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The growth of interest in newly developed porous materials has prompted the writing of this book for those who have the need to make meaningful measurements without the benefit of years of experience. One might consider this new book as the 4th edition of "Powder Surface Area and Porosity" (Lowell & Shields), but for this new edition we set out to incorporate recent developments in the understanding of fluids in many types of porous materials, not just powders. Based on this, we felt that it would be prudent to change the title to "Characterization of Porous Solids and Powders: Surface Area, Porosity and Density". This book gives a unique overview of principles associated with the characterization of solids with regard to their surface area, pore size, pore volume and density. It covers methods based on gas adsorption (both physi and chemisorption), mercury porosimetry and pycnometry. Not only are the theoretical and experimental basics of these techniques presented in detail but also, in light of the tremendous progress made in recent years in materials science and nanotechnology, the most recent developments are described. In particular, the application of classical theories and methods for pore size analysis are contrasted with the most advanced microscopic theories based on statistical mechanics (e.g. Density Functional Theory and Molecular Simulation). The characterization of heterogeneous catalysts is more prominent than in earlier editions; the sections on mercury porosimetry and particularly chemisorption have been updated and greatly expanded.

Characterization of Porous Solids and Powders: Surface Area, Pore Size and Density

1 Theoretical.- 1 Introduction.- 1.1 Real Surfaces.- 1.2 Factors Affecting Surface area.- 1.3 Surface Area from Particle Size Distributions.- 1.4 References.- 2 Gas Adsorption.- 2.1 Introduction.- 2.2 Physical and Chemical Adsorption.- 2.3 Physical Adsorption Forces.- 2.4 Physical Adsorption on a Planar Surface.- 2.5 References.- 3 Adsorption Isotherms.- 3.1 Pore Size and Adsorption Potential.- 3.2 Classification of Adsorption Isotherms.- 3.3 References.- 4 Adsorption Mechanism.- 4.1 Langmuir and BET Theories (Kinetic Isotherms).- 4.1.1 The Langmuir Isotherm.- 4.1.2 The Brunauer, Emmett, and Teller (BET) Theory.- 4.2 The Frenkel-Halsey-Hill (FHH) Theory of Multilayer Adsorption.- 4.3 Adsorption in Microporous Materials.- 4.3.1 Introduction.- 4.3.2 Aspects of Classical, Thermodynamic Theories for Adsorption in Micropores: Extension of Polanyi's Theory.- 4.3.3 Aspects of Modern, Microscopic Theories for Adsorption in Micropores: Density Functional Theory and Molecular Simulation.- 4.3.3.1 Density Functional Theory (DFT).- 4.3.3.2 Computer Simulation Studies: Monte Carlo Simulation and Molecular Dynamics.- 4.3.3.3 NLDFT and Monte Carlo Simulation for Pore Size Analysis.- 4.4 Adsorption in Mesopores.- 4.4.1 Introduction.- 4.4.2 Multilayer Adsorption, Pore Condensation and Hysteresis.- 4.4.3 Pore Condensation: Macroscopic, Thermodynamic Approaches.- 4.4.3.1 Classical Kelvin Equation.- 4.4.3.2 Modified Kelvin Equation.- 4.4.4 Adsorption Hysteresis.- 4.4.4.1 Classification of Hysteresis Loops.- 4.4.4.2 Origin of Hysteresis.- 4.4.5 Effects of Temperature and Pore Size: Experiments and Predictions of Modern, Microscopic Theories.- 4.5 References.- 5 Surface Area from the Langmuir and BET Theories.- 5.1 Specific Surface Area from the Langmuir Equation.- 5.2 Specific Surface Area from the BET Equation.- 5.2.1. BET-Plot and Calculation of the Specific Surface Area.- 5.2.2 The Meaning of Monolayer Coverage.- 5.2.3 The BET Constant and Site Occupancy.- 5.2.4 The Single Point BET Method.- 5.2.5 Comparison of the Single Point and Multipoint Methods.