Parametric Study on the Effect of Congeners on Molecular Sieve Dusting during Ethanol Dehydration
Sieve dusting reduces the efficiency of molecular sieve adsorption during ethanol dehydration. As a result, the recoverable yield of pure ethanol is lowered. This study explored the contribution of congeners (acetone, ethyl acetate, and methanol) in molecular sieve dusting by varying the number of pressure cycles and congener concentrations during ethanol dehydration. A general two-factorial design with three levels was used to statistically test these factors. Degree of dusting was evaluated by measuring cumulative decrease in mass and change in crush strength of sieves. The number of pressure cycles and congener concentration had a positive effect on the decrease in mass of Type 3A molecular sieves and a negative effect with crush strength. There was an 11.20 %, 18.56 %, and 34.11 % change in crushing strength from 400, 800, and 1200 mg L-1 acetone concentration for a five-cycle dehydration run, respectively. Greatest decrease in bulk mass was found to be 0.53% (cumulative) and 0.25% (non-cumulative) for acetone and 0.60% (cumulative) and 0.31% (non-cumulative) for congener mixture. The parameters had no significant interaction towards each other; thus, the effect of the number of pressure cycle and congener concentration was additive to sieve dusting.