Greener Method to Obtain a Key Intermediate of Vitamin E over Cu-ZSM-5

The catalytic oxidation of 2,3,5-trimethylphenol was performed over transition metals modified ZSM-5 zeolites employing hydrogen peroxide as oxidant under mild reaction conditions. Catalysts samples were characterized by several techniques (XRD, FTIR, BET, AA) and cristallinity and orthorhombic symmetry were confirmed for all of them. Best catalytic results were obtained for Cu-ZSM-5 sample, so further activity studies were done over this material. 2,3,5-trimethyl-1,4-benzoquinone was obtained as the main product of the selective oxidation. Reaction parameters (nature of the solvent, hydrogen peroxide concentration, reaction time, catalyst mass, substrate initial concentration and reaction temperature) were evaluated to reach the optimum reaction conditions. According to the obtained results, an apparent activation energy of 52.33 kJ/mol was calculated.Fil: Saux, Clara. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Cordoba. Centro de Investigacion y Tecnologia Quimica; Argentina. Universidad Tecnologica Nacional. Facultad Regional Cordoba; ArgentinaFil: Renzini, Maria Soledad. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Cordoba. Centro de Investigacion y Tecnologia Quimica; Argentina. Universidad Tecnologica Nacional. Facultad Regional Cordoba; ArgentinaFil: Gómez, Silvina. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Cordoba. Centro de Investigacion y Tecnologia Quimica; Argentina. Universidad Tecnologica Nacional. Facultad Regional Cordoba; ArgentinaFil: Pierella, Liliana Beatriz. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Cordoba. Centro de Investigacion y Tecnologia Quimica; Argentina. Universidad Tecnologica Nacional. Facultad Regional Cordoba; Argentin

Natural diatomites: Efficient green catalyst for Fenton-like oxidation of Orange II

doi: 10.1016/j.apcatb.2015.08.022The Fenton-like oxidation of the anionic azo-dye Orange II (100-500 mg/L) was batchwise performed using commercial grade diatomites (3.5% Fe content) thermally treated. Solid samples were thoroughly characterized by several techniques. Peroxidation experiments were performed varying the diatomite calcination temperature (500, 700, 1000 degrees C), reaction temperature (50, 60, 70, 80 degrees C), catalyst load (0.47, 0.94, 1.89 and 3.78g), H2O2 concentration (11.0, 13.7, 20.6 mmol/L) and dosing, pH (2-3.5) and initial dye concentration (0.28, 0.57, 1.43 mmol/L). The influence of NaCl and oxalic acid on the catalytic performance and stability was also addressed. The best results were obtained with samples calcined at 700 degrees C, with initial pH 3, at 70 degrees C and using the stoichiometric amount of H2O2, since complete decoloration, TOC reduction close to 67% and negligible Fe leaching were achieved. The stability of the catalyst maintains after 20 h of usage, with a final Fe loss of 2.25%. An average of 0.88 mg/L of iron leached after each run, which is below the discharge limit

Kinetic modeling of a heterogeneous Fenton-type oxidative treatment of complex industrial effluent

Abstract This work proposes a kinetic model for the reactions involved in the heterogeneous copper-based Fenton-type oxidation of mixed recalcitrant compounds in a real industrial effluent from the alkaline sulfite treatment of wood. This kind of treatment is unusual in this industry due to the complexity of the effluents and the high costs involved in total mineralization of the organic matter. Nevertheless, conversion of recalcitrant to degradable compounds and catalyst recovery can make the difference. The complexity of the effluent and the great number of compounds formed as intermediates, make extremely difficult the identification and quantification of the individual reactions that occur during oxidation. To solve this drawback TOC parameter was used as a representative measurement. To verify the level of TOC degradation produced by the heterogeneous catalysis reaction, experiences of homogeneous catalysis and adsorption were accomplished. The studied temperature range was 45–80 °C. A “two-step” kinetic model was applied to TOC reduction in heterogeneous and homogeneous oxidations, admitting two sequential steps of oxidation: a first fast stage (“seconds stage”) followed by a slow one (“minutes stages”). Kinetic constants were obtained for both processes and activation energies were also determined for the “minutes stage” step (33.17 kJ/mol and 15.13 kJ/mol, respectively). Homogeneous catalysis studies confirm mass transfer limitations in heterogeneous oxidations. Experiences of adsorption of organic matter on CuO/γ-Al2O3 catalyst demonstrated that this phenomenon is exothermic and cannot be neglected. The activation energy of adsorption was determined as 7.32 kJ/mol. Catalysts were characterized through SEM, EDS, XRD, FTIR, and TGA. Graphical Abstrac