Experimental Study on the Adsorption of Water and Ethanol by Cornmeal for Ethanol Dehydration

A fixed-bed apparatus was designed to investigate the gas adsorption capacity and selectivity of cornmeal for ethanol dehydration. The experiments were performed at near atmospheric pressure and at different temperatures and different ethanol vapor concentrations. Both equilibrium and kinetic adsorptions at the breakthrough point were conducted. The effects of superficial velocity, temperature, and vapor feed concentration on the adsorption capability were studied. The experimental results show that the water selectivity over ethanol on cornmeal is on the order of 0.5-0.6 for both equilibrium and kinetic conditions at the breakthrough point, the equilibrium adsorption capacity for cornmeal is 2.9 g of water/100 g of adsorbent and 2.5 g of ethanol/100 g of adsorbent under the conditions of 91 °C and 93.8 wt % ethanol vapor feed concentration, and the kinetic selectivity of water over ethanol at the breakthrough point is slightly higher than the equilibrium value. The adsorption isotherm for water was correlated as a linear expression for ethanol vapor feed concentrations of 85.0-95.2 wt % The experimental results demonstrate that the likelihood of selective adsorption can be given by the dynamic behavior of the adsorption of water and ethanol on cornmeal.