微波誘導大豆油及廢食用油快速轉酯化之研究

Microwave enhanced transesterification of soybean oil and waste cooking oil

張永宏(Yung-Hung Chang)

指導教授 ： 蕭明謙

崑山科技大學/工程學院/環境工程研究所/碩士(2009年)

摘要

目前石化燃料日漸減少，因此，開發再生能源勢在必行。生質柴油又稱為脂 肪酸甲酯，主要是透過轉酯化反應製得。本研究使用大豆油及廢食用油作為反應 物，透過開放式及密閉式微波方式進行轉酯化反應，分別利用均相及非均相觸媒 催化製造生質柴油。 以大豆油為原料，在開放式微波下，使用奈米氧化鈣進行催化反應，最佳反 應條件為：醇油莫耳比7:1，3 wt%的奈米氧化鈣，在65℃下反應1 小時，生質柴 油轉化率可達96.63%。在密閉式微波下，考量到醇油不相溶的因素，利用兩種不 同方式進行反應，一是使用超音波將反應物混合後進行密閉微波反應，另一是添 加共溶劑使反應物能充分混和。使用超音波混合下最佳條件為：醇油莫耳比6:1， 1 wt%的氫氧化鈉，反應溫度60℃，反應時間2 分鐘，生質柴油轉化率能有效的達 到97.68％。而添加共溶劑最佳條件為：醇油莫耳比12:1，氫氧化鈉添加1 wt%， 溫度為60℃反應2 分鐘，生質柴油轉化率為97.36%。從結果可知，不論是利用開 放式微波或密閉式微波，使用大豆油作為原料，生質柴油轉化率皆能夠有效符合 台灣CNS 15072 之96.5％標準值。 以廢食用油為原料的情況，利用兩種不同的方式進行反應，其一是添加共溶 劑，另一是添加共溶劑並使用超音波促進混合。在添加共溶劑的情況下，第一段 酸催化酯化反應最佳條件為醇油莫耳比9:1，硫酸添加量1 wt %，溫度在60℃下反 應7.5 分鐘，可將含有酸價為4.36 mg KOH/g 之廢食用油降至2 mg KOH/g，再利 用第二段鹼催化轉酯化反應製造生質柴油，總反應時間為9 分鐘，生質柴油轉化 率可達97.38％。另外在添加共溶劑並使用超音波促進混合方面，酸催化條件為醇 油莫耳比9:1，硫酸添加量1 wt%，先利用超音波混合1 分鐘後，再使用微波進行 反應，反應溫度為60℃，反應時間5 分鐘，能有效的將廢食用油之酸價降低至2 mg KOH/g，接著進行鹼催化反應，反應花費總時間為8 分鐘，生質柴油轉化率可達 99.01％。此兩種結果，可有效將廢食用油製造生質柴油並符合台灣CNS 15072 之 96.5％標準值。 製備四種不同酸性離子液體在密閉微波下催化大豆油與甲醇進行轉酯化反應 製造生質柴油。研究結果顯示，微波功率設定在300 W，當醇油莫耳比為15:1， 離子液體添加量4 wt%，反應溫度於150℃，反應60 分鐘，[SO3H-BMIM] [HSO4] 具有較好的催化活性，且生質柴油轉化率可達97％，此轉酯化反應之活化能為 18.21 kJ/mole，離子液體容易與產物分離，具有很好的穩定性，且對環境友好。 本研究利用大豆油與廢食用油製造生質柴油皆能夠符合台灣CNS 15072 之 96.5％標準值，使用微波的方式可有效的縮短反應時間，增加轉化率，並減少能耗， 達到節能減碳的目的。

關鍵字

生質柴油 ； 轉酯化反應 ； 微波 ； 共溶劑 ； 離子液體 ； 動力學

並列摘要

The fossil fuels is limited, therefore, the development of renewable energy is
imperative. Biodiesel is defined as the fatty acid methyl esters made by
transesterification of a refined oil or waste cooking oil. In this study, the use of soybean
oil and waste cooking oil as a reactant, through open and closed method to microwave
transesterification reaction, the use of homogeneous and heterogeneous catalysis
production biodiesel.
In soybean oil as raw material, in an open microwave, the use of nano calcium
oxide catalytic reaction, the optimum conditions was as follows: molar ratio of
methanol to oil is 7:1 with CaO concentration of 3 wt% and reaction time for 1 hour.
The conversion of soybean oil into biodiesel was achieved 96.63% for 1 hour. In closed
microwave, oil and alcohols are not totally miscible, so their reaction takes place at the
interface and it is a very slow process, therefore, used of two different ways to reaction,
first, the use of ultrasonic to be a mixture, and the other was to added solvent. The used
ultrasonic optimum conditions was as follows: molar ratio of methanol to oil is 6:1 with
NaOH concentration of 1 wt% and reaction time for 2 minutes, conversion was reached
97.68%. Added co-solvents the optimum conditions was as follows: molar ratio of methanol to oil is 12:1 with NaOH concentration of 1 wt% and reaction time for 2
minutes, biodiesel conversion of 97.36%. In the presence results, whether open or
closed microwave, the use of soybean oil as raw materials, biodiesel conversion are
conformed the Taiwan CNS 15072 standard value of 96.5%.
Waste cooking oil as raw materials, the use of two different ways to reaction, one
of which is to added co-solvents, and the other is to added co-solvents and the use of
ultrasound to promote mixed. Added co-solvents, the high acid value (4.36 mg KOH /g)
of waste cooking oil can be reduced to less than 2 mg KOH/g by acid catalyzed reaction
for 7.5 minutes reaction time. The second step by transesterification reaction with a total
reaction time of 9 minutes, the biodiesel conversion reached 97.38%. Besides, added
co-solvents and the use of ultrasound to promote mixed, the acid-catalyzed conditions
was as follows: ultrasound after 1 minutes, molar ratio of methanol to oil is 9:1 with
H2SO4 concentration of 1 wt% and microwave reaction temperature to 60 ℃, reaction
time 5 minutes, the acid value of waste cooking oil decreased to 2 mg KOH/g, then,
followed by alkali-catalyzed reaction, the reaction time to spend a total of 8 minutes,
and biodiesel conversion up to 99.01%.
Preparation of four different acidic ionic liquids under closed microwave and
catalyze soybean oil with methanol for transesterification to product biodiesel. The
results showed that microwave power at 300 W, soybean oil-methnaol molar ratio of
15:1, ionic liquid concentration of 4 wt%, reaction temperature at 150 ℃, reaction for
60 minutes, [SO3H-BMIM] [HSO4] with better catalytic activity, and biodiesel
conversion rate of up to 97%. Transesterification reaction of the activation energy for
the 18.21 kJ / mole, the product of ionic liquids with easy separation, has good stability,
and friendly to the environment.
In this study, soybean oil and waste cooking oil production biodiesel to conformed
Taiwan CNS 15072 standard value of 96.5%. The microwave irradiation method is
provides efficient reduce the reaction time, increase in conversion and reduced the
energy consumption, to achieve of energy saving and carbon reduction.

並列關鍵字

Biodiesel ； transesterification ； microwave ； co-solvent ； ionic liquid ； kinetics

參考文獻

Abreu, F. R., Alves, M. B., Macふedo, C. C. S., Zara, L. F., Suarez, A. Z., 2005. Newmulti-phase catalytic systems based on tin compounds active for vegetable oil transesterificaton reaction. Journal of Molecular Catalysis A: Chemical, 227, 263-267.

Adams, C., Peters, J. F., Rand, M. C., Schroer, B. J., Ziemke, M. C., 1983. Investigation of soybean oil as a diesel fuel extender: endurance tests. Journal of the American Oil Chemists' Society, 60, 1574-1579.

Alt1parmak, D., Keskin, A., Koca, A., Guru, M., 2007. Alternative fuel properties of tall oil fatty acid methyl ester–diesel fuel blends. Bioresource Technology, 98, 241-246.

Antczak, M. S., Kubiak, A., Antczak, T., Bielecki, S., 2009. Enzymatic biodiesel synthesis – key factors affecting efficiency of the process. Renewable Energy, 34, 1185-1194.

Azcan, N., Danisman, A., 2007. Alkali catalyzed transesterification of cottonseed oil by microwave irradiation. Fuel, 86, 2639-2644.