Nanopartículas de MgFe₂O₄ preparadas por el método del complejo del malato-nitrato activas bajo luz solar

En este trabajo se sintetizó ferrita magnesio nanoestructurada por el método del complejo del malato-nitrato a partir de Mg(NO₃)₂, Fe(NO₃)₃ y empleando como agente acomplejante ácido málico. El complejo formado se analizó por termogravimetría (TGA) para establecer su tratamiento térmico. La muestra obtenida se caracterizó por difracción de rayos X (DRX), espectroscopia UV-vis, microscopía electrónica de barrido (MEB), espectroscopia de energía dispersiva de rayos X (EED) y fisisorción de nitrógeno. Los resultados muestran que el material es cristalino y con características propias de un fotocatalizador.In this work, nanostructured magnesium ferrite was synthesized by the malate-nitrate complex method from Mg(NO₃)₂, Fe(NO₃)₃ and using malic acid as a complexing agent. The formed complex was analyzed by thermogravimetry (TGA) to establish its thermal treatment. The sample obtained was characterized by X-ray diffraction (XRD), UV-vis spectroscopy, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and nitrogen physisorption. The results show that is a crystalline material with photocatalytic features

CaFe₂O₄ nanocristalina preparada por el método del malato-nitrato activa bajo luz solar

Se sintetizaron polvos de ferrita de calcio (CaFe₂O₄) en su fase espinela a partir de Ca(NO₃)₂’ Fe(NO₃)₃ y empleando como agente acomplejante ácido málico. El precursor obtenido se analizó por análisis termogravimétrico (ATG) y se estudió el efecto del tratamiento térmico en la pureza de las muestras obtenidas por análisis de difracción de rayos X (DRX). Experimentalmente se obtuvo CaFe₂O₄ pura desde un tratamiento térmico final de 700ºC por 3 horas, la muestra obtenida a estas condiciones tiene un tamaño de cristal promedio de 4 7 nm de acuerdo con la ecuación de Scherrer por lo que es un material nanocristalino, se caracterizó por espectroscopía de reflectancia difusa UV-vis y presentó un "band gap" óptico directo de 1. 9 eV, lo que indica que es semiconductor fotoactivo a longitudes de onda de radiación electromagnética menores a 653 nm

Catalyzed Regioselective Synthesis of β-Amino Alcohols Under Solvent-Free Conditions

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Comparative Study of the Regioselective Synthesis of β-Aminoalcohols under Solventless Conditions Catalyzed by

Abstract: Sulfated zirconia and SZ/MCM-41 were used as catalysts for the synthesis of β-aminoalcohols via epoxide aminolysis. Sulfated zirconia was prepared by sol-gel and SZ/MCM-41 was obtained by impregnation. Solid catalysts were characterized by XRD, SEM-EDS, UV-Vis, FT-IR pyridine desorption and Nitrogen physisorption. Both acid materials were useful as catalysts, even when they were recycled several times. The β-aminoalcohols were characterized by FT-IR, 1 H- and 13 C-NMR and GC-MS

Sulfated Zirconia-Catalyzed Synthesis of 3,4-Dihydropyrimidin-2(1H)-ones (DHPMs) Under Solventless Conditions: Competitive Multicomponent Biginelli vs. Hantzsch Reactions

The catalytic ability of ZrO2/SO42- to promote solventless three-componentcondensation reactions of a diversity of aromatic aldehydes, urea or thoiurea and ethylacetoacetate was studied. Products resulting from Hantzsch and/or Biginelli multi-component reactions are obtained in the presence of solid acid catalysts using the samereactants but different temperature conditions. The sulfated zirconia catalyst can berecovered and recycled in subsequent reactions with a gradual decrease of activity

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

Synthesis of Azanucleosides through Regioselective Ring-Opening of Epoxides Catalyzed by Sulphated Zirconia under Microwave and Solvent-Free Conditions

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Comparative Study of Regioselective Synthesis of β-Aminoalcohols under Solventless Conditions Catalyzed by Sulfated Zirconia and SZ/MCM-41

Sulfated zirconia and SZ/MCM-41 were used as catalysts for the synthesis of β-aminoalcohols via epoxide aminolysis. Sulfated zirconia was prepared by sol-gel andSZ/MCM-41 was obtained by impregnation. Solid catalysts were characterized by XRD,SEM-EDS, UV-Vis, FT-IR pyridine desorption and Nitrogen physisorption. Both acidmaterials were useful as catalysts, even when they were recycled several times. The β-aminoalcohols were characterized by FT-IR, 1H- and 13C-NMR and GC-MS

Synthesis of New 1,2,3-Triazole Derivatives of Uracil and Thymine with Potential Inhibitory Activity against Acidic Corrosion of Steels

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Synthesis of New Pentacyclo[5.4.0.02,6.03,10.05,9]undecane-8,11-dione (PCU) Cyanosilylated Derivatives Using Sulphated Zirconia and Hydrotalcite as Catalysts in Microwave-Assisted Reactions under Solvent Free Conditions

A comparison was made of the effectiveness of the functionalization reactions of pentacyclo[5.4.0.02,6.03,10.05,9]undecane-8,11-dione (PCU) using sulphated zirconia in protection-deprotection reactions and Mg/Al hydrotalcite in a cyanosilylation reaction, under classical thermal conditions and imposing microwave radiation; improved yields and reaction times were considered