Chapter: Chemical Adsorption
Physical and chemical adsorption differentiated Theory Chemisorption and its energies Classical theories of chemical adsorption isotherms -- Langmuir theory -- Freundlich and Temkin isotherms Analysis and data reduction Static volumetric -- Isolating the chemisorption isotherm -- Chemisorption monolayer volume -- Number of accessible active sites -- Metal dispersion -- Active metal area -- Active particle size -- Isosteric heat of adsorption Dynamic technique: pulse chemisorption Temperature-programmed reactions Temperature-programmed reduction Temperature-programmed desorption Temperature-programmed oxidation Instrumentation Dynamic (flowing gas) instruments Instrumentation for the study of temperature-programmed reactions -- Relation of function to valves and flow paths -- Temperature controlled internal modules -- Temperature monitoring -- Thermal conductivity detector -- Response times and synchronization -- Subambient analysis -- Monitoring and controlling gas flow -- Mixed gases -- Vapor generation Static volumetric chemisorption analyzer -- Gas delivery system -- Materials of construction -- Sample holder assembly -- Sample temperature -- Sample degassing, pretreatment, and analysis Analytical techniques and data reduction methods Measurement of surface acidity by ammonia titration TPD applied to the distribution of acid site strength Determination of isosteric heat of adsorption Active Surface area and percent dispersion of metal oxides by the dynamic technique Sample preparation Analysis Data reduction -- Quantifying reaction gas volumes -- Specific volume chemisorbed -- Total volume of nitrogen produced -- Surface area of copper -- Metal dispersion Temperature-programmed techniques -- TPR of metals on AlO 2 -- TPD of H 2 from reduced Pt on Al 2 O 3 -- TPD of ammonia on ZSM-5 zeolite -- TPR of CuO -- TPR of Fe 2 O 3 -- TPR method for characterizing the interaction between active metal and support -- TPR applied to the formation of alloys -- TPR applied to the study of promoters in bimetallic catalysts Symbols used in this chapter
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