INCREASED SEPARATION BY VARIABLE-TEMPERATURE STEPWISE DESORPTION IN MULTICOMPONENT ADSORPTION PROCESSES

When more components than desired are adsorbed, adsorption-desorption separation processes may not be satisfactory. However, in the cases of ethanol and water adsorption on activated carbon, propane and propylene adsorption on molecular sieves, and hydrogen sulfide, carbon dioxide, and propane adsorption on molecular sieves, it has been found that a variable-temperature stepwise desorption (VTSD) procedure following the adsorption stage can significantly increase the degree of separation achieved compared to a complete desorption of all adsorbed components. Studies indicate that these increased separations are in part due to nonequilibrium effects. An estimation of economic factors in separating low concentration propylene in propane indicates VTSD is favorable compared to distillation, because of lower energy costs. It appears that the VTSD method could be useful in bulk separations of mutlicomponent mixtures. © 1990, American Chemical Society. All rights reserved.