Production of Pure Ethanol from Azeotropic Solution by Pressure Swing Adsorption

2009 American Journal of Engineering and Applied Sciences  
There has been a gaining interest in the use of fuel ethanol from fermentation process. A main challenge in producing the ethanol concerned the production cost which was largely contributed by the process of water removal. Distillation could remove water to a certain level but due to ethanolwater azeotrope an extra process was needed before ethanol could be blended with gasoline. Problem statement: Pressure Swing Adsorption (PSA) process was attractive for final separation since it required
more » ... energy and lower setup cost. Despite many researches on simulation and experimental works on adsorption of water on 3A zeolite in a fixed bed, none have studied a process with the actual PSA system. Approach: The purpose of this research was to study the PSA process with two adsorbers and effects of several parameters. The research also included analysis of kinetic and thermodynamic data of ethanol-water adsorption on commercial 3A zeolites in a single fixed bed. Two-level factorial design experiment was used in this research works to preliminary screen the influence and interaction among each factor. Results: From the experimental works, it was found that the most suitable condition for water adsorption on 30 g of zeolite was at 90°C initial bed temperature, feed flow rate of 1 mL min −1 and feed concentration of 95% vol ethanol. Langmuir isotherm could best predict the experimental results and the corresponding equation was proposed. In the PSA pilot test, the principal factors, which had an effect on the adsorption rate, recovery, and the enrichment of the product, were feed rate, feed concentration, adsorption pressure and the cycle time. Prediction of the process efficiency in terms of ethanol recovery and enrichment was proposed in the form of regression models. Conclusions/Recommendations: The results of the study in a fixed bed adsorber could help designing a pilot scale PSA unit. The experiments proved to be successful in terms of producing high concentration ethanol with acceptable percentage of ethanol recovery. With further simulation works, the process could be scaled up for an industrial use.
doi:10.3844/ajeas.2009.1.7 fatcat:q2oxtkvnpbhfblz4qhd2fwfebi