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This book proposes a closer look at chemical kinetics, which in this specific case, should be understood as a more detailed study of the connections of this discipline with other branches of chemistry and, even more, with other areas of science and technology. The first part which includes two chapters explores theoretical developments where the connections of chemical kinetics with mathematical modeling of scientific and industrial problems are clearly illustrated. The second part of the volume is devoted to experimental chemical kinetics, where specific reactions are studied in Chapters Three to Six. In all these chapters, kinetic studies allow the authors to propose mechanisms consistent with the experimental results obtained. In the third part of the book which includes the following two chapters different types of catalytic processes are studied, particularly those related to electrocatalysis, photocatalysis, and surface phenomena. The fourth part of this volume presents a work related to nanotechnology and its catalytic applications. The fifth and last part of this volume exemplifies the link between chemical kinetics and industrial processes, particularly in metallurgy.

Chemical kinetic studies of the β-scission reaction class of hydroperoxyl alkyl hydroperoxyl radicals (•P(OOH)2) from normal-alkyl cyclohexanes are carried out systematically through high-level ab initio calculations. Geometry optimizations and frequency calculations for all species involved in the reactions are performed at the B3LYP/CBSB7 level of theory. Electronic single-point energy calculations are calculated at the CBS-QB3 level of theory. Rate constants for the reactions of β-scission, in the temperature range of 500–1500 K and the pressure range of 0.01–100 atm, are calculated using transition state theory (TST) and Rice-Ramsberger-Kassel-Marcus/Master-Equation (RRKM/ME) theory taking asymmetric Eckart tunneling corrections and the one-dimensional hindered rotor approximation into consideration. The rate rules are obtained by averaging the rate constants of the representative reactions of this class. These rate rules can greatly assist in constructing more accurate low-temperature combustion mechanisms for normal-alkyl cyclohexanes.

This work aims to explain aluminum hydrolysis reaction kinetics based on a properly chosen theoretical model with machined aluminum waste chips as well as alkali solutions up to 1M as a promoter and to estimate the overall reaction profit. The purpose of this work is to assess the optimal alkali concentration in the production of small- and medium-scale green hydrogen. To obtain results with better accuracy, we worked with flat Al waste chips, because a flat surface is preferable to maximally increase the time for the created hydrogen bubbles to reach the critical gas pressure. Describing the reaction kinetics, a flat shape allows for the use of a planar one-dimensional shrinking core model instead of a much more complicated polydisperse spheric shrinking core model. We analyzed the surface chemical reaction and mass transfer rate steps to obtain the first-order rate constant for the surface reaction and the diffusion coefficient of the aqueous reactant in the byproduct layer, respectively. We noted that measurements of the diffusion coefficient in the byproduct layer performed and discussed in this paper are rare to find in publications at alkali concentrations below 1M. With our reactor, we achieved a H2 yield of 1145 mL per 1 g of Al with 1M NaOH, which is 92% of the theoretical maximum. In the estimation of profit, the authors’ novelty is in paying great attention to the loss in alkali and finding a crucial dependence on its price. Nevertheless, in terms of consumed and originated materials for sale, the conversion of aluminum waste material into green hydrogen with properly chosen reaction parameters has positive profit even when consuming an alkali of a chemical grade.

Natural extracts with antioxidant properties can be used as sustainable alternatives compared to synthetic products, as they can inhibit the biodiesel oxidation reaction, resulting in increased oxidative stability, measured by the Rancimat method, and reducing the reaction rate, which is a key advantage in this study. This research evaluated the efficiency of ethanolic extracts from cayenne pepper leaves (Capsicum annuum), etna pepper leaves (Capsicum frutescens), red pitaya peels (Hylocereus costaricensis) and purple heart leaves (Transdescantia pallida purpurea) through the optimization of the biodiesel oxidation reaction rate at 110 °C using an experimental mixture design. All extracts showed antioxidant activity when compared to the control sample, reducing the reaction rate. However, the mixture containing extract of etna pepper leaves (Capsicum frutescens) and red pitaya peels (Hylocereus costaricensis) was the one that presented the lowest experimental value of k (0.1358 h-1). The optimization of the mathematical model indicated that the most effective mixture of antioxidant compounds for reducing the oxidation reaction consisted of 57.14% etna pepper extract (Capsicum frutescens) and 42.86% red pitaya peel extract (Hylocereus costaricensis), resulting in a reaction rate of 0.1396 h-1. The application of the t-test for a simple sample showed that there was no significant difference (p = 0.8777) between the optimized value and the average value experimentally obtained under optimal conditions (k = 0.1402), validating the predictive equation obtained. All ethanolic extracts used showed antioxidant activity and could be sustainable alternatives when compared to synthetic products.

