Functionalized mesoporous polymer ionic liquids for efficient immobilization of lipase: Effects of ethyl oleate

Abstract

Herein, fatty acid esters were synthesized cost-effectively from various fatty acids using reusable lipase (L) immobilized with novel porous ionic polymer (PIP) (l–PIP). The functionalized mesoporous PIP was synthesized through Friedel–Crafts alkylation reaction of 1, 4-bis(bromomethyl) benzene in the presence of ferric chloride as catalyst, and lipase was completely immobilized with PIP at varied time, forming l–PIP–6H, l–PIP–12H, l–PIP–18H, l–PIP–24H, l–PIP–30H, and l–PIP–36H, which were applied in ester production. l–PIP–30H was characterized using FT–IR, SEM, XPS, solid–state 13C NMR, and N2 adsorption–desorption isotherms. The conversion of oleic acid reached 88.21 % under optimized conditions (12:1 ethanol/oleic acid molar ratio after 5 h at 45 °C with 250 wt% catalyst at 300 rpm). The stability and reusability of l–PIP–30H were demonstrated by the sustained catalytic efficiency for at least six reaction cycles. Good catalytic activity during the esterification of various free fatty acids with ethanol was observed. This cost–efficient and effective lipase–immobilized PIP catalyst may have positive economic and environmental repercussions to inspire further academic and industrial research on biodiesel.