DEVELOPING INEXPENSIVE EUTECTIC IONIC LIQUIDS FOR BIODIESEL SYNTHESIS

摘要

Recently, ionic liquids have been studied as solvents for enzymatic synthesis of biodiesel. The enzymatic (and chemical) transesterification of vegetable oils has been demonstrated by several groups in producing biodiesel. Ha et al screened 23 different ionic liquids for the methanolysis of soybean oil catalyzed by immobilized Candida antarctica lipase (Novozym~R 435), and identified the hydrophilic ionic liquid (i.e. [EMIM][OTf]) as the best solvent for achieving the highest yield (80%) of fatty acid methyl esters at 12 h. On the other hand, Sunitha et al obtained 98–99% yields of fatty acid methyl esters within 10 h of methanolysis of sunflower oil in hydrophobic [BMIM][PF6] and [EMIM][PF6] when catalyzed by Novozym~R 435. Gamba et al also utilized several ionic liquids (i.e. [BMIM][Tf2N], [BMIM][BF4] and [BMIM][PF6]) as solvents in the enzymatic transesterification of soybean oil, achieving over 90% biodiesel yield in 48 h. Arai et al investigated the fungus whole-cell catalyzed production of biodiesel from soybean oil in ionic liquids ([EMIM][BF4] and [BMIM][BF4]), and observed that ionic liquids enabled the lipase to be more tolerant to methanol inhibition and allowed quantitative synthesis of biodiesel under optimized conditions. Our group recently demonstrated that ether- functionalized ionic liquids based on acetate were capable of dissolving oils and afforded high enzymatic activities in biodiesel synthesis. However, although these ionic liquids have led to efficient synthesis of biodiesel, they are practically too expensive for large- scale production of biodiesel.