Separation of gas mixtures by adsorption

Gas mixtures are separated primarily by absorption and rectification. Rectification requires at least (v+1)-fold of the enthalpy of the distillate as heat energy (v is the reflux ratio). In the case of absorption, the resulting solution is frequently subjected to thermal regeneration with the energy requirement depending inter alia on the boiling point of the solvent. In view of the high energy requirements of these processes and the development of new adsorbents, possibilities of separating by adsorption with subsequent regeneration of the adsorbents, above all by change in pressure, are investigated. The separation of gas mixtures in adsorber beds (e.g. molecular sieves, silica gel, activated charcoal and coke, or alumina) depend upon various separating effets: steric effects, equilibrium effects, kinetic effects. A survey is given of proposed and practical industrial separation processes utilizing adsorption. (orig.)