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Reaction intermediate
About: Reaction intermediate is a research topic. Over the lifetime, 6512 publications have been published within this topic receiving 202436 citations. The topic is also known as: intermediate.
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TL;DR: In this paper, the stability of reaction intermediates of electrochemical processes on the basis of electronic structure calculations was analyzed and a detailed description of the free energy landscape of the electrochemical oxygen reduction reaction over Pt(111) as a function of applied bias was presented.
Abstract: We present a method for calculating the stability of reaction intermediates of electrochemical processes on the basis of electronic structure calculations. We used that method in combination with detailed density functional calculations to develop a detailed description of the free-energy landscape of the electrochemical oxygen reduction reaction over Pt(111) as a function of applied bias. This allowed us to identify the origin of the overpotential found for this reaction. Adsorbed oxygen and hydroxyl are found to be very stable intermediates at potentials close to equilibrium, and the calculated rate constant for the activated proton/electron transfer to adsorbed oxygen or hydroxyl can account quantitatively for the observed kinetics. On the basis of a database of calculated oxygen and hydroxyl adsorption energies, the trends in the oxygen reduction rate for a large number of different transition and noble metals can be accounted for. Alternative reaction mechanisms involving proton/electron transfer to ...
7,711 citations
TL;DR: This paper presents a meta-analyses of six classes of enzyme involving reactions at phosphorus and some of the mechanisms leading to these reactions are described.
Abstract: PERSPECTIVES AND SUMMARY ... 877 Classes of enzyme involving reactions at phosphorus 878 COVALENT REACTION INTERMEDIATES, CRYPTIC AND OTHERWISE 879 Reactions of Phosphoric Monoesters ..... 879 Phosphatoses ..... ..... 879 Phosphokinases • •..•.....• • 881 Phosphomutases 886 Reactions of Phosphoric Diesters 890 REACTION ENERGETICS 892 "Off" Rates 893 Internal Thermodynamics ... .. ... ..... ...... ...... ... 896 THE NATURE OF THE ELEMENTARY STEP ....... ...... 898 Associative versus Diss ociative Pathways 898 Stereochemistry . .. ......... . ... 902 Prochiral substrate ..... prochiral product ... 902 Prochira/ substrate ..... pro-prochira/ product :.... ...... 903 Pro-prochiral substrate ..... pro-prochira/ product .. ........ ...... ........ ...... 905 Metal Ions 907 Cation-dependent diastereoisomer preference 908 Substitution-inert complexes of nucleotides 909 Catalysis ......... 911
1,035 citations
TL;DR: Based on density functional theory calculations, kinetic measurements, microkinetic and Monte Carlo simulations, thermogravimetric analysis (TGA) experiments, extended X-ray absorption spectroscopy (EXAFS) measurements, and experimental results from the literature, this paper presented a detailed and comprehensive mechanistic picture of the steam reforming process on a Ni catalyst.
1,002 citations
954 citations
TL;DR: In this article, a mean-field microkinetic model for methanol synthesis and water-gas-shift (WGS) reactions is presented, which includes novel reaction intermediates, such as formic acid (HCOOH) and hydroxymethoxy (CH3O2) and allows for the formation of formic acids, formaldehyde (CH2O), and methyl formate (HCOCH3) as byproducts.
Abstract: We present a comprehensive mean-field microkinetic model for the methanol synthesis and water-gas-shift (WGS) reactions that includes novel reaction intermediates, such as formic acid (HCOOH) and hydroxymethoxy (CH3O2) and allows for the formation of formic acid (HCOOH), formaldehyde (CH2O), and methyl formate (HCOOCH3) as byproducts. All input model parameters were initially derived from periodic, self-consistent, GGA-PW91 density functional theory calculations on the Cu(111) surface and subsequently fitted to published experimental methanol synthesis rate data, which were collected under realistic conditions on a commercial Cu/ZnO/Al2O3 catalyst. We find that the WGS reaction follows the carboxyl (COOH)-mediated path and that both CO and CO2 hydrogenation pathways are active for methanol synthesis. Under typical industrial methanol synthesis conditions, CO2 hydrogenation is responsible for ∼2/3 of the methanol produced. The intermediates of the CO2 pathway for methanol synthesis include HCOO*, HCOOH*, C...
904 citations