In this work, the kinetics of natural quartz reduction by Mg to produce either Si or Mg2Si was studied through quantitative phase analysis. Reduction reaction experiments were performed at various temperatures, reaction times and Mg to SiO2 mole ratios of 2 and 4. Rietveld refinement of X-ray diffraction patterns was used to obtain phase distributions in the reacted samples. SEM and EPMA examinations were performed to evaluate the microstructural change during reduction. The results indicated that the reduction reaction rate was slower at a mole ratio of 2 than 4 at the same temperature, as illustrated by the total amount of Si formed (the percent of Si that is reduced to either Si or Mg2Si to total amount of Si) being 59% and 75%, respectively, after 240 min reaction time for mole ratios of 2 and 4. At the mole ratio of 4, the reaction rate was strongly dependent on the reaction temperature, where SiO2 was completely reduced after 20 min at 1273 K. At the lower temperatures of 1173 and 1073 K, total Si formed was 75% and 39%, respectively, after 240 min reaction time. The results of the current work show that Mg2Si can be produced through the magnesiothermic reduction of natural quartz with high yield. The obtained Mg2Si can be processed further to produce silane gas as a precursor to high purity Si. The combination of these two processes offers the potential for a more direct and low carbon method to produce Si with high purity.

A guide to the theoretical and computational toolkits for the modern study of molecular kinetics in condensed phases Molecular Kinetics in Condensed Phases: Theory, Simulation and Analysis puts the focus on the theory, algorithms, simulations methods and analysis of molecular kinetics in condensed phases. The authors – noted experts on the topic – offer a detailed and thorough description of modern theories and simulation methods to model molecular events. They highlight the rigorous stochastic modelling of molecular processes and the use of mathematical models to reproduce experimental observations, such as rate coefficients, mean first passage times and transition path times. The book's exploration of simulations examines atomically detailed modelling of molecules in action and the connections of these simulations to theory and experiment. The authors also explore the applications that range from simple intuitive examples of one- and two-dimensional systems to complex solvated macromolecules. This important book: * Offers an introduction to the topic that combines theory, simulation and analysis * Presents a guide written by authors that are well-known and highly regarded leaders in their fields * Contains detailed examples and explanation of how to conduct computer simulations of kinetics. A detailed study of a two-dimensional system and of a solvated peptide are discussed. * Discusses modern developments in the field and explains their connection to the more traditional concepts in chemical dynamics Written for students and academic researchers in the fields of chemical kinetics, chemistry, computational statistical mechanics, biophysics and computational biology, Molecular Kinetics in Condensed Phases is the authoritative guide to the theoretical and computational toolkits for the study of molecular kinetics in condensed phases.

Rate coefficients for the reactions of OH radicals with C.sub.3 -C.sub.11 alkanes were determined using the multivariate relative-rate technique. A total of 25 relative-rate coefficients at room temperature and 24 Arrhenius expressions in the temperature range of 273-323 K were obtained. Notably, a new room temperature relative-rate coefficient for 3-methylheptane that had not been previously reported was determined, and the obtained k.sub.OH value (in units of 10.sup.-12 cm.sup.3 molec..sup.-1 s.sup.-1) was 7.71 ± 0.35. Interestingly, whilst results for n-alkanes agreed well with available structure-activity relationship (SAR) calculations of Kwok and Atkinson (1995), Neeb (2000), Wilson et al. (2006), Jenkin et al. (2018), and McGillen et al. (2020), the three cycloalkanes (cyclopentane, methylcyclopentane, cyclohexane) and one branched alkane (2,2,4-trimethylpentane) were found to be less reactive than predicted by the SAR approach. Conversely, the SAR estimates for 2,3-dimethylbutane were approximately 25 % lower than the experimental values, with the exception of those estimated by the Wilson group, highlighting that there may be additional factors that govern the reactivity of highly branched alkanes that are not captured by current SAR techniques. Arrhenius expressions (in units of cm.sup.3 molec..sup.-1 s.sup.-1) for the reactions of various branched alkanes with OH radicals were determined for the first time: 2-methylheptane, 1.37±0.48x10-11expâ¡-209±100/T, and 3-methylheptane, 3.54±0.45x10-11expâ¡-374±49/T. The reactivity relation of saturated alkanes with OH radicals and chlorine atoms was obtained: logâ¡10k(Cl+alkanes)=0.569xlogâ¡10k(OH+alkanes)-3.111 (R.sup.2 = 0.86). In addition, the rate coefficients for the 24 previously studied OH + alkanes reactions were consistent with existing literature values, demonstrating the reliability and efficiency of this method for the simultaneous investigation of gas-phase reaction kinetics.

Geochemical kinetics as a topic is now of importance to a wide range of geochemists in academia, industry, and government, and all geochemists need a rudimentary knowledge of the field.