- 5.2.6 Applicability of the BET Theory.- 5.2.7 Importance of the Cross-Sectional Area.- 5.2.8 Nitrogen as the Standard Adsorptive for Surface Area Measurements.- 5.2.9 Low Surface Area Analysis.- 5.3 References.- 6 Other Surface Area Methods.- 6.1 Introduction.- 6.2 Gas Adsorption: Harkins and Jura Relative Method.- 6.3 Immersion Calorimetry: Harkins and Jura Absolute Method.- 6.4 Permeametry.- 6.5 References.- 7 Evaluation of the Fractal Dimension by Gas Adsorption.- 7.1 Introduction.- 7.2 Method of Molecular Tiling.- 7.3 The Frenkel-Halsey-Hill Method.- 7.4 The Thermodynamic Method.- 7.5 Comments About Fractal Dimensions Obtained from Gas Adsorption.- 7.6 References.- 8 Mesopore Analysis.- 8.1 Introduction.- 8.2 Methods based on the Kelvin equation.- 8.3 Modelless Pore Size Analysis.- 8.4 Total Pore Volume and Average Pore Size.- 8.5 Classical, Macroscopic Thermodynamic Methods versus Modern, Microscopic Models for Pore Size Analysis.- 8.6 Mesopore Analysis and Hysteresis.- 8.6.1 Use of Adsorption or Desorption Branch for Pore Size Calculation?.- 8.6.2 Lower Limit of the Hysteresis Loop- Tensile Strength Hypothesis.- 8.7 Adsorptives other than Nitrogen for Mesopore Analysis.- 8.8 References.- 9 Micropore Analysis.- 9.1 Introduction.- 9.2 Micropore Analysis by Isotherm Comparison.- 9.2.1 Concept of V-t curves.- 9.2.2 The t- Method.- 9.2.3 The ?s method.- 9.3 The Micropore Analysis (MP) Method).- 9.4 Total Micropore Volume and Surface Area.- 9.5 The Dubinin-Radushkevich (DR) Method.- 9.6 The Horvath-Kawazoe (HK) Approach and Related Methods.- 9.7 Application of NLDFT: Combined Micro/Mesopore Analysis With a Single Method.- 9.8 Adsorptives other than Nitrogen for Super- and Ultramicroporosimetry.- 9.9 References.- 10 Mercury Porosimetry: Non-Wetting Liquid Penetration.- 10.1 Introduction.- 10.2 Young-Laplace Equation.- 10.3 Contact Angles and Wetting.- 10.4 Capillarity.- 10.5 The Washburn Equation.- 10.6 Intrusion - Extrusion Curves.- 10.7 Common Features of Porosimetry Curves.- 10.8 Hysteresis, Entrapment and Contact Angle.- 10.9 Contact Angle Changes.- 10.10 Porosimetric Work.- 10.12 Theory of Porosimetry Hysteresis.- 10.13 Pore Potential.- 10.14 Other Hysteresis Theories (Throat-Pore Ratio Network Model).- 10.15 Equivalency of Mercury Porosimetry and Gas Sorption.- 10.16 References.- 11 Pore Size and Surface Characteristics of Porous Solids by Mercury Porosimetry.- 11.1 Application of The Washburn Equation.- 11.2 Pore Size and Pore Size Distribution from Mercury Porosimetry.- 11.2.1 Linear Pore Volume Distribution.- 11.2.2 Logarithmic Pore Volume Distribution.- 11.2.3 Pore Number Distributions.- 11.2.4 Pore Length Distribution.- 11.2.5 Pore Population (Number Distribution).- 11.2.6 Surface Area and Surface Area Distribution from Intrusion Curves.- 11.2.7 Pore Area Distributions.- 11.3 Pore Shape from Hysteresis.- 11.4 Fractal Dimension.- 11.5 Permeability.- 11.6 Tortuosity.- 11.7 Particle Size Distribution.- 11.7.1 Mayer & Stowe Approach.- 11.7.2 Smith & Stermer Approach.- 11.8 Comparison of Porosimetry and Gas Sorption.- 11.9 Solid Compressibility.- 11.10 References.- 12 Chemisorption: Site Specific Gas Adsorption.- 12.1 Chemical Adsorption.- 12.2 Quantitative Measurements.- 12.3 Stoichiometry.- 12.4 Monolayer Coverage.- 12.4.1 Extrapolation.- 12.4.2 Irreversible Isotherm and Bracketing.- 12.4.3 Langmuir Theory.- 12.4.4 Temperature Dependent Models.- 12.4.5 Temkin Method.- 12.4.6 Freundlich Method.- 12.4.7 Isotherm Subtraction - Accessing Spillover.- 12.4.8 Surface Titration.- 12.5 Active Metal Area.- 12.6 Dispersion.- 12.7 Crystallite (Nanoparticle) Size.- 12.8 Heats of Adsorption and Activation Energy.- 12.8.1 Differential Heats of Adsorption.- 12.8.2 Integral Heat of Adsorption.