Isolation of ethanol from its aqueous solution by liquid phase adsorption and gas phase desorption using molecular sievi
- PDF / 893,588 Bytes
- 11 Pages / 595.276 x 790.866 pts Page_size
- 29 Downloads / 163 Views
Isolation of ethanol from its aqueous solution by liquid phase adsorption and gas phase desorption using molecular sieving carbon Hirotaka Fujita · Qingrong Qian · Takao Fujii · Kazuhiro Mochizuki · Akiyoshi Sakoda
Received: 16 May 2010 / Accepted: 1 March 2011 / Published online: 17 March 2011 © Springer Science+Business Media, LLC 2011
Abstract A novel bioethanol separation process was proposed in this study employing molecular sieving carbon (MSC) as an adsorbent, whose pore diameter is close to molecular size of ethanol. In the proposed process, fermentation broth is first introduced to the adsorption bed packed with MSC. In this step, ethanol is selectively adsorbed onto MSC, with highly enriching ethanol in the micropore of MSC. Subsequently, the concentrated ethanol is desorbed from MSC to gaseous phase, resulting in further purification of ethanol owing to a considerable difference in desorption rate between water and ethanol; Because of molecular sieving effect of MSC, the desorption rate of ethanol is much smaller than that of water. To establish this process, adsorption equilibrium and kinetics of ethanol on various MSCs were investigated in aqueous phase as the first step. Also, desorption kinetics of ethanol and water in gaseous phase were investigated. As a result, it was suggested that highly concentrated ethanol could be obtained with high recovery ratio through these simple operations, meaning the proposed process is quite promising. Keywords Bioethanol · Adsorption · Desorption · Separation
1 Introduction Bioethanol has recently attracted great attention as an alternative for fossil fuels. Bioethanol production generally consists of four processes in series (Huang et al. H. Fujita () · Q. Qian · T. Fujii · K. Mochizuki · A. Sakoda Institute of Industrial Science University of Tokyo, 4-6-1 Komaba Meguro-ku, Tokyo 153-8505, Japan e-mail: [email protected]
2008): (i) Saccharification of biomass, (ii) fermentation, (iii) concentration of bioethanol by distillation (ethanol concentration: approximately 93%), and (iv) anhydration of bioethanol by azeotropic distillation (ethanol concentration: over 99%). However, these distillation processes employed for bioethanol separation and purification require a large amount of energy, which is approximately equal to 50% of the combustion energy of produced bioethanol. Hence, energy saving in the separation is a key issue for bioethanol production. To overcome this problem, several separation processes were proposed and its efficiency was evaluated (Gomez et al. 2008; Vane and Alvarez 2008; Modla and Lang 2008; Brousse et al. 1985; Annakou and Mizsey 1995; Weilnhammer and Blass 1994; Boudereau and Hill 2006). A novel ethanol separation is proposed in this study employing molecular sieving carbon (MSC) as an adsorbent for bioethanol. In this process, ethanol in the fermentation broth is adsorbed in liquid phase, and the adsorbed ethanol is desorbed to gaseous phase for recovery. The detailed explanation with reference to the process is described below.
Data Loading...
