Fatty Acid Alkyl Esters as Feedstocks for the Enzymatic Synthesis of Alkyl Methacrylates and Polystyrene‐co‐alkyl Methacrylates for use as Cold Flow Improvers in Diesel Fuels

Abstract

AbstractThe enzymatic transesterifications of fatty acid methyl esters (FAME) with hydroxyethyl methacrylate (HEMA) were carried out using the Candida antarctica lipase B immobilized within a porous polymethacrylate resin. The enzymatic activity in the transesterification reaction of FAME with HEMA depended on the polarity of the solvent and the highest yield was obtained in toluene (non‐polar). The molar ratio of 1:4 (for methyl laurate:HEMA) and 1:2 (for methyl oleate:HEMA) was most favorable for the transesterification yield. The reaction condition (at 60 °C/24 h), and the enzyme concentration of 5% (w/w) for methyl laurate with HEMA, 2% (w/w) for methyl oleate with HEMA resulted in the highest final yield. Under these conditions, the maximum yields for the transesterification of methyl laurate with HEMA, methyl oleate with HEMA were 97 ± 5.4% and 91 ± 4.7%, respectively. After ten batches of transesterification of FAME with HEMA, enzyme activity was retained at the level of 88 ± 2.6% and 76 ± 2.3%, respectively, compared with their initial activity. Also, alkyl methacrylate/styrene copolymers were synthesized by radical polymerization of HEMA‐LMA (or HEMA‐OMA) and styrene. The prepared copolymers have average molecular weights from 2.6 × 104 to 5.5 × 104. Especially, the poly(styrene‐co‐alkyl methacrylate)s (PStmHAMAn) led to a reduction in the pour point in ultra low sulfur diesel (ULSD) treated with 200–1,000 ppm of poly(styrene‐co‐alkyl methacrylate). Diesel fuel containing 1,000 ppm of the copolymer (PSt2HLMA8) showed a 15 ± 1.25 °C reduction in its pour point.