Biodiesel has received extensive attention as a kind of renewable and clean fuel. However, because of its intrinsic unsaturated composition, it is prone to auto-oxidation and corruption in long-term storage. Fortunately, the partial hydrogenation of biodiesel, in which the high unsaturated fatty acid esters are selectively converted to the low unsaturated or saturated fatty acid esters, has been an effective measure to improve the oxidation stability as well as the cetane number. In this study, the partially hydrogenated soybean methyl ester (PHSME) was produced from soybean methyl ester (SME) via the catalytic transfer hydrogenation. The catalytic transfer hydrogenation of SME was implemented using isopropanol as the hydrogen donor, water as the reaction medium and Raney-Ni as the catalyst. The ratio of solvent water, isopropanol and SEM was 100:32:7, and the catalyst loading accounted for 13% of SME approximately. The hydrogenation reaction was progressing under the water bath of (85±1) ℃ with a magnetic stirring speed of 600 r/min. After about 100 min, the degree of hydrogenation for biodiesel was found to reach the maximum, and the final product PHSME was collected by suitable separation. By the gas chromatography-mass spectrometry (GC-MS) analysis, methyl palmitate (C16:0), methyl stearate (C18:0), methyl oleate (C18:1), methyl linoleate (C18:2), methyl linolenate (C18:3), methyl eicosanoate (C20:0) and methyl docosanoate (C22:0) were detected out in sequence for SME sample, however, C18:3 did not exist in the PHSME. The total amount of unsaturated components C18:3, C18:2 and C18:1 in the SME was 70.9%. After moderate hydrogenation, the high unsaturated components C18:3 and C18:2 containing 3 and 2 double bonds were converted into C18:1 and C18:0 preferentially, and the conversion rate could reach 37.8%. In view of the number of unsaturated double bonds in carbon chain, the unsaturation degree of SME was reduced by 46.2%. Compared with SME, although the kinematic viscosity of PHSME increased slightly, its oxidation stability was improved significantly, and the cetane number of PHSME rose to a desirable level as well. In air atmosphere, the oxidation and combustion characteristics of SME and PHSME were comprehensively explored in a thermal analyzer. Due to the molecular structure change and increased kinematic viscosity, the start of weight loss for PHSME was a little late, whose TG (thermogravimetry) profile shifted to the high temperature region with respect to that for SME, however eventually the finish of weight loss advanced by 7.2 , which affirmatively indicated that PHSME, owning a℃greater average oxidation rate than SME, was more prone to be oxidized and burned. Meanwhile, in DSC (differential scanning calorimeter) profiles, due to the desirable cetane number, the exothermic onset temperature of PHSME was 10.7 earlier than℃that of SME. In summary, the fuel properties including the oxidation stability, iodine value and cetane number of SME are beneficially upgraded by moderate hydrogenation. The better quality of partially hydrogenated biodiesel makes it more popular in the fuel blend market.%采用催化转移加氢法对大豆油生物柴油(SME,soybean methyl ester)进行适度加氢制备部分加氢大豆油生物柴油(PHSME,partially hydrogenated soybean methyl ester),分析比较生物柴油加氢前后的组分、过氧化值、碘值、十六烷值与运动黏度等燃料特性参数,并基于热重-差示扫描量热法(TG-DSC,thermogravimetry-differential scanning calorimeter)研究加氢提质生物柴油的着火燃烧性能.结果表明:以异丙醇为供氢体、水为反应介质和Raney-Ni为催化剂,在温度85℃和常压下对SME进行催化转移加氢反应,经GC-MS(gas chromatography-mass spectrometry)检测发现高不饱和组分选择性转化为低不饱和或饱和组分,不饱和程度降低了46.2%.尽管PHSME的运动黏度略有增加,但其氧化安定性得到明显改善,且十六烷值也升高至合理的范围.在空气氛围下,由于PHSME相比于SME的分子结构变化及运动黏度增加,其在初始阶段不易挥发,但在高温阶段平均氧化速率更高,其终了失质量温度比SME提前7.2℃.由于PHSME的适度的高十六烷值属性,在DSC曲线可见其放热始点温度比SME提前10.7℃,说明提质生物柴油具有优越的着火性能.
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