Bueso Francisco, Moreno Luis, Cedeño Mathew, Manzanarez Karla
Department of Food Science and Technology, EAP Zamorano University, P.O. Box 93, Tegucigalpa, Honduras.
J Biol Eng. 2015 Jul 24;9:12. doi: 10.1186/s13036-015-0009-9. eCollection 2015.
Extensive native Jatropha curcas L. (Jatropha) crop areas have been planted in Central America marginal lands since 2008 as a non-edible prospective feedstock alternative to high-value, edible palm oil. Jatropha biodiesel is currently exclusively produced in the region at commercial scale utilizing alkaline catalysts. Recently, a free, soluble Thermomyces lanuginosus (TL) 1,3 specific lipase has shown promise as biocatalyst, reportedly yielding up to 96 % ASTM D6751 compliant biodiesel after 24 h transesterification of soybean, canola oils and other feedstocks. Biodiesel conversion rate and quality of enzymatically catalyzed transesterification of Jatropha oil was evaluated. Two lipases: free, soluble TL and immobilized Candida antarctica (CA) catalyzed methanolic transesterification of crude Jatropha and refined palm oil.
Jatropha yields were similar to palm biodiesel with NaOH as catalyst. After 24 h transesterification, Jatropha (81 %) and palm oil (86 %) biodiesel yields with TL as catalyst were significantly higher than CA (<70 %) but inferior to NaOH (>90 %). Enzymatic catalysts (TL and CA) produced Jatropha biodiesel with optimum flow properties but did not complied with ASTM D6751 stability parameters (free fatty acid content and oil stability index).
Biodiesel production with filtered, degummed, low FFA Jatropha oil using a free liquid lipase (TL) as catalyst showed higher yielding potential than immobilized CA lipase as substitute of RBD palm oil with alkaline catalyst. However, Jatropha enzymatic biodiesel yield and stability were inferior to alkaline catalyzed biodiesel and not in compliance with international quality standards. Lower quality due to incomplete alcoholysis and esterification, potential added costs due to need of more than 24 h to achieve comparable biodiesel yields and extra post-transesterification refining reactions are among the remaining drawbacks for the environmentally friendlier enzymatic catalysis of crude Jatropha oil to become an economically viable alternative to chemical catalysis.
自2008年以来，中美洲的边际土地上种植了大面积的麻风树（麻疯树）作物，作为高价值食用棕榈油的非食用潜在原料替代品。目前，麻疯树生物柴油在该地区仅以商业规模利用碱性催化剂生产。最近，一种游离的、可溶的嗜热栖热放线菌（TL）1,3特异性脂肪酶已显示出作为生物催化剂的潜力，据报道，在大豆油、菜籽油和其他原料进行24小时酯交换反应后，可生产出高达96%符合ASTM D6751标准的生物柴油。评估了麻疯树油酶促催化酯交换反应的生物柴油转化率和质量。两种脂肪酶：游离的、可溶的TL和固定化南极假丝酵母（CA）催化了粗麻疯树油和精炼棕榈油的甲醇酯交换反应。
以氢氧化钠为催化剂时，麻疯树的产量与棕榈生物柴油相似。酯交换反应24小时后，以TL为催化剂时，麻疯树（81%）和棕榈油（86%）的生物柴油产量显著高于CA（<70%），但低于氢氧化钠（>90%）。酶催化剂（TL和CA）生产的麻疯树生物柴油具有最佳的流动性能，但不符合ASTM D6751稳定性参数（游离脂肪酸含量和油稳定性指数）。
使用游离液体脂肪酶（TL）作为催化剂，用经过过滤、脱胶、低游离脂肪酸的麻疯树油生产生物柴油，比用固定化CA脂肪酶替代碱性催化剂的精炼棕榈油具有更高的产量潜力。然而，麻疯树酶促生物柴油的产量和稳定性低于碱性催化生物柴油，且不符合国际质量标准。由于醇解和酯化不完全导致质量较低，由于需要超过24小时才能获得可比的生物柴油产量而可能增加成本，以及酯交换反应后需要额外的精炼反应，这些都是粗麻疯树油更环保的酶促催化成为化学催化经济可行替代方案的剩余缺点。
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