Production of pure ethanol from azeotropic solution by pressure swing adsorption

Abstract

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 ethanol-water 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 less 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.

Ethanol Dehydration in a Pressure Swing Adsorption Process Using Canola Meal

“…Several research projects have been conducted using molecular sieves zeolites (Jeong et al, 2009;Pruksathorn and Vitidsant 2009;Simo et al, 2009;Carmo and Gubulin 2002) and biobased adsorbents (Boonfung and Rattanaphanee 2010;Beery et al, 1998) in PSA processes to dehydrate ethanol. For example, Simo and his co-workers (Simo et al, 2009) As it can be seen from Figure 2.1, water and ethanol is mixed with nitrogen gas (carrier gas) in the CEM (control-evaporation-mixing) unit, which is a vapor generating system.…”

Exergetic and Economic Assessment of Distillation Hybrid Configurations for Bioethanol Refining

“…The hybrid configurations of distillation with three extractive sequences were compared based on energy requirement and second law efficiency on the basis of similar feed and product specifications [9]. Several attempts were made to study and investigate bioethanol refining using molecular sieves and to investigate the effects of several operating parameters for process improvements [10,11,12,13]. Bioethanol refining was also studied using hybrid distillation-pervaporation process and the serially connected module was chosen as the best [14].…”

Effect of Some Fermentation Parameters on Ethanol Production from Beet Molasses by <i>Saccharomyces cerevisiae</i> CAIM13

“…At present, ethanol fermentation technology generally employs batch bioreactor systems and only occasionally continues reactors where the cells are freely suspended in the liquid phase (Choi et al, 2009;Hong et al, 2009;Zhang et al, 2009;Turhan et al, 2010;Ghorbani et al, 2011;Li et al, 2010;Tang et al, 2010) in recent years, many workers have used immobilized-cell systems to ferment a wide variety of carbohydrates to ethanol (Liu et al, 2009;Singh et al, 2009;Pacheco et al, 2010;Ghorbani et al, 2011;Pruksathorn and Vitidsant, 2009) reported that certain strains of S. cerveisiae can undergo up to 10 fermentation cycles using molasses-containing medium. Alshiyab et al (2009) reported that by using bigger reactor size, the effect of gaseous products in fermentation medium was reduced and enhanced both bacterial productivity and biomass concentration, where Brethauer and Wyman (2010) reported that some continuous fermentations are now employed for commercial ethanol production from cane sugar and corn to take advantage of higher volumetric productivity, reduced labor costs, and reduced vessel down time for cleaning and filling.…”