Dynamic determination of the concentration of volatile alcohols in a fixed bed of zeolite 13X by FT-IR.

A series of dynamic adsorptions of volatile methanol, ethanol, and iso-propanol (IPA) onto zeolite 13X were studied. Instead of traditional gas chromatography (GC), a gas-phase Fourier Transformation-IR (FT-IR) spectrometer was used to measure the evolution of concentrations of these volatile alcohols due to its quick response to the instantaneous changes of the gas concentration. Even though it has rarely been used in dynamic adsorption experiments in the literature, an FT-IR equipped with a constant-temperature gas cell was shown to be adequate to obtain breakthrough curves. In this study, the experiments were carried out at different gas flow rates and feed concentrations for each type of alcohol. Significant influences of the operating conditions on the breakthrough time, the shape of the breakthrough curve, and the uptake of each alcohol were found. A simple mathematical model proposed by Yoon and Nelson was applied to fit the experimental data. Good consistency between the experimental data and the regressed breakthrough curves was observed.