Pore size, sorbent design

Pore size, sorbent design, 87-88 Potential energy, adsorption, 81-83 Precipitation, nanostructured materials,... 

This chapter discusses the fundamental principles for designing nanoporous adsorbents and recent progress in new sorbent materials. For sorbent design, detail discussion is given on both fundamental interaction forces and the effects of pore size and geometry on adsorption. A summary discussion is made on recent progress on the following types of materials as sorbents activated carbon, activated alumina, silica gel, MCM-41, zeolites, n -complexation sorbents, carbon nano tubes, heteropoly compounds, and pillared clays. 2001 Academic Press. 

In designing an adsorption column, the characterization of adsorbents should be done prior to experiments. In particular, one should know not only the specific area but also the pore size distribution of the adsorbent in order to confirm that it would be proper for a given purpose. Nitrogen adsorption and desorption isotherms, BET surface areas, and BJH (Barrett, Joyner and Halenda) pore size distributions of the synthesized sorbents... 

They found that the average pore size and the total pore volume are not adequate measures to predict the CO2 uptake of microporous carbon sorbents, the pore volume of micropores strongly governs the amount of adsorbed CO2 [161]. Neither high surface area CDC after chemical activation (surface area 3,101 m g ) nor high pore volume nano-TiC-CDC (Vtotai 1-61 cm g ) correspond with the highest CO2 adsorption capacity. At ambient pressure, the CO2 uptake closely follows a linear correlation with the volume of pores smaller or equal to a diameter of 1.5 mn. Pores smaller than 0.5 mn contribute to the amount of adsorbed CO2, but the best correlation is found for pore volume smaller than 0.8 mn (Fig. 2.29). The correlation between the amount of adsorbed CO2 at low partial pressures and volume of smaller pores is the basis for the well-known application of CO2 sorption as a method to calculate the pore characteristics of microporous materials. Subatmospheric pressures are of particular interest for industrial applications, where partial pressure of CO2 is below 1 bar, and here, the best prediction of the CO2 uptake capacity at 0.1 bar would be based on the volume of pores smaller or equal to a diameter of 0.5 nm (Fig. 2.29). This correlation can be used to design better CO2 sorbents and CCS devices. 

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