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Synthesis of Phytosteryl Esters by Using Alumina‐Supported Zinc Oxide (ZnO/Al 2 O 3 ) from Esterification Production of Phytosterol with Fatty Acid
Author(s) -
Meng Xianghe,
Pan Qiuyue,
Yang Tiankui
Publication year - 2011
Publication title -
journal of the american oil chemists' society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.512
H-Index - 117
eISSN - 1558-9331
pISSN - 0003-021X
DOI - 10.1007/s11746-010-1654-2
Subject(s) - phytosterol , catalysis , chemistry , zinc , oleic acid , transesterification , sterol , fatty acid , selectivity , organic chemistry , fatty acid methyl ester , reusability , chromatography , cholesterol , biochemistry , biodiesel , software , computer science , programming language
The feasibility of zinc oxide‐catalyzed esterification of natural phytosterols with oleic acid was investigated well by a chemical process. The influences of various reaction parameters were evaluated. Basic solid zinc oxide is the most desirable catalyst due to its high selectivity (more than 90%), reusability, activity and less corrosivity, whereas sterol selectivity with other catalysts, such as H 2 SO 4 , NaHSO 4 and NaOMe, did not exceed 80%. Further results showed that during zinc oxide‐catalyzed synthesis, the nature of the acyl donor was of paramount importance with direct esterification with fatty acids, which gives better results with higher conversion rate selectivity and more mild reaction conditions than transesterification with methyl esters. The substrate molar ratio of 2:1 (oleic acid/phytosterol) was optimal. Other parameters such as optimal catalyst load (0.5%) and temperature (170 °C) showed a maximum production of steryl esters close to 98% after 8 h. It was also found that the amount of trans fatty acid formed in esterification was low, and the trans fatty acid content (%) in the phytosterol oleate ester fraction (3.26%) was much lower than that in free oleic oil (7.35%), which suggested that fatty acids in esters were more stable than free fatty acids regarding the combination with sterol. Immobilized ZnO could be a promising catalyst for replacing homogeneous and corrosive catalysts for esterification reactions of sterol.