1996 Volume 2 Issue 3 Pages 174-179
For the basic study on removal of methyl mercaptan from coffee volatiles, adsorption characteristics on zeolite 5A were evaluated for 6 model components in a coffee aroma-containing gas. They were methyl mercaptan, acetaldehyde and 2,3-butanedione as aroma components, and nitrogen, carbon dioxide and water as coexisting gas components. Adsorption isotherms for the above components were measured, and heats of adsorption were calculated from the measured isotherms. From the breakthrough curves for binary mixture, the order of adsorption selectivity was determined as water>acetaldehyde>methyl mercaptan>carbon dioxide>2,3-butanedione>nitrogen. The order roughly corresponded to the relative order of heats of adsorption. The results suggest that it is necessary to remove water vapor in the aroma-containing gas before the adsorption process for improving the adsorption efficiency of methyl mercaptan. Partial condensation was calculated for a model component system, and it was found that the condensation operation would be useful for the removal of water vapor from an aroma-containing gas.