The Properties Of Solid Sorbents Relevant On The Performance And Cost Of Co2 Capture

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Sorbent characteristics This chapter discusses the properties of solid sorbents relevant to the performance and cost of CO2 capture. The chapter begins with a discussion of the solid sorbent properties that are important for CO2 capture. The discussion then broadens to include a range of factors which affect the CO2-capture process, such as the interactions between the solid sorbent and other flue gas components, sorbent attrition and degradation, and the influence of reaction kinetics. The chapter concludes with a summary of ?best estimate? characteristics of the specific solid sorbents analyzed in this work. Solid sorbent properties Solid sorbents are small porous particles which can selectively adsorb or complex with gaseous chemical species (in this case, CO2), thereby removing the species from a gas mixture. Molecules of CO2 may be held loosely by weak intermolecular forces termed ?physiosorption? or strongly via covalent bonding, termed ?chemisorption.? Generally, physiosorption occurs when the heat of adsorption is greater than approximately -40 kJ/mol of CO2 (i.e. -20 to -40 kJ/mol), while chemisorption occurs with the heats of adsorption less than -60 kJ/mole (Yang, 2003). These are rules of thumb, however, and exceptions do exist. For instance, the heat of physiosorption of CO2 in some zeolites has been reported to be as low as -210 kJ/mol CO2 (Shen, et al., 2000), with heats of chemisorption known to extend from as low as -62 kJ/mol to over -420 kJ/mol. The heat

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