초록
<P><B>Highlights</B></P><P>► Differently substituted imidazolium-based ionic liquids were synthesized. ► 19 Ionic liquids were screened as solvents for lipase-catalyzed esterification. ► [C<SUB>7</SUB>mmim][Tf<SUB>2</SUB>N] was selected as the best medium for isoamyl acetate synthesis. ► Further process optimization was accomplished in a packed bed microbioreactor. ► A volumetric productivity of 61mmoll<SUP>−1</SUP>min<SUP>−1</SUP> of isoamyl acetate was achieved.</P> <P><B>Abstract</B></P><P>The acylation of isoamyl alcohol with acetic anhydride catalyzed by immobilized <I>Candida antarctica</I> lipase B was studied in ionic liquids (ILs) based on quaternary imidazolium cations with alkyl, alkenyl, alkynyl, benzyl, alkoxyl or <I>N</I>-aminopropyl side chains. Among the tested ILs, the highest enzyme activity together with the highest isoamyl acetate yield were obtained in [C<SUB>7</SUB>mmim][Tf<SUB>2</SUB>N]. No loss of lipase B activity was observed during one-month incubation in this hydrophobic IL without the presence of substrates. Isoamyl acetate synthesis using [C<SUB>7</SUB>mmim][Tf<SUB>2</SUB>N] as solvent was further studied in a continuously operated miniaturized enzymatic packed bed reactor at various flow rates and temperatures. Up to 92% isoamyl acetate yield could be obtained within 15min by using 0.5M acetic anhydride and 1.5M isoamyl alcohol inlet concentrations at 55°C, corresponding to the volumetric productivity of 61mmoll<SUP>−1</SUP>min<SUP>−1</SUP>, which to the best of our knowledge is the highest reported so far for this reaction. No decrease in productivity was experienced during the subsequent runs of continuous microbioreactor operation performed within 14 consecutive days. The benefits of reactor miniaturization along with the green solvent application were therefore successfully exploited for the development of a sustainable flavour ester production.</P>