間歇與直接超音波輔助處理技術應用於痲瘋油之酯化與轉酯化以產製生質柴油之研究

Esterification and transesterification of jatropha oil to produce biodiesel via different combination of direct and sequential ultrasound irradiation

唐凱沙(Cesar Augusto Andrade Tacca)

指導教授 ： 張慶源

國立臺灣大學/工學院/環境工程學研究所/博士(2014年)

https://doi.org/10.6342/NTU.2014.10910

摘要

無資料

關鍵字

生質柴油 ； 麻瘋油 ； 酯化 ； 轉酯化 ； 超音波 ； 間歇式超音波 ； 直接超音波

並列摘要

A two-step process consisting of acid esterification and base transesterification via ultrasound irradiation (UI) at moderate high and ambient temperatures for Jatropha oil (Jatropha Curcas Lineaus oil, JO) were studied. The key properties of biodiesel such as acid value (AV), iodine value (IV), kinematic viscosity (KV), density (ρLO), water content (mw) and cold filter plugging point (CFPP) were investigated. The background experimental conditions were as follows. The molar ratio of methanol to oil (M/O) for esterification and transesterification are 11:1 and 6:1 respectively. Concentrations of H2SO4 and KOH catalysts relative to JO (MC) are 0.92 and 2 wt. %, respectively.
The sequential esterification (SE) of JO via UI and dosing of methanol-catalyst mixture were examined at various esterifications temperatures (TE) kept in temperature intervals of 75 to 120 °C, 85 to 120 °C, 100 to 120 °C and 108.9 to 120 °C, with various doses of 25, 16.6, 10 and 5 mL, respectively. The ultrasonic frequency (fUI) and ultrasonic power (PWUI) were kept at 20 kHz and 270 W, respectively. The sample volume (VL) was 300 mL. The esterification time (tE) was set at 108.79, 128.23, 145.41 and 167.39 min. The esterification conversion efficiencies (η) were determined and assessed. η of 99.35% was obtained in temperature interval of 108.9 to 120 °C with twenty 5 mL doses and tE of 167.39 min (denoted as Process U120-5), which is slightly higher than η of 98.87% in temperature interval of 75 to 120 °C with four 25 mL doses and tE of 108.79 min (noted as Process U120-25). The η via SE are higher than 83.23% and 42.48% such were respectively obtained by conventional direct UI (direct esterification, DE) and mechanical mixing process for the mixture of JO, methanol and catalyst. The yield (YF) of fatty acids methyl esters (FAMEs) reaches values of 56.7 and 20.38 % for SE in temperature interval of 100 to 120°C and DE starting from ambient temperature, respectively.
As for two-step process of esterification and transesterification, the combined SE (100-120 °C with ten 10 mL doses) and sequential transesterification (ST) (62.4-65 °C with five 10 mL doses and one 3.6 mL dose) gives YF of about 96.9%. If the SE is followed by direct transesterification (DT) with 53.65 mL M/C, the YF reaches about 99.18%. The combined DE with 100 mL M/C and DT with 53.65 mL M/C obtains YF of about 97.18%. Although combined DE and DT also gives high YF, however it suffers saponification and thus loss of biodiesel products due to substantial free fatty acid remained after DE. Thus, either SE/ST or SE/DT is more appropriate than DE/DT.
The crude jaropha methyl ester (JME) produced via SE with twenty 5 mL doses in 108.9 – 120 °C possess AV of 0.24 mg KOH/g, IV of 124.77 g I2/100 g, KV of 9.89 mm2/s, ρLO of 901.73 kg/m3 and mw of 0.3 wt.%. The JME obtained in temperature interval of 100 to 120°C via SE with ten 10 mL doses has AV of 0.64 mg KOH/g, IV of 101.39 g I2/100 g, KV of 7.62 mm2/s, ρLO of 903.3 kg/m3 and mw of 1.690 wt.%. The results show that SE with temperature higher than 100 °C can reduce the AV to a very low value compared with 36.56 mg KOH/g of original oil.
The properties of product resulted by combined SE and ST are with AV of 0.103 mg KOH/g, IV of 92.114 g I2/100 g, KV of 4.57 mm2/s, ρLO of 882.48 kg/m3 and mw of 0.111 wt.%. Except mw, all others match the requirement for biodiesel. For the combined SE and DT, the product has AV of 0.233 mg KOH/g, IV of 107.57 g I2/100 g, KV of 4.501 mm2/s, ρLO of 881.98 kg/m3 and mw of 0.129 wt.%. Also all properties except the mw satisfy with the biodiesel standards. As for combined DE and DT, the properties of product of AV of 0.187 mg KOH/g, IV of 106.23 g I2/100 g, KV of 4.557 mm2/s and ρLO of 881.5 kg/m3 meet with the biodiesel regulation, while mw of 0.094 wt.% does not. The above three combined processes give satisfactory properties except mw which, however, can be easily reduced by adsorption using magnesium sulfate so as to meet the requirement.
The information obtained in this study is useful for the proper use of jatropha oil for the production of biodiesel with satisfactory qualities and the rational design and operation of ultrasound assisted catalytic esterification and transesterification processes.

並列關鍵字

Biodiesel ； Jatropha oil ； Esterification ； Transesterification ； Ultrasound

參考文獻

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Andrade-Tacca CA, Chang CC, Chen YH, Manh DV, Chang CY. Esterification of jatropha oil by sequential ultrasonic irradiation with auto-induced temperature rise and dosing of methanol and sulfuric acid catalyst. J Taiwan Inst Chem Eng 2014b; 45(4):1523-1531.

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