Topic
Chemical decomposition
About: Chemical decomposition is a research topic. Over the lifetime, 5210 publications have been published within this topic receiving 127503 citations. The topic is also known as: analysis reaction & chemical decomposition reaction.
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TL;DR: In this paper, the present position of decomposition catalysts is mentioned and the catalytic performance of copper ion-exchanged zeolites and Ag-Co3O4 oxides is summarized based on the respective authors' results.
749 citations
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TL;DR: It is shown that acid pretreatment of a carbon support for gold-palladium alloy catalysts switches off the decomposition of H2O2, and the acid-pretreated catalysts give high yields of H 2O2 with hydrogen selectivities greater than 95%.
Abstract: Hydrogen peroxide (H2O2) is an important disinfectant and bleach and is currently manufactured from an indirect process involving sequential hydrogenation/oxidation of anthaquinones. However, a direct process in which H2 and O2 are reacted would be preferable. Unfortunately, catalysts for the direct synthesis of H2O2 are also effective for its subsequent decomposition, and this has limited their development. We show that acid pretreatment of a carbon support for gold-palladium alloy catalysts switches off the decomposition of H2O2. This treatment decreases the size of the alloy nanoparticles, and these smaller nanoparticles presumably decorate and inhibit the sites for the decomposition reaction. Hence, when used in the direct synthesis of H2O2, the acid-pretreated catalysts give high yields of H2O2 with hydrogen selectivities greater than 95%.
730 citations
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TL;DR: In this paper, a kinetic model for the decomposition of hydrogen peroxide by ferric ion in homogeneous aqueous solution (pH < 3) was described and the reaction was investigated experimentally at 25.0 °C and I = 0.1 M in a completely mixed batch reactor and under a wide range of experimental conditions.
Abstract: This paper describes a kinetic model for the decomposition of hydrogen peroxide by ferric ion in homogeneous aqueous solution (pH < 3). The reaction was investigated experimentally at 25.0 °C and I = 0.1 M (HClO4/NaClO4), in a completely mixed batch reactor and under a wide range of experimental conditions (1 ≤ pH ≤ 3; 0.2 mM ≤ [H2O2]0 ≤ 1 M; 50 μM ≤ [Fe(III)]0 ≤ 1 mM; 1 ≤ [H2O2]0/[Fe(III)]0 ≤ 5000). The results of this study demonstrated that the rate of decomposition of hydrogen peroxide by Fe(III) could be predicted very accurately by a kinetic model which takes into account the rapid formation and the slower decomposition of Fe(III)−hydroperoxy complexes (FeIII(HO2)2+ and FeIII(OH)(HO2)+). The rate constant for the unimolecular decomposition of the Fe(III)−hydroperoxy complexes was determined to be 2.7 × 10-3 s-1. The use of the kinetic model allows a better understanding of the effects of operational parameters (i.e., pH and [H2O2]0/[Fe(III)]0) on the complex kinetics of decomposition of H2O2 by Fe(III).
680 citations
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TL;DR: In this paper, microcrystalline cellulose decomposition experiments were conducted in subcritical and supercritical water (25 MPa, 320−400 °C, and 0.05−10.0 s).
Abstract: Decomposition experiments of microcrystalline cellulose were conducted in subcritical and supercritical water (25 MPa, 320−400 °C, and 0.05−10.0 s). At 400 °C hydrolysis products were mainly obtained, while in 320−350 °C water, aqueous decomposition products of glucose were the main products. Kinetic studies of cellulose, cellobiose, and glucose at these conditions showed that below 350 °C the cellulose decomposition rate was slower than the glucose and cellobiose decomposition rates, while above 350 °C, the cellulose hydrolysis rate drastically increased and became higher than the glucose and cellobiose decomposition rates. Direct observation of the cellulose reaction in high-temperature water at high-pressure conditions by using a diamond anvil cell (DAC) showed that, below 280 °C, cellulose particles became gradually smaller with increasing reaction time but, at high temperatures (300−320 °C), cellulose particles disappeared with increasing transparency and much more rapidly than expected from the lowe...
665 citations
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TL;DR: The question whether free .OH radicals are being formed or not via the Fenton reaction depends on the relative rates of the decomposition reactions of the metal-peroxide complex and that of its reaction with organic substrates.
610 citations