Diffusion And Heterogeneous Reaction

The theoretical analysis of a transient method is presented for the quantitative study of heterogeneous reaction rates and gaseous, multi-component diffusion coefficients. From observations of the rate of decay of reactant after its source of supply has been shut off, the kinetics of chemical reaction on the catalytic surface may be obtained. Combined with steady-state measurements, the diffusional transport of reactant to the catalyst may be evaluated. This experimental approach is particularly applicable to systems involving highly reactive species such as free radicals and atoms. (Author).

Volume is indexed by Thomson Reuters BCI (WoS). This monograph deals with a physico-chemical approach to the problem of the solid-state growth of chemical compound layers and reaction-diffusion in binary heterogeneous systems formed by two solids; as well as a solid with a liquid or a gas. It is explained why the number of compound layers growing at the interface between the original phases is usually much lower than the number of chemical compounds in the phase diagram of a given binary system. For example, of the eight intermetallic compounds which exist in the aluminium-zirconium binary system, only ZrAl3 was found to grow as a separate layer at the Al–Zr interface under isothermal conditions. The physico-chemical approach predicts that, in most cases, the number of compound layers should not exceed two; with the main factor, resulting in the appearance of additional layers, being crack formation due to thermal expansion and volume effects.

This monograph is an account of some problems involving diffusion or diffusion with simultaneous reaction that can be illuminated by the use of variational principles. It was written during a period that included sabbatical leaves of one of us (W. S. ) at the University of Minnesota and the other (R. A. ) at the University of Cambridge and we are grateful to the Petroleum Research Fund for helping to support the former and the Guggenheim Foundation for making possible the latter. We would also like to thank Stephen Prager for getting us together in the first place and for showing how interesting and useful these methods can be. We have also benefitted from correspondence with Dr. A. M. Arthurs of the University of York and from the counsel of Dr. B. D. Coleman the general editor of this series. Table of Contents Chapter 1. Introduction and Preliminaries . 1. 1. General Survey 1 1. 2. Phenomenological Descriptions of Diffusion and Reaction 2 1. 3. Correlation Functions for Random Suspensions 4 1. 4. Mean Free Path Statistics . 8 1. 5. Void Point-Surface Statistics . 11 1. 6. Variational Principles Applied to the Diffusion Equation. 12 1. 7. Notation. 16 Chapter 2. Diffusion Through a Porous Medium . 18 2. 1. Introduction 18 2. 2. Diffusion Through an Isotropic Porous Medium 18 2. 3. Variational Formulation for De . 20 2. 4. Bounds on De for an Isotropic Suspension 22 2. 5.

A theoretical analysis is made of the simultaneous removal of atoms by a first-order, heterogeneous reaction and their generation by a second-order, gas-phase reaction. Such a model is found applicable to a system in which hydrogen atoms recombine on the walls of a cylindrical vessel in the presence of hydroxyl radicals which may interact in the gas by reaction with hydrogen molecules. The perturbation of the hydrogen-atom concentration profile in the cylinder due to OH as measured by electron spin resonance spectroscopy is employed to calculate the rate constant for the gasphase reaction OH + H2 yields H2O + H. (Author).

"The fourth edition of Elements of Chemical Reaction Engineering is a completely revised version of the book. It combines authoritative coverage of the principles of chemical reaction engineering with an unsurpassed focus on critical thinking and creative problem solving, employing open-ended questions and stressing the Socratic method. Clear and organized, it integrates text, visuals, and computer simulations to help readers solve even the most challenging problems through reasoning, rather than by memorizing equations."--BOOK JACKET.