In the fermentation, it is hard for most of the butanol-producing strains to tolerate a butanol concentration higher than 15
g/L and thus the final butanol titre is usually low (Ishii et al., 1985
; Taya et al., 1985
). As a result, the recovery of butanol by traditional distillation is generally economically infeasible because of high energy consumption. Concurrently, various in situ product removal/recovery strategies ...