; Vallejos, Carlos; Mendoza, Romina
    The arid Coquimbo region of Chile has experienced a significant economic growth in recent decades, fueled in large part by water-intensive activities such as mining and agriculture. Under this context, a monthly and annual trend analysis of precipitation, streamflow, and piezometric levels was carried out. Thus, 43 pluviometric stations, 11 fluviometric stations, and 11 wells were selected. These stations were evaluated for their temporal trends using the Mann-Kendall test. Results revealed a significant decrease in river flows, with negative and significant trends concentrated in the mean and maximum flows, both at annual and monthly levels. Likewise, positive trends were found in the depth to water table on wells, with significant trends in 81.8% of the monthly cases, and in 72.7% of the annual cases. While also decreasing over the same period, rainfall trends exhibit high variability and lacked significance. Although the amounts of precipitation have decreased, this does not seem to be the main factor responsible for the scarcity of water in the region, but rather an excessive consumption of this resource. This is endorsed by the increase in GDP (Gross Domestic Product), which is explained by activities that consume water (mining and agriculture). Similarly, an increase in the granting of underground water rights was verified, which speaks of the high demands for the resource. However, future modeling is advised to better understand the regional hydrology of the area and quantify the anthropic effects on water resources more precisely.