Physisorption Kinetics

This monograph deals with the kinetics of adsorption and desorption of molecules physisorbed on solid surfaces. Although frequent and detailed reference is made to experiment, it is mainly concerned with the theory of the subject. In this, we have attempted to present a unified picture based on the master equation approach. Physisorption kinetics is by no means a closed and mature subject; rather, in writing this monograph we intended to survey a field very much in flux, to assess its achievements so far, and to give a reasonable basis from which further developments can take off. For this reason we have included many papers in the bibliography that are not referred to in the text but are of relevance to physisorption. To keep this monograph to a reasonable size, and also to allow for some unity in the presentation of the material, we had to omit a number of topics related to physisorption kinetics. We have not covered to any extent the equilibrium properties of physisorbed layers such as structures, phase tr- sitions and thermodynamic properties in general. A number of excellent revIew articles, listed in the bibliography, cover this material. Likewise, little is said about scattering off solid surfaces; this subject is again covered in several books and many review articles. Lastly, little is said about chemisorption kinetics, for which microscopic thebries and models have not been fully developed but are still at a rather early exploratory stage.

The fact that the surfaces of real solids are geometrically distorted and chemically non-uniform has long been realized by the scientists investigating various phenomena occurring on solid surfaces. Even in the case when diffraction experiments show a well-organized bulk solid structure, the surface atoms or molecules will usually exhibit a much smaller degree of surface organization. In addition to the results obtained from electron diffraction, this can be seen in the impressive images obtained from STM and AFM microscopies. This geometric and chemical disorder is the source of the energetic heterogeneity for molecules adsorbing on real solid surfaces. Hundreds of papers have been published showing that this heterogeneity is a major factor in determining the behaviour of real adsorption systems. Studies of adsorption on energetically heterogeneous surfaces have proceeded along three somewhat separate paths, with only minor coupling of ideas. One was the study of adsorption equilibria on heterogeneous solid surfaces. The second path was the study of time evolution of adsorption processes such as surface diffusion or adsorption-desorption kinetics on heterogeneous surfaces, and the third was the study of adsorption in porous solids, or more generally, adsorption in systems with limited dimensions. The present monograph is a first attempt to provide a synthesis of the ways that surface geometric and energetic heterogeneities affect both the equilibria and the time evolution of adsorption on real solids. The book contains 17 chapters written by a team of internationally recognized specialists, some of whom have already published books on adsorption.

This book contains the proceedings of the first Workshop on Interface Phenomena, organized jointly by the surface science groups at Dalhousie University and the University of Maine. It was our intention to concentrate on just three topics related to the kinetics of interface reactions which, in our opinion, were frequently obscured unnecessarily in the literature and whose fundamental nature warranted an extensive discussion to help clarify the issues, very much in the spirit of the Discussions of the Faraday Society. Each session (day) saw two principal speakers expounding the different views; the session chairmen were asked to summarize the ensuing discussions. To understand the complexity of interface reactions, paradigms must be formulated to provide a framework for the interpretation of experimen tal data and for the construction of theoretical models. Phenomenological approaches have been based on a small number of rate equations for the concentrations or mole numbers of the various species involved in a par ticular system with the relevant rate constants either fitted (in the form of the Arrheniusparametrization) to experimental data or calculated on the basis of microscopic models. The former procedure can at best serve as a guide to the latter, and is, in most cases, confined to ruling out certain reaction pathways rather than to ascertaining a unique answer.

Surface Area and Porosity Determinations by Physisorption: Measurement, Classical Theories and Quantum Theory, Second Edition, covers the experimental method for measuring physical adsorption, various methods for analyzing the data obtained, and the theoretical background to these calculation techniques. This latest edition includes additional theoretical topics, such as the criterion to avoid theoretical anomalies, increased data on physical adsorption—including data on monolayers, and the important concept of the critical pressure for adsorption initiation. The experimental apparatus is also described, along with the various data analyses that yield surface area and porosity measurements and their analysis techniques. Modern techniques are also presented, such as the chi, disjoining pressure and DFT analysis methods, all of which yield realistic and consistent answers. Designed for both novice and researchers in the field who need to become better acquainted with recent developments Explains how to complete data analyses that yield surface area and porosity measurements Includes experimental and data analysis problems and solutions Provides comparisons between both methods and data analysis

There has been a lack of authoritative, current information on the structure, investigation and preparation of inorganic sorbents, their numerous applications as well as the adsorption from gaseous and liquid phases on new and chemically modified inorganic solids. This volume deals with the above-mentioned themes and presents 34 up-to-date comprehensive and critical reviews written by well-recognized authorities. The sorbents discussed are primarily mineral ones. Each contribution treats a problem critically by showing its development, presenting documentation on the state-of-the-art and identifying subjects for further research. The book will be of interest to researchers in academic institutes and industrial laboratories engaged in the fields of surface chemistry, inorganic chemistry, adsorption, ion-exchange, catalysis, chromatography and spectroscopy of the surface phenomena, as well as to students attending graduate and postgraduate courses.

Surface Area and Porosity Determinations by Physisorption is a practical guide for industry or academics to the measurement of surface area and pore size using the tool of physical adsorption. Starting with a brief description of what physical adsorption is and the raw data that is obtained. The instrumentation for measuring this isotherm is described in some details. Recommendations are presented as to what instrumentation would be most appropriate for a particular application. An appendix of current commercial instruments is included. The mathematics required for the simple analysis of the obtained isotherm is presented with step-wise instructions for the analysis of the more useful analysis methods. Subsequent chapters describe the analyses and the theories behind the analyses in more detail. * Includes over 150 figures and tables which illustrate the equipment and examples data acquired * Provides a practical guide for measuring and interpreting physical adsorption * Up-to-date aspects of the more subtle physical adsorption theories such as density functional theory and the quantum mechanical chi theory are presented

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This volume presents computer simulation methods and mathematical modelling of physical processes used in surface science research. It offers in-depth analysis of advanced theoretical approaches to behaviours of fluids in contact with porous, semiporous and nonporous solid surfaces. The book also explores interfacial systems for a wide variety of p