- 12.8.3 Activation Energy.- 12.9 References.- 2 Experimental.- 13 Physical Adsorption Measurements - Preliminaries.- 13.1 Experimental Techniques for Physical Adsorption Measurements.- 13.2 Reference Standards.- 13.3 Representative Samples.- 13.4 Sample Conditioning: Outgassing of the Adsorbent.- 13.5 Elutriation and Its Prevention.- 13.6 References.- 14 Vacuum Volumetric Measurements (Manometry).- 14.1 Basics of Volumetric Adsorption Measurement.- 14.2 Deviations from Ideality.- 14.3 Void Volume Determination.- 14.4 Coolant Level and Temperature Control.- 14.5 Saturation Vapor Pressure, P0 and Temperature of the Sample Cell.- 14.6 Sample Cells.- 14.7 Low Surface Area.- 14.8 Micro- and Mesopore Analysis.- 14.8.1 Experimental Requirements.- 14.8.2 Micropore Analysis and Void Volume Determination.- 14.8.3 Thermal Transpiration Correction.- 14.8.4 Adsorptives other than Nitrogen for Micro- and Mesopore Analysis - Experimental Aspects.- 14.9 Automated Instrumentation.- 14.9.1 Multistation Sorption Analyzer.- 14.9.2 The NOVA Concept.- 14.10 References.- 15 Dynamic Flow Method.- 15.1 Nelson and Eggertsen Continuous Flow Method.- 15.2 Carrier Gas (Helium) and Detector Sensitivity.- 15.3. Design Parameters for Continuous Flow Apparatus.- 15.4 Signals and Signal Calibration.- 15.5 Adsorption and Desorption Isotherms by Continuous Flow.- 15.6 Low Surface Areas Measurement.- 15.7 Data Reduction - Continuous Flow Method.- 15.8 Single Point Method.- 15.9 References.- 16 Volumetric Chemisorption: Catalyst Characterization by Static Methods.- 16.1 Applications.- 16.2 Sample Requirements.- 16.3 General Description of Equipment.- 16.4 Measuring System.- 16.4.1 Pressure Measurement.- 16.4.2 Valves.- 16.4.3 Vacuum.- 16.4.4 Sample Cell.- 16.4.5 Heating System.- 16.4.6 Gases and Chemical Compatibilities.- 16.5 Pretreatment.- 16.5.1 Heating.- 16.5.2 Atmosphere.- 16.6 Isotherms.- 16.6.1 Reactive Gas.- 16.6.2 The Combined Isotherm.- 16.6.3 The Weak Isotherm.- 16.6.4 The Strong Isotherm.- 16.6.5 Multiple Isotherms.- 16.7 References.- 17 Dynamic Chemisorption: Catalyst Characterization By Flow Techniques.- 17.1 Applications.- 17.2 Sample Requirements.- 17.3 General Description of Equipment.- 17.3.1 Flow Path.- 17.3.2 Sample Cell.- 17.3.3 Gases.- 17.3.4 Heating.- 17.3.5 Pulse Injection.- 17.3.6 Detector.- 17.4 Pretreatment.- 17.5 Pulse Titration.- 17.6 Additional Requirements for Temperature Programmed Methods.- 17.6.1 Programmed Heating.- 17.6.2 Sample Temperature.- 17.7 Temperature Programmed Reduction.- 17.8 Temperature Programmed Oxidation.- 17.9 Temperature Programmed Desorption.- 17.9.1 Some Specific Applications.- 17.8.1.1 Acid/Base.- 17.8.1.2 Oxidizers.- 17.8.1.3 Reducers.- 17.10 Mass Spectrometry.- 17.11 Metal Parameters.- 17.11 References.- 18 Mercury Porosimetry: Intra and Inter- Particle Characterization.- 18.1 Applications.- 18.2 Working with Mercury.- 18.3 Experimental Requirements.- 18.4 Sample Cell.- 18.5 Volume Measurement.- 18.6 Contact Angle.- 18.6.1 Dynamic Contact Angle.- 18.6.2 Static Contact Angle.- 18.7 A Modern Porosimeter.- 18.8 Low Pressure Measurements.- 18.8.1 Sample Cell Evacuation.- 18.8.2 Filling with Mercury.- 18.8.3 Low Pressure Intrusion-Extrusion.- 18.9 High Pressure Measurements.- 18.10 Scanning Method.- 18.11 Stepwise Method.- 18.12 Mercury Entrapment.- 18.13 Working with Powders.- 18.14 Inter/Intra Particle Porosity.- 18.15 Isostatic Crush Strength.- 18.16 References.- 19 Density Measurement.- 19.1 Introduction.- 19.2 True Density.- 19.3 Apparent Density.- 19.4 Open-Closed Porosity.- 19.5 Bulk Density.- 19.6 Tap Density.- 19.7 Envelope or Geometric Density.- 19.8 Effective Density.- 19.9 Density by Mercury Porosimetry.- 19.10 Standard Methods.- 19.11 References.