Adsorption–Desorption Cycles for the Separation of Vapour-Phase Ethanol/Water Mixtures

Kupiec, Krzysztof; Rakoczy, Jan; Zieliński, Łukasz; Georgiou, A.

doi:10.1260/026361708786036098

Cited by 18 publications

(13 citation statements)

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“…5 The economic viability of the ethanol production process is strongly affected by the low ethanol concentration obtained in the fermenter, as well as the need to break the azeotrope between ethanol and water, which occurs at an ethanol concentration of 95.57 wt %. A lot of research has been directed toward using adsorption to break the azeotrope at high ethanol concentrations, including the use of zeolites [6][7][8] and cellulosic adsorbents. [9][10][11][12][13] One alternative to decrease the cost of production of ethanol is to increase the productivity by reducing ethanol inhibition within the fermentation broth.…”

Section: Introductionmentioning

confidence: 99%

Ethanol Recovery from Fermentation Broth via Carbon Dioxide Stripping and Adsorption

2010

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With the depletion of fossil fuels, research in alternative energy sources that can provide the world's energy demand has increased significantly during the past decade. One alternative energy source in particular that has gained worldwide recognition as a potential replacement to oil is bioethanol. It is renewable and environmentally friendlier than fossil fuels. In this study, adsorption is used to increase the efficiency of ethanol production by decreasing the effect of product inhibition using carbon dioxide stripping technology. The reduction in product inhibition is particularly important when ethanol is produced from lignocellulosic biomass because microorganisms that are able to use all fermentable sugars are less tolerant to ethanol. Carbon dioxide removes ethanol from the fermentation broth and reduces the level of ethanol toxicity, while adsorption is used to recover the entrained ethanol from the vapor phase. The literature review showed that activated carbon and hydrophobic zeolites would be the most appropriate adsorbents for ethanol recovery in the vapor phase. A series of adsorption screening experiments were performed to compare four activated carbon adsorbents (Filtrasorb 200, Nuchar RGC 40, Sorbonorit B4, and WV-B 1500) and two hydrophobic ZSM-5-type zeolites (HiSiv 3000 and CBV 8014). The vapor composition used was controlled to resemble the fermenter outlet vapor concentration after stripping with carbon dioxide. Activated WV-B 1500 exhibited the highest ethanol capacity among activated carbons, having higher ethanol adsorption capacities than the two zeolites. Adsorption isotherms for ethanol and water in the presence of carbon dioxide at different temperatures were determined using WV-B 1500 as the adsorbent with the temperature-dependent Toth isotherm model providing satisfactory fits for these isotherms. Ethanol adsorption experiments with and without the presence of water were conducted and showed similar ethanol adsorption capacities, indicating that the presence of water has a negligible effect on ethanol adsorption.

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Section: Introductionmentioning

confidence: 99%

Ethanol Recovery from Fermentation Broth via Carbon Dioxide Stripping and Adsorption

2010

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“…In addition, the usage of ethanol fuel helps the current global warming issue by reducing the net emissions of carbon dioxide in the atmosphere. This is because the amount of carbon dioxide released during the production and combustion of ethanol fuel is the same as the one bound into the replanted biomass (Kupiec et al, 2008). Another advantage of using ethanol in gasoline is that no anti-freeze is required in the hydrocarbon based fuel containing at least 10 wt% ethanol (Frolkova and Raeva 2010).…”

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confidence: 99%

Ethanol Dehydration in a Pressure Swing Adsorption Process Using Canola Meal

2013

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Canola meal was used as an adsorbent in a pressure swing adsorption (PSA) apparatus for ethanol dehydration. The experiments were conducted at different pressures, temperatures, vapor superficial velocities, vapor concentrations and particle sizes. Adsorption experiments were performed at equilibrium and breakthrough points. The results demonstrated that canola meal can break the azeotropic point 95.6 wt% and produce over 99 wt% ethanol. At elevated temperature, feed water concentration, and vapor superficial velocity, it was found that the mass transfer rate increased. In addition, the mass transfer rate decreases when either the total pressure or the size of the adsorbent particles are increased. Breakthrough curves were simulated and the overall mass transfer resistance was evaluated at all experimental runs. The internal mass transfer resistance was identified as the relevant mass transfer mechanism.For canola meal, the equilibrium water/ethanol uptake was achieved at 100, 105, and 110˚C. The Frenkel-Halsey-Hill (FHH) and Guggenheim-Andrson-de-Boer (GAB) models perfectly simulated the water adsorption isotherms. By applying Dubinin-Polanyi model to the experimental data, canola meal was identified as a large pore (non-porous) material.The heat of adsorption on canola meal with particle size of 0.43-1.18 mm was determined to be -32.11 kJ/mol. The result confirms that the adsorption process is an exothermic phenomenon and is of physical type due to the fact that the value obtained as the heat of adsorption is negative and its magnitude is within the range 20-80 kJ/mol. The equilibrium water uptake on canola meal was similar to that reported for other starchy and cellulosic adsorbents, while the ethanol uptake was higher.Water saturated canola meal was successfully regenerated by passing nitrogen at 110˚C which is lower than that for molecular sieves commonly used in industry for bioethanol dehydration. The canola meal bio-adsorbent was re-used for more than 32 cycles and no significant change in adsorption capacity was observed.iii ACKNOWLEDGEMENTS

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“…These results clearly show that 3 Å molecular sieve has the highest absorption capacity for water [3]. A number of researchers have studied the adsorption kinetics and pressure swing adsorption methods for dehydration of rectify-ing column ethanol to fuel grade ethanol [5,6,4,[7][8][9].…”

Section: Dehydration Of Ethanol Using Zeolite Molecular Sievesmentioning

confidence: 99%