Elementary reaction

About: Elementary reaction is a research topic. Over the lifetime, 2972 publications have been published within this topic receiving 76110 citations.

Direct determination of the rate constant for the reaction CH2+O2 with a LMR-spectrometer

Abstract: The reaction was studied at room temperature in an isothermal discharge flow system. CH2-radicals were produced either in a microwave discharge of CH2CO highly diluted in Helium or via the reaction O + CH2CO CH2 + CO2. The CH2-concentration was measured by laser magnetic resonance. From the pseudo first order decay of CH2 in the presence of a large excess of oxygen the rate constant for reaction (1) was found to be

Search Directions for Direct H2O2 Synthesis Catalysts Starting from Au12 Nanoclusters

Abstract: We present density functional theory calculations on the direct synthesis of H2O2 from H2 and O2 over an Au12 corner model of a gold nanoparticle. We first show a simple route for the direct formation of H2O2 over a gold nanocatalyst, by studying the energetics of 20 possible elementary reactions involved in the oxidation of H2 by O2. The unwanted side reaction to H2O is also considered. Next we evaluate the degree of catalyst control and address the factors controlling the activity and the selectivity. By combining well-known energy scaling relations with microkinetic modeling, we show that the rate of H2O2 and H2O formation can be determined from a single descriptor, namely, the binding energy of oxygen (EO). Our model predicts the search direction starting from an Au12 nanocluster for an optimal catalyst in terms of activity and selectivity for direct H2O2 synthesis. Taking also stability considerations into account, we find that binary Au–Pd and Au–Ag alloys are most suited for this reaction.

Elementary reaction mechanism of methylamine oxidation in supercritical water

Abstract: An elementary reaction model for the supercritical water oxidation (SCWO) of methylamine was proposed, based on a combustion mechanism that involved reactions relevant to NH2CH2O2. A comparison of the predicted results of our proposed model with the experimental data revealed that our model could predict the conversion via the SCWO of methylamine and the effects of temperature and oxygen concentrations on the NH3 selectivity quantitatively well, and also could qualitatively explain the trends of the measured product distribution, especially NH3 as the exclusive nitrogen-containing product of the SCWO of methylamine. This work clarified that the peroxy radical NH2CH2O2, which appears in low-temperature combustion through the reaction of O2 with CH2NH2, and the relevant elementary reactions and intermediate species had key roles in the SCWO of methylamine.

Elucidating the field influence on the energetics of the methane steam reforming reaction: A density functional theory study

Abstract: To help realize lower operating-temperatures for the highly endothermic Ni-catalytic methane steam reforming (MSR) process, we focused on elucidating the influence of an applied electric field on the energetics of the said reaction. Two aspects were considered in this study: the electric field effects on (i) the adsorption and electronic properties of the MSR-involved species, and (ii) the overall MSR energy profile. Our results show that for Ni-based MSR processes, a positive field strengthens the adsorption of the reactants, promotes product desorption, impedes coke formation, lowers the overall energy profiles and consequently, reduces the temperature requirements for the overall MSR-on-Ni reaction. Based on our phase diagram obtained from first principles, we show that CO can be obtained from the dehydrogenation of COH and CHO at moderate hydrogen partial pressure values with a negative field, while methanol is formed on the surface via hydroxyl oxidation of CH 3 at high hydrogen partial pressures and positive field values. This investigation suggests ways to facilitate the MSR reforming reaction in the presence of an electric field and also points toward a number of elementary reactions that need to be considered for establishing microkinetic model studies.