Sistemas CaO-CuO y MgO-CuO para la adsorción de dióxido de carbono

Se empleó óxido de cobre en composición variable depositado en soportes de óxido de calcio y de óxido de magnesio con la finalidad de sintetizar materiales, capaces de efectuar la adsorción de dióxido de carbono. Los prototipos YOS01 a YOS04, de composiciones 5 a 30% de CuO fueron sintetizadas mediante el método de impregnación, a partir de CaO y (Cu(NO₃)₂·3H₂O), igualmente fueron sintetizados los prototipos YOS05 a YOS08, de composiciones 5 a 30 % de cobre a partir de MgO, controlando variables como: el tiempo de contacto, temperaturas de síntesis y de calcinación. Los prototipos fueron caracterizados por diferentes técnicas tales como: Volumetría dinámica de adsorción, difracción de rayos-X y área específica BJH. Los resultados indican que la adsorción de CO₂ está directamente relacionada con la composición o carga de Cu, con la distribución de sitios activos en el soporte y con la estructura porosa de los materiales sintetizados.Deposited copper in variable composition oxide was used in supports of oxide of calcium and magnesium oxide in order to synthesize materials, capable of performing the adsorption of carbon dioxide. The prototype materials YOS01 to YOS04, from 5 to 30% of CuO compositions were synthesized by the method of impregnation, from CaO and (Cu(NO₃)₂·3H₂O), also were synthesized prototypes YOS05 a YOS08 of compositions 5 to 30% copper from MgO, controlling variables such as: the time of contact, synthesis and calcination temperatures. The prototypes were characterized by different techniques such as: volumetry dynamic of adsorption, diffraction of X-rays and area specific BJH. The results indicate that the adsorption of CO₂ is directly related with the composition or load of Cu, with the distribution of sites active in the support and with the structure porous of them materials synthesized

Evaluación de óxido de calcio promovido con cobre para la adsorción de dióxido de carbono

Se empleó óxido de Cobre en composición variable depositado en soportes de óxido de calcio; con la finalidad de cuantificar la adsorción de dióxido de carbono. Las muestras se sintetizaron mediante el método de impregnación, mediante agitación mecánica por contacto en solución acuosa de la sal precursora del metal (Cu(NO₃)₂·3H₂O), controlando variables como la temperatura de calcinación, agitación y tiempo de contacto. Se caracterizaron por diferentes técnicas como: Microscopía electrónica de barrido (SEM), Espectroscopía de energía dispersiva (EDS), análisis de área específica y volumetría dinámica de adsorción.Copper oxide deposited on supports variable composition of calcium oxide was employed; in order to quantify carbon dioxide adsorption. Samples were synthesized by the method of impregnation, through mechanical agitation by contact in aqueous solution of precursor salt of the metal (Cu(NO₃)₂·3H₂O), controlling variables such as temperature of calcining, agitation and contact time. They were characterized by different techniques such as: scanning electron microscopy (SEM), spectroscopy, energy dispersive (EDS), specific area and dynamic volumetric analysis of adsorption

Estudio de catalizadores monolíticos de Ag/Al₂O₃ y catalizadores monolíticos bimetálicos de Pt-Ag/Al₂O₃ promovidos con WOx

Se estudiaron catalizadores monolíticos de Ag/Al₂O₃y catalizadores monolíticos bimetálicos de Pt-Ag/Al₂O₃ promovidos con WOx como una de de las altermativas para la eliminacion de NOx basándose en la reducción catalítica selectiva (HC-SCR) usando un hidrocarburo como agente reductor. Se utilizó γ-Al₂O₃ preparada por coprecipitacion, misma que fue depositada sobre el monolito de cordierita comercial. Estos materiales catalíticos se caracterizaron por análisis térmico gravimétrico (TGA), textura y área BET, cristalinidad por difracción de rayos-X (XRD), la morfología cristalina por microscopia electrónica de barrido (SEM/EDS) y la cantidad de Pt y Ag dispersos sobre el soporte fueron determinados por quimisorción de hidrógeno. Por difracción de rayos-X, el catalizador 0.1%Pt-2%Ag/γ-Al₂O₃ mostró que contenía óxido de plata (AgO₂), asimismo se observaron agrupaciones esféricas por SEM y se observó una concentración de Ag (2.40%) por EDS. Todos los catalizadores también resultaron ser activos en la combustión de CO y propano, hacia la formación de CO₂.Monolithic catalysts Ag/Al₂O3 and bimetallic monolithic catalysts Pt-Ag/Al₂O₃ promoted with WOx as one of the altermatives for removal of NOx based on the selective catalytic reduction (HC-SCR) using a hydrocarbon as a reducing agent were studied. It was used γ-Al₂O₃ prepared by coprecipitation, same that was deposited on the monolith commercial cordierite. These catalytic materials were characterized by thermal gravimetric analysis (TGA), texture and BET area, crystallinity by diffraction X-ray (XRD), crystal morphology by scanning electron microscopy (SEM/EDS) and the amount of Pt and Ag dispersed on the support they were determined by hydrogen chemisorption. By X-rays, the catalyst 0.1%Pt-2%Ag /γ-Al₂O₃showed that it contained silver oxide (AgO₂), also spherical clusters were observed by SEM and a concentration of Ag (2.40%) was observed by EDS. All catalysts also proved active in CO combustion and propane, to the formation of CO₂

Catalytic Pyrolysis Process to Produce Styrene from Waste Expanded Polystyrene Using a Semi-Batch Rotary Reactor

Thermal and catalytic pyrolysis of waste expanded polystyrene (WEPS) was studied to obtain mainly styrene monomer, which can be recycled in the polystyrene industry. Initially, preliminary experiments were carried out in a static semi-batch glass reactor with basic catalysts and without catalysts, using toluene as solvent at 250 °C, determining their styrene yields to select the best catalyst. MgO turned out to be the best catalyst due to its stability and cost. This catalyst was characterized by XRD, BET area, SEM-EDS, Raman spectroscopy, UV–VIS, and TGA. The kinetic equation for WEPS pyrolysis in the glass reactor was determined as a first-order reaction. The heat of reaction, the Gibbs free energy change, and the entropy change were calculated. Finally, WEPS pyrolysis experiments were carried out using a rotating semi-batch steel reactor, at higher temperatures and without using solvents, evaluating the styrene yield and its performance for its possible industrial application. In this reaction, the activity remained almost constant after four catalyst regenerations. The best styrene yield was 94 wt%, which could be one of the highest reported in the literature. This result may be associated with the back-mixing obtained in the rotary reactor, in contrast to the performance observed in the static glass reactor