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Methyl, ethyl, 2-propyl and butyl esters were prepared from canola and linseed oils through transesterification using KOH and/or sodium alkoxides as catalysts. In addition, methyl and ethyl esters were prepared from rapeseed and sunflower oils using the same catalysts. Chemical composition of the esters was determined by HPLC for the class of lipids and by GC for fatty acid compositions. The bio-diesel esters were characterized for their physical and fuel properties including density, viscosity, iodine value, acid value, cloud point, pure point, gross heat of combustion and volatility. Methyl and ethyl esters prepared from a particular vegetable oil had similar viscosities, cloud points and pour points, whereas methyl, ethyl, 2-propyl and butyl esters derived from a particular vegetable oil had similar gross heating values. However, their densities, which were 2–7% higher than those of diesel fuels, statistically decreased in the order of methyl 2-propyl>ethyl>butylesters. Butyl esters showed reduced cloud points (−6°C to −10°C) and pour points (−13°C to −16°C) similar to those of summer diesel fuel having cloud and pour points of −8°C and −15°C, respectively. The viscosities of bio-diesels (3.3–7.6×10−4 Pa s at 40°C) were much less than those of pure oils (22.4–45.1×10−4 Pa s at 40°C) and were twice those of summer and winter diesel fuels (3.50 and 1.72×10−4 Pa s at 40°C), and their gross heat contents of approximately 40 MJ/kg were 11% less than those of diesel fuels (45 MJ/kg). For different esters from the same vegetable oil, methyl esters were the most volatile, and the volatility decreased as the alkyl group grew bulkier. However, the bio-diesels were considerably less volatile than the conventional diesel fuels.


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  • 1 decade ago
    Best Answer

    甲基,乙基, 2丙基和丁基酯類從canola和亚麻仁油準備了通過酯交換反應使用酸值和鈉醇鹽作為催化劑。 另外,使用同樣催化劑,甲醇和乙基酯類從油菜籽和向日葵油準備了。 酯類的化學成分取決於由油脂類的HPLC和脂肪酸成份遺傳的GC。 生物劑量酯類為他們的物理被描繪了並且給物產加油包括密度、黏度、碘價、酸值、浊點、純淨的點、總燃燒熱和揮發性。 從特殊菜油準備的甲醇和乙基酯類有相似的黏度,浊點並且燒铸點,而甲基,乙基, 2丙基和丁基酯類從特殊菜油獲得了有相似的總熱值。 然而,他們的密度,高于那些是2-7%柴油,統計地減少了按甲醇2-propyl>的順序; ethyl> butylesters。 丁基酯類顯示了減少的浊點(−6°C到−10°C)和燒铸點(對−16°C)類似的−13°C那些有夏天的柴油雲彩和燒铸點−8°C和−15°C,分別。 黏度生物diesels (3.3-7.6×10−4 Pa在40°C)的s比那些是較少純淨的油(22.4-45.1×10−4 Pa在40°C)的s和兩次是那些夏天和冬天柴油(3.50和1.72×10−4 Pa在40°C)的s和大约40 MJ/kg他們的總熱容量比那些是11%柴油(45 MJ/kg)。 對於從同樣菜油的不同的酯類,甲基酯最揮發性,並且作為烷基被減少的揮發性增長更加龐大。 然而,生物diesels比常規柴油相當地較不揮發性。

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