Department of Applied Chemistry, Institute of Technology, Banaras Hindu University, Varanasi 221 005, India.
J Agric Food Chem. 2010 Jan 13;58(1):242-7. doi: 10.1021/jf903227e.
An efficient approach has been adopted for the synthesis of biodiesel developed from karanja, a nonedible oil feedstock. A two-step reaction was followed for synthesis of biodiesel. Karanja oil possessing a high free fatty acid content was esterified with sulfuric acid, and the product obtained was further converted to fatty acid alkyl esters (biodiesel) by transesterification reactions. A moderate molar ratio of 6:1 (methanol/oil) was efficient for acid esterification with 1.5% v/v H2SO4 and 1 h of reaction time at 60+/-0.5 degrees C, which resulted in reduction of FFA from 19.88 to 1.86 mg of KOH/g. During alkaline transesterification, 8:1 molar ratio (methanol/oil), 0.8 wt % sodium hydroxide (NaOH), 1.0 wt % sodium methoxide (CH3ONa), or 1.0 wt % potassium hydroxide (KOH) as catalyst at 60+/-0.5 degrees C gave optimized yield (90-95%) and high conversion (96-100%). Optimum times for alkaline transesterification were 45 min for CH3ONa and 1 h for NaOH and KOH. Conversion of karanja oil feedstock to its respective fatty acid methyl esters was identified on a gas chromatograph-mass spectrometer and determined by 1H nuclear magnetic resonance and gas chromatography. The fuel properties, such as cetane number of the methyl ester synthesized, were studied and found to be within the limits and specification of ASTM D 6751 and EN 14112 except for oxidation stability.
已经采用了一种有效的方法来合成生物柴油，这种生物柴油是由非食用油原料卡兰加制成的。该合成方法采用两步反应。高游离脂肪酸含量的卡兰加油先与硫酸酯化，然后将得到的产物进一步通过酯交换反应转化为脂肪酸烷基酯（生物柴油）。在 60±0.5°C 的温度下，6:1（甲醇/油）的中等摩尔比用 1.5% v/v 的硫酸进行酸酯化 1 小时，可将 FFA 从 19.88 毫克降低到 1.86 毫克 KOH/g。在碱性酯交换过程中，8:1 的甲醇/油摩尔比、0.8 wt% 的氢氧化钠（NaOH）、1.0 wt% 的甲醇钠（CH3ONa）或 1.0 wt% 的氢氧化钾（KOH）作为催化剂，在 60±0.5°C 的温度下可获得最佳产率（90-95%）和高转化率（96-100%）。碱性酯交换的最佳时间为 CH3ONa 的 45 分钟和 NaOH 和 KOH 的 1 小时。卡兰加油原料转化为相应的脂肪酸甲酯在气相色谱-质谱联用仪上进行了鉴定，并通过 1H 核磁共振和气相色谱进行了测定。合成的甲酯的燃料特性，如十六烷值，进行了研究，发现除了氧化稳定性外，均在 ASTM D 6751 和 EN 14112 的限制和规范内。
