Adsorption, nanoporous materials adsorbate interaction

Gas, or vapor molecules, after the degasitication process, can go through the pore structure of crystalline and ordered nanoporous materials through a series of channels and/or cavities. Each layer of these channels and cavities is separated by a dense, gas-impermeable division, and within this adsorption space the molecules are subjected to force fields. The interaction with this adsorption field within the adsorption space is the base for the use of these materials in adsorption processes. Sorption operations used for separation processes imply molecular transfer from a gas or a liquid to the adsorbent pore network [2],... 

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 the case of alkane cracking, dispersion forces between the alkane molecules and the siliceous walls of the zeolites and perhaps other nanoporous crystalline and ordered materials are possibly the most important interactions for stabilizing adsorption in the cavities, since the proton affinity of alkanes is low [104] and the electrostatic interactions between the alkane and the adsorbent are negligible [97],... 

The basis for thermodynamic calculations is the adsorption isotherm, which gives the amount of gas adsorbed in the nanopores as a function of the external pressure. Adsorption isotherms are measured experimentally or calculated from theory using molecular simulations. Potential functions are used to constmct a detailed molecular model for atom-atom interactions and a distribution of point charges is used to reproduce the polarity of the solid material and the adsorbing molecules. Recently, ab initio quantum chemistry has been applied to the theoretical determination of these potentials, as discussed in another chapter of this book. 

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