ARS | Publication request: Energy Requirement for Butanol Recovery from Fermentation Broth Using Adsorption As An Alternative Technique

Submitted to: Biotechnology for Fuels and Chemicals Symposium Proceedings
Publication Type: Abstract
Publication Acceptance Date: May 12, 2004
Publication Date: May 1, 2004
Citation: Qureshi, N., Cotta, M.A. 2004. Energy requirement for butanol recovery from fermentation broth using adsorption as an alternative technique [abstract]. Biotechnology for Fuels and Chemicals. Paper No. 3-12.

Technical Abstract: Butanol, a superior liquid fuel to ethanol, can be produced from renewable biomass. However, its economics is hampered by substrate cost and energy intensive recovery by traditional distillation. Distillative recovery of butanol requires more energy than in the product itself. This is due to low concentration of butanol in the fermentation product and butanol's higher boiling point than water. The maximum concentration of butanol that can be achieved in fermentation broth is 21 gL**-1 and that of acetone butanol ethanol (ABE) it is 26.5 gL**-1. In order to produce 1 kg of butanol, 47.62 kg of liquid fermentation medium has to be used. At the end of fermentation of the 47.62 kg of broth, 46.36 kg is water (1 kg butanol, 238 g acetone, and 24 g ethanol) that has to be removed for butanol/ABE recovery. In order to make butanol fermentation a viable option, several product recovery techniques have been investigated. These techniques include pervaporation, gas stripping, liquid-liquid extraction, adsorption, reverse osmosis, and aqueous two phase separation, in addition to distillation and steam stripping distillation. In order to make butanol recovery energy efficient, adsorption of butanol on to molecular sieve or silicalite has been considered. It is estimated that adsorption requires 392.6 kcal kg**-1 butanol as compared to 5309.1 kcal kg**-1 butanol by steam stripping distillation. The energy content of butanol is 7786.9 kcal kg**-1. Simple distillative recovery of butanol requires 28,695 kcal kg**-1 butanol.