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Reaction Kinetics, Mechanisms and Catalysis
Authors: Evandro de Queiroz, Augusto Knoechelmann, Eliane de Moraes Medeiros, Cesar de Abreu, and Nelson de Lima Filho

Abstract  

In this work, in addition to the nitrous acid formed by reactive uptake of nitrogen dioxide (NO2) in water, it is proposed to reduce the nitrous ions levels by amino sulfonic acid (HSO3NH2) in a mechanically agitated reactor. To this end, the following parameters were considered: agitation speed, pH, temperature, initial concentration of the reagents and their stoichiometric ratios. It was observed that the nitrous acid conversion (98.54%) was enhanced in acidic medium (pH < 2.5), obeying a first-order reaction in relation to both reagents. A heterogeneous model for nitrogen production was proposed and the kinetics for the gas–liquid process was formulated, where the kinetic rate constants were in the range of 2.62–5.52 m3 kmol−1 s−1 and the gas–liquid mass transfer coefficients were in the range of 0.00502–0.00825 s−1.

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. Silver dispersion was measured using an H 2 –O 2 titration (pulse mode, AutoChem 2920 Micromeritics). Prior to the H 2 –O 2 titration, 400 mg of sample was subjected to treatment in 10 vol% O 2 /He (30 cm 3 min −1 , 20 °C min −1 ) at 300 °C for 0.5 h

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the interface between platinum and titania stabilize platinum particles, achieving a high dispersion even with a high platinum loading of 4 wt% after exposure to a reductive flow at 400 °C. Further treatment of the platinum precursor impregnated on

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Reaction Kinetics, Mechanisms and Catalysis
Authors: Olga Yugay, Tatyana Mikhailovskaya, Lyudmila Saurambaeva, Dauren Sembaev, and Pavel Vorobiov

systems to make effective modified vanadium oxide catalysts containing TiO 2 . The goal of this study is to investigate the stability of anatase (TiO 2 ) depending on the duration of the heat treatment in the following systems: TiO 2 –V 2 O 5 , TiO 2 –ZrO

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nitrogen doping to Ta 2 O 5 or the formation of the nitride at a given doping temperature were to be devised, it would be advantageous to improve the photocatalytic activity. Here we report that a carbothermal reduction followed by heat treatment of Ta 2 O

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treatment of aqueous solutions with pollutant loading because its low liquid to catalyst ratio minimizes the undesired parallel reactions that produce polymerization compounds. However, the development of stable heterogeneous catalysts during this process is

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sol–gel derived ZnO nanopowders produced with PEG addition after heat treatment at different temperatures. The diffraction lines observed at 2θ = 31.76°, 34.39° and 36.24° are due to the (100), (002), (101) reflections of the wurtzite structure. It is

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. The current work investigates the potential of the photocatalytic activity of the N-doped Ta 2 O 5 , synthesized by an NH 3 heat treatment of Ta 2 O 5 powder, to decompose one of the actively investigated water pollutants, rhodamine B (Rh B

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corrections, the absolute intensity of the corrected M/e = 15 signal was always less than 7% of the original M/e = 15 signal, confirming the validity of the proposed data treatment [ 16 ]. Temperature programmed surface reactions (TPSR

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Abstract  

Phenol is industrially produced by the Hock process, in which cumene hydroperoxide (CHP) is decomposed with sulfuric acid to obtain equimolar amounts of phenol and acetone. Use of the liquid acid requires subsequent neutralization and purification of the phenol at substantial cost, and a waste stream generation that could be avoided if an effective solid acid catalyst could be used. Modified clays exhibit attractive properties as solid acids. Acid treatment produces an increase in surface area and acidity. The present study was undertaken to modify bentonite clay by treatment with hydrochloric acid for the production of phenol and acetone via the decomposition of cumene hydroperoxide. The effects of various parameters such as acid activation, catalyst weight, concentration of CHP, reaction temperature and reusability of catalyst were studied. The results indicate that the acid-modified bentonite catalyst may be used instead of sulfuric acid for selective decomposition of CHP into phenol and acetone